Aggressive VC versus Sports VC

Hi Everyone,

SO I have been reading lately more then I ever have found online before about viscous couplings - see this very interesting forum discussion about the possibility and what's involved rebuilding viscous couplings - http://forum.club8090.co.uk/viewtopic.php?f=4&t=66501

Also in this thread it is said that an failing aggressive VC can be caused by;
-burnt oxidized viscous coupling fluid or
-warped / damaged internal plates
-oil being sucked from the front diff into the VC

Anyway, my question that I would like answered, is IF you have a decoupler, is there much difference in practice between an aggressive VC and a rebuilt sports VC eg from van cafe http://www.van-cafe.com/home/van/page_109_1248/rebuilt_viscous_coupling.html

Will the aggressive VC still work the same as the sports VC offroad? Or will the aggressive VC not be able to transmit as much torque to the front wheels and therefore not work as well e.g. driving in sand dunes? Will the aggressive VC still be able to used e.g. driving on the highway when raining heavy?

Thanks. Sam

Sam,

This question needs a lot of background explanation to answer fully, starting from the VAG design intention for the Syncro.  

The Syncro was intended as a multipurpose vehicle, ranging from safe family transport in all (European) weather conditions, including snow and ice, to commercial and military applications.   It was not designed primarily as a purely off-road vehicle.

Consequently, VAG opted for the viscous coupling as the means to deliver drive to the front axle as dictated by the prevailing road conditions without the need for any driver decision or action, a point stressed in all of the release publicity.  

Most viscous couplings become more aggressive (meaning that they begin to operate at an earlier point than a new, unworn VC) with time and use.   The effects of this are noticeable as a binding action when the vehicle is on full lock turns on dry, high grip surfaces, mainly low speed parking.

At higher speeds and very small steering inputs, as in normal point to point driving, a more pronounced VC effect has benefits as it distributes more drive effort to the front axle.   This is evident in steering precision and increased cornering adhesion, plus better braking effort distribution.

My VC is on the aggressive side and I find it preferable to the normal VC range.   To avoid the heavy loading of the full lock manoeuvres, I use a decoupler.   I run in all wheel drive except when making full lock turns.   My assessment of the handling and braking characteristics of my aggressive VC is based on rather a long time spent as a professional motor vehicle development engineer.

The “sports” viscous couplings are a very different matter.   They are set to provide a very high front axle input all the time.   I have never had a chance to try one but, from everything that I read, their most advantageous use would probably be for a vehicle that spends most of its life running on seriously degraded surfaces where good grip become a safety issue.   It is very difficult to determine an actual figure (percentage) of difference between the “sports” VC and a standard VC; none of the vendors appear to commit themselves to a figure.

Unless you intend to run off road 90+% of the time, you will be better served by running a new or reconditioned VC.    It must be noted hat, until you have run a standard VC, I is very difficult to make comparisons with an aggressive VC or a “sports” VC.

Sand is a different matter entirely but the balance of usage must be taken into account.   A solid shaft (which replaces the VC) works very well in sand but can’t be used on ordinary roads because it destroys the gearbox very quickly.   It can be used with a decoupler but then all of the very significant grip and safety advantages of the VC are lost and you have a two wheel drive Syncro.

Les

 


From: Syncro_T3_Australia@yahoogroups.com [mailto: Syncro_T3_Australia@yahoogroups.com ] On Behalf Of heysamuelarnold
Sent: 17 June 2011 10:07
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Aggressive VC versus Sports VC

 

 

Hi Everyone,

SO I have been reading lately more then I ever have found online before about viscous couplings - see this very interesting forum discussion about the possibility and what's involved rebuilding viscous couplings - http://forum.club8090.co.uk/viewtopic.php?f=4&t=66501

Also in this thread it is said that a failing aggressive VC can be caused by;
-burnt oxidized viscous coupling fluid or
-warped / damaged internal plates
-oil being sucked from the front diff into the VC

Anyway, my question that I would like answered, is IF you have a decoupler, is there much difference in practice between an aggressive VC and a rebuilt sports VC e.g. from van cafe http://www.van-cafe.com/home/van/page_109_1248/rebuilt_viscous_coupling.html

Will the aggressive VC still work the same as the sports VC off road? Or will the aggressive VC not be able to transmit as much torque to the front wheels and therefore not work as well e.g. driving in sand dunes? Will the aggressive VC still be able to used e.g. driving on the highway when raining heavy?

Thanks. Sam

Sorry, two silly typos in there:

 

It must be noted that, until you have run a standard VC, it is very difficult to make comparisons with an aggressive VC or a “sports” VC.

 


From: Syncro_T3_Australia@yahoogroups.com [mailto: Syncro_T3_Australia@yahoogroups.com ] On Behalf Of Les Harris
Sent: 17 June 2011 10:59
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Aggressive VC versus Sports VC

 

 

Sam,

This question needs a lot of background explanation to answer fully, starting from the VAG design intention for the Syncro.  

The Syncro was intended as a multipurpose vehicle, ranging from safe family transport in all (European) weather conditions, including snow and ice, to commercial and military applications.   It was not designed primarily as a purely off-road vehicle.

Consequently, VAG opted for the viscous coupling as the means to deliver drive to the front axle as dictated by the prevailing road conditions without the need for any driver decision or action, a point stressed in all of the release publicity.  

Most viscous couplings become more aggressive (meaning that they begin to operate at an earlier point than a new, unworn VC) with time and use.   The effects of this are noticeable as a binding action when the vehicle is on full lock turns on dry, high grip surfaces, mainly low speed parking.

At higher speeds and very small steering inputs, as in normal point to point driving, a more pronounced VC effect has benefits as it distributes more drive effort to the front axle.   This is evident in steering precision and increased cornering adhesion, plus better braking effort distribution.

My VC is on the aggressive side and I find it preferable to the normal VC range.   To avoid the heavy loading of the full lock manoeuvres, I use a decoupler.   I run in all wheel drive except when making full lock turns.   My assessment of the handling and braking characteristics of my aggressive VC is based on rather a long time spent as a professional motor vehicle development engineer.

The “sports” viscous couplings are a very different matter.   They are set to provide a very high front axle input all the time.   I have never had a chance to try one but, from everything that I read, their most advantageous use would probably be for a vehicle that spends most of its life running on seriously degraded surfaces where good grip become a safety issue.   It is very difficult to determine an actual figure (percentage) of difference between the “sports” VC and a standard VC; none of the vendors appear to commit themselves to a figure.

Unless you intend to run off road 90+% of the time, you will be better served by running a new or reconditioned VC.    It must be noted hat, until you have run a standard VC, I is very difficult to make comparisons with an aggressive VC or a “sports” VC.

Sand is a different matter entirely but the balance of usage must be taken into account.   A solid shaft (which replaces the VC) works very well in sand but can’t be used on ordinary roads because it destroys the gearbox very quickly.   It can be used with a decoupler but then all of the very significant grip and safety advantages of the VC are lost and you have a two wheel drive Syncro.

Les

 

Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam



--- In Syncro_T3_Australia@yahoogroups.com, "Les Harris" <leslieharris@...> wrote:
>
> Sam,
>
> This question needs a lot of background explanation to answer fully,
> starting from the VAG design intention for the Syncro.
>
> The Syncro was intended as a multipurpose vehicle, ranging from safe family
> transport in all (European) weather conditions, including snow and ice, to
> commercial and military applications. It was not designed primarily as a
> purely off-road vehicle.
>
> Consequently, VAG opted for the viscous coupling as the means to deliver
> drive to the front axle as dictated by the prevailing road conditions
> without the need for any driver decision or action, a point stressed in all
> of the release publicity.
>
> Most viscous couplings become more aggressive (meaning that they begin to
> operate at an earlier point than a new, unworn VC) with time and use. The
> effects of this are noticeable as a binding action when the vehicle is on
> full lock turns on dry, high grip surfaces, mainly low speed parking.
>
> At higher speeds and very small steering inputs, as in normal point to point
> driving, a more pronounced VC effect has benefits as it distributes more
> drive effort to the front axle. This is evident in steering precision and
> increased cornering adhesion, plus better braking effort distribution.
>
> My VC is on the aggressive side and I find it preferable to the normal VC
> range. To avoid the heavy loading of the full lock manoeuvres, I use a
> decoupler. I run in all wheel drive except when making full lock turns.
> My assessment of the handling and braking characteristics of my aggressive
> VC is based on rather a long time spent as a professional motor vehicle
> development engineer.
>
> The "sports" viscous couplings are a very different matter. They are set
> to provide a very high front axle input all the time. I have never had a
> chance to try one but, from everything that I read, their most advantageous
> use would probably be for a vehicle that spends most of its life running on
> seriously degraded surfaces where good grip become a safety issue. It is
> very difficult to determine an actual figure (percentage) of difference
> between the "sports" VC and a standard VC; none of the vendors appear to
> commit themselves to a figure.
>
> Unless you intend to run off road 90+% of the time, you will be better
> served by running a new or reconditioned VC. It must be noted hat, until
> you have run a standard VC, I is very difficult to make comparisons with an
> aggressive VC or a "sports" VC.
>
> Sand is a different matter entirely but the balance of usage must be taken
> into account. A solid shaft (which replaces the VC) works very well in
> sand but can't be used on ordinary roads because it destroys the gearbox
> very quickly. It can be used with a decoupler but then all of the very
> significant grip and safety advantages of the VC are lost and you have a two
> wheel drive Syncro.
>
> Les
>
>
>
> _____
>
> From: Syncro_T3_Australia@yahoogroups.com
> [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
> Sent: 17 June 2011 10:07
> To: Syncro_T3_Australia@yahoogroups.com
> Subject: [Syncro_T3_Australia] Aggressive VC versus Sports VC
>
>
>
>
>
> Hi Everyone,
>
> SO I have been reading lately more then I ever have found online before
> about viscous couplings - see this very interesting forum discussion about
> the possibility and what's involved rebuilding viscous couplings -
> http://forum.club8090.co.uk/viewtopic.php?f=4
> <http://forum.club8090.co.uk/viewtopic.php?f=4&t=66501> &t=66501
>
> Also in this thread it is said that a failing aggressive VC can be caused
> by;
> -burnt oxidized viscous coupling fluid or
> -warped / damaged internal plates
> -oil being sucked from the front diff into the VC
>
> Anyway, my question that I would like answered, is IF you have a decoupler,
> is there much difference in practice between an aggressive VC and a rebuilt
> sports VC e.g. from van cafe
> http://www.van-cafe.com/home/van/page_109_1248/rebuilt_viscous_coupling.html
>
> Will the aggressive VC still work the same as the sports VC off road? Or
> will the aggressive VC not be able to transmit as much torque to the front
> wheels and therefore not work as well e.g. driving in sand dunes? Will the
> aggressive VC still be able to used e.g. driving on the highway when raining
> heavy?
>
> Thanks. Sam
>

Sam,

Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!  

As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers.   Some owners have had the experience of stalling the engine on full lock, grippy surface turns.   (This happens because the VC is trying to drive the front and rear axles at the same speed.)   This probably represents the upper end of the usability range.

I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving.  This level of aggression is therefore acceptable.   Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle.   This is something that was probably not evident to the designers until the vehicle went into service.

Binding on slight turns (your last paragraph) would be very difficult to detect.   About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input.   At any level of aggression less that that, the end result is still advantageous.

Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.

I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night.   I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain.   The driver in front of me got into trouble and drifted into the outside lane.   I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro.   I had just come out of a service station and had not re-engaged the decoupler!!!!!

I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked.   I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.  

Les

 


From: Syncro_T3_Australia@yahoogroups.com [mailto: Syncro_T3_Australia@yahoogroups.com ] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam


Many thanks Les. Sam

--- In Syncro_T3_Australia@yahoogroups.com, "Les Harris" <leslieharris@...> wrote:
>
> Sam,
>
> Unfortunately, the only way to determine if a VC is aggressive or not is to
> run it in a vehicle!
>
> As to how to determine if a VC is "too aggressive", we again face the
> problem of attaching meaningful numbers. Some owners have had the
> experience of stalling the engine on full lock, grippy surface turns.
> (This happens because the VC is trying to drive the front and rear axles at
> the same speed.) This probably represents the upper end of the usability
> range.
>
> I must stress that the gearbox load imposed in such manoeuvres is actually
> far higher than ordinary point to point driving. This level of aggression
> is therefore acceptable. Sadly, the Syncro gearbox is not as strong as it
> could have been, given the capabilities of the vehicle. This is something
> that was probably not evident to the designers until the vehicle went into
> service.
>
> Binding on slight turns (your last paragraph) would be very difficult to
> detect. About the only way to determine that would be on a smooth concrete
> surface where you could hear tyre chirp at low angles of steering input.
> At any level of aggression less that that, the end result is still
> advantageous.
>
> Ultimately, discussion on levels of aggressive response is hampered by the
> fact that we can't assign a value and an unavoidable level of subjectivity
> is introduced.
>
> I got an object lesson in aggressive VC versus two wheel drive one
> never-to-be-forgotten night. I was coming off the Western Ring Road on a
> long downhill flat cambered curve when the road was awash with rain. The
> driver in front of me got into trouble and drifted into the outside lane.
> I headed inside him, normally a piece of cake, and found myself travelling
> sideways in several tons of Syncro. I had just come out of a service
> station and had not re-engaged the decoupler!!!!!
>
> I had another lesson when I was joining the Princes Freeway one wet night
> and the car in front of me baulked. I hit the brakes, normally a very safe
> option, and got lock-up on several wheels, again because I had not engaged
> the decoupler.
>
> Les
>
>
>
> _____
>
> From: Syncro_T3_Australia@yahoogroups.com
> [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
> Sent: 17 June 2011 11:28
> To: Syncro_T3_Australia@yahoogroups.com
> Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC
>
>
>
> Hi Les,
>
> Many thanks for the detailed reply. I think that I am looking for an
> aggressive VC then. I guess that the question left for me is, how can you
> tell if your aggressive VC is possibly too aggressive? I like the idea of
> driving in AWD most of the time, though using the decoupler before making
> tight turns. Though if driving most of the time with an aggressive VC on,
> are you damaging gearboxes or other parts of the driveline? If you are
> pulling off the highway and notice binding on slight turns, then that is the
> sign then that the VC has become so aggressive as to be driven mostly
> decoupled?
>
> Sam
>
Sam,
My two bobs worth. Two questions we first need your clear answers to, otherwise it's nigh impossible to suggest a "best fit" solution for your circumstances. 

ONE - Is cost, both short and long term, a high/low concern for you? Your answer cuts off certain options, leaves other options open.
TWO - Please spell out clearly, in order of priority, top to bottom, your intended use of your syncro including how you intend it to mostly function ie., ... 2WD or 4WD. This answer also cuts off options, leaves other options open.

Please be fulsome with your answers. A consideration then of both answers coupled together, homes in on the most likely best (read compromise) option/s for your circumstances.

In answer to your query, all WORKING VCs other than original specced/correctly functioning or a going passive VC, would/should be classed as aggressive. So this includes "Sports". It's just a matter of degree of aggressiveness.
All aggressive classed VCs, as with a solid shaft setup, if used on hard surfaces, will damage expensive components of your drivetrain SOONER (probably much sooner) than a correctly specced/functioning VC. How soon is just a matter of the degree of aggressiveness and continuous/occasional use of that VC. Is this what you want?

The cost of a replacement VC is easily less than the cost and inconvenience of rebuilding drivetrain components, in particular the transaxle, front diff, CVs and prop-shaft. Discounting this fact, one does so at ones peril and extended time inconvenience off the road and a badly depleted bank balance. To that end, you are then faced with the angst of locating a known qualified/competent mechanic to entrust your expensive remedial repairs to. Good luck in Sydney! Who do you believe and anyway, wouldn't it be best to try and avoid this scenario in the first place?

Whatever you decide, it'll still be a compromise. Even a correctly specced and working VC is a compromise. It was designed to suit the mass market.

I'm presently thinking your best compromise & cheapest solution is a bog standard factory specced replacement VC. Supply us with the requested answers, I may well change that view. 

Cheers.
Ken



To: Syncro_T3_Australia@yahoogroups.com
From: leslieharris@optusnet.com.au
Date: Fri, 17 Jun 2011 11:15:45 +1000
Subject: RE: [Syncro_T3_Australia] Aggressive VC versus Sports VC

 

Sorry, two silly typos in there:

 

It must be noted that, until you have run a standard VC, it is very difficult to make comparisons with an aggressive VC or a “sports” VC.

 


From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: 17 June 2011 10:59
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Aggressive VC versus Sports VC

 

 

Sam,

This question needs a lot of background explanation to answer fully, starting from the VAG design intention for the Syncro.  

The Syncro was intended as a multipurpose vehicle, ranging from safe family transport in all (European) weather conditions, including snow and ice, to commercial and military applications.   It was not designed primarily as a purely off-road vehicle.

Consequently, VAG opted for the viscous coupling as the means to deliver drive to the front axle as dictated by the prevailing road conditions without the need for any driver decision or action, a point stressed in all of the release publicity.  

Most viscous couplings become more aggressive (meaning that they begin to operate at an earlier point than a new, unworn VC) with time and use.   The effects of this are noticeable as a binding action when the vehicle is on full lock turns on dry, high grip surfaces, mainly low speed parking.

At higher speeds and very small steering inputs, as in normal point to point driving, a more pronounced VC effect has benefits as it distributes more drive effort to the front axle.   This is evident in steering precision and increased cornering adhesion, plus better braking effort distribution.

My VC is on the aggressive side and I find it preferable to the normal VC range.   To avoid the heavy loading of the full lock manoeuvres, I use a decoupler.   I run in all wheel drive except when making full lock turns.   My assessment of the handling and braking characteristics of my aggressive VC is based on rather a long time spent as a professional motor vehicle development engineer.

The “sports” viscous couplings are a very different matter.   They are set to provide a very high front axle input all the time.   I have never had a chance to try one but, from everything that I read, their most advantageous use would probably be for a vehicle that spends most of its life running on seriously degraded surfaces where good grip become a safety issue.   It is very difficult to determine an actual figure (percentage) of difference between the “sports” VC and a standard VC; none of the vendors appear to commit themselves to a figure.

Unless you intend to run off road 90+% of the time, you will be better served by running a new or reconditioned VC.    It must be noted hat, until you have run a standard VC, I is very difficult to make comparisons with an aggressive VC or a “sports” VC.

Sand is a different matter entirely but the balance of usage must be taken into account.   A solid shaft (which replaces the VC) works very well in sand but can’t be used on ordinary roads because it destroys the gearbox very quickly.   It can be used with a decoupler but then all of the very significant grip and safety advantages of the VC are lost and you have a two wheel drive Syncro.

Les

 


Hi Ken,

In response to your questions:

1. Short term cost is a definite consideration. If cost is too high then I will not be able to have funds released by the finance manager and will remain a 2wd only syncro.
2. The majority of time I use my van on Sydney roads or inter-state highways. However, I do regularly visit places where dirt roads are the only access, and when I go to our regular weekender in the wet, my van won't make it up the mud driveway. It's hard to even get in the car spot down the bottom of the hill without sliding everywhere. The long term goal is to travel around Oz, so I would like my van to be very capable offroad when I need it. Though I do like having AWD on-road, as I can remember when I first got my van and the VC was still somewhat working, people (including myself) were amazed how well such a big van would corner and brake. Particularly I would like to have AWD on road when there is heavy rain, I think this is a significant safety measure. Driving in 2wd on a dry day doesn't bother me so much, I am a defensive driver on most days and leave a good gap between me and the next car e.g., as this is a heavy van I am driving not a light passenger car.

All this said, I am thinking the best option for me is a used aggressive VC (hopefully not too aggressive) and a decoupler. If I had more cash at my disposal, I probably would purchase a 'sports vc' and decoupler, so that I am sure of what I am getting and it's longevity. Hence my original question. Though I am still unsure -

Will an aggressive VC (in lock mode) transmit as much (or similar) power to the front wheels as a sports VC (in lock mode)? Is this the same power transmitted as a standard VC in lock mode? Is the only difference the amount of give before entering lock mode? Or do we not specifically have the answer to this questions - is that what you were suggesting Les?

Thanks all, Sam



--- In Syncro_T3_Australia@yahoogroups.com, Ken Garratt <unclekenz@...> wrote:
>
>
>
>
>
>
>
>
>
>
> Sam,My two bobs worth. Two questions we first need your clear answers to, otherwise it's nigh impossible to suggest a "best fit" solution for your circumstances.
> ONE - Is cost, both short and long term, a high/low concern for you? Your answer cuts off certain options, leaves other options open.TWO - Please spell out clearly, in order of priority, top to bottom, your intended use of your syncro including how you intend it to mostly function ie., ... 2WD or 4WD. This answer also cuts off options, leaves other options open.Please be fulsome with your answers. A consideration then of both answers coupled together, homes in on the most likely best (read compromise) option/s for your circumstances.In answer to your query, all WORKING VCs other than original specced/correctly functioning or a going passive VC, would/should be classed as aggressive. So this includes "Sports". It's just a matter of degree of aggressiveness.All aggressive classed VCs, as with a solid shaft setup, if used on hard surfaces, will damage expensive components of your drivetrain SOONER (probably much sooner) than a correctly specced/functioning VC. How soon is just a matter of the degree of aggressiveness and continuous/occasional use of that VC. Is this what you want?The cost of a replacement VC is easily less than the cost and inconvenience of rebuilding drivetrain components, in particular the transaxle, front diff, CVs and prop-shaft. Discounting this fact, one does so at ones peril and extended time inconvenience off the road and a badly depleted bank balance. To that end, you are then faced with the angst of locating a known qualified/competent mechanic to entrust your expensive remedial repairs to. Good luck in Sydney! Who do you believe and anyway, wouldn't it be best to try and avoid this scenario in the first place?Whatever you decide, it'll still be a compromise. Even a correctly specced and working VC is a compromise. It was designed to suit the mass market.
> I'm presently thinking your best compromise & cheapest solution is a bog standard factory specced replacement VC. Supply us with the requested answers, I may well change that view.
> Cheers.Ken
>
> To: Syncro_T3_Australia@yahoogroups.com
> From: leslieharris@...
> Date: Fri, 17 Jun 2011 11:15:45 +1000
> Subject: RE: [Syncro_T3_Australia] Aggressive VC versus Sports VC
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Sorry, two silly typos in there:
>
>
>
> It must be noted that, until you have run a standard VC, it is very difficult to make comparisons with an
> aggressive VC or a "sports" VC.
>
>
>
>
>
>
>
>
>
>
>
> From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
>
> Sent: 17 June 2011 10:59
>
> To: Syncro_T3_Australia@yahoogroups.com
>
> Subject: RE: [Syncro_T3_Australia]
> Aggressive VC versus Sports VC
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Sam,
>
> This question needs a lot of background
> explanation to answer fully, starting from the VAG design intention for the
> Syncro.
>
> The Syncro was intended as a multipurpose
> vehicle, ranging from safe family transport in all (European) weather
> conditions, including snow and ice, to commercial and military
> applications. It was not designed primarily as a purely off-road
> vehicle.
>
> Consequently, VAG opted for the viscous
> coupling as the means to deliver drive to the front axle as dictated by the
> prevailing road conditions without the need for any driver decision or action,
> a point stressed in all of the release publicity.
>
> Most viscous couplings become more aggressive
> (meaning that they begin to operate at an earlier point than a new, unworn VC)
> with time and use. The effects of this are noticeable as a binding
> action when the vehicle is on full lock turns on dry, high grip surfaces,
> mainly low speed parking.
>
> At higher speeds and very small steering
> inputs, as in normal point to point driving, a more pronounced VC effect has
> benefits as it distributes more drive effort to the front axle.
> This is evident in steering precision and increased cornering adhesion, plus
> better braking effort distribution.
>
> My VC is on the aggressive side and I find it
> preferable to the normal VC range. To avoid the heavy loading of
> the full lock manoeuvres, I use a decoupler. I run in all wheel
> drive except when making full lock turns. My assessment of the
> handling and braking characteristics of my aggressive VC is based on rather a
> long time spent as a professional motor vehicle development engineer.
>
> The "sports" viscous couplings are
> a very different matter. They are set to provide a very high front
> axle input all the time. I have never had a chance to try one but,
> from everything that I read, their most advantageous use would probably be for
> a vehicle that spends most of its life running on seriously degraded surfaces
> where good grip become a safety issue. It is very difficult to
> determine an actual figure (percentage) of difference between the
> "sports" VC and a standard VC; none of the vendors appear to commit
> themselves to a figure.
>
> Unless you intend to run off road 90+% of the
> time, you will be better served by running a new or reconditioned
> VC. It must be
> noted hat, until you have run a standard VC, I is very difficult to make
> comparisons with an aggressive VC or a "sports" VC.
>
> Sand is a different matter entirely but the
> balance of usage must be taken into account. A solid shaft (which
> replaces the VC) works very well in sand but can't be used on ordinary
> roads because it destroys the gearbox very quickly. It can be used
> with a decoupler but then all of the very significant grip and safety
> advantages of the VC are lost and you have a two wheel drive Syncro.
>
> Les
>

Answers interspersed:

 

Short term cost is a definite consideration. If cost is too high then I will not be able to have funds released by the finance manager and will remain a 2wd only Syncro.


The majority of time I use my van on Sydney roads or inter-state highways.  However, I do regularly visit places where dirt roads are the only access, and when I go to our regular weekender in the wet, my van won't make it up the mud driveway.   It's hard to even get in the car spot down the bottom of the hill without sliding everywhere. 

It sounds like tyres are also a factor in this situation   

 

The long term goal is to travel around Oz, so I would like my van to be very capable off-road when I need it.   Though I do like having AWD on-road, as I can remember when I first got my van and the VC was still somewhat working, people (including myself) were amazed how well such a big van would corner and brake.   Particularly I would like to have AWD on road when there is heavy rain; I think this is a significant safety measure.

The capabilities afforded by the standard VC provide a level of grip and handling which very few people have the skills to employ.  

 

Driving in 2wd on a dry day doesn't bother me so much, I am a defensive driver on most days and leave a good gap between me and the next car e.g., as this is a heavy van I am driving not a light passenger car.

All this said, I am thinking the best option for me is a used aggressive VC (hopefully not too aggressive) and a decoupler.

Sam, I can’t think of any way that you are going to find an aggressive VC.   You might find one second hand somewhere but how are you going to know if it is a ‘suitably’ aggressive VC until it is in your vehicle and been driven?  

 

If I had more cash at my disposal, I probably would purchase a 'sports VC' and decoupler, so that I am sure of what I am getting and it's longevity. Hence my original question. Though I am still unsure –

OK, so you buy a “sports” VC and then spend most of your time driving a two wheel drive Syncro, thus depriving yourself of the very high levels of handling, grip and braking that is afforded by a bog standard VC.   To me, that is a very poor trade-off.

The design intent of the Syncro was to provide sure handling and braking and it does that in truckloads.   As I said earlier, so much so that there aren’t too many people who can make full use of what it offers.

Will an aggressive VC (in lock mode) transmit as much (or similar) power to the front wheels as a sports VC (in lock mode)?   Is this the same power transmitted as a standard VC in lock mode? Is the only difference the amount of give before entering lock mode? Or do we not specifically have the answer to this questions - is that what you were suggesting Les?

A bog standard VC reaches the full lock stage when there is a difference between front and rear axle speeds; from my reading, this occurs at around the 7-8% point.   An aggressive VC will probably lock at around 5-6% and a “sports” VC will probably lock at around 2-4%.   These differences are not particularly significant for off-road use of a Syncro and I seriously question whether they are going to make the difference between getting through a stretch of poor trail and not getting through.   Bear also in mind that, when the tyres lose adhesion, no drive system in the world will make the vehicle move.

Absent from this discussion is the matter of a rear diff lock.   A rear diff lock is a substantial aid to traction and I would put it as equal to the contribution made by the VC.

In summary, my advice is to buy a new or reconditioned VC – no need for a decoupler – and explore what it has to offer.   I think that you will be very amazed at the capabilities available.   Unless you are going to run the Finke Race, you will find that your can safely and comfortably negotiate very badly broken up fire trails and tracks, even with the sort of load that you would have on board for extended travelling.  Wanting your Syncro to be “very capable off-road” will be very difficult to achieve with such a load without making serious compromises.   I think that I can safely predict that you find that your tyre grip will be the limiting factor, not the state of the VC.

 

Les

 

Sam,

From what you say, I will stick with my original view ... a bog standard replacement VC is best for you, unless you alter some of your perceptions, needs and wants.

Fitting an aggressive/sports VC flies in the face of logic and increases your costs in having to buy a decoupler as well which deprives you of full-time 4WD potential, except if you choose to ignore the increased risk of premature drivetrain component failure requiring remediation at great expense and inconvenience when it happens.

Sam, you can't have it both ways I'm sorry. Wanting to pay as little as possible yet wanting so much including reliability .... it just cannot happen, especially in the short term.

Clearly your perceptions are different to mine, that's why my syncro setup is different to what I believe would best suit you.

So in conclusion, as you feel you need full time potential 4WD, need to limit costs and I assume then you would also need to avoid high remedial costs of premature failure of drivetrain components, then give aggressive/sports VCs a miss and consider a decoupler further down the track whenever it can be afforded. Limit your short term costs, buy a bog standard VC, forget the rest for now ... the other items reflect your wants, not your needs. You'll have a very capable syncro, on the road and at the least cost.

Cheers.

Ken






To: Syncro_T3_Australia@yahoogroups.com
From: me@samarnold.org
Date: Fri, 17 Jun 2011 06:11:05 +0000
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 
Hi Ken,

In response to your questions:

1. Short term cost is a definite consideration. If cost is too high then I will not be able to have funds released by the finance manager and will remain a 2wd only syncro.
2. The majority of time I use my van on Sydney roads or inter-state highways. However, I do regularly visit places where dirt roads are the only access, and when I go to our regular weekender in the wet, my van won't make it up the mud driveway. It's hard to even get in the car spot down the bottom of the hill without sliding everywhere. The long term goal is to travel around Oz, so I would like my van to be very capable offroad when I need it. Though I do like having AWD on-road, as I can remember when I first got my van and the VC was still somewhat working, people (including myself) were amazed how well such a big van would corner and brake. Particularly I would like to have AWD on road when there is heavy rain, I think this is a significant safety measure. Driving in 2wd on a dry day doesn't bother me so much, I am a defensive driver on most days and leave a good gap between me and the next car e.g., as this is a heavy van I am driving not a light passenger car.

All this said, I am thinking the best option for me is a used aggressive VC (hopefully not too aggressive) and a decoupler. If I had more cash at my disposal, I probably would purchase a 'sports vc' and decoupler, so that I am sure of what I am getting and it's longevity. Hence my original question. Though I am still unsure -

Will an aggressive VC (in lock mode) transmit as much (or similar) power to the front wheels as a sports VC (in lock mode)? Is this the same power transmitted as a standard VC in lock mode? Is the only difference the amount of give before entering lock mode? Or do we not specifically have the answer to this questions - is that what you were suggesting Les?

Thanks all, Sam

--- In Syncro_T3_Australia@yahoogroups.com, Ken Garratt <unclekenz@...> wrote:
>
>
>
>
>
>
>
>
>
>
> Sam,My two bobs worth. Two questions we first need your clear answers to, otherwise it's nigh impossible to suggest a "best fit" solution for your circumstances.
> ONE - Is cost, both short and long term, a high/low concern for you? Your answer cuts off certain options, leaves other options open.TWO - Please spell out clearly, in order of priority, top to bottom, your intended use of your syncro including how you intend it to mostly function ie., ... 2WD or 4WD. This answer also cuts off options, leaves other options open.Please be fulsome with your answers. A consideration then of both answers coupled together, homes in on the most likely best (read compromise) option/s for your circumstances.In answer to your query, all WORKING VCs other than original specced/correctly functioning or a going passive VC, would/should be classed as aggressive. So this includes "Sports". It's just a matter of degree of aggressiveness.All aggressive classed VCs, as with a solid shaft setup, if used on hard surfaces, will damage expensive components of your drivetrain SOONER (probably much sooner) than a correctly specced/functioning VC. How soon is just a matter of the degree of aggressiveness and continuous/occasional use of that VC. Is this what you want?The cost of a replacement VC is easily less than the cost and inconvenience of rebuilding drivetrain components, in particular the transaxle, front diff, CVs and prop-shaft. Discounting this fact, one does so at ones peril and extended time inconvenience off the road and a badly depleted bank balance. To that end, you are then faced with the angst of locating a known qualified/competent mechanic to entrust your expensive remedial repairs to. Good luck in Sydney! Who do you believe and anyway, wouldn't it be best to try and avoid this scenario in the first place?Whatever you decide, it'll still be a compromise. Even a correctly specced and working VC is a compromise. It was designed to suit the mass market.
> I'm presently thinking your best compromise & cheapest solution is a bog standard factory specced replacement VC. Supply us with the requested answers, I may well change that view.
> Cheers.Ken
>
> To: Syncro_T3_Australia@yahoogroups.com
> From: leslieharris@...
> Date: Fri, 17 Jun 2011 11:15:45 +1000
> Subject: RE: [Syncro_T3_Australia] Aggressive VC versus Sports VC
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Sorry, two silly typos in there:
>
>
>
> It must be noted that, until you have run a standard VC, it is very difficult to make comparisons with an
> aggressive VC or a "sports" VC.
>
>
>
>
>
>
>
>
>
>
>
> From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
>
> Sent: 17 June 2011 10:59
>
> To: Syncro_T3_Australia@yahoogroups.com
>
> Subject: RE: [Syncro_T3_Australia]
> Aggressive VC versus Sports VC
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Sam,
>
> This question needs a lot of background
> explanation to answer fully, starting from the VAG design intention for the
> Syncro.
>
> The Syncro was intended as a multipurpose
> vehicle, ranging from safe family transport in all (European) weather
> conditions, including snow and ice, to commercial and military
> applications. It was not designed primarily as a purely off-road
> vehicle.
>
> Consequently, VAG opted for the viscous
> coupling as the means to deliver drive to the front axle as dictated by the
> prevailing road conditions without the need for any driver decision or action,
> a point stressed in all of the release publicity.
>
> Most viscous couplings become more aggressive
> (meaning that they begin to operate at an earlier point than a new, unworn VC)
> with time and use. The effects of this are noticeable as a binding
> action when the vehicle is on full lock turns on dry, high grip surfaces,
> mainly low speed parking.
>
> At higher speeds and very small steering
> inputs, as in normal point to point driving, a more pronounced VC effect has
> benefits as it distributes more drive effort to the front axle.
> This is evident in steering precision and increased cornering adhesion, plus
> better braking effort distribution.
>
> My VC is on the aggressive side and I find it
> preferable to the normal VC range. To avoid the heavy loading of
> the full lock manoeuvres, I use a decoupler. I run in all wheel
> drive except when making full lock turns. My assessment of the
> handling and braking characteristics of my aggressive VC is based on rather a
> long time spent as a professional motor vehicle development engineer.
>
> The "sports" viscous couplings are
> a very different matter. They are set to provide a very high front
> axle input all the time. I have never had a chance to try one but,
> from everything that I read, their most advantageous use would probably be for
> a vehicle that spends most of its life running on seriously degraded surfaces
> where good grip become a safety issue. It is very difficult to
> determine an actual figure (percentage) of difference between the
> "sports" VC and a standard VC; none of the vendors appear to commit
> themselves to a figure.
>
> Unless you intend to run off road 90+% of the
> time, you will be better served by running a new or reconditioned
> VC. It must be
> noted hat, until you have run a standard VC, I is very difficult to make
> comparisons with an aggressive VC or a "sports" VC.
>
> Sand is a different matter entirely but the
> balance of usage must be taken into account. A solid shaft (which
> replaces the VC) works very well in sand but can't be used on ordinary
> roads because it destroys the gearbox very quickly. It can be used
> with a decoupler but then all of the very significant grip and safety
> advantages of the VC are lost and you have a two wheel drive Syncro.
>
> Les
>


Thanks for the food for thought Ken and Les. It would be the cheaper option at the moment. Will see what the finance manager has to say.


--- In Syncro_T3_Australia@yahoogroups.com, Ken Garratt <unclekenz@...> wrote:
>
>
>
>
>
>
> Sam,
> From what you say, I will stick with my original view ... a bog standard replacement VC is best for you, unless you alter some of your perceptions, needs and wants.
> Fitting an aggressive/sports VC flies in the face of logic and increases your costs in having to buy a decoupler as well which deprives you of full-time 4WD potential, except if you choose to ignore the increased risk of premature drivetrain component failure requiring remediation at great expense and inconvenience when it happens.
> Sam, you can't have it both ways I'm sorry. Wanting to pay as little as possible yet wanting so much including reliability .... it just cannot happen, especially in the short term.
> Clearly your perceptions are different to mine, that's why my syncro setup is different to what I believe would best suit you.
> So in conclusion, as you feel you need full time potential 4WD, need to limit costs and I assume then you would also need to avoid high remedial costs of premature failure of drivetrain components, then give aggressive/sports VCs a miss and consider a decoupler further down the track whenever it can be afforded. Limit your short term costs, buy a bog standard VC, forget the rest for now ... the other items reflect your wants, not your needs. You'll have a very capable syncro, on the road and at the least cost.
> Cheers.
> Ken
>
>
>
>
>
> To: Syncro_T3_Australia@yahoogroups.com
> From: me@...
> Date: Fri, 17 Jun 2011 06:11:05 +0000
> Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Hi Ken,
>
>
>
> In response to your questions:
>
>
>
> 1. Short term cost is a definite consideration. If cost is too high then I will not be able to have funds released by the finance manager and will remain a 2wd only syncro.
>
> 2. The majority of time I use my van on Sydney roads or inter-state highways. However, I do regularly visit places where dirt roads are the only access, and when I go to our regular weekender in the wet, my van won't make it up the mud driveway. It's hard to even get in the car spot down the bottom of the hill without sliding everywhere. The long term goal is to travel around Oz, so I would like my van to be very capable offroad when I need it. Though I do like having AWD on-road, as I can remember when I first got my van and the VC was still somewhat working, people (including myself) were amazed how well such a big van would corner and brake. Particularly I would like to have AWD on road when there is heavy rain, I think this is a significant safety measure. Driving in 2wd on a dry day doesn't bother me so much, I am a defensive driver on most days and leave a good gap between me and the next car e.g., as this is a heavy van I am driving not a light passenger car.
>
>
>
> All this said, I am thinking the best option for me is a used aggressive VC (hopefully not too aggressive) and a decoupler. If I had more cash at my disposal, I probably would purchase a 'sports vc' and decoupler, so that I am sure of what I am getting and it's longevity. Hence my original question. Though I am still unsure -
>
>
>
> Will an aggressive VC (in lock mode) transmit as much (or similar) power to the front wheels as a sports VC (in lock mode)? Is this the same power transmitted as a standard VC in lock mode? Is the only difference the amount of give before entering lock mode? Or do we not specifically have the answer to this questions - is that what you were suggesting Les?
>
>
>
> Thanks all, Sam
>
>
>
> --- In Syncro_T3_Australia@yahoogroups.com, Ken Garratt <unclekenz@> wrote:
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Sam,My two bobs worth. Two questions we first need your clear answers to, otherwise it's nigh impossible to suggest a "best fit" solution for your circumstances.
>
> > ONE - Is cost, both short and long term, a high/low concern for you? Your answer cuts off certain options, leaves other options open.TWO - Please spell out clearly, in order of priority, top to bottom, your intended use of your syncro including how you intend it to mostly function ie., ... 2WD or 4WD. This answer also cuts off options, leaves other options open.Please be fulsome with your answers. A consideration then of both answers coupled together, homes in on the most likely best (read compromise) option/s for your circumstances.In answer to your query, all WORKING VCs other than original specced/correctly functioning or a going passive VC, would/should be classed as aggressive. So this includes "Sports". It's just a matter of degree of aggressiveness.All aggressive classed VCs, as with a solid shaft setup, if used on hard surfaces, will damage expensive components of your drivetrain SOONER (probably much sooner) than a correctly specced/functioning VC. How soon is just a matter of the degree of aggressiveness and continuous/occasional use of that VC. Is this what you want?The cost of a replacement VC is easily less than the cost and inconvenience of rebuilding drivetrain components, in particular the transaxle, front diff, CVs and prop-shaft. Discounting this fact, one does so at ones peril and extended time inconvenience off the road and a badly depleted bank balance. To that end, you are then faced with the angst of locating a known qualified/competent mechanic to entrust your expensive remedial repairs to. Good luck in Sydney! Who do you believe and anyway, wouldn't it be best to try and avoid this scenario in the first place?Whatever you decide, it'll still be a compromise. Even a correctly specced and working VC is a compromise. It was designed to suit the mass market.
>
> > I'm presently thinking your best compromise & cheapest solution is a bog standard factory specced replacement VC. Supply us with the requested answers, I may well change that view.
>
> > Cheers.Ken
>
> >
>
> > To: Syncro_T3_Australia@yahoogroups.com
>
> > From: leslieharris@
>
> > Date: Fri, 17 Jun 2011 11:15:45 +1000
>
> > Subject: RE: [Syncro_T3_Australia] Aggressive VC versus Sports VC
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Sorry, two silly typos in there:
>
> >
>
> >
>
> >
>
> > It must be noted that, until you have run a standard VC, it is very difficult to make comparisons with an
>
> > aggressive VC or a "sports" VC.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
>
> >
>
> > Sent: 17 June 2011 10:59
>
> >
>
> > To: Syncro_T3_Australia@yahoogroups.com
>
> >
>
> > Subject: RE: [Syncro_T3_Australia]
>
> > Aggressive VC versus Sports VC
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Sam,
>
> >
>
> > This question needs a lot of background
>
> > explanation to answer fully, starting from the VAG design intention for the
>
> > Syncro.
>
> >
>
> > The Syncro was intended as a multipurpose
>
> > vehicle, ranging from safe family transport in all (European) weather
>
> > conditions, including snow and ice, to commercial and military
>
> > applications. It was not designed primarily as a purely off-road
>
> > vehicle.
>
> >
>
> > Consequently, VAG opted for the viscous
>
> > coupling as the means to deliver drive to the front axle as dictated by the
>
> > prevailing road conditions without the need for any driver decision or action,
>
> > a point stressed in all of the release publicity.
>
> >
>
> > Most viscous couplings become more aggressive
>
> > (meaning that they begin to operate at an earlier point than a new, unworn VC)
>
> > with time and use. The effects of this are noticeable as a binding
>
> > action when the vehicle is on full lock turns on dry, high grip surfaces,
>
> > mainly low speed parking.
>
> >
>
> > At higher speeds and very small steering
>
> > inputs, as in normal point to point driving, a more pronounced VC effect has
>
> > benefits as it distributes more drive effort to the front axle.
>
> > This is evident in steering precision and increased cornering adhesion, plus
>
> > better braking effort distribution.
>
> >
>
> > My VC is on the aggressive side and I find it
>
> > preferable to the normal VC range. To avoid the heavy loading of
>
> > the full lock manoeuvres, I use a decoupler. I run in all wheel
>
> > drive except when making full lock turns. My assessment of the
>
> > handling and braking characteristics of my aggressive VC is based on rather a
>
> > long time spent as a professional motor vehicle development engineer.
>
> >
>
> > The "sports" viscous couplings are
>
> > a very different matter. They are set to provide a very high front
>
> > axle input all the time. I have never had a chance to try one but,
>
> > from everything that I read, their most advantageous use would probably be for
>
> > a vehicle that spends most of its life running on seriously degraded surfaces
>
> > where good grip become a safety issue. It is very difficult to
>
> > determine an actual figure (percentage) of difference between the
>
> > "sports" VC and a standard VC; none of the vendors appear to commit
>
> > themselves to a figure.
>
> >
>
> > Unless you intend to run off road 90+% of the
>
> > time, you will be better served by running a new or reconditioned
>
> > VC. It must be
>
> > noted hat, until you have run a standard VC, I is very difficult to make
>
> > comparisons with an aggressive VC or a "sports" VC.
>
> >
>
> > Sand is a different matter entirely but the
>
> > balance of usage must be taken into account. A solid shaft (which
>
> > replaces the VC) works very well in sand but can't be used on ordinary
>
> > roads because it destroys the gearbox very quickly. It can be used
>
> > with a decoupler but then all of the very significant grip and safety
>
> > advantages of the VC are lost and you have a two wheel drive Syncro.
>
> >
>
> > Les
>
> >
>

Hi Les and Sam,

 

I rarely buy into these VC discussions these days now that I have the T5 (Haldex instead, although similar in practise). However, the experiences Les relates parallel my own from my T3 days, and explain why I always maintained that decouplers were a retrograde idea. It's always at that moment that you most need it, that you happen to have the decoupler 'out'.

 

And I don't believe that a properly functioning standard VC has that many limitations. As I understand it's function, due to the thixotropic nature of the fluid, the standard VC will lock solid (ie 100% torque transfer) within 1/6th of a wheel turn if there is sufficient wheel slip at either end. An 'aggressive' VC might reduce this to 1/12th or 1/20th of a turn. This might be a slight theoretical advantage in sand, where that 1/6th turn might allow a wheel to 'dig in',  but it's hard to see a difference anywhere else. They are still both capable of rapid 100% lock-op when required. The standard VC allows a sufficient amount of low variability of speed (a figure of 6% comes to mind, but it's a long time since I checked) between front and rear axles for normal turning on hard surfaces, where the aggressive one is a bit short in that department, and so stresses the rest of the drive train.

 

The popularity of decouplers and tight VC's, or solid shafts, seems to be predicated on the idea that the standard VC will 'slip' and fail to transfer the required torque in severe conditions, but in fact, as I understand it,  the more severe the conditions, the stronger the 'locking' characteristics of the VC. I can back this up to a degree, as there once was a time (following an accident that pushed on a rear wheel) when I was driving around for a couple of weeks with what turned out to be a destroyed spider gear in the transaxle, which meant no drive to the rear axle (no diff lock either). Thus I had a totally front wheel drive Syncro. If the VC allowed much, or any, slip when the rear wheels had no effective 'traction', it would have been felt like a 'slurring' automatic transmission. This was completely absent, and I only became aware of the extent of the transaxle damage when some rather grumbly noises developed as the 'bits' shifted around, and at the subsequent rebuild.

 

Brian R.

 

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: Friday, 17 June 2011 12:03 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

 

Sam,

Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!  

As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers.   Some owners have had the experience of stalling the engine on full lock, grippy surface turns.   (This happens because the VC is trying to drive the front and rear axles at the same speed.)   This probably represents the upper end of the usability range.

I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving.  This level of aggression is therefore acceptable.   Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle.   This is something that was probably not evident to the designers until the vehicle went into service.

Binding on slight turns (your last paragraph) would be very difficult to detect.   About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input.   At any level of aggression less that that, the end result is still advantageous.

Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.

I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night.   I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain.   The driver in front of me got into trouble and drifted into the outside lane.   I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro.   I had just come out of a service station and had not re-engaged the decoupler!!!!!

I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked.   I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.  

Les

 


From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam



Apologies to Ken & Les, I didn't get to read all your posts before making my most recent.

 

Anyway, it seems we are basically in agreement. Sam's best bet would be a standard replacement VC (my bias is that that is every-one's best bet). Things may be different now, from when I bought mine over a decade ago, but new, rather than rebuilt, was the go then. The cost savings were not that great, and the reliability of rebuilding (which seems a bit of a black art) was very much questioned back then. The dollar will help now as well. I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.

 

And as Les says, good tyres and a diff lock (if you don't already have one) would be a higher priority than a modified drive train.

 

Brian.

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Brian Reed
Sent: Friday, 17 June 2011 11:29 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 

 

Hi Les and Sam,

 

I rarely buy into these VC discussions these days now that I have the T5 (Haldex instead, although similar in practise). However, the experiences Les relates parallel my own from my T3 days, and explain why I always maintained that decouplers were a retrograde idea. It's always at that moment that you most need it, that you happen to have the decoupler 'out'.

 

And I don't believe that a properly functioning standard VC has that many limitations. As I understand it's function, due to the thixotropic nature of the fluid, the standard VC will lock solid (ie 100% torque transfer) within 1/6th of a wheel turn if there is sufficient wheel slip at either end. An 'aggressive' VC might reduce this to 1/12th or 1/20th of a turn. This might be a slight theoretical advantage in sand, where that 1/6th turn might allow a wheel to 'dig in',  but it's hard to see a difference anywhere else. They are still both capable of rapid 100% lock-op when required. The standard VC allows a sufficient amount of low variability of speed (a figure of 6% comes to mind, but it's a long time since I checked) between front and rear axles for normal turning on hard surfaces, where the aggressive one is a bit short in that department, and so stresses the rest of the drive train.

 

The popularity of decouplers and tight VC's, or solid shafts, seems to be predicated on the idea that the standard VC will 'slip' and fail to transfer the required torque in severe conditions, but in fact, as I understand it,  the more severe the conditions, the stronger the 'locking' characteristics of the VC. I can back this up to a degree, as there once was a time (following an accident that pushed on a rear wheel) when I was driving around for a couple of weeks with what turned out to be a destroyed spider gear in the transaxle, which meant no drive to the rear axle (no diff lock either). Thus I had a totally front wheel drive Syncro. If the VC allowed much, or any, slip when the rear wheels had no effective 'traction', it would have been felt like a 'slurring' automatic transmission. This was completely absent, and I only became aware of the extent of the transaxle damage when some rather grumbly noises developed as the 'bits' shifted around, and at the subsequent rebuild.

 

Brian R.

 

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: Friday, 17 June 2011 12:03 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

 

Sam,

Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!  

As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers.   Some owners have had the experience of stalling the engine on full lock, grippy surface turns.   (This happens because the VC is trying to drive the front and rear axles at the same speed.)   This probably represents the upper end of the usability range.

I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving.  This level of aggression is therefore acceptable.   Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle.   This is something that was probably not evident to the designers until the vehicle went into service.

Binding on slight turns (your last paragraph) would be very difficult to detect.   About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input.   At any level of aggression less that that, the end result is still advantageous.

Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.

I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night.   I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain.   The driver in front of me got into trouble and drifted into the outside lane.   I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro.   I had just come out of a service station and had not re-engaged the decoupler!!!!!

I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked.   I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.  

Les

 


From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam




Brian,

That may have been true when Derek was offering VC's for about US$750 whilst decouplers w/o solid shafts were about US$1500. Solid shafts added US$300 to that price tag.

These days, new VC's are being offered in US$1500-US$2000 range here in the US. Decouplers are in the US$1000-US$1300 ballpark. Solid shaft prices about the same.


BenT

sent from my electronic leash

On Jun 17, 2011, at 7:11 AM, "Brian Reed" <breed@bigpond.net.au> wrote:

I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.

 

Brian

Enjoyed and concurred with your comments re VC. However the comment "and a diff lock (if you don't already have one) would be a higher priority" is not always applicable, as my understanding is is that not all synco's are adaptable to the retro fitting of a diff lock.


On 18 June 2011 00:11, Brian Reed <breed@bigpond.net.au> wrote:

Apologies to Ken & Les, I didn't get to read all your posts before making my most recent.

Anyway, it seems we are basically in agreement. Sam's best bet would be a standard replacement VC (my bias is that that is every-one's best bet). Things may be different now, from when I bought mine over a decade ago, but new, rather than rebuilt, was the go then. The cost savings were not that great, and the reliability of rebuilding (which seems a bit of a black art) was very much questioned back then. The dollar will help now as well. I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.

And as Les says, good tyres and a diff lock (if you don't already have one) would be a higher priority than a modified drive train.

Brian.

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Brian Reed
Sent: Friday, 17 June 2011 11:29 PM

Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

Hi Les and Sam,

I rarely buy into these VC discussions these days now that I have the T5 (Haldex instead, although similar in practise). However, the experiences Les relates parallel my own from my T3 days, and explain why I always maintained that decouplers were a retrograde idea. It's always at that moment that you most need it, that you happen to have the decoupler 'out'.

And I don't believe that a properly functioning standard VC has that many limitations. As I understand it's function, due to the thixotropic nature of the fluid, the standard VC will lock solid (ie 100% torque transfer) within 1/6th of a wheel turn if there is sufficient wheel slip at either end. An 'aggressive' VC might reduce this to 1/12th or 1/20th of a turn. This might be a slight theoretical advantage in sand, where that 1/6th turn might allow a wheel to 'dig in', but it's hard to see a difference anywhere else. They are still both capable of rapid 100% lock-op when required. The standard VC allows a sufficient amount of low variability of speed (a figure of 6% comes to mind, but it's a long time since I checked) between front and rear axles for normal turning on hard surfaces, where the aggressive one is a bit short in that department, and so stresses the rest of the drive train.

The popularity of decouplers and tight VC's, or solid shafts, seems to be predicated on the idea that the standard VC will 'slip' and fail to transfer the required torque in severe conditions, but in fact, as I understand it, the more severe the conditions, the stronger the 'locking' characteristics of the VC. I can back this up to a degree, as there once was a time (following an accident that pushed on a rear wheel) when I was driving around for a couple of weeks with what turned out to be a destroyed spider gear in the transaxle, which meant no drive to the rear axle (no diff lock either). Thus I had a totally front wheel drive Syncro. If the VC allowed much, or any, slip when the rear wheels had no effective 'traction', it would have been felt like a 'slurring' automatic transmission. This was completely absent, and I only became aware of the extent of the transaxle damage when some rather grumbly noises developed as the 'bits' shifted around, and at the subsequent rebuild.

Brian R.

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: Friday, 17 June 2011 12:03 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

Sam,

Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!

As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers. Some owners have had the experience of stalling the engine on full lock, grippy surface turns. (This happens because the VC is trying to drive the front and rear axles at the same speed.) This probably represents the upper end of the usability range.

I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving. This level of aggression is therefore acceptable. Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle. This is something that was probably not evident to the designers until the vehicle went into service.

Binding on slight turns (your last paragraph) would be very difficult to detect. About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input. At any level of aggression less that that, the end result is still advantageous.

Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.

I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night. I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain. The driver in front of me got into trouble and drifted into the outside lane. I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro. I had just come out of a service station and had not re-engaged the decoupler!!!!!

I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked. I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.

Les


From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam







--
Regards

Michael

Michael Rayner East Light Photography
PO Box 144
MALLACOOTA VIC 3892

MOB: 0409 241 672
BUS: 0351169401
A/H: (03)5158 0346

Web: www.michaelraynerphotography.com.au
Email: michaelrayner@exemail.com.au


Diff lock can be added to the front or rear of any syncro. If you have no locks you just need to add the vacuum circuit and warning light loom - no biggy. Greg E

From: Michael Rayner <mallaner@gmail.com>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Saturday, 18 June 2011 9:38 AM
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 
Brian

Enjoyed and concurred with your comments re VC. However the comment "and a diff lock (if you don't already have one) would be a higher priority" is not always applicable, as my understanding is is that not all synco's are adaptable to the retro fitting of a diff lock.


On 18 June 2011 00:11, Brian Reed <breed@bigpond.net.au> wrote:
 
Apologies to Ken & Les, I didn't get to read all your posts before making my most recent.
 
Anyway, it seems we are basically in agreement. Sam's best bet would be a standard replacement VC (my bias is that that is every-one's best bet). Things may be different now, from when I bought mine over a decade ago, but new, rather than rebuilt, was the go then. The cost savings were not that great, and the reliability of rebuilding (which seems a bit of a black art) was very much questioned back then. The dollar will help now as well. I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.
 
And as Les says, good tyres and a diff lock (if you don't already have one) would be a higher priority than a modified drive train.
 
Brian.
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Brian Reed
Sent: Friday, 17 June 2011 11:29 PM
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC
 
 
Hi Les and Sam,
 
I rarely buy into these VC discussions these days now that I have the T5 (Haldex instead, although similar in practise). However, the experiences Les relates parallel my own from my T3 days, and explain why I always maintained that decouplers were a retrograde idea. It's always at that moment that you most need it, that you happen to have the decoupler 'out'.
 
And I don't believe that a properly functioning standard VC has that many limitations. As I understand it's function, due to the thixotropic nature of the fluid, the standard VC will lock solid (ie 100% torque transfer) within 1/6th of a wheel turn if there is sufficient wheel slip at either end. An 'aggressive' VC might reduce this to 1/12th or 1/20th of a turn. This might be a slight theoretical advantage in sand, where that 1/6th turn might allow a wheel to 'dig in',  but it's hard to see a difference anywhere else. They are still both capable of rapid 100% lock-op when required. The standard VC allows a sufficient amount of low variability of speed (a figure of 6% comes to mind, but it's a long time since I checked) between front and rear axles for normal turning on hard surfaces, where the aggressive one is a bit short in that department, and so stresses the rest of the drive train.
 
The popularity of decouplers and tight VC's, or solid shafts, seems to be predicated on the idea that the standard VC will 'slip' and fail to transfer the required torque in severe conditions, but in fact, as I understand it,  the more severe the conditions, the stronger the 'locking' characteristics of the VC. I can back this up to a degree, as there once was a time (following an accident that pushed on a rear wheel) when I was driving around for a couple of weeks with what turned out to be a destroyed spider gear in the transaxle, which meant no drive to the rear axle (no diff lock either). Thus I had a totally front wheel drive Syncro. If the VC allowed much, or any, slip when the rear wheels had no effective 'traction', it would have been felt like a 'slurring' automatic transmission. This was completely absent, and I only became aware of the extent of the transaxle damage when some rather grumbly noises developed as the 'bits' shifted around, and at the subsequent rebuild.
 
Brian R.
 
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: Friday, 17 June 2011 12:03 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC
 
 
Sam,
Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!  
As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers.   Some owners have had the experience of stalling the engine on full lock, grippy surface turns.   (This happens because the VC is trying to drive the front and rear axles at the same speed.)   This probably represents the upper end of the usability range.
I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving.  This level of aggression is therefore acceptable.   Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle.   This is something that was probably not evident to the designers until the vehicle went into service.
Binding on slight turns (your last paragraph) would be very difficult to detect.   About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input.   At any level of aggression less that that, the end result is still advantageous.
Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.
I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night.   I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain.   The driver in front of me got into trouble and drifted into the outside lane.   I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro.   I had just come out of a service station and had not re-engaged the decoupler!!!!!
I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked.   I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.  
Les
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC
 
Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam







--
Regards

Michael

Michael Rayner East Light Photography
PO Box 144
MALLACOOTA  VIC  3892

MOB: 0409 241 672
BUS:  0351169401
A/H:   (03)5158 0346

Web:   www.michaelraynerphotography.com.au
Email:  michaelrayner@exemail.com.au




Hi Ben,

 

Interesting to look at the relativities. I think I paid Derek around US$800, but with shipping, the then current exchange rate of not much over 50c to the US$, and duties, it cost me a bit over AUD$2000 landed. At least fitting was relatively simple and cheap. With the current exchange rate (about $AUD1 to US $1.06) the cost should be quite similar. The decoupler, on the other hand, has got a lot cheaper, but I still think a good new VC is the best bet. Might also be worth researching European prices.

 

Brian.

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of BenT Syncro
Sent: Saturday, 18 June 2011 12:25 AM
To: Syncro_T3_Australia@yahoogroups.com
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 

 

Brian,

 

That may have been true when Derek was offering VC's for about US$750 whilst decouplers w/o solid shafts were about US$1500. Solid shafts added US$300 to that price tag.

 

These days, new VC's are being offered in US$1500-US$2000 range here in the US. Decouplers are in the US$1000-US$1300 ballpark. Solid shaft prices about the same.

 

 

BenT

sent from my electronic leash


On Jun 17, 2011, at 7:11 AM, "Brian Reed" <breed@bigpond.net.au> wrote:

I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.

 

Hi Greg,

 

You and Micheal are both correct to a degree. As I remember from the first Bateman's Bay meet (and I think it was Rudi who had the info), some non difflock syncro gearbox cases had the appropriate bit of casting to accept a difflock (a little drilling was required), and some did not. The appropriate loom and vacuum lines may, or may not, also be present in a non difflock van. However, as Rudi has now been able to engineer these difflocks even into T2 boxes, I'd imagine he could also do this for any-one unfortunate enough to have the wrong style of case.

 

Brian.

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of greg esposito
Sent: Saturday, 18 June 2011 10:51 AM
To: Syncro_T3_Australia@yahoogroups.com
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 

 

Diff lock can be added to the front or rear of any syncro. If you have no locks you just need to add the vacuum circuit and warning light loom - no biggy. Greg E

 

From: Michael Rayner <mallaner@gmail.com>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Saturday, 18 June 2011 9:38 AM
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 

Brian

 

Enjoyed and concurred with your comments re VC. However the comment "and a diff lock (if you don't already have one) would be a higher priority" is not always applicable, as my understanding is is that not all synco's are adaptable to the retro fitting of a diff lock.

 

On 18 June 2011 00:11, Brian Reed <breed@bigpond.net.au> wrote:

 

Apologies to Ken & Les, I didn't get to read all your posts before making my most recent.

 

Anyway, it seems we are basically in agreement. Sam's best bet would be a standard replacement VC (my bias is that that is every-one's best bet). Things may be different now, from when I bought mine over a decade ago, but new, rather than rebuilt, was the go then. The cost savings were not that great, and the reliability of rebuilding (which seems a bit of a black art) was very much questioned back then. The dollar will help now as well. I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.

 

And as Les says, good tyres and a diff lock (if you don't already have one) would be a higher priority than a modified drive train.

 

Brian.

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Brian Reed
Sent: Friday, 17 June 2011 11:29 PM

Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 

 

Hi Les and Sam,

 

I rarely buy into these VC discussions these days now that I have the T5 (Haldex instead, although similar in practise). However, the experiences Les relates parallel my own from my T3 days, and explain why I always maintained that decouplers were a retrograde idea. It's always at that moment that you most need it, that you happen to have the decoupler 'out'.

 

And I don't believe that a properly functioning standard VC has that many limitations. As I understand it's function, due to the thixotropic nature of the fluid, the standard VC will lock solid (ie 100% torque transfer) within 1/6th of a wheel turn if there is sufficient wheel slip at either end. An 'aggressive' VC might reduce this to 1/12th or 1/20th of a turn. This might be a slight theoretical advantage in sand, where that 1/6th turn might allow a wheel to 'dig in',  but it's hard to see a difference anywhere else. They are still both capable of rapid 100% lock-op when required. The standard VC allows a sufficient amount of low variability of speed (a figure of 6% comes to mind, but it's a long time since I checked) between front and rear axles for normal turning on hard surfaces, where the aggressive one is a bit short in that department, and so stresses the rest of the drive train.

 

The popularity of decouplers and tight VC's, or solid shafts, seems to be predicated on the idea that the standard VC will 'slip' and fail to transfer the required torque in severe conditions, but in fact, as I understand it,  the more severe the conditions, the stronger the 'locking' characteristics of the VC. I can back this up to a degree, as there once was a time (following an accident that pushed on a rear wheel) when I was driving around for a couple of weeks with what turned out to be a destroyed spider gear in the transaxle, which meant no drive to the rear axle (no diff lock either). Thus I had a totally front wheel drive Syncro. If the VC allowed much, or any, slip when the rear wheels had no effective 'traction', it would have been felt like a 'slurring' automatic transmission. This was completely absent, and I only became aware of the extent of the transaxle damage when some rather grumbly noises developed as the 'bits' shifted around, and at the subsequent rebuild.

 

Brian R.

 

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: Friday, 17 June 2011 12:03 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

 

Sam,

Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!  

As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers.   Some owners have had the experience of stalling the engine on full lock, grippy surface turns.   (This happens because the VC is trying to drive the front and rear axles at the same speed.)   This probably represents the upper end of the usability range.

I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving.  This level of aggression is therefore acceptable.   Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle.   This is something that was probably not evident to the designers until the vehicle went into service.

Binding on slight turns (your last paragraph) would be very difficult to detect.   About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input.   At any level of aggression less that that, the end result is still advantageous.

Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.

I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night.   I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain.   The driver in front of me got into trouble and drifted into the outside lane.   I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro.   I had just come out of a service station and had not re-engaged the decoupler!!!!!

I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked.   I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.  

Les

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC

 

Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam






--
Regards

Michael

Michael Rayner East Light Photography
PO Box 144
MALLACOOTA  VIC  3892

MOB: 0409 241 672
BUS:  0351169401
A/H:   (03)5158 0346

Web:   www.michaelraynerphotography.com.au
Email:  michaelrayner@exemail.com.au

 

Brian,

Times have changed indeed. During that time, VC's were NLA. IIRC, Derek had to persuade SDP to make a batch. Now VW Classic Parts has returned them to production.

In those early days of decoupler installations, I only knew of one supplier in the US. There's a half dozen now with two different styles. The Lengyel brothers who popularized them in the US are now producing their version for GoWesty from what I heard through the grapevine. You already know Florian is assembling the German version and offering them in this forum.



Regards,

BenT

sent from my Viscous Communicator

On Jun 17, 2011, at 7:09 PM, "Brian Reed" <breed@bigpond.net.au> wrote:

Hi Ben,

 

Interesting to look at the relativities. I think I paid Derek around US$800, but with shipping, the then current exchange rate of not much over 50c to the US$, and duties, it cost me a bit over AUD$2000 landed. At least fitting was relatively simple and cheap. With the current exchange rate (about $AUD1 to US $1.06) the cost should be quite similar. The decoupler, on the other hand, has got a lot cheaper, but I still think a good new VC is the best bet. Might also be worth researching European prices.

 

Brian.

 

From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of BenT Syncro
Sent: Saturday, 18 June 2011 12:25 AM
To: Syncro_T3_Australia@yahoogroups.com
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 

 

Brian,

 

That may have been true when Derek was offering VC's for about US$750 whilst decouplers w/o solid shafts were about US$1500. Solid shafts added US$300 to that price tag.

 

These days, new VC's are being offered in US$1500-US$2000 range here in the US. Decouplers are in the US$1000-US$1300 ballpark. Solid shaft prices about the same.

 

 

BenT

sent from my electronic leash


On Jun 17, 2011, at 7:11 AM, "Brian Reed" <breed@bigpond.net.au> wrote:

I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.

 

Hi Brian, As far as I can make out those non locker boxs without bosses are pretty rare. The four ex telecom buses I have worked on had bosses. It would take someone as experienced as Rudi to tell you but I wonder if these odd boxes have just had their intermediate housing swapped? In any case I stand by my original comment as the easiest way to get locking diffs is to import a whole g/box or diff with a loom and vacuum bits. Greg E

From: Brian Reed <breed@bigpond.net.au>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Saturday, 18 June 2011 12:23 PM
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC

 
Hi Greg,
 
You and Micheal are both correct to a degree. As I remember from the first Bateman's Bay meet (and I think it was Rudi who had the info), some non difflock syncro gearbox cases had the appropriate bit of casting to accept a difflock (a little drilling was required), and some did not.  The appropriate loom and vacuum lines may, or may not, also be present in a non difflock van. However, as Rudi has now been able to engineer these difflocks even into T2 boxes, I'd imagine he could also do this for any-one unfortunate enough to have the wrong style of case.
 
Brian.
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of greg esposito
Sent: Saturday, 18 June 2011 10:51 AM
To: Syncro_T3_Australia@yahoogroups.com
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC
 
 
Diff lock can be added to the front or rear of any syncro. If you have no locks you just need to add the vacuum circuit and warning light loom - no biggy. Greg E
 
From: Michael Rayner <mallaner@gmail.com>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Saturday, 18 June 2011 9:38 AM
Subject: Re: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC
 
Brian
 
Enjoyed and concurred with your comments re VC. However the comment "and a diff lock (if you don't already have one) would be a higher priority" is not always applicable, as my understanding is is that not all synco's are adaptable to the retro fitting of a diff lock.
 
On 18 June 2011 00:11, Brian Reed <breed@bigpond.net.au> wrote:
 
Apologies to Ken & Les, I didn't get to read all your posts before making my most recent.
 
Anyway, it seems we are basically in agreement. Sam's best bet would be a standard replacement VC (my bias is that that is every-one's best bet). Things may be different now, from when I bought mine over a decade ago, but new, rather than rebuilt, was the go then. The cost savings were not that great, and the reliability of rebuilding (which seems a bit of a black art) was very much questioned back then. The dollar will help now as well. I got mine from Derek Drew in USA, but there are probably more vendors around now. If I recall, a new VC was cheaper than a decoupler anyway. Not sure if it still is.
 
And as Les says, good tyres and a diff lock (if you don't already have one) would be a higher priority than a modified drive train.
 
Brian.
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Brian Reed
Sent: Friday, 17 June 2011 11:29 PM
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC versus good standard VC
 
 
Hi Les and Sam,
 
I rarely buy into these VC discussions these days now that I have the T5 (Haldex instead, although similar in practise). However, the experiences Les relates parallel my own from my T3 days, and explain why I always maintained that decouplers were a retrograde idea. It's always at that moment that you most need it, that you happen to have the decoupler 'out'.
 
And I don't believe that a properly functioning standard VC has that many limitations. As I understand it's function, due to the thixotropic nature of the fluid, the standard VC will lock solid (ie 100% torque transfer) within 1/6th of a wheel turn if there is sufficient wheel slip at either end. An 'aggressive' VC might reduce this to 1/12th or 1/20th of a turn. This might be a slight theoretical advantage in sand, where that 1/6th turn might allow a wheel to 'dig in',  but it's hard to see a difference anywhere else. They are still both capable of rapid 100% lock-op when required. The standard VC allows a sufficient amount of low variability of speed (a figure of 6% comes to mind, but it's a long time since I checked) between front and rear axles for normal turning on hard surfaces, where the aggressive one is a bit short in that department, and so stresses the rest of the drive train.
 
The popularity of decouplers and tight VC's, or solid shafts, seems to be predicated on the idea that the standard VC will 'slip' and fail to transfer the required torque in severe conditions, but in fact, as I understand it,  the more severe the conditions, the stronger the 'locking' characteristics of the VC. I can back this up to a degree, as there once was a time (following an accident that pushed on a rear wheel) when I was driving around for a couple of weeks with what turned out to be a destroyed spider gear in the transaxle, which meant no drive to the rear axle (no diff lock either). Thus I had a totally front wheel drive Syncro. If the VC allowed much, or any, slip when the rear wheels had no effective 'traction', it would have been felt like a 'slurring' automatic transmission. This was completely absent, and I only became aware of the extent of the transaxle damage when some rather grumbly noises developed as the 'bits' shifted around, and at the subsequent rebuild.
 
Brian R.
 
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of Les Harris
Sent: Friday, 17 June 2011 12:03 PM
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC
 
 
Sam,
Unfortunately, the only way to determine if a VC is aggressive or not is to run it in a vehicle!  
As to how to determine if a VC is “too aggressive”, we again face the problem of attaching meaningful numbers.   Some owners have had the experience of stalling the engine on full lock, grippy surface turns.   (This happens because the VC is trying to drive the front and rear axles at the same speed.)   This probably represents the upper end of the usability range.
I must stress that the gearbox load imposed in such manoeuvres is actually far higher than ordinary point to point driving.  This level of aggression is therefore acceptable.   Sadly, the Syncro gearbox is not as strong as it could have been, given the capabilities of the vehicle.   This is something that was probably not evident to the designers until the vehicle went into service.
Binding on slight turns (your last paragraph) would be very difficult to detect.   About the only way to determine that would be on a smooth concrete surface where you could hear tyre chirp at low angles of steering input.   At any level of aggression less that that, the end result is still advantageous.
Ultimately, discussion on levels of aggressive response is hampered by the fact that we can’t assign a value and an unavoidable level of subjectivity is introduced.
I got an object lesson in aggressive VC versus two wheel drive one never-to-be-forgotten night.   I was coming off the Western Ring Road on a long downhill flat cambered curve when the road was awash with rain.   The driver in front of me got into trouble and drifted into the outside lane.   I headed inside him, normally a piece of cake, and found myself travelling sideways in several tons of Syncro.   I had just come out of a service station and had not re-engaged the decoupler!!!!!
I had another lesson when I was joining the Princes Freeway one wet night and the car in front of me baulked.   I hit the brakes, normally a very safe option, and got lock-up on several wheels, again because I had not engaged the decoupler.  
Les
 
From: Syncro_T3_Australia@yahoogroups.com [mailto:Syncro_T3_Australia@yahoogroups.com] On Behalf Of heysamuelarnold
Sent: 17 June 2011 11:28
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] Re: Aggressive VC versus Sports VC
 
Hi Les,

Many thanks for the detailed reply. I think that I am looking for an aggressive VC then. I guess that the question left for me is, how can you tell if your aggressive VC is possibly too aggressive? I like the idea of driving in AWD most of the time, though using the decoupler before making tight turns. Though if driving most of the time with an aggressive VC on, are you damaging gearboxes or other parts of the driveline? If you are pulling off the highway and notice binding on slight turns, then that is the sign then that the VC has become so aggressive as to be driven mostly decoupled?

Sam






--
Regards

Michael

Michael Rayner East Light Photography
PO Box 144
MALLACOOTA  VIC  3892

MOB: 0409 241 672
BUS:  0351169401
A/H:   (03)5158 0346

Web:   www.michaelraynerphotography.com.au
Email:  michaelrayner@exemail.com.au