Pros and cons of a solid drive

The matter of using a solid (no VC) drive and decoupler comes up on
the several world Syncro sites fairly regularly. There are a couple
of basics to keep in mind.

This arrangement is said to be suitable for sand driving but is very
limited for general gravel/forestry road driving and an absolute no-
no for bitumen.

Except for driving in an absolute straight line at low to moderate
accelerator settings, all four wheels travel at different speeds.
When steering is applied, the differences become much greater.
Since the front and rear axles are locked together, something has to
give and what gives is the traction of one or more wheels.

The situation then becomes one in which traction to one or more
wheels is lost at the very time that you need it most - the opposite
to what is most desirable. Whilst this is said to work well in
sand, it works less well on unmade road surfaces and this includes
winding your way down a difficult slope. Locking any wheel is the
last thing you want.

On bitumen surfaces, the strain imposed on the gearbox, front diff
and all CVs becomes dangerously high and will always eventually
result in very costly failures in the driveline.

All motor vehicle design is a compromise, which is why we can't buy
a vehicle that is faster than Schumaker's Ferrari, seats ten people,
has a built in jacuzzi and gets 100 km per litre. Fitting a
decoupler but leaving the VC in place offers the best compromise for
safe traction on a very wide variety of surfaces. I again state
that the solid drive is said to be the best drive for sand, but the
VC/decoupler combination will cover everything else very efficiently.

Les
Gday Les,

Am I talking here about the same thing as you or not please?

At the VW Nationals Show in April I bought a VAG Service publication
called "Volkswagen Transporter and Caravelle Syncro ... Construction and
Operation" Self Study Programme/No.66

It's full of colour graphics showing all the main working parts to do
with the Syncro drive train and an explanation of how they all work.

On Page 28 it shows a colour graphic detail of an optional
engageable/disengageable 4WD gearbox where there is no VC at all,
instead in its place there is a lengthened straight through pinion
shaft. The 4WD is engaged or disengaged via a Bowden cable or else by
use of the cross-country gear.

So the question remains .. are we talking about the same thing? Maybe,
maybe not. If so, then VW designed and manufactured it and surely
someone has this set up. If you like I can email you a scan from the
publication of what I believe may be relevant. Thanks again Les for all
your informative info. Cheers.

Ken


--- In Syncro_T3_Australia@yahoogroups.com, "Leslie C E Harris"
<leslieharris@...> wrote:
>
> The matter of using a solid (no VC) drive and decoupler comes up on
> the several world Syncro sites fairly regularly. There are a couple
> of basics to keep in mind.
>
> This arrangement is said to be suitable for sand driving but is very
> limited for general gravel/forestry road driving and an absolute no-
> no for bitumen.
>
> Except for driving in an absolute straight line at low to moderate
> accelerator settings, all four wheels travel at different speeds.
> When steering is applied, the differences become much greater.
> Since the front and rear axles are locked together, something has to
> give and what gives is the traction of one or more wheels.
>
> The situation then becomes one in which traction to one or more
> wheels is lost at the very time that you need it most - the opposite
> to what is most desirable. Whilst this is said to work well in
> sand, it works less well on unmade road surfaces and this includes
> winding your way down a difficult slope. Locking any wheel is the
> last thing you want.
>
> On bitumen surfaces, the strain imposed on the gearbox, front diff
> and all CVs becomes dangerously high and will always eventually
> result in very costly failures in the driveline.
>
> All motor vehicle design is a compromise, which is why we can't buy
> a vehicle that is faster than Schumaker's Ferrari, seats ten people,
> has a built in jacuzzi and gets 100 km per litre. Fitting a
> decoupler but leaving the VC in place offers the best compromise for
> safe traction on a very wide variety of surfaces. I again state
> that the solid drive is said to be the best drive for sand, but the
> VC/decoupler combination will cover everything else very efficiently.
>
> Les
>