Graham, BenT, Theo and All,
Thanks for the timely pics Graham ... saved me a lot of work!
I've modded three of those pics and they are attached. Two pics simply show where the relevant bush needs to be positioned to be in any of 1st-2nd or G-Reverse or 3rd-4th gear alignments. The other pic shows where the gear selector is aligned (distance is outside of left bush to outside of right bush) when neutral is selected.
BenT, concerning your figures: ...
W1 = 72mm is good. The available distance (space) between the inner edges of the left and right gear selector metal guides fixed inside the gear selector housing is approx. 73mm. So that gives a 1mm greaseable slack space to permit the 72mm wide selector forks assembly to slide forwards and backwards, which is what happens when it is in 1st-2nd gear alignment.
W2 = 66mm is good. This establishes that the "working" outer faces of both bushes are each nominally 3mm thick (ignoring the taper issue for now).
W3 = 59mm is good ... I think, it may though need clarification. This establishes the "non-working" inner faces of each bush. So by deduction and accepting that the thickness of the selector fingers are both 3mm thick (see my drawing), then deduct 2 x 3mm = 6mm from W2 (66mm), that leaves 60mm. So from that 60mm, deduct W3 (59mm). That leaves 1mm, which, when divided in two, establishes that the thickness of the moulded-on inner (non-working) sides of both bushes are each approx. 0.5mm thick. That's pretty thin!
Co-incidently, I happened to find hidden in a glob of grease on the floor of the gear selector housing a remnant of the LHS bush. Close inspection confirmed that the "working" side of the bush had indeed worn down in thickness over time, however the striking thing though was the fact that it was the thin-ness of the "non-working" side of the bush that had also worn and subsequently split/cracked, so causing the bush to fail and fall off. So clearly in my view, that thin side of the moulded bush is the "weak link in the chain".
H1 = 20mm and H2 = 15mm are both good.
H3 = 13mm/14mm and H4 = 15mm/16mm are partly good, though partly unexplainable. I accept that H4 must be taller than H3. That RHS bush ought to have a sloping (angled) top edge from inner face up to outer face as that slope (angle of 62 degrees) correlates with the sloping (angled) underside of the RHS gear selector metal guide for the G-Reverse gears alignment. See my modded pic where I've marked it ... the slope is clearly showing on the underside of that selector guide.
What I don't understand is the purpose for that RHS bush also having a top edge slope in the other (length) direction as well, as explained by BenT. It doesn't make any sense to me if for no other reason than it isn't needed ... serves no purpose nor advantage. So I would fabricate this bush with the firstmentioned slope and ignore the lattermentioned slope.
Bare in mind also that when deciding on how tall to fabricate H4, a taller height affords a more secure G-Reverse lockout, whereas a less tall height affords a less secure lockout, paticularly if the height gradually wears down over time.
BenT, the two other dimensions I listed/sought dimensions for were the L1 and L2 (length ) of each bush. If you could please measure the length of both bushes and advise. Thanks.
For fabrication purposes, it seems to me the RHS bush can only have a maximum length of 21mm. This is because, shaped into the leftside underside of the gear selector guide is a 21mm long slipway located midway along the length of that guide. This is the position to where the selector forks by default shifts to when you commence to shift out of either G or Reverse and it then automatically aligns with the slipway so as to exit left sideways when directed to and the gearshift then springs back up into either of the 1st-2nd or neutral alignment positions, depending how far you push the gearshift sideways. So I intend fabricating that RHS bush at 21mm long. I'll probably start with a 12mm thick bush and trim it down, as fine tuning proceeds.
I think that in fabricating this pair of bushes, the RHS bush is the most critical in terms of functionality and fine tuning as it needs to be able to engage each of 4 gears AND provide the G-Reverse lockout AND be shaped on its top edge to be able to also slip sideways out of the G-Reverse alignment .... correctly, (not too easily and not too much resistance). I also think how thick you make either/both faces of this bush has a major bearing upon your success or not at aligning/engaging each of the 4 gears. So understanding the functionality and alignments first and then dabbling in some trial and error as well is the order of the day on this bush when it comes to the fine tuning stage. I think the correct order then for fabricating these bushes is to fabricate & fit the RHS bush first. If one gets it to function correctly, then the fabrication of the other bush is self evident, less problematic, particularly as it only has to engage 3rd-4th gears. At the moment, I'm still in favour of fabricating the thickness of the LHS bush at 12mm slip fit into the available LHS guide slide space of 12mm. This offers the best opportunity to get rid of as much gearshift wobble, certainly for 3rd-4th gears. I'm also thinking I'll first trial a LHS bush length of at least 30mm, maybe even longer. I believe that what that will do will eliminate excess gearshift wobble (swimming) when its in the neutral position also. Nevertheless, if I find its too long and causes gear change difficulties between any gear and neutral, well I can simply trim its length bit by bit to get it working how I'd like it to.
Finally, concerning the perceived moulded "tapering" of the bush facings, this is because when the gearsfift nob is moved fully sideways left to right or right to left between 3rd-4th and 1st-2nd end stops, the gear selector fork at the bottom is correspondingly moving (in the opposite direction) sideways also, but is following an arc (circumference) segment that is approx. 95mm in length. So because its following a circular path, when the bush reaches either extremity stop, the face of the bush needs to have a tapered face to fully mate with the angled stop at each end. Now this is where the final fine tuning comes into play. If its felt that the thickness of either side face of the RHS bush is preventing any one or more of 1st-2nd and/or G-reverse gears from aligning/engaging smoothly, then tapering the culprit face of the bush is an option to trial (after physically re-checking the actual gear alignment postions!) .... this probably will make the difference in achieving proper engagement of those 4 gears.
All part of the fun, a learning curve and what else have we all got to do anyway?! ... haha.
Feel free to pick all this to bits .... I probably will still learn something more I haven't thought of yet. Cheers.
Ken
To: Syncro_T3_Australia@yahoogroups.com
From: g.adams2@bigpond.com
Date: Sat, 12 Feb 2011 22:49:14 +1100
Subject: Re: [Syncro_T3_Australia] RE: Gear selector
Ken,BenT and all
I happened to start overhauling my gear shift just as Ken raised this issue.
I tended to use the trial and error approach rather than Kens to be commended scientific approach but his and BentTs info has been invaluable.
For those that dont know what we are talking about .Here it is.
Pic 884 Very worn left side aluminium cast selector , rebuilt by alloy welding and then reprofiled. RHS is welded steel.
Pic 885 Position of same in selector box above spare wheel.
Pic 892 Reprofiling same
Pic 906 Fork refitted without new plastic bushes showing large clearances.
Pic 914 Bushes made from very hard dense plastic drilling left rough for better glueing.
Pic 920 LHS New bushes glued in Araldite.10mm wide giving minimal clearance. Sliding fit.
Pic 921 RHS again minimal clearance.Now covered in Lithium grease
Ken and I figure that overall bush widths vary from 12mm for Ken and Yurick to my 10mm to BenTs original equipment 6.5mm so maybe VW took the easy sloppy approach whereas we are looking for perfection.My gear stick now has a sideways wobble of 5mm max on the knob in gear.
Have now replaced rear linkages and new bellows (Just Kampers) and both hydraulic cylinders.All have given 20 yrs service.
Please anyone how do you adjust the clutch master cylinder adjustment which is situated above the master cylinder behind the lower steering column behind the crumple bar.? A VW mech said to remove instrument panel,brake master cylinder and booster and go in from the top.He wants $250 for his trouble.
I tried and gave up at the booster.
Cheers Graham
----- Original Message -----
Sent: Saturday, February 12, 2011 12:28 PM
Subject: Re: [Syncro_T3_Australia] RE: Gear selector
No worries. I forgot to mention that it looked to me as if the the metal forks, besides not being centered in the bushes that they are not even straight in them. This is why I came to the conclusion that the tolerances are based on the finished assembly rather than a specific thickness on each surface as Yurik has pointed out. Or perhaps these specifications are not as critical.
On another forum, a member of the group made his own intermediate bushes. That was on a 2wd. He attributed the disappearance of slop in his shifter to replacement if that piece.
BenT
Sent from my mobile device
BenT,
Thanks a lot for the figures, I've studied them to some degree but unfortunately I'm caught up here on the domestic front at the moment.
I will respond with a few comments and perhaps a few queries as soon as I can ok. Thanks.
Cheers.
Ken
To:
Syncro_T3_Australia@yahoogroups.comFrom:
syncro@gmail.comDate: Fri, 11 Feb 2011 00:32:18 -0800
Subject: Re: [Syncro_T3_Australia] RE: Gear selector
Here's the figures as promised. Just a caveat. I only have one spare NOS shiftrod. All these measurements were taken with a machinist's caliper. Measurements were checked twice for accuracy.
W3 = 59mm
W2 = 66mm
W1 = 72mm
H1 = 20mm
H2 = 15mm
H3 = 13mm short side inner edge
H3 = 14mm tall side inner edge
H4 = 15mm short side outer edge
H4 = 16mm tall side outer edge
There are two sets of H3 and two sets of H4 measurements because the right fork has an angled top. See attached pic.
The bushes also taper top to bottom (between the forks). The inside corners are then radiused. The taper is minimal but at 1.5mm difference on either side at 12mm from the top. Let's call that W4. That means W3 + 3mm = W4 or W4 = 62mm.
The bushes appear thicker on the outer edges. In other words, the metal forks are not exactly centered in bushes. I do not know if this is intentional. It would appear to me that the critical dimensions are that of the complete assembly. Meaning the bushes appear to have a secondary use as a way to correct slight variances in the space between the fork. I think of it as putting a stick in a Popsicle. Popsicle shape and size is the same regardless of where the wooden stick is embedded in it.
I hope this make sense to someone besides myself. I sometimes have to think in one language then translate into American English. Then adjust for OZ. There often unintended consequences.;-(
Regards,
BenT