Club 80-90 Forums

ninja.turtle007 wrote: I've ridden motorbikes for years and the rear tyre always wear before the front. Sometimes 2 rears to one front.

Yup thats true, I used to ride bikes myself and sometimes Id wear a chain out quicker that a front tyre. Bikes is bikes though ...

I know it seems a bit odd but I assume you it is true. Just rotated my wheels the day before last and the fronts had worn more than the rears.

Okay, I have I have learnt something new. Thanks.

Sorry, I got the 6% figure from Volkswagen. But it turns out that this information, like much from Volkswagen, is not exactly accurate. The fact is that the VC is ALWAYS engaged to a certain degree. So, it doesn't take 6% differential rotation for traction to reach the front wheels..... traction is always reaching there..... but the FORCE of the traction is low and relatively stable until the VC suddently turns superhard. You can verify this yourself by seeing how difficult it is to turn one front wheel with your hands while the other three wheels are on the ground..... there is resistance force ALREADY out of the box with the VC. I think we should look at the 6% number as a guideline recommendation from an engineer associated with VW as the percentage number which would be known to fry the VC in extended use. That's all I would be able to draw a conclusion about it at the moment. The writings you refer to are from very early on.... around 2000 or so, and we have learnt a lot more since then.

PetenAli wrote:.......(this seemed a good idea because using this rotation each pair of tyres is always on the same axle). It then dawned on me that the new tyres (which are currently on the back) have a greater rolling radius than the fronts and would this damage the VC? The new tyres have a tread depth of 12mm and the old ones (on the front and the two spares) are 9mm.



I'd be very grateful for any comments that the engineers and other knowlegable people on here may have.

Thanks,

Pete

I'm missing something here and hope I get to understand it before I lose a transmission. The way I see it if you have (as in this case) 9mm tyres on one axle and 12 mm tyres on the other then the rolling radius of each axle is different (forget percentages for now) so leading to wind up as Pete says.

So is it it not better to have one 9mm and one 12mm tyre on EACH axle, thereby the rolling radius of each axle is the same so no difference for the VC to take up. The difference in rolling radius of each wheel on the same axle being allowed for by the axle differential.

Regards

Peter

syncropaddy wrote:

slobbo wrote: It can be seen sometimes when that wheel 'jumps' and is felt through the steering wheel.

Im experiencing this, but only when on full lock, and turning the vehicle around at the end of our cul-de-sac. I can clearly feel some stress, slow down, and then one of the front wheels jump whilst carrying out this manoeuvre of turning the vehicle around 180 degrees with full lock on.

Cause for concern? Anything I can do to check system? Have considered putting Syncro up on four axel stands to check all 4 wheels rotate when in gear.

The above is experienced with four exactly, brand new tyres, 205/70/R14

all syncros with a functioning VC will scrub on full lock ime, because they have such a good turning circle, much better than a LR90 of the same effective wheelbase, but the VC is acting as a damper and can dump/absorb the majority of wind up induced in normal driving so only noticeable on full lock, often more noticeable when cold as VC behaves a bit stiff when cold - check out the VC performance spec graph
test is hot transmission can it do it (turn on full lock) in G gear with no throttle without stalling or feathering the clutch, if so then VC ok(maybe ish, maybe fine this test is not definative)

Ah, that makes sense Aidan, will try it in G Gear! Thanks mate, put my mind at rest.