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Re: Handling setup advice please

Posted: Mon Jun 23, 2014 10:51 pm
by Piledriver
Half a degree or esp more toe out on a street driven ACVW vehicle is dangerous.
Perhaps the 1/2" spec works for the example given, a sand rail?

Spec from the Bentley manual for a T3, but the rear is ~same

Rear wheel camber: double joint: -1 degree 20' +/- 40'
max difference between sides double-joint 45'

Rear wheel toe with correct camber:
Double joint rear axle:
5' +/-15' (that's 5 seconds, or 1/60th of a degree, not bloody 1/2 degree)
max deviation 10'

I have the SA specs too, but do not want to cloud the issue.
Any significant rear toe out on an ACVW is dangerous.

It SHOULD be toed out 5' +/-15', which is basically translates to as straight ahead as you can set it.

Re: Handling setup advice please

Posted: Tue Jun 24, 2014 12:03 am
by carl4x4
Thanks for the feedback, what do you think about fitting a rear anti-sway bar? bearing in mind the Red9 system doesn't have a front sway bar - Red9 say it doesn't need one as it's stiff enough due to it's design.

Re: Handling setup advice please

Posted: Tue Jun 24, 2014 1:25 am
by helowrench
I would drive it, hard, before I made that decision.
your butt will tell you which end is trying to step out.

apparent understeer, or push, would mean add rear sway bar, or lower front tire pressures. (if you can ,you need a pyrometer to check temps across the tire surface), oversteer, rear stepping out, meanr less rear sway, or drop rear tire pressures.

Re: Handling setup advice please

Posted: Thu Jul 17, 2014 4:06 am
by carl4x4
As an update, I have re-done the camber & toe settings front & back. Rear is now 1 deg neg camber, plus toe in 0.2deg, front is 0 deg toe, with 1.5 deg neg camber.

Also changed to a 370mm steering wheel (from a 350) which has made quite a marked difference to the ease of steering which I'm pleased about. The geometry changes have had a positive effect, the delayed feeling of the rear turning after the front at speed seems to have almost gone which is a relief as it was quite un-nerving!
There is still however an odd feeling of the rear swaying a little when you change lanes on the motorway (the rear still does not give me huge confidence to push the car) My guess is that this is because the front is quite solid with the the Red9 wishbones & coil overs, whereas the rear is still torsion bars (albeit type3 spec)

The plan is to stiffen up the rear shocks a few more clicks and fit an anti-roll bar at the rear of the car to stop the slight swaying feeling. Also contemplating raising the front an inch or two on the coil-overs to match the rear more as there's a great article here http://www.aircooled.net/vw-handling-suspension-tuning/ where the author had good results raising the front suspension rather than lowering it !

Re: Handling setup advice please

Posted: Thu Jul 17, 2014 4:55 am
by helowrench
Good to hear of the forward progress.

What tire pressures are you running, currently?

Re: Handling setup advice please

Posted: Thu Jul 17, 2014 6:38 am
by carl4x4
helowrench wrote:Good to hear of the forward progress.

What tire pressures are you running, currently?
Actually you've just reminded me I haven't checked the rear tyre pressures since I was on the rolling road a couple of weeks ago. I suspect they could still be quite high as they pumped them up when on the rollers. Fronts are about 19psi from memory.