Handling setup advice please

VW underneath a classic Italian body design.
carl4x4
Posts: 77
Joined: Wed Jul 20, 2011 2:32 pm

Handling setup advice please

Post by carl4x4 »

Hello, I haven’t posted for a while but have been lurking reading posts ☺
recently managed to get my Ghia onto the road after a three year restoration.

I’m looking for some advice on setting up the handling as most of it is all new so I’m working my way through the list of snags and things to set up as I put more miles on the car.

The setup is as follows;

Red9Design front suspension – dual wishbones with adjustable coilovers for height & spax adjustable shocks
Steering is Red9 rack & pinion conversion.
Rear has had an IRS conversion, plus adjustable spring plates & spax shocks to match the front. The rear torsion bar has been upgraded to a squareback one (I forget the thickness but from memory it was thicker & stiffer)
Tyre pressures – 18psi front, (175 tyres 5.5” rims)
- 28psi rear, (185 tyres 5.5” rims)

Done so far to get the car on the road;
- Rear IRS arm camber adjusted to give 0 degree camber at the rear
- Front tracking set up to give 0.5 degree toe-in

I am conscious that I haven’t set up the camber on the front yet and will be doing so this weekend with the top concentric ball joint. Not sure if the caster needs setting up yet.
The ride comfort is surprisingly good! but the car has a strange handling characteristic at the moment which is when you change direction at speed (over 40mph) it feels like there’s a delay and the rear then follows the front about ½ second later. Sort of sways changing lanes on the motorway rather than being precise.
This could be that the rear shocks are not set stiff enough compared to the fronts, but I was contemplating if a rear anti-roll bar might help tighten up the rear as the front seems a lot more planted than the rear.

Any advice would be appreciated thanks ☺

Here’s some pictures of her completed (used to have a build thread on here I must dig out &
Image

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helowrench
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Joined: Wed Aug 11, 2004 6:20 am

Re: Handling setup advice please

Post by helowrench »

Is your rear camber set with weight on wheels and an additional dummy weight of 100kilo in the car, and what is the rear toe?

Also. Tire pressures?
carl4x4
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Joined: Wed Jul 20, 2011 2:32 pm

Re: Handling setup advice please

Post by carl4x4 »

Tyre pressures – 18psi front, (175 tyres 5.5” rims)
- 28psi rear, (185 tyres 5.5” rims)

rear camber was measured with car on the ground, but no 100kg extra
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ONEBADBUG
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Re: Handling setup advice please

Post by ONEBADBUG »

Might have too much toe in at the rear.
carl4x4
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Joined: Wed Jul 20, 2011 2:32 pm

Re: Handling setup advice please

Post by carl4x4 »

Aha! something is starting to dawn on me, when I adjusted the camber by twisting the hub the holes were slotted and the hub could slide forward or back a few mm. It didn't dawn on me at the time but I guess if I push the hub towards the front of the car it gives toe-in at the rear, and if you pull it away it'll give toe-out?

I'll check the rear alignment, is toe-out by 1/2 degree the recommended setting for IRS then?
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ONEBADBUG
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Re: Handling setup advice please

Post by ONEBADBUG »

Toe out in the rear is scary, the car is really twitchy. You want a little toe in.
carl4x4
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Joined: Wed Jul 20, 2011 2:32 pm

Re: Handling setup advice please

Post by carl4x4 »

thats what I would have thought, but this site says it should be set to toe-out; http://www.vw-resource.com/rear_suspension.html#adjust

And Aircooled.net says toe-in; http://www.aircooled.net/vw-handling-suspension-tuning/ (which sounds less scary!)
helowrench
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Re: Handling setup advice please

Post by helowrench »

Excessive toe out can give a delay, then the rear goes quickly.
Slight toe out gives zero toe under accel,,and more toe out under decel (keeps rear end behind you under panic stops)
carl4x4
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Joined: Wed Jul 20, 2011 2:32 pm

Re: Handling setup advice please

Post by carl4x4 »

helowrench wrote:Excessive toe out can give a delay, then the rear goes quickly.
That is exactly how I would describe it !

Thanks for all the feedback guys
carl4x4
Posts: 77
Joined: Wed Jul 20, 2011 2:32 pm

Re: Handling setup advice please

Post by carl4x4 »

Update: just checked the alignment by using my Dunlop gauges on the rear wheels (never done that before!) and it's showing a slight toe out of around 1/4 of a degree. But I did notice that the rear wheels at the back were at slightly different angles so I suspect I have not set each with the same toe-setting when I did the camber. (based on the fact that I didn't know it was possible :lol: )

Might combine setting this up with fitting a rear anti-roll bar at the same time seeing as it fixes to the same bolts (or could this make the situation worse?)
Steve Arndt
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Joined: Sat Mar 10, 2001 12:01 am

Re: Handling setup advice please

Post by Steve Arndt »

Half a degree of toe in on the front is quite a bit, especially for a double a arm design. What are the specs from Red9?
helowrench
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Joined: Wed Aug 11, 2004 6:20 am

Re: Handling setup advice please

Post by helowrench »

carl4x4 wrote:Update: just checked the alignment by using my Dunlop gauges on the rear wheels (never done that before!) and it's showing a slight toe out of around 1/4 of a degree. But I did notice that the rear wheels at the back were at slightly different angles so I suspect I have not set each with the same toe-setting when I did the camber. (based on the fact that I didn't know it was possible :lol: )

Might combine setting this up with fitting a rear anti-roll bar at the same time seeing as it fixes to the same bolts (or could this make the situation worse?)
When getting my baselines, the colored (I use pink) builders string gives me a nice set of straight lines to compare to.
Using a point on the chassis (don't use the body on Ghias) measure out accurately, and run string parallel down each side using jackstands or such to hold it.
then you can measure in to the wheel rims, front edge and back, and determine toe measurements.
(you do have to have straight rims for this, or you use an alternate procedure)
helowrench
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Re: Handling setup advice please

Post by helowrench »

BTW, I purchased a car that was originally set up for autocross. Scirocco II 16v
It had 7/8" of toe out on the rear------ :shock:
I did not notice it until first drive, wow, when you turned in hard and the weight shifted, the rear steered its own way around the corner.
fast around a corner, but chewed up tires quickly for street use :D

reset that one using string and the shimming procedures for the rear (scirocco) got the rears down to .005 degree toe in, and 1.5 negative camber. still handles great, but imperceptible tire wear after 10k miles.
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Piledriver
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Re: Handling setup advice please

Post by Piledriver »

helowrench wrote:BTW, I purchased a car that was originally set up for autocross. Scirocco II 16v
It had 7/8" of toe out on the rear------ :shock:
I did not notice it until first drive, wow, when you turned in hard and the weight shifted, the rear steered its own way around the corner.
fast around a corner, but chewed up tires quickly for street use :D

reset that one using string and the shimming procedures for the rear (scirocco) got the rears down to .005 degree toe in, and 1.5 negative camber. still handles great, but imperceptible tire wear after 10k miles.
For extra fun, 50 PSI in front tires and 18 in rears...
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
helowrench
Posts: 1925
Joined: Wed Aug 11, 2004 6:20 am

Re: Handling setup advice please

Post by helowrench »

Piledriver wrote:
helowrench wrote:BTW, I purchased a car that was originally set up for autocross. Scirocco II 16v
It had 7/8" of toe out on the rear------ :shock:
I did not notice it until first drive, wow, when you turned in hard and the weight shifted, the rear steered its own way around the corner.
fast around a corner, but chewed up tires quickly for street use :D

reset that one using string and the shimming procedures for the rear (scirocco) got the rears down to .005 degree toe in, and 1.5 negative camber. still handles great, but imperceptible tire wear after 10k miles.
For extra fun, 50 PSI in front tires and 18 in rears...
It already reminded me of a active rear steering car.
and I was handing it to a first time driver... so ... no.

reset everything to a very stable config. lotso rear camber (which necessitated being extremely picky with the toe in)
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