A2 Jetta Ride Height...

[rmicroys]

I've got a suspension/ride height questions... I've recently had to rebuild my front suspension following an accident at Mosport in my Jetta.

The suspension is the following:

Front: Koni Sport Adj, Afcoil threaded coilovers with 550# springs
Rear: Bilstiens with 400# springs

I'm wondering how one should determine one's ride height. Where to measure it from? What I should likely set it to for best results? Of course, this also may require the car to be corner weighted too, and I can get that done locally too.

Ultimately, I know that the lower a-arms should be flat to reduce bump steer, so I don't want to lower the car too much. I know that SCCA IT classes prevent much playing around with suspension components, but has anybody developed anything to allow better geometery? I have seen some people run a spacer under the ball joint and flip the steering rack rod end to be under the steering knuckle instead of on top...

Any ideas/suggestions?

 

[Bill Miller]

The balljoint spacers and the flipped tie rod ends are not legal in IT. The tie rods require that you modify the knuckle.

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MARRS #25 ITB Rabbit GTI
SCCA 279608

 

[rmicroys]

Originally posted by Bill Miller:
The balljoint spacers and the flipped tie rod ends are not legal in IT. The tie rods require that you modify the knuckle.

I know that, that's why I mentioned it in my post - so that's just part of the question.

But what settings would you guys normally use? So do people lower their cars as much as possible, and set it to the point where the bump steer is just managable, what are people's opinions on this?

Ride height, toe, camber?

 

[Bildon]

>> I'm wondering how one should determine one's ride height.

>> Where to measure it from?
Anywhere that is consistent. We measure from the rear bolt of the front control arms and the rear axle beam mounting plate.

>>What I should likely set it to for best results?

Depends. Use your flat control arm theory at first and lower it to there. Later if you play with stiffer springs you may get away with a lower setup.

>> Of course, this also may require the car to be corner weighted too

Absolutely. That's the most important part.

>>toe, camber?

Toe: Do you have solid or compliant bushings? And it depends on your camber. Try 1/8th out front for starters. Rear depends on whether your car oversteers or not.

Camber: Depends on tires, track, but mainly temps. Get a pyrometer.

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Bill Sulouff - Bildon Motorsport
Volkswagen Racing Equipment

 

[rmicroys]

Originally posted by Bildon:
> Anywhere that is consistent. We measure
> from the rear bolt of the front control
> arms and the rear axle beam mounting plate.

Sounds good.

> Depends. Use your flat control arm theory
> at first and lower it to there. Later if
> you play with stiffer springs you may get
> away with a lower setup.

Again, not bad advice either...

> Absolutely. That's the most important part.

Shouldn't be a problem getting the car corner weighted.

> Toe: Do you have solid or compliant bushings?

Right now I use OE rubber - and have some poly on order - but likely they are not going to get in to the car in time for my next race.

> And it depends on your camber.

> Try 1/8th
> out front for starters. Rear depends on
> whether your car oversteers or not.

an 1/8 toe on the front? Wouldn't that make a car quite darty? Is it to adjust the car's characteristics under cornering and braking. When the suspension squats, does it induce toe-in?

> Camber: Depends on tires, track, but
> mainly temps. Get a pyrometer.

Running Toyo RA-1s, 205/50/15, currently with 3deg of camber on the front. Promotes fairly good wear. I'm certain the rears can get more camber.

 

[Bildon]

>>an 1/8 toe on the front?

Yes. Toe out.

>> Wouldn't that make a car quite darty?

Race cars are darty.

>> Is it to adjust the car's characteristics under cornering and braking. When the suspension squats, does it induce toe-in?

It's to compensate for your rubber bushings. Under power the axle torque will toe your wheels back in. Once you've gone to harder bushings it will still be advisable to run some toe out becuase it improves turn in greatly...furthermore the more camber you put in the more toe out you need to ruduce straight line scrub.

>>I'm certain the rears can get more camber.

Again, get a pyrometer and only put in the min. camber you need. Camber causes scrub which will slow your straight line speed.



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Bill Sulouff - Bildon Motorsport
Volkswagen Racing Equipment

 

[rmicroys]

Excellent, thanks for the info - that's pretty much exactly what I was looking for. Now the trick is getting it all set just 'right'.