Stiffer Front Sway in FWD cars?

[762]

So I know a few people here have had experience with driving/tracking FWD cars.

My question is what is the point of adding a slightly stiffer sway bar to the front wheels. It has always been my understanding that the stiffer front bar would simply induce understeer in the same way a stiff rear bar induces oversteer.

However, some people on the VW forums were discussing that the stiffer front bar could help disappate camber loss. Is there any truth to this? or is there really any reason to add a stiffer front sway bar to a FWD car?

[ken o]

No. Add it to the rear. You want to add the bigger bar to the opposite end you want to keep planted. Wheels on ground = power.

[762]

Yeah, that is what I thought. Which is why I already bought the biggest rear bar made for the car. However I still have a 150 dollar store credit with the company so I figured I would see if anyone had opinions for the front bar.

[ken o]

You could buy something for an M3.

[goofygrin]

So... I was talking to someone (an older than Ken guy, so you know, really old) and he mentioned that on some of the older VWs in the stock class, the way to go fast was to put a REALLY big front bar on and then, for some reason, it just worked well that way.

Not saying that's the same for you, but maybe.

$150 gets you started on a nice set of brake pads. Don't get HP+ or HPS though. Sucky pads for front heavy cars.

[Miatamoto]

I've heard Andy Hollis talking about that concept with FWD cars, but I think it pertains to cars with massive body roll and limited dynamic camber curve. I think the stiff chassis and limited body roll in your car would lead to understeer with the addition of a big front bar.

Of course you might not need the biggest rear bar in the catalog with the addition of that fancy suspension and camber plates you're getting. The balance will be a combination of your alignment, spring rates, and swaybars.

[762]

Unfortunately my 150 dollar credit is with APR and APR only makes the bigger ticket items such as $6000 380 hp turbo kits. Nothing reasonable like brake pads .

However, I actually have been talking to their motorsport group, and it seems they may be able to do a custom ECU tune for me without altering boost levels for when I run SCCA classed events. As well as I am trying to get alignment specs from them. The APR Koni Challenge GTI's have won 3 events recently so I figure they must be doing something right.

Also Ken if you come out to the Texas Time Trials I would consider buying something for the M3. I am thinking an exact dummy of me to sit in the passenger seat so you could go fast even when I am not there in person.

[miata_racer]

A larger front bar will reduce roll a LOT on the MkV. They have no damn camber up front at all. And no camber change with ride height given the Strut suspension design up front.

A big front bar will limit camber loss thus yielding better times. They do work.

Also I found on my MkV GLI that about 1/8 toe our F and R as well as 0.5 neg camber out back helped with rotation a LOT :)

[762]

hmm interesting. Would you still recommend the front bar on a car with stiff suspension. The car will soon be on AST 4100's with Vorshlag adjustable camber plates that can give me around -3 degrees.

With that in place do you still think the front bar would be effective?

[Davidss]

With that in place do you still think the front bar would be effective?

Maybe it will maybe it won't.

Change one thing at a time. Then test. That is the only way to know for sure.

[PTPForrest]

The APR front bar is adjustable and from what Ive read it compliments a rear swaybar very well. I agree with David that it is very important to keep the changes to one thing at a time. I usually get my DE and autocross customers to go with swaybars first, coilovers second.

Let me know when you get your coilovers, I'd love to see them.

[Vandit]

I'd probably wait till you did the suspension work w/ all the new negative camber dialed in up front before considering the bar. I bet the camber alone is going to help tremendously.

[762]

Yeah I will drive with the new suspension before I do the bar. My actual current worry is the ASTs are too soft. It may just be the dampening but compared to my bilsteins they do seem softer. However, I will see if they actually are softer during the texas time trial this weekend.

Also Matt (previous owner and employee of Vorshlag) said the spring rates were 350 in the front 250 rear. If my understanding is correct I should want a stiffer rate in the rear to help rotation. So I guess maybe I can consider buying new springs.

We were only able to get -2 degrees front camber because any more requires the removal of the adjustment turrets to change dampening. The strut towers just block any further movement.

[762]

Well I finished the texas time trials, and I got a very interesting first response from the ASTs. First off is that the car, compared to my previous Bilstien Sport + Eibach Sportline setup, now has much much more body roll. This is not good because it unnerves me and does not inspire confidence in the grip levels. However, speaking of grip, oh my god. There is so much of it, I was constantly under driving the car. Instead of just pushing on through the body roll to the real limits of grip I would let off. However, one lap I did manage to get the tires to squeal more I ran a 43.75 which was very quick. Up there with David's C5 Z06 and Robert Jones' S2000 CR.

So now the question is, besides learning to drive through body roll, whether or not I should go with the stiffer springs or the front sway bar first. The front bar will probably run me 100 dollars because of my store credit, so that may be the first step.

Also how exactly will ride height factor in to the equation?

Even though the car would stay neutral and not really understeer unless I lighted up the front wheels. Turn in remained slightly delayed. I am currently running 0 degrees of toe in the front. Would the front bar and springs help alleviate that issue or is it purely me just needing to be more aggressive with the toe settings.

[CosmosMpower]

Sounds like you need a stiffer spring rate.

[jrj512]

The beauty of the ASTs is that you can run very stiff springs and still maintain your street ride quality. I am running 700# front and 450# rear springs. The car has little roll on the track and it is very livable on the street.

[Miatamoto]

Sounds like you need a stiffer spring rate.

+1

Don't be afraid to go with stiffer springs on the ASTs. The shocks/struts are incredible and can really control some serious spring rates.

jrj512's car with 700/450 spring rates is more comfortable on the street than his old stock class setup with Koni's and stock springs.

[762]

Ok so I heard back from Vorshlag, they recommend 500 being the highest because anymore would be pushing what the shocks are valved for. So now I have to determine which rates and I am a complete novice here. I understand stiffer springs in the rear promote rotation and softer front springs aide in front grip. Where does it matter though that most of the weight is forward or is that important at all?

Currently it is 350 ft lbs Front 250 Ft Lbs Rear. Does anyone have any recommendations concerning any form of tuning?

I may be getting my strut towers cut to get full adjustment out of the camber plates and it would be nice to do all this at once. (Would this move me out of STX?)

The cap of the strut tower being cut off would look like this

[goofygrin]

Any idea on your suspension what the effective spring rate will be? On some cars (Evo 8/9), the rear springs are inset on the suspension arms and the effective rate is something like 2/3 of the nominal rate. Just something you might keep in mind.

[762]

Unfortunately I have no idea. No one has done much performance suspension work on the GTI here in the states concerning all this technical stuff.

The only thing I have heard was that 9k front (500 ft lbs) and 9k rear was to much oversteer for street tires in the rear. However the guy who posted that I think referred to street tires as like a general exclaim, and a "race" tire as something such as a XS or RE11.

However he also had a stiffer custom rear sway bar then I do. Mine is 27mm his was 28.5mm.