340Elise

Need some help from the alignment experts please. Here is my current setup on my GT3:

18 x 9 with 255 Toyo front
18 x12 with 315 Toyo rear

OMP Motorsports steering wheel used in Cup cars (320 mm)

Alignment specs (rough estimate):

somewhere around 2.5 - 2.7 negative camber in the front and a bit less in the back. I Used the shime kit to achive this. I wanted just a little bit of front outward toe (maybe 0.5 mm per side). Then I would like the rears to be toed in by about 2mm per side.

So they got the camber right,but i think they ignored, or just didn't pay attention to the other important alignment specs (ie the toe)

So here is how my GT3 drives. all sweet, until I go fast and hit some corners My GT3 begins to drive like a big rig. Lots of steering effort and a very imprecise. It starts to float to one side and you start to correct. As you are correcting, it then slowly reacts to a previous input with the result binging very slow.

I realize that the small diameter wheel will increase the steering effort, but not by that much.

The front tires are wider, but have never given me problems before, so I think it isi the allignement.

Any help would be very much appreicated.

Stephen

997gt3north

- your desired specs look fine
- if something feels wrong it likely is
- get a alignment readout to start with
- if these tires were on a different alignment before and a big change has been made you may need new tires
- have you changed any other suspension components?
- have you significantly changed the ride height?
- if the r888s are brand new, it can take some hot laps to scrub the crap off them but i don't think that is your problem here

paul

mdrums

New R888's? If so they are slow to respond and very squirmy until you get them 1/2 worn down.

Bob Rouleau

Stephen,

1) Are you running new R 888s? If so the comment above is right on, they squirm like ad when at full depth tread. I hate them.

2) Have you had toe out in front before? Paul likes his car that way whereas I prefer zero toe or a tiny bit of toe in so that my car tracks straight while I have a boring 3 hour drive to the track.

3) GT3s are notorious for being sensitive to rear toe. Any time my car starts to handle oddly I get the alignment checked. Unless you have installed racing style toe links, your rear toe can be upset by even small bumps.

Best,

TRAKCAR

What truck do you drive?

Your specs seem close to what I run with R888's and should not be that bad, I agree, somthing must be off, check the allignment again..

996FLT6

LSD fried? Is braking late makes rear feel unsettled? Mike

drqiman

I drove 340Elise's car and it really drives like a truck requiring lot's of steering effort and large steering corrections to get the car to respond. It feels like driving a car with no power steering with two flat front tires. There is no pushing once you get the car to turn. If you let go of the steering wheel while turning, it doesn't want to return to center as quickly as it used to. I believe that he lowered the car some. I also drove the car with the same wheel/tire combination but before the alignment and steering wheel changes and it was sharp as a tack. The other change he did is that he dropped over 250 pounds of weight which I suppose would make the car turn better not worse.

va122

Wait...you added that much camber with only the shims?? you need more castor. Castor will cause that weird steering issue you mentioned. you need about 8.5 deg in the front. any more you may rub the fender wells. you're camber values are fine, I run 2mm toe out front and rear and the car rotates like a top. Granted that's a LOT of toe and dont' do it unless you have excellent car control and a good tire budget. .5mm toe out front and 2mm in rear is ideal but again that is s driving style issue. Some guys like 0 toe, some like toe out for turn in and some like toe in for straight line stability.

if you're rear toe is off, and if you have the stock suspension it will always be. the car will wander to one side or the other, step on the throttle while the car is going str8 and lift if it goes to one side your toe is off. Careful if you try this on the street since most roads are crowned for water run off and can give you false results.

go to your alignment shop and get a printout of your current aligment and compare it to what you got when you aligned the car before, obviously correct whatever moved and use a sharipe to mark the eccentrics so you can do a visual inspection before your next race/de or whatever you do. You will probably see that your castor has been reduced to about 8.

NJ-GT

Alignment problem. Take it to a good shop. Get a reading before changing anything.

With a good alignment, no matter what tires you run, the car feels great.

I run F:2mm toe-out -2.7 camber, 7mm shims, rotated tops. R: 4mm toe-in, -2.5 camber.

Terry L

I agree with the caster analysis based on your description. But, in my experience, lowering the car decreases camber while you are describing increased caster. My experience was in my Lotus Elise but the geometry should be the same. Did the shop reset caster? You haven't told us how much you lowered the car - how much?

C.J. Ichiban

if the steering is messed up, is it possible you've got a bad rack somehow or a blown out pump?

todinlaw

I would agree that you should just check the alignment first before you do anything. Also I thought that caster was not adjustable in this car??

Greygt3

Frank,

Remember the front suspension has three attach points. If you adjust any of the three you will effect the caster setting. If you shim only for camber you pull the wheel forward affecting the caster. Thats why the camber setting must be a combo of moving the strut top and shimming so the caster remains near the desired eight degrees the factory recommends. So to answer your question there isn't a caster adjustment per say but adjusting other variables will in turn change the caster. Hope this helps.

Carrera GT

As I understand it, caster will not change in a MacPherson strut. Rotating the upper hat could alter caster, but I would assume the design of the hat specifically avoids changing caster. In any case, changing camber does not change caster. Within reason. There's a sequence of change in terms of cause and effect which must be observed when aligning a car: caster->camber->toe. In other words, changing caster, changes camber. Changing camber changes toe, but not caster. And changing toe does not change either camber or caster.

You might be thinking of steering angle inclination. If I try to describe SAI, people reading this thread might die of boredom.


As for this car, I don't have enough experience with R888's, so I'll take those comments as true and useful, but I'd never describe a properly "set up" GT3 as behaving in the way described. This sounds like something more than just poorly aligned. Having listened to customers describe their GT3's from street to track, competent and incompetent drivers alike, the vocabulary and metaphors are a challenge to decipher. I find that unless it's a dedicated track car (being trailered to the track) there's no joy in front toe out -- the nervous tram-lining is not useful even on slower tracks like Sears and Laguna. On faster tracks, it's a liability and an accident waiting to happen. I like zero toe set by "drawing in" the front from toe out. This only works if the rear toe is meticulously symetrical (and that's tough if the car doesn't have threaded toe arms ... the factory eccentrics are woefully imprecise.)

Anyway, I'm curious to find out what happened with this car. It's a long shot, but a broken front spring would explain these peculiar driving problems. So would a bad ball joint, especially in terms of heavy steering. A failed steering rack or faulty power assist. Maybe the steering wheel is contributing to or accentuating the symptoms.

sws1

When I had the camber on front changed (more negative), the caster did in fact change. The shop didn't explicity set the caster, but it did alter. It's now more negative than spec.