Alignment for track

[san rensho]

I'm trying to set up my bone stock 2000 on Bridgestone S-02 A tires for less understeer on the track, what are your recommendations for alignment front and rear?

Tire Rack says to increase front camber, reduce front toe and to reduce rear camber and increase rear toe. Is this good advice?

[Brad Roberts]

that is a good rule of thumb, but you know you are limited to about -0.8 to -1.0 for camber up front.. its not enough, it will never be enough

Tell us what size tires you are planning on running.

There is a reason why people are leaning towards running the cars square More front grip with just a tire/wheel change.



B

[Topless]

Lots of opinions but these were my target settings on stock suspension:
Front: -1 degree negative camber (could only get -.8) Zero toe, max castor.
Rear: -1 degree negative camber, 1/16th" total toe in.

It gave the best combination of car balance and tire wear I could get on stock struts. This setup worked ok with street tires and completely shredded R-comps.

[san rensho]

Thanks. After some more searches here and on rennlist, I'm leaning towards as much front negative camber as I can get, which I realize will probably be not much, but I was thinking of taking out rear camber, to maybe 0, if I can get it?

I have stock tire sizes, so the rears are a lot wider than the fronts, so i was thinking of running lower pressure in the rears, 2-6 psi, to reduce understeer.

I'll be at Homesterad, which has really only 2 high speed turns, 1 and 10, which for me are probably 90- 110 mph. What do you think?

[Brad Roberts]

You can get zero in the rear no problem.. the issue becomes toe at that point. One adjustment effects the other on these cars

The lower rear tire pressures are really going to show on the tires.

Can you buy a 235? in the S-02? I have not looked?

Can you buy a 245 in the S-02 for the rear?

You see where I'm going with this? Run a narrower rear tire. We ran Grand-Am pro in a Boxster at Homestead... 225 front and 245 rear


B

[san rensho]

Originally Posted by Brad Roberts

You can get zero in the rear no problem.. the issue becomes toe at that point. One adjustment effects the other on these cars

The lower rear tire pressures are really going to show on the tires.

Can you buy a 235? in the S-02? I have not looked?

Can you buy a 245 in the S-02 for the rear?

You see where I'm going with this? Run a narrower rear tire. We ran Grand-Am pro in a Boxster at Homestead... 225 front and 245 rear


B

I hear you on the tire sizes, but I haven't picked up the "track pipe" yet so I'm just trying to get the most out of the stock set up I have without spending a lot on tires. I still have a lot of tread left on mine.

So if I go to 0 camber on the rears, what should i set the toe at? Go up to 1/8 inch or so?

[Topless]

The answer really depends on your driving experience and your goals. If you are at the top of your game in Fla and going for a big TT win I would suggest looking hard at your rulebook first and choose tires and alignment very carefully. If you are going out for a DE with the club, don't overthink your setup. Get a good neutral camber setting close to what I listed earlier and go out and have some fun. A car with understeer can still be driven quite fast, you just drive it a little differently. Too much tinkering with the car and you will miss the joy of driving flat out

As to zero rear camber... I wouldn't do it. You may get a bit less understeer but the tradeoff will be tragic outer edge wear on your rear tires. Not the best plan.

[Brad Roberts]

what should i set the toe at? Go up to 1/8 inch or so

No no.. with zero camber you may not be able to pull enough toe out of the alignment to match his 1/16th total toe in (which is a good place to start) the alignment guy may find that at 0 to -.3 you end up with too much static toe (more than Topless suggested)

My rule of thumb is: half degree split from front camber to rear camber.

If front = -.8
Then Rear = -.3

I know you ran motorcycles at one point, are you OK with making changes to the car at the track? Do you have a floorjack and at least one jackstand?


B

[Jittsl]

If Brad hasn't made it clear enough - rear tow (or lack thereof) is more critical than camber.

I would try:
Front camber - as much as you can get
Front tow - none
Rear tow - no more than 1/16" (I run none in my spec Boxster)
Rear camber - whatever you end up with as long as its less than the front.

A soon as the track pipe takes hold buy yourself some GT3 lower control arms (more camber in front) for the front and some adjustable Rear Toe control arms (right combination of toe and camber in the rear). Until you do I suggest you will find it hard to dial out the understeer to your satisfaction.

I would not screw too much with tire pressures. For not much more than the price of a set of tires you can make the mods above. I would hate you to waste the money on ruining a set of tires. In your attempt to remove the understeer you are already reducing the performance of the rear by reducing the camber which will take a toll on the outer edge. Lower the pressures and you will increase the flex (in another attempt to reduce the performance) and further burdening the outer edge.

[san rensho]

Originally Posted by Brad Roberts

No no.. with zero camber you may not be able to pull enough toe out of the alignment to match his 1/16th total toe in (which is a good place to start) the alignment guy may find that at 0 to -.3 you end up with too much static toe (more than Topless suggested)

My rule of thumb is: half degree split from front camber to rear camber.

If front = -.8
Then Rear = -.3

I know you ran motorcycles at one point, are you OK with making changes to the car at the track? Do you have a floorjack and at least one jackstand?


B

I have the jack and stands, but if you are suggesting I play with alignment at the track, I'm not comfortable with that yet. Or maybe i am, whats involved?

[san rensho]

Originally Posted by Jittsl

If Brad hasn't made it clear enough - rear tow (or lack thereof) is more critical than camber.

I would try:
Front camber - as much as you can get
Front tow - none
Rear tow - no more than 1/16" (I run none in my spec Boxster)
Rear camber - whatever you end up with as long as its less than the front.

A soon as the track pipe takes hold buy yourself some GT3 lower control arms (more camber in front) for the front and some adjustable Rear Toe control arms (right combination of toe and camber in the rear). Until you do I suggest you will find it hard to dial out the understeer to your satisfaction.

I would not screw too much with tire pressures. For not much more than the price of a set of tires you can make the mods above. I would hate you to waste the money on ruining a set of tires. In your attempt to remove the understeer you are already reducing the performance of the rear by reducing the camber which will take a toll on the outer edge. Lower the pressures and you will increase the flex (in another attempt to reduce the performance) and further burdening the outer edge.

Ok. I'll just get a conservative alignment done and keep the tire pressures the same all around, which works pretty well now, and see how it feels.

[Brad Roberts]

I want you to learn your car. You ran motorcycles!! I know.. know you can balance a bike with the throttle on two miniscule contact patches!!

Disconnect the front bar for one session.

Then disconnect the rear bar for one session.

You can zip tie the drop link in the rear to the toe link (they both move at the same rate)

and you can zip tie the front drop link to the upright..

you'll need two wrenches..

People flip out when I tell them to do this.. lol don't like it? come in and put the drop link back on. I do it on grid during a pit stop/driver change...


B

[ChrisZang]

for what it's worth, here is my alignment:

front -2 neg. camber (GT3 lower control arms)
rear -2.5 neg. camber (with just a tad of toe in) with adjustable toe arms

PSS9 + Tarrett front and rear swaybars and drop links

just by using lowering springs you can reach up to -1.25 front and -2.25 in the rear (also here you need adjustable toe arms)

I went wider for my front tires to 225/17 front and kept the rears the way they were 255/17

[Mrmaddbrad]

For what its worth:

Everyone has been avoiding the sad truth... THESE CARS UNDERSTEER!! its the sad truth about mid engine cars....

There are only a few ways to change this in most mid engine cars...
1) Mass amounts of front negative camber
2) Tire Pressures
3) Tire sizes
4) Suspension...

Most of these have already been touched on, and i know you want to keep your car stock so here we go....
1) This option is out of running, stock suspension will never get you over -1.0 degrees of negative camber in the front, and sadly, this isn't enough But should defiantly still be done if you're trying to get the best performance/handling out of the car.

2) Again, should still be done but will not magically turn off your understeer... You mentioned running lower tire pressures in the rear. Wrong school of thought. As a rule of thumb, lower pressures means more grip. So if anything run lower pressures in the front. Porsche recommends 29 Front 36 Rear (which is a 7 PSI gap compared to the 5-6 PSI you were thinking about running)

3)Okay here we go. The magic number here is 245s all the way around. They fit in the front, and in the rear. For autocross i've been running 245/40/18 Hoosier A6's all the way around. I know you're not Autocrossing, but its still a good number to run with. Keeps the car very well balanced.

4) Obviously out of the running if you want to keep the car stock.

My '02 S is also bone stock, and seemed to find its happiness after completing the first 3 of these. An aggressive alignment is very needed, and playing with tire pressures really makes you learn your car. After it is closely balance with tires, playing with tire pressures can make you find what your car is actually capable of. However, i have no idea what to recommend for track racing on that front. Maybe ask some one else where to start, or just get out there and try it!!

Good luck!
~Brad
Cheers!

[ganseg]

Sorry for bumping the old thread. I tried 235/40 18 on the front of my 2002 Boxster S. The right strut perch rubbed hard on the inner 3/4 inch of the tire. I stepped down to 225 which is fine, but i had been hoping for more tire up front. Is this uncommon - ie there is something funny about my right front strut perch?

[Brad Roberts]

Show us a picture of the wheel tire combo. There is NO way that combo should rub. Many times in the past I have run 275's on stock rear wheels UP FRONT!!

B

[stephen wilson]

How'd you do that? IIRC the 9" rear wheels on my 987 don't have enough offset to fit on the front?

[Brad Roberts]

He has a 02 BoxsterS. The 987 is much different.

We run 987's square on 285's. 10in rears 9inch fronts

[Brad Roberts]

I just had wheels built for a CaymanS to run it 295 square with the GT2 front fender lips (on 11inch wheels) It will all be under the rear of the car, and hanging out just right in the front for the 997GT2 factory fender lip.

[stephen wilson]

Ah, I thought 986/987 fitments were nearly identical. Why only 9" wheels with 285's on the front, I'll assume they won't fit on 10's?