Alignment for track

[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 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

[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?