Track alignment spec

ValidusVentus

I would tend to think that if your going to just mess with camber/toe F+R, from stock you would want to toe it in slightly, keep the Fcamber maxd and the Rcamber maybe 1.6 so it doesnt get overly sticky through a corner compared to the front camber of 1.5 and gives you slightly better power delivery out of corners than say 1.8. This being a FR car with a natural weight bias to the front you would ideally want a little more camber up front (to reduce understeer) as thats where the weight is going into turns. This is not based on experience but just me thinking about it here for a min so i may be way off : )

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Mods: Dedicated caged track car, lots of things. ||| Valkyrie Autosport |||

ChrisSlicks

It depends on how much street driving you do.

For an aggressive track alignment I use:

Front:
0.03 toe
-3.5 camber

Rear:
0.05 toe
-1.8 camber

This gives an aggressive turn in feel and good corner stability. I found that going beyond this for rear camber is detrimental overall. If you are street driving a lot I would back the camber down slightly.

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WWJD

0.03 and 0.05 are toe in or toe out? I guess toe in?

ChrisSlicks

Yes, positive is toe-in.

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WWJD

Thank you. I will try that spec. I'm on stock alignment still, the car is pretty under during turn in. I could feel the understeering even driving on streets.

ChrisSlicks

The low speed understeer can get worse if you add stiffer springs or sway bar bars but the increased camber more than compensates for it.

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Red__Zed

Do you have sway bars?

WWJD

not yet. and I notice body roll a lot as well. I might go with away bars, full stiff front and full rear rear, then play with the camber like Chris suggests.

WWJD

Why sway bars would make this worse?

Red__Zed

If memory serves, chris is running hotchkis bars. His dynamic is very different than the stock car. I would not recommend that alignment on a stock setup (or at least be prepared to play around with it a bunch)

ChrisSlicks

Stiff sway bars prevent weight transfer, the weight transfer helps to give compressed camber gain, so without this gain it is like you have even less camber than stock.

Yes, I started out with the stock car and Hotchkis sway bars and SPC camber arms (and that alignment). If you don't have aftermarket sway bars you won't need as much camber up front.

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Mike

Mine is -3 camber -.01 toe front and
-2.5 /.04 rear

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wutfun

Although it is true that a stiffer swaybar will prevent body roll and thus reduce the camber gain on the outside wheel, because the car rolls more you need more camber gain...so it is really not about the reduction in camber gain.

A stiffer swaybar actually transfers more vertical load on the outside wheel and reduce the vertical load on the inside tire. This is the nature of a swaybar as the outside tire gets pushed up, the bar will start to put some of that upward force onto the inside tire...thus decreasing the vertical load on the inside tire.

This increase in the difference between the outside and inside tire vertical load means the overall lateral grip will be less. The reason for this is something called the tire performance curve. I added is a picture of a tire performance curve from my app below. Basically as you increase the vertical load on a tire it does increase it's lateral grip, but the increase in lateral grip is not linear. In other words for each 10lbs of vertical load you add to the outside tire you will get a smaller amount of incremental lateral grip. Conversely as you reduce vertical load on a tire, it looses a greater amount of lateral grip for every 10lbs of vertical load it looses.

This is a key reason why stiffer swaybars reduce lateral grip. This is why the end of the car you add a stiffer swaybar to will have less lateral grip.

So you might ask...why run swaybars at all? They are there to make the car handle more consistently and predictably and also to help with achieving the balance of the car you like.

I hope this helps.

Cheers
Martin Crisp
Setup Workbench - Home
iPhone version Setup App

Attached Images

tire performance curve.jpg (30.4 KB, 43 views)

gtkiller

Nice write up, so if one adds adjustable sway bars without adjustable camber plates should the sway bars be set to the softest settings on a complete stock suspension setup?

Shamu

Wow there is so much more to this. What tire are you using? What shocks and bars, How wide are wheels and tires.

There isnt a set spec that is good for track in my opinion. It depends on your setup and tires. I was running -4 camber up front with 1/4 toe out and about -2.75 rear with a little toe in on my 370Z nismo with 1000 lb front spring and 450 lb rears. 37mm Progress front bar and stock nismo rear. 315 Hoosier A6 rear and 295 Hoosier a6 front.

On track that was ideal setup that Grand Am team settled on. Car was perfectly nueteral and tire heat/wear was ideal.

I went back to -2.75 front and -2.0 rear with similar toe recently and really dont like track handling compared to more aggressive alignment specs.

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Grant