autocross alignment ?'s

[hose101772]

Went and watched a buddy run today in his near stock 1g awd.Got to the track before his last run.He said it was plowing badly so we lowered the rear tire pressures and he said it made a noticable difference.
But..it still looked like it was plowing heavily.

So seems maybe some rear toe out is in order but how much?

What about front toe?

Any other advice?

I know I've read on forum somewhere about alignment for autocross but I cant seem to find it now.Any help would be appreciated.thanks.

 

[hose101772]

found it-it was a link.

for anyone wanting some pointers for a 1g-

http://www.wincom.net/trog/autocross/1G_SM.html

 

[jtmcinder]

What are you talking about? FWDs don't understeer!

Warning: this is a joke which might only make sense to some people.

- Jtoby

ps. while rear toe out helps a lot, it will increase treadwear a lot. Only if you are dreadfully serious should you do this to a daily-driver. I'd tell your friend to focus more on entering the tighter turns slower and waiting until he is unwinding the wheel before adding too much gas. Line is more important that carrying speed in autoXing. A pretty standard mistake among beginning FWD autoXers is to add too much gas too early on corner exit. The car will not rotate under power and you cannot ask the front tires to turn (at the limit) and accelerate at the same time ... something has to give and it's the cornering that loses, which is why the car ploughs wide on exit. One way to train yourself to exit better is to think of the gas pedal and the steering wheel as being connected: you are only allowed to add gas when you are unwinding and you are only allowed to add as much gas as you have unwound.

 

[hose101772]

Its an awd and its not an exit only problem.It rolls over on the fronts even at 36psi in them.Entrance,mid,exit-its all the same.Either some camber or caster changes are in needed.

Thinking the answer is more caster and leave the static camber stock.

 

[jtmcinder]

What the heck do you mean by "even at 36 psi"??? Of course it's rolling over at that low a pressure! Doesn't the group you autoX with have a Novice Advisor? You should have 40 psi in the front tires, minimum; you should start at the rated maximum for the tire, at least, and work down from there. (I'm assuming some sort of street tire, probably on an undersized rim.) When I was running 235/45/17 Excta Supras on 17x8s, I would have to put 42 psi in, even when it was asphalt.

As to adding caster ... what for? You add in 3 more degrees of caster and what do you get? Maybe a half-degree of extra camber at half-lock. Plus, now your power-steering pump is straining all the time and the high-rpm cut-out leaves you totally screwed in the middle of a 1st-gear corner. No, if you want to start dialing out understeer, you need a lot more front camber. Get it to 2.5 degrees, minimum, while stiffening the rear end. Then it will turn.

But you're missing my point. You can focus on engineering (which is a process that never ends) or you can leave the car along for a minute and focus on driving. If a DSM is ploughing - whether it be FWD or AWD - then you are either entering turns too fast, getting back on it too soon, or both. And if you clean up your lines, you'll be a lot faster.

- Jtoby

 

[hose101772]

Yea I mean 36psi in the front,tracks "a little" bumpy and you're right about the advisors.They had him at 40 all the way around-like everyone else.

Skipped like a rock through the rough-like everyone else.He had already figured out to lower the front down to 36.We lowered the rear to 30 against the advice of the "pros".Gained a second and a half just from that.

Not saying those guys dont know or anything of the sort just what they were sayin wasnt working on this car.

Next time he'll have zero rear toe and a touch more caster.Should be fine for tire life-daily driven-and get rid of some bind in the middle.

I suppose when I originally asked for any other advice I should have asked specifically for any other technial advice as I'm not his driving coach,merely the guy he turned to for setup help.But thanks anyway.