I posted this in the suspension forum, but never got an awnser. figured I'd try it here maybe more experenced person would see it.

ok, I recently sold my 03 evo and got an 06. Just autoxed my 06 for the first time after being aligned yesterday. My 06 is alot more tail happy then my 03, as far as setups the only main difference is in rear camber. Also could be because the tires have only 700 miles on them . Anyways here are the specs tell if you guys think these are ok. I"m alittle nervous about how sensitive the car is, compared to what I was used to. I'm sure it will just take alittle time, but I wanna do some lapping days this year, and I wanna be safe and not oversteer to much. Those of you that understand alignement well can hopefully offer me some insite..

specs.

Front
camber -2.5 both sides
toe -0.03 both sides

rear
camber -1.0 both sides
toe left -0.07
toe right -0.06

 

Bump for the slow guy in SM...




What were your rear pressures again?

 

I get confused on the toe settings, is a -0.06 and -0.07 in the rear toe out? If so that would be my guess.

I would run a touch of toe out in the front to help turn in and keep the rear at zero toe, maybe even toed in a little to keep it stable at high speed. Toe out in the rear is hard to drive.

 

ya, its towed out right now in the rear, it roates excellent the problem is high speed slaloms or quick left rights, it gets loose easy.

 

ran 45front 40 rear. I"m sure the tires need more miles on them, but I think I"m just used to more camber in the rear which bit more in the turns.

 

Less air in the rear will help too. I'll try to dig up my old sheets from when I was running the Advans and see what hot pressures I was running.

 

I would be willing to bet that it is the toe out in the rear and your tire pressure. I would make your pressures more balanced instead of a 5 psi bias towards oversteer. I ran about 38 psi front and rear on my stock tires for auto-x. After the first few runs I would let the air out to keep them at around 38 psi.

And get rid of the toe out in the rear. At low speeds it is great for rotating. BUT at speed it makes the car very sensitive and the slaloms would be the perfect example.

I would balance the pressure at 38 all around and take out the toe from the rear and give it another test. If it is still loose than add some negative camber to the rear.

 

I find the oppissite, it was at 38 I upped it to 40 little better. Coming from front wheel drive, I used to let air out to get more rotation out of th rear, add more to the tire to get grip. Obviously if u add to much it will slip aswell. In my old car I ran 45 and 38.

45 in the front to me feels like the sweet spot, I ran once on sunday with 40 on accident it the tire squealled like a pig around every corner. Wear makes on the tire are right at the arrow on the side of tire.

between runs I check pressure to keep it at 45.

 

from stock suspension i got
-1.8 f
-1.0 r
0 toe f+r

thats the alignment we worked out at rogerkrause racing
works very well for both street and track (street tires) once you move to R compounds its time to look for more than -2.5 f

 

Front
camber -2.5
toe 0.00

Rear
camber -1.5
toe 0.00

Reduce your air pressure in the rear tires a few pounds and/or add more air to the front tires. Also, driving style can change the handling characteristics of the car as well. Make sure you are NOT on the brakes when turning and that you are at least slightly on the power when making manuevers.

 

ya, I think it just needs more rear camber, thats y it feels so tail happy to me.

 

I'm gonna throw some stuff out that may run counter to what some others have said. Just want to givee you some food for thought if you want to get serious about tuning your set up. I'm assuming you have adjustable camber, so this advice would actually be worthwhile.

- Have you checked tire temperatures? Checking the temperature across the tread pattern immediately after finishing a hot run will tell you if you're camber is correct or not. You want no more than a 5-10 degree difference from the outside to the center to the shoulder, with the inside being hotter. It will also tell you if you are running over or underinflated (center temps too high/too low).

- Talk to the company that makes your tires and ask them what pressure the tires want to be at when they're hot. Then, play with your cold pressures until you hit that temp when running hard. Bleed it down after a run if necessary. If you want the car to rotate better, drop the rear pressure a couple of pounds relative to the front. If you want it to rotate less, make them more equal.

- Toe adjustment will always make the car "twitchy". You can use this to your advantage on tight corners, or it can bite you in the *** as the car darts under braking/accelleration and makes you busy in high speed corners.

Hope some of this helps. There's a great little book you can carry with you to events that's sort of a "troubleshooter" for suspension set-up. It's by Carroll Smith, who is famous for his race car engineering books:

http://www.motorbooks.com/ProductDet...852&SID=129569

Really handy book.

 

wow that tire temp suggestion is the first I have heard of that... Thats really interesting. I usually guage pressure, by feeling, sound and rolloever of the outside tread. How much would a temp gun that will read pressures like that cost?

 

Tire temp is how all of the race teams set up their suspension, and is the only really reliable way for someone at our level to know what the contact patch is doing at speed. Stay away from the infrared as they're not accurate enough for initial set-up. Inexpensive probe-type pyrometers start at $100 and run as high as $500 for the memory-type that will store each reading at each point on the tire. A quick check on Froogle came back with this:

http://froogle.google.com/froogle_cl...le&scoring=mrd

 

I might have to invest in one of those, seems like it would help out quite a bit in chasing correct tire pressures.