Alignment and Tire Pressure for Auto-X

[stivo]

I think the Progress sway bar is my next mod. The shocks will come later... christmas bonus? Santa?



....please!

[focusedaddiction]

Originally Posted by LazarusZX3

1. Winning races is so much more about driving talent than car.

2. I don't mind the thread jack ;-)

3. I've decided to keep the current near-stock set up for now, and next season I'll mess with it more. And I'll take lots of notes. It's hard to remember every factor that goes into each turn, especially since the course is different every time.

your best friend right now will be LOTS of seat timeanyway( many times i've seen a nearly stock car whip a high end car) . scca is 75% driver anyhow just keep working on your lines & such
as far as tire pressures go with my azenis i like to run front:40-42 and rear:34-36 PSI

[LazarusZX3]

Does the lower rear tire pressure promote oversteer? Our FWD cars are prone to understeer.

[SVT Robzor]

Originally Posted by SVT Robzor

If you're pushing (understeering) too much, you can add front negative camber, or try dropping your rear tire pressure a few PSI. It sounds contradictory, but you will gain grip by adding pressure, until the point that the contact patch starts to round out. Cornering work is done by the tire's shoulder, lower pressure lets the contact patch roll onto the sidewall, which is not made to grip.

Yep, within a certain range, lower pressure mitigates grip.

[stivo]

I have some questions about this as well. Drag racers usually have lower pressure in the drive wheels to promote grip, but in a corner lower pressure will allow the tire to roll over a lot more on to the sidewall. I believe that this is when they will break away, but I'm guessing you will also be wearing the tires down on the sidewalls... where they are not designed to be driven on.

I am more inclined to try the high pressure approach for the rear tires. testing and recording the results is really the only way to know for sure.

[stivo]

hmm... Ok, I'll try lowering the psi.

[WeeAsp]

Stivo -

You are correct. Lower PSI on a drag racer will promote traction - BUT ONLY ON THE DRIVE WHEELS.

We drive FWD cars. So, we are in a bit of a dilemna. We have to fight the rolling resistance of the tires (at the front), but also find a compromise that allows for greater traction.

AX is not that dissimilar. The rear tires help to keep the car planted in corners and on the straights. By tweaking the tire pressures in the rear, you can affect cornering and rotation. A stiffer sidewall in the rear can translate to greater rotation and more lateral grip through sweeping turns. Conversely, lower the tire pressure too much and you create drag.

As I said before, a lot is dependent on your driving style. If you are a "point and shoot" kind of driver, then you may not want or like a lot of rotation from the rear. Will it make you faster? Depends on the course and your line.

Higher pressures mean more rotation. Will that make you faster as the rear hangs out? Depends on how comfortable you are with that scenario and how you adjust to bring the car straight.

That's why I say experiment and find what works for YOU,

[03OrangeSVT]

Personally I've never AX'd but I have had the joy of running on a road course (VIR) and I saw guys in Focus's with pretty much STOCK suspension setups that would just amaze you... even with 300whp (at the time) my POWER wasn't enough to keep up with their skill.... it was a learning experience for me.

Experience is the greatest thing that will help you, even though you have gotten some really good advice from the other guys on here.

[stivo]

I see. I tried it for the ride home. Granted, I have a basically stock suspension and am running Kazera KZ-V wheels with Avon Tech M500 "tyres." I pumped the fronts up to about 42 and the rears to 35 and hit a twisty back road.

This wasn't a track test for sure, but I did push it on a few corners. I can feel a difference at the limit as the back would rotate instead of the front pushing straight through. The technique was to break, heel-toe downshift, turn in and lift off the throttle... drifting a little wide with the back end rotating a touch, then back on the throttle. I didn't pull a Burt Reynolds.

I try not to drive too stupid on the street though... just a couple corners, I promise.

[WeeAsp]

Originally Posted by 03OrangeSVT

Personally I've never AX'd but I have had the joy of running on a road course (VIR) and I saw guys in Focus's with pretty much STOCK suspension setups that would just amaze you... even with 300whp (at the time) my POWER wasn't enough to keep up with their skill.... it was a learning experience for me.

Experience is the greatest thing that will help you, even though you have gotten some really good advice from the other guys on here.

I know what you mean.

I swear on my Mother's eyes that this is a true story...

At Summit Point they have a weekly event called "Friday at the Track" or FATT. Basically, it is an open event where any car, any driver can show up and do hot laps with an instructor or solo (if their experience permits it).

A true novice had a really modified RX7 (3rd Gen) and was being instructed by my friend Charlie.

After the 2nd session (with 2 more to go) Charlie told the guy that he wasn't going out with him unless he listened. The guy coped an attitude and basically complained that Charlie wasn't giving him his due. Charlie, in front of the student, told the track marshall that the RX7 driver was unsafe.

They came to an agreement. Charlie agreed to let the guy go on his own and they would but a clock on the RX7 driver. Charlie would go out in his car. Whoever turned the fastest lap time had the final say.

...RX7 driver was faster - RX7 driver was able to solo.

...Charlie was faster - RX7 driver had to unconditionally listen to Charlie in order to continue.

Charlie had the better lap time by nearly 3 full seconds.

Why is this important?

Charlie was driving a diesel VW Rabbit...

Honest to Pete a true story.