986 Autocrossing Racing Strategies

[JayG]

I found I reduce understeer by raising the front PSI
I run 35/37 hot F/R and found it to be more neutral

My 04 S is bone stock

[GatorLapis]

Originally Posted by JayG

I found I reduce understeer by raising the front PSI
I run 35/37 hot F/R and found it to be more neutral

My 04 S is bone stock

Well, generally speaking If a car is understeering, it means the car turns less into the corner than it should for the steering input. So obviously, the rear tires, which want to go straight have more grip than the front tires which are trying to turn. To solve this problem we can increase the contact patch of the tires that need more help. That means lower pressures on the front, or we can decrease the contact patch size on the tires that have too much grip, so increase rear pressures.

However.... your rear air pressure was higher as well which could have balanced it out. Also it depends on the tires... If they are all season vs summer vs racing slicks.

P.S. to reduce understeer try using a NON S front sway bar. It is only .5 inch narrower but it will make a difference.

[Racer Boy]

Originally Posted by GatorLapis

Well, generally speaking If a car is understeering, it means the car turns less into the corner than it should for the steering input. So obviously, the rear tires, which want to go straight have more grip than the front tires which are trying to turn. To solve this problem we can increase the contact patch of the tires that need more help. That means lower pressures on the front, or we can decrease the contact patch size on the tires that have too much grip, so increase rear pressures.

That isn't always the case. Generally speaking, higher air pressure will increase the contact patch, as the tire doesn't roll over as much on the rim with more psi. But you will reach a point of diminishing returns.

Of course, it all depends on the tire, the car, the alignment, and so on. But for most cars, higher tire pressures = more grip.

[j.fro]

Steve0x, thanks for the Daytona vid and the compliment! It looked pretty neat running on the course with fewer cones and more of just the road course. For the Richmond Porsche Meet we rent Southside Speedway, kinda a third-tier Nascar oval. The walls are effin scary! For the past 5 years I have finished 2nd to Bobby Smith in his 914 ... he was the PCA FTD at the 2006 Parade in Charlotte. He's a great guy and we're having fun with our little rivalry. Here's the link to my best run from this year:
https://www.youtube.com/watch?v=QEbOXw26yU0

I appreciate being called smooth, and I'd like to toss out a tip about smoothness. Being smooth is one of the tips everyone offers to novice AXers. For a couple of years I worked hard at being smooth and was stuck in the middle of the field. I started paying attention to the FTD contenders at SCCA events and it really hit me... screw smooth, you've gotta be fast. When I put fast first, I got faster. Smoothness is an accessory to speed, not the other way around. To win, get comfortable driving on the ragged edge of control (don,t be afraid to totally loose it or kill some cones) and then make it smooth, not the other way around.
Lot's of the best AXers only have one clean run in an event... and it's the winner!