AutoX brakes & tires

[Topless]

I run 29F 32R cold pressures for typical events. You are right. The brakes never get hot enough in AX to make best use of race pads. Nice runs!

[kabel]

I concur with much of the above.

Stock pads and rotors are more than adequate for a typical autocross situation.
I run the PS2's and always start out with cold pressures at 34 front 38 rear and adjust as needed throughout the day.

Oh, and I am running 225/45ZR17 up front.

[stephen wilson]

I just had a general comment, not Boxster specific. Pressures are adjusted to maximize grip, not reduce rolling resistance. You generally want an even temperature gradient across the tire contact patch, with the inside being hotter than the outside. In some instances higher pressures are required to prevent tire "roll-over" in heavier cars. The pressure also changes the spring rate of the tire, lowering pressures on a cold day can gain mechanical grip thru more tire compliance.
Steve

[Perfectlap]

PCA autocross around here isn't the most competitive. I've seen folks win by a second on occasion but that would never happen in SCCA or the other regional clubs. The difference there is as little as .001 in some of the classes. I remember one event where the difference was less than .3's down to 9th place.

I wouldn't make any equipment changes until you have at least 12 autox events under your belt. After that many events you'll see that autox has basically a limited number of type of turns to master. hairpin, slalom, "chicago box", six pin turn, four pin turn, hard right, hard left. Not a whole lot you can do in a confined space. Bascially, Grind what you have first.
I started on street tires and I was slip sliding all over and very tempted to go right into the r-comps. After I put in a ton of mistakes by deliberately pushing hard to test the limits my tires were shot for autox but fine for regualr driving. Then I ordered a set of 14 pound wheels with Azenis and minimized the brutalization and in the first even I was about a second and a half quicker with little punishmment to the stickier tires.

some tips I picked up which could be helpful:
Drive with your shoulders and arms and not your wrists.
keep your shoulder blades pinned, no rocking side to side.
put a piece of tape at the 12 o'clock position to keep you aware of wheel shuffle.
always have your foot on the gas or the brake. time loss comes from hesitation.
sketch a map of the course and number the braking points.

Do a search for Randy Probst the Porsche driver. He autocrosses, still, and had an interesting article about his a-ha momment that made him quicker. basically has to do with deliberately driving slow during a lap.

[Adam]

Mike, how many boxsters were there? I run the same pressure as I do on the street which is 33 front, 36 rear.

[Mike_Yi]

Originally Posted by Adam

Mike, how many boxsters were there? I run the same pressure as I do on the street which is 33 front, 36 rear.

I think there were 7 Boxsters there. I don't know how many were Ss, though there was at least one. I know two of them had upgraded brakes and DOT legal race tires. It sounds like everybody's using pressures that are around where I ended up.

I was surprised that there weren't more cars there, and at the layout of the course. It's not anything like driving on a track. However, it only cost $35, and it's a hell of a lot of fun if you are at all competitive. I am, so in that respect, it's more fun that HPDE. I prefer HPDE, but it is great fun to compete and try to continually improve your time. I guess I could do that on the track if I invested in a lap counter. That's not a high priority now though.

The course at the tire rack was really spread out. Much more than any other autocross I've ever seen before. My only prior experience with autocross was those Mazda Rev-It-Up events where you get three runs on their autocross track in a Mazda 6 (or whatever model it was). Those courses were always much tighter than this one. It was fun as hell though.

[kabel]

it is refreshing to hear your positive opinion of autocross. All too often once someone has had a taste of track days, they have a hard time enjoying the autox format.

[Sammy]

Originally Posted by Mike_Yi

I think there were 7 Boxsters there. I don't know how many were Ss, though there was at least one. I know two of them had upgraded brakes and DOT legal race tires. It sounds like everybody's using pressures that are around where I ended up.

I was surprised that there weren't more cars there, and at the layout of the course. It's not anything like driving on a track. However, it only cost $35, and it's a hell of a lot of fun if you are at all competitive. I am, so in that respect, it's more fun that HPDE. I prefer HPDE, but it is great fun to compete and try to continually improve your time. I guess I could do that on the track if I invested in a lap counter. That's not a high priority now though.

The course at the tire rack was really spread out. Much more than any other autocross I've ever seen before. My only prior experience with autocross was those Mazda Rev-It-Up events where you get three runs on their autocross track in a Mazda 6 (or whatever model it was). Those courses were always much tighter than this one. It was fun as hell though.

I start with 34 front/38 rear cold and adjust as needed. I run R-comps with 245 front/275 rear.

I'll be running at least one (if not two) events this weekend in Gary with the Northwest Indiana SCCA. They have a new site at one of the Casinos which is comparable to the Tire Rack events in South Bend or the bigger SCCA clubs in Chicago or Milwaukee. If interested PM me for details. It's a nice club with typically 50-80 cars (may be a little bigger with their new site) and some pretty fast Porsches.

[Mike_Yi]

I'm going out of town for a wedding this weekend.

I may look into some SCCA events later in the summer depending on my work schedule (I work a lot on weekends).