'87 911 Cab Autocrossing Tire Pressure Question

Brian Estep · 10-03-2002, 09:33 AM

Getting ready to autocross this Sunday (I'm usually heading up last place. Love doing it, but really suck.) Anyhow, I'm going to TRY to place midfield in the stock class this time, can someone recommend a good starting tire pressure to run front and rear for my '87 911 Cab? I'm running 15x6 and 15x7, with new Yokohama 509's. Thanks!

jwill911 · jwill911's Garage

You have 15" x 6" and 7" fuchs on your `87?? The Yokohama rep recommended to me as a starting tire pressure 1 pound for every 100 pounds of car. Go a little below that in front and a little above in the rear. I have 15" x 7" and 8" with Yokohama A032R for track/autoX and start at 31(f) 33(r).

that's my .02

Brian Estep · 10-03-2002, 10:07 AM

Yup, at least as far as I can tell. They may be 15x7 and 8, but I don't think so. Can't swap them, cuz they are polished, and I just *so* love the way they look on the car. (you can see them at http://homepage.mac.com/brian_estep/car/car.htm but I made that page when I thought they were 7 and 8's.)

Thanks for the info, didn't really know where to start, and since I only get three runs, it doesn't allow for a lot of fiddling with.

Lewis Ledyard · 10-03-2002, 10:43 AM

Nice cab. What color is that?

Brian Estep · 10-03-2002, 10:46 AM

Beats the heck outta me, sort of a silver or a grey. I think the factory color is some kind of blue, though someone was on acid when they named it. Works a lot better with the navy top and interior than one would think in my opinion. I love the car, but I'm wrestling with the idea of trading it for a 930 or a Ferrar 308/328 these days. I'm not much for cabs, I think they destroy the clean lines of the coupe's.

Brian Estep · 10-03-2002, 11:38 AM

BTW, I have a couple of test videos of the car online at http://www.theesteps.org/ in case any of you are as bored at work as I am today

HarryD · 10-03-2002, 12:04 PM

Quote:

Originally posted by Brian Estep
Getting ready to autocross this Sunday (I'm usually heading up last place. Love doing it, but really suck.) Anyhow, I'm going to TRY to place midfield in the stock class this time, can someone recommend a good starting tire pressure to run front and rear for my '87 911 Cab? I'm running 15x6 and 15x7, with new Yokohama 509's. Thanks!

Brian,

I add about 5 psi to each tire when they are cold. Seems to help.

If you have not already, get a copy of Henry Watts book "Secrets of Solo Racing: Expert Techniques for Autocross and Time Trials". Lots of good info.

When I started this year, I owned dead last. Armed with nithing but what i read in the book, I moved to mid pack. Last AutoX I drove a 996 and shaved 4 seconds off of my best time in my 73.

Good luck.

Don Plumley · Don Plumley's Garage

Brian,

Regarding tire pressure, this is a particularly useful thread on autox tire pressure. Note, tire pressures for DE are a separate subject.

The punch line is Warren recommended having front pressures at 35-45 and rears 25-30 to reduce understeer. I tried this at my last autox and my results were much better and more importantly, I felt more in control of the car and better able to predict slippage. It's certainly worth a try as you can always let air out.

I started with about 37-40 cold in the front and 28-30 cold in the rears, I think I ended up around 42/35 hot. You want to check your tire pressures right away when you get back into the pits. There is of course the shoe polish/chalk trick to see how far on the sidewall you are rolling.

Anyway, the thread is certainly very interesting.

Have a great time!

carnut169 · carnut169's Garage

Quote:

Two senile old people that should not have been driving in the first place cost me my lifelong dream and ambition, a 1975 Porsche 911 Carrera.

Hmmmm.

Brian Estep · 10-03-2002, 03:00 PM

Grrr.

Just finished washing the Porsche, and I finally figured out what was 'clunking' on the rear driver's side - the sway bar thing is broke off. Oh well, for a car with 135k on it, I guess something should be allowed to break. Guess this also explains why it's felt like it's been wanting to understeer lately, too. At least I'll have an excuse to (a) place dead last and (b) buy new sway bars now.

I read Secrets of Solo Racing many times, but I have not read the sequel. I will have to order that one, if it's half as good as the first, it's worth twice it's price.

Carnut169, I was pretty emotional when I wrote that. Turns out this elderly couple was on their way to the hospital for the husband's final chemotherapy treatement. I totally looked like the bad guy on that wreck, although there was not a thing I coulda done. I left FOUR ten feet long black marks on the road, actually locked up all four wheels. That was was immaculate, totally restored. After I 'kept' the stereo system (nice Alpine setup), the wing, the wheels, and my mechanic 'borrowed' half the gauges and lots of odds and ends, it still brought 8500 bucks through the auto auction. Had just gotten it back from the shop the day before from getting a new starter and synthetic oil change. That car was THE car I always wanted (ok, for a normally apirated one anyhow) ever since I saw the movie, "Condorman" (anyone remember THAT one?) when I was about twelve years old.