dking3

Any of you who autocross your 350Z with 18" stock Bridgestones mind sharing your experience on what tire pressures to use? My Touring is broken in now, so it's time to eat Porsche, S2000, etc, etc.

Thanks,
Dave King, 2003 Redline Touring

C Ray Z

iTrader: (2)

I ran pressures of 38 to 40 front then the rear 2 PSI lower to get the rear to rotate.

reccomendation:

Get the EVO front swat bar to reduce push by 1/2.

It is a blast to drive.

dking3

Thanks for passing on your air pressures and other ideas. It's surprising that the EVO front sway bar is just right to reduce the understeer.

I had a factory competition rear sway bar on my old 240Z, and took the front completely off, which made it near neutral. That car had no limited slip differential, so you couldn't kick the rear end out. I also had 3/4 racing springs from BRE and big Goodyear slicks on it, very different from stock.

I'm not sure how seriously I'm going to get into Autocrossing the 350Z. I'm going to try a couple times and see how the events are run.

Thanks again,

Dave

MannishBoy

iTrader: (1)

I run 40-42 up front, and depending on the course, down to 36 or so in the rear to help get traction in the back on launches and coming out of corners.

C Ray Z

iTrader: (2)

I believe the stiffer front sway helps because it keeps the front flatter at turn in. You will also need to get the car slowed down into the turn. Too hot and it just slides.
The biggest improvement is the bigger tires I am running this year. 265x35 front and rear.

Take ever oprotunity to take leasons and lear to drive. Drive in Acr's, learn to balance the braking to improve turn in.

Good luck

BA Cutler

Dave,

I've logged about 35 autocross runs on my Z running on the RE040 tire. I'm running 35-37 up front and 28-30 in the rear. In the first SCCA Regional this season, I was the quickest BS car (in the wet). Saturday, our club had a practice... I ran 9 runs. They were still going at it when I left... but I was the fastest car on street tires at the point I left. We had a short 30 something second course... and I actually had the opportunity to use 3rd gear after bouncing off the rev limiter in 2nd during my second run... really had to stand on the binders to whoa the Z down within the stop box. I biffed a cone in the stop box and earned a passenger's side black eye on the Z's nose.

I have been encouraged by how close I'm coming to the cars on race rubber. I was just over two seconds of the fast time of day. I'm not sure what the current belief is about how much time race rubber will earn you... but I'm pretty optimistic about my Z's chances in B-Stock, at least within this region. I keep wondering if this coming weekend's event is coming to hand me a dose of reality!

My strategy has been to get massive amounts of seat time with the Z, then add all the B-Stock allowables. I've added the air filter, cat-back exhaust, Konis are on order (I'm one of the lucky five who's Koni's missed the boat!), I'm talking to BJ about a front 350EVO sway bar, trying to figure out how I want to install a harness (I have a nasty habit of leaning forward while driving, I need to be pinned in)... I know the Kirk roll bar is the safest way to go... but I'm not planning on using the Z for anything that would require a roll bar anyhow... and the roll bar is very heavy... the Avalon harness bar is my latest idea... tires, .25" spacers and an alignment... and I'll have the car set-up. I'm holding off on tires until I have everything else dialed in.

Give the tire pressures a try, I know my pressures are way off of what everyone else is running... but these pressures are working for me.

Brian

dking3

C Ray Z,

I'm sure you've got it backwards. The sway bar is attached to the car, so it's supposed to reduce the amount of sway that the car does in a hard turn. In doing that, it tends to lift the inside wheel. That's OK on the end you have plenty of traction with, and it's the opposite you want on an end that tends to break loose. The Z plows, understeers, is too tight, which ever way you want to say it. That means you want to let the front end free to plant both tires on the ground. Use more stiffness in the rear.

Dave