AX tire pressure vs. tread roll, kumho V710 Options

[mskala]

Question is this for autocross purposes: If I'm running 24PSI hot and the
tread wear triangles are still not touched, should I go lower? My thought
is that either:
1) lower pressure will improve the contact patch and more grip will improve my time.
or
2) lower pressure will make slaloms slower by having more flex/lean in the car which will increase my time.

Using Kumho V710 215/40/16 on a 7.5" rim on my narrow -6. 21mm torsion bars
in front and 180 pound springs in the rear, because that's as high as I want to go
and still be driving this thing on the street regularly.

Appreciate any input.

Mark S.

[ConeDodger]

Not really related to the original question but seeing as this thread evolved to questions of 'cushy' on the tushy...

I modified my suspension in steps... Not really because it was planned but because I learned as I went and less money was spent at one time. First, I put in stock bars front and rear. My car didn't come with them and the difference was purely dramatic. Next, I put in Koni Yellow adjustables all the way around. A note here, when these were set to full stiff the suspension was jarring enough to keep a family dentist's kids in tuition money. Then, I put in a Tarret bar and Elephant bushings... Here is where I got a really unexpected result. With the Elephant bushings, it didn't matter what my shocks were set at. The ride was very supple. The bushings suck up everything the road throws at it and allow the shocks to work. Lastly, I sent my car over to IPB Autosport in Sacramento. Ron Kain who really knows his way around a 914 and is a good friend of Brad Roberts, called Brad to consult on my suspension. When I came to pick it up, I found that they had put 200# coilovers in the rear. I was a bit apprehensive. What would happen to my ride? Still supple.

This last weekend, I drove a two day autocross at Reno-Fernley Raceway. My friend and neighbor, Brady Halbasch was going with me in his 350Z. Brady had never autocrossed before but is a former National shifter kart champion who trained Marco Andretti and Graham Rahal among others. We discussed which car I should take and Brady wanted to drive them both. "Oh my God! This is the closest thing to a go-kart I have ever driven that isn't an open-wheeled car!" I pointed out that it was also very smooth on city streets and he said "yes, your suspension is very active" "what is that?" I told him about the bushings and he said that they were very much like the roller bushings he used in racing...

Bottom line; if you use roller bushings (source - Original Customs) or Elephant Bushings (source - Elephant Racing) you don't have to 'suffer' through your suspension on the street.

(IMG:style_emoticons/default/agree.gif) with Randal on the TB differential. Raby keeps saying I will break mine in the 901 with the torque from this motor but I will soft launch until then and put one in a 915 when it does break. I would not be without one...