View single post by Judson Manning
 Posted: 07-01-2007 01:09 pm
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Judson Manning



Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
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Clif,

The Delta-supplied street legal Panasports Ron is running actually weigh a good bit more than the stock (magnesium alloy) JH wheels.  Ron's wheels were on my car when I was running BFG R1s 205/60R13s many years ago.  The re-occuring problem I always had with an open diff was rear grip.  That inside tire would unload and I'd always go into a spin.

Fast-forward to this year and my experiment with JH wheels and a set of 20-8x13 Hoosier racing slicks.  These cantilevered tires are designed for Production cars running 5.5" (i.e. stock JH) wheels.  These things stuck like glue even with an open diff and the 907/910 hybrid pushing them through the W58.  Power and grip were not a problem, but what I quickly found was the limitations of my braking system!

Much like my braking example, the bearing loads are a problem.  Our bearings are the same as a small trailer and will not withstand the constant pounding of 8" slicks or 225 R-compound tires.  Pushing the tire outboard makes the situation worse.  Ron is resigned to the fact that much like the Neon guys, he'll be changing bearings every couple of races.

The other issue is front end scrub-radius.  Once you start pushing the tire outboard with spacers, steering effort increases along with understeer.  There is always a balance between getting more grip with fatter rubber and losing grip due to less efficient geometry.  The rules allow me to solve this problem on my Production car, but it's not an option for a street JH.

Assuming your rules won't allow a set of slicks, I'd get a set of 15x6 Panasports off the shelf at Delta.  Along the lines of what Ron has done, slap a set of 225s out back and 205s up front.  That will give you a good balance of grip without having to worry too much about bearing or steering failure.

Judson

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Last edited on 07-01-2007 01:09 pm by Judson Manning