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      06-11-2019, 12:08 AM   #8
toy4speed
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Drives: bmw m2
Join Date: Apr 2019
Location: Livermore, CA

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Quote:
Originally Posted by OldDirtyCoaks View Post
Maybe it's the extra tire and square set up giving you the understeer?

I run my tire pressures at 38-40psi cold, I find if it's not higher my sidewalls on the outer edge of my front tires will get scuffed.
I'm inclined to think the front sway bar was set too stiff, causing the understeer effects. Will need to adjust and test to confirm though.

Going to a square tire setup, especially increasing the front tire width by 30mm, and the rears by only 10mm, would have expected less understeer from just the tire changes alone. Not to mention going from stock MPSS to the RE71R tires. Last thing I expected was lots of understeer.

Very little information I could find on relative stiffness of the Hotchkis bar compared to the Dinan bar. Have read some owners were favoring the 2nd holes (from stiff) on the Dinan bar, so that is how I set my Hotchkis bar.

Some indication I found on line that the Hotchkis bar I weighed at 10 lbs, might be a bit heavier than the Dinan bar. Although both claim a 32mm hollow design, that doesn't specify wall thickness of the bar, the arm relative lengths or angles.

Planning to go FULL soft on the Hotchkis bar for next event.

Front RE71R tires did not have unusually large wearing toward the sidewalls, eg. doesn't appear the tires needed more pressure since they didn't appear to roll over much. They just didn't stick.

I also realize the forward rake of the car decreased slightly going to the square tire setup, vs. stock sizes. Very slight change, but in theory that could cause a small likelihood of understeer.

Can't wait till the next event.
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