Babkin Racing (babkinracing) wrote in autocrossers,
Babkin Racing

shock absorber lessons

It was cold at the first autox events of this year, temperatures in the 40s and 50s, so the tires were real slippery. And the car was a beast, plowing in every turn, and if the steering wheel was turning a little, trying to flat-spot the inner front tire. I've softened the front shocks from 0.6 to 0.4 and it made a world of a transformation! The car was finally handling pretty decently! and it immediately dropped my times by 2 seconds (from 54 or so).

What happened there? At about the same time at Perry's forum someone has posted a link to the Autocross performance handlbook, which provided me with a partial explanation: the important reminder is that the only thing adjustable in the single-adjustable Konis is rebound. The compression rate stays fixed. That book also says that the reasonable adjustment rate for Konis is between 0.4 and 0.6, anything higher goes disproportionally stiff.

If you adjust the rebound too harsh in the rear, you get the wheelhop under acceleration. It develops because when a wheel jumps a little, the stiff rebound rate of the shocks don't let it get back to the ground. Now, when you get the front rebound rates too stiff, you end up with a symmetric thing: a wheelhop under braking. Once a front wheel hops, it gets locked up and immediately wears into a flat spot. No wonder I've been flatspotting the tires like crazy during the last 2 years.

Then I've tried the same stuff on Camaro and it worked too.
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