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Old 03-01-2009
jedwards3 jedwards3 is offline
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Join Date: Nov 2008
Posts: 9
Red face Tire shake

What causes tire shake?
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Old 03-02-2009
Big Red Engine's Avatar
Big Red Engine Big Red Engine is offline
Join Date: Dec 2008
Location: Columbus, IN
Posts: 35

I'm sure there's others on here that can explain it better than me, but I'll give it a shot.

Basically tire shake is caused by too much grip at the rear tires. When a car launches there's a certain amount of wheel spin that needs to be achieved in order for a car to launch properly. Too much and it goes up in smoke, to little and you can get into tire shake.

Tire shake is typically caused by not enough power being applied to the rear wheels during the launch. Since not enough power is being applied, you do not get the needed wheel spin (to much grib) and the tire wads itself around the rim. The tire can only take so much before it wants to unwrapped itself and thats when you get into shake.

It's similar to wheel hop on a rear wheel drive vehicle. The pinion angle changes when you launch and if not enough power is applied the axle housing will snap back and you'll start wheel hopping. This is why guys install trac bars to keep the axle housing from wrapping during the launch and keeps the pinion angle the same through all conditions.

Here's a quick video that will show some the tire sleep i was refering to
If everything seems under control, you're just not going fast enough. - Mario Andretti
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Old 03-02-2009
HEMI_guy HEMI_guy is offline
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Join Date: Jan 2008
Posts: 10,016

You're correct that tire shake comes from wheel speed not matching the motion or intertia of the car. But it's not always about not making enough power for a given tire size nor is it always the result of too slow of wheel speed. WE went through a spell where we were experiencing shake on a way to consistant basis with almost any track condition with our 2,500 hp, 3,000 pound car. What we learned was we were giving the wheel too much speed. The tire and wheel was trying to push the heavy car faster than heavy car wabted to go. It was right on the edge of hazing and sometimes would. Once we figured this out we fixed things by putting a numerically higher firs gear in the Lenco. This fixed things right away, though we still experienced shake ocasionally. The next season we swapped our 4.10 rear-end for a 4.56 and went to a shorter tire and shake became a distant memory and our 60' times dropped by .015.
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