weight ratio

Old 08-11-2007, 07:56 PM
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twistacain
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Default weight ratio

Anyone know what a good percentage to start with a a altered? Is there anywhere I can find information on tunning the chassis ona solid suspension car? Right now I have 60% on the rear 1050 lbs and 700 lbs on the front.
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Old 08-13-2007, 05:03 AM
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BillyShope
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The percentage of static weight on the rear wheels should be no more than:

(L-2.5H)/L

where "L" is the wheelbase and "H" is the center of gravity height. The "2.5" is the coefficient of friction for a good set of slicks. The static weight bias should be determined with the driver in the car, of course. It would appear that you'll need to shift some weight to avoid unloading the rear tires with excessive wheelie bar loads.

With no suspension, it is important to build some "droop" into the left front in order to keep the rear tires equally loaded on launch (and, it should be stressed, to maintain some degree of driving safety). To determine the amount and its effectiveness, you'll need to use a traction dyno. (See Pages 4, 5, and 6 below.)

Hope this helps.
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Old 08-13-2007, 06:41 AM
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mcracecars
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Billy, is that formula for alters only? I have a doorslammer in the shop, with the formula, it comes out to 63% max on rear tires......
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Old 08-13-2007, 04:56 PM
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BillyShope
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Originally Posted by mcracecars
Billy, is that formula for alters only? I have a doorslammer in the shop, with the formula, it comes out to 63% max on rear tires......
Works on anything. Sounds like you have a pretty low CG and/or a pretty long wheelbase.
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Old 08-14-2007, 04:57 AM
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BillyShope
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Originally Posted by BillyShope
The percentage of static weight on the rear wheels should be no more than:

(L-2.5H)/L
I suppose it's as obvious to everyone as it was to Ed, but, just in case anyone's confused, the above equation must be multiplied by 100 to get a percentage. I should have said, "The FRACTION of static weight...."
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