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-   -   Chassis Flex (https://www.racingjunk.com/forums/showthread.php?t=21276)

edvancedengines 07-14-2008 05:49 PM


Do any of you think that possibly lengthing the top right bar one flat would help?
No' Don't think about doing it!

Sure. It will help you get into the wall quicker. If your car is launching , is driving and stopping straight don't monkey around with preload changes.

Besides that lengtheing the top right bar will take weight off the left front and right rear. Even if it magically still went straight the left front would go higher.

Take the time to fully read my article and think.

Ed

onedragracer 08-29-2008 02:09 PM

I have the same type of roadster. It was doing the same thing until I scaled it and found out what my weight distribution was. My car was leaving very straight also. I kept shorten the top right bar one flat at a time until it stopped picking up the left before the right. I rescaled after getting the launch to my satisfaction and found that the left front weight was 180lbs more than the right front. The car still sits level with me in it.

BillyShope 09-01-2008 05:04 AM

The reaction to the driveshaft torque, taken at the engine/transmission mounts, is distributed, front-to-rear, in proportion to the relative roll stiffness. If all the roll stiffness were at the rear, all of the driveshaft torque reaction would be fed back to the rear axle assembly, completely balancing and canceling the the normal tendency to unload the right rear. An anti-roll bar, with its extremely high roll stiffness, approaches this ideal condition, but, since there is always some roll stiffness at the front, complete cancellation is never possible.

The misdirected reaction torque...that which goes to the front...is seen when the left front rises higher (or before) the right. THIS IS NOT TO BE CONSIDERED "NORMAL" AND IS, INSTEAD, TO BE AVOIDED!! The torque necessary to twist the chassis is exactly equal to the uncanceled torque acting to unload the right rear. Since performance of a tire pair, whether in traction or in cornering, is optimized when the tires are equally loaded (verified by testing performed by both the tire and automobile manufacturers), performance will ALWAYS be improved when the twisting is eliminated and the fronts rise evenly.

As for the question originally posed, I would recommend the 4link be adjusted for 100% anti-squat and that some means of dynamic cancellation of the driveshaft torque be incorporated. This can be either in the form of an asymmetric 4link adjustment or the use of different spring rates, left-to-right, at the front. Final tuning should be with a traction dyno.

dparker 09-03-2008 03:23 AM

What!!!

and 123,568x584,766=72,258,365,088


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