“Weight and Weight Dynamics”

The goal of the racing setup is to keep the car's four tires in contact with the track surface. It goes a little farther than that, though. You want to make the four tires all have the same weight on them during the dynamic situation of the race. This is to say that in the turn, when dynamic forces are at their highest, all four tires have the same relative weight pushing them into the track. If this is achieved, all four tires will have equal grip, and the car will corner properly and easily.

To make the corners of the car all weigh the same while in the turn, you must work “backwards” from the dynamic situation in the middle of the turn to a static situation in the shop. Since weight transfers to the right in the middle of the turn, the static weight should be biased to the left so that when the weight transfers, is transfers to be equal left to right. The same is true for rear to front transfer of weight and transfer of weight diagonally across the car. When you actually set up the car in the shop, you are helping the car compensate for all of this weight transfer on the track so that all four corners of the car weigh the same in the turn.

Your track rules will determine the overall minimum weight of your car. The rules will also specify where that weight can be placed by specifying Left/Right Percentage (LR%) and Front/Rear Percentage (FR%). These percentages vary from track to track. But the setup procedures are the same regardless of the percentages for your track. Common short track L% is around 58%. As the inclination of the track banking increases, L% normally decreases. Simply put, the need for high left side weight bias decreases as banking increases. Flat tracks need lots of left side bias to compensate for the weight transfer.

The FR% is normally biased to the rear of the car. A rear bias of 50 - 50.5% is common, while some setups will dictate a R% of 48% - making the car nose heavy. The problem with F% is that the weight transfers from the rear to the front when entering the turn, but transfers front to rear when accelerating out of the turn. It all depends on the driver style.

Mike Loescher is the owner and chief instructor at FinishLine Racing School in Daytona Beach, Florida.  Mike holds Chassis Seminars throughout the year - all around the USA & Canada. View our class schedule or call 386-427-8522 to schedule a private setup date.

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