Check Out That Chassis

By Jim Salemi

Jim, I have a Top Sportsman car that is running in the 7.60 range, 1.09 60-ft times. On launch, the car hits the wheelie bars for approximately 12 inches, then there is a gap of about 18 inches, then the bars hit again as evidenced by the shoe polish left on the track. The bars extend about 12 inches rearward of the car body, and are set at 5.5 inches from the ground to the centerline of the wheel. I suspect this is unloading the rear tires. The 4 link instant center is 68 inches, 3 inches off the ground. The front struts are all the way loose (top) and midpoint on the bottom adjustment. The rear shocks are 6sweeps on top (midpoint) and midpoint on the bottom adjustment. Any suggestions on adjustment to improve launch and eliminate the possible unloading condition?


John, first off your car is not transferring weight properly. Obviously that's why you're double tapping the wheelie bar. For starters I would raise the instant center intersect point
to 7 to 8 inches. Keep the distance from the center line in the same area.

When you plot the four link setting, make sure you can also have a setting that pulls the point back because the car might transfer weight too easily in its new location. If it does, keep the height the same and shorten the distance from the center line.

I would also raise the wheelie bar 1 to 1.5 inches so I was sure that it wasn't the bar causing the unloading problem.

Hopefully this will improve consistency and help you win more rounds.

Jim Salemi
G-Force Race Cars inc.

To contact Jim Salemi write

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Check Out That Chassis — 8/8/03


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