How NASCAR Wedge Adjustments Work

Wedge Adjustment during a NASCAR Pit Stop
This pit crew member is adjusting the wedge mid-race to give the driver improved handling.
This pit crew member is adjusting the wedge mid-race to give the driver improved handling.
Stephen Dunn/Getty Images

­The right percentage of wedge depends on current driving conditions and a slew of other factors. Because there's no set formula, a driver might not be able to predict the optimal amount of wedge. During the race, however, he'll feel the car's tendency to swing out or push forward in a turn. When he stops, he can have his pit crew adjust the wedge.

You may be wondering how a stock car can get a wedge adjustment during a pit stop. To make this task quick and easy, engineers fashion a shortcut into every NASCAR race car. Two jack bolts extend from the rear springs in the suspension system up through the car. A member of the pit crew called a "tire changer" uses an extended ratchet that reaches through one of the openings in the rear window to fit onto the bolt. This bolt raises or lowers the post that supports the spring [source: Demere]. By turning the ratchet, the tire changer can add or subtract wedge. The adjustments are measured in turns (of the wrench) or rounds. Often, the car may only need half a round of wedge adjustment.

­These quick-access jack bolts are only available on the rear wheels, however. Getting to the springs on front wheels entails opening the hood. But, thankfully, that usually isn't necessary. As we learned, adjusting the wedge in one wheel can affect the weight distribution on all of them. As it turns out, most of the time pit crews need to adjust only one wheel.

If the driver makes another pit stop because the car's too tight, the tire changer must subtract wedge. Instead of the left side, he mi­ght go to the opening on the right side of the rear window with his ratchet. He screws down half a round, putting slightly more pressure on the right-rear spring -- but this time he subtracts wedge and loosens the car for left turns.

­So now that that you've gotten down and dirty to learn the nuts and bolts of NASCAR wedge adjustment, learn more about NASCAR and other related subjects from the links below.

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More Great Links


  • Bloomfield, Louis A. How Things Work: The Physics of Everyday Life. 2nd Ed.John Wiley & Sons, Inc, New York: 2001.
  • Burt, William. "Stock Car Race Fan's Reference Guide." MotorBooks/MBI Publishing Company, 1999. (Nov. 5, 2008)
  • Demere, Mac. "NASCAR Mid-Race Adjustments." Valvoline. (Nov. 5, 2008)
  • Grassroots Motorsports. "Understanding corner weights."Grassroots Motorsports. (Nov. 5, 2008)
  • Guerrero, Michael. "What is Wedge?" Stock Car Racing. (Nov. 5, 2008)
  • Ovcharik, Miroslav. "Front Bias, Left Bias, and Cross Weight: Suspension Turning with Weight Adjustments." (Nov. 5, 2008)