NASCAR Tech: Adjusting wedge

By Michael Guerrero, Stock Car Racing Magazine
September 21, 2001
3:46 PM EDT (1946 GMT)

If you've watched NASCAR racing for any length of time, you've heard the word "wedge" thrown around quite a bit. You normally hear a driver or crew chief talking about putting a round of wedge in or taking out a round to "free" or "tighten up" the car.

What does that really mean? To find out, Stock Car Racing magazine spoke with Royce McGee, head wrench for Mike Skinner's #31 Lowe's Chevrolet in the NASCAR Winston Cup Series.

"Wedge is a term that racers have used for years to refer to the amount of weight between the right-front and left-rear wheels," McGee says. "Another slang term for wedge is cross-sway or diagonal. The total weight between the right-front and left-rear tires of the cars is usually a smaller percentage than the carrier between the right-rear and left-front tires.

The cut outs and jack bolts are made for easy access.

"That's what we call running a car 'de-wedged.' There's usually about 45 to 48 percent of the total weight between the right-front and left-rear tires."

McGee offers an example of how wedge works, using a piece of furniture as a prop. "If you take a table on a level floor and shorten the right-front and the left-rear legs ¼-inch, the other two legs will carry more weight. If you then adjust those two legs by adding a 1/8-inch shim underneath them, that table will rock less."

Drivers let the crew chiefs know how the car is handling and what might need to be done to make it better. Oftentimes the solution is a quick wedge adjustment.

The wedge wrench is placed into the jack bolt.

"If the driver says that the car is loose in the gas exiting the corner, we'll put the wedge wrench in a jack bolt in the left-rear window," McGee says. "When you screw down on that left-rear spring, it puts pressure on it and tightens up the car in the gas.

"If the car is too tight, we go to the right side of the car with the wedge wrench and make the adjustment there. The wedge adjustment changes the load that the springs carry."

Wedge adjustments are usually made in half and full-turn increments during pit stops. During a pit stop, a tire carrier usually makes the actual adjustment after he has given the tire changer the tire. As the tire changer is bolting on the tire, the tire carrier sticks the wedge wrench into one of the jack bolts and makes a turn.

Just one turn of a wedge wrench can help a driver go from chasing his car all over the track to charging to the front of the pack.