1993 Ford Mustang - Three-Step Program

For maximum traction, Buck says the lower control arms should point upward between 0.5 and 2 degrees. Using the middle setting on the Competition Engineering lower control arm relocation brackets enabled achieving the ideal angle.

The pinion angle was set at 2 degrees by adjusting the upper control arm length when the driveshaft was installed, but Buck placed an angle gauge on the rearend cover just to confirm that it hadn't changed. Since Project Fox's rear suspension uses stiff Heim joints, it doesn't need much pinion angle. Cars with rubber control arm bushings need -6 to -7 degrees, while urethane bushings reduce the required angle to -3 to -4 degrees. Reducing pinion angle decreases vibrations and parasitic power loss.

The heavy-duty Competition Engineering sway bar is a great tuning tool, as it allows adjusting preload over the rear tires. For instance, lengthening the right-side endlink increase the weight over the right tire and decreases the weight over the left tire. This adjustability proved very useful when adjusting the corner weights.

The rear suspension must be adjusted on the ground, on a four-post lift, or with the tires on blocks. One important fact to keep in mind is that as the rear tires get taller, the rear ride height increases as well. Simply cranking down on the coilovers to lower the ride height will adversely affect the instant center of the suspension.

Project Fox uses Strange single-adjustable shocks up front, and Competition Engineering single-adjustable shocks in the rear. Since we'll be running off of a foot brake, Buck set the shock settings right in the middle at each corner of the car. He advises against going too soft on the settings for the first few passes to prevent pulling the front tires off the ground. Since transbrake cars hit the rear tires harder, they need stiffer front shock valving.

With the driver sitting inside the cabin and the car on scales, Buck adjusted the rear corner weights. Initial readings revealed 685 pounds over the left-rear tire and 645 pounds over the right-rear. To compensate for this, Buck added tension to the right-rear sway bar endlink until the scale read 675 and 667 over the left and right tires, respectively. For a baseline tune, Buck shoots to get each side within 20 pounds of the other. For a drag car, the difference in weight between the front-left and front-right is inconsequential. Weight on the left-front will transfer to right-rear during a wheelie, but this effect is greatly reduced if the front tires stay on the ground.