Another way to go is with a set of No-Hop bars from Lakewood or Bill Miller Racing. Before we get into that, we should review something called the rear suspension's instant center. The instant center is a point where imaginary lines extended forward from both the upper and lower control arms (as viewed from the side of the car) converge. By changing the rear mounting point of the upper rear control arm, this changes the position of the instant center and causes the rear suspension to rise slightly upon acceleration. Lakewood and Bill Miller Racing offer these bars for both GM A body cars and the ubiquitous Fox-body Mustangs. If there is a downside to these No-Hop bars it's that there is a limit to lowering the rear of the car since these bars reduce the clearance between the upper control arms and the floor kick-up over the rearend. In those cases, lowering the rear of the rear lower control arms is an alternative to raising the rear of the upper control arms.
Get it StraightIn order to have a fast car of any kind, it must track straight down the track. This means the alignment has to be dialed in and this goes way beyond just setting it to the factory specs. But before we get into that, you have to make sure the rest of the front suspension is in good shape. This means inspecting the ball joints and control-arm bushings. If you're working with any older musclecar, the A-arm bushings are no doubt wasted. Replacing them with a stock rubber or even polyurethane bushing is acceptable, but a better idea is a bushing that allows you to dial in a given amount of preload.
Global West makes front control-arm bushings that are near solid yet can be used on the street and are also adjustable. The aluminum-bodied Del-A-Lum bushings feature a Teflon-like material called Delrin that separates the steel shaft from the aluminum bushing body and can be preloaded. The beauty is that these bushings do not deflect thereby maintaining a very accurate alignment for a very long time.
For a drag-race-style alignment, it's important that the settings be made at race weight with the equivalent of driver weight in the seat. Then, the front suspension should be raised to the ride height achieved as the car goes down track. This is important since all three variables of toe-in, caster, and camber are ride-height dependent.
As for the specs, maximum positive caster offers excellent high-speed stability, so 4 or more degrees of positive caster is a good goal. Some strut cars like Fox-body Mustangs do not provide caster adjustments, but aftermarket plates like those from Global West can make this happen. Camber should be kept as close to zero as possible. Toe-in should be set at 11/416-inch total or 11/432-inch per side. This minimizes tire scrub that might be worth a small trap-speed improvement.
Launching With LeavesThe leaf spring is the oldest form of spring yet is still very popular in drag racing. The biggest problem with leaf springs is their tendency to cause wheelhop. This action starts with the twisting motion of the rear axle, which rotates around the rear-axle centerline. This twist imparts an S-shaped bend into the front half of the leaf spring, which eventually binds and then snaps back, forcing the tire to literally bounce off the ground, creating that evil wheelhop.
The quick fix is a set of traction bars. These bolt-on devices work on the track but tend to bind the rear suspension anytime the snubber hits the spring. Many bolt-on bars are universal and somewhat short, placing the snubber short of the spring eye, which will eventually bend the spring. Ideally, the snubber should be placed directly under the spring eye. Eliminating deflection with a solid bushing is also a good idea, but they don't live long on the street. Global West makes a Del-A-Lum bushing for these applications; they work like a solid bushing but without the wear problems.