One of the most popular modifications for any Mustang is lowering the body. The S197 is a case in point. These Gen 5s sure take on a hot performance look with a one- to two-inch drop.
Lowering is also part of the formula for better handling. However, lowering changes key factory settings and must be accompanied by other modifications for proper alignment.
The 2005 and later Mustangs feature a solid rear axle held in place by a 3-link design. The independent front suspension consists of conventional MacPherson struts and lower control arms.
In the rear, lowering pushes the axle out of its center position and changes the angle of the driveshaft to the differential housing. A street driver might not notice the slightly denigrated handling. On the track, a racer would feel the car is not as predictable on right and left turns. Kicking the rear end off center also causes premature factory bushing wear by creating additional stresses on the lower control arms. Lowering also changes the camber up front causing uneven tire wear.
However, when done right, lowering improves handling. At the Shelby Bash in Las Vegas, I ran into Keith Criswell of Shelby Performance Parts. Keith actually works for Scott Drake Enterprises, who operates in a joint venture with Shelby. Drake is located in Henderson, Nevada, about a 30-minute drive down the 215-freeway from Shelby Automobiles.
I took an interest in the rear suspension setup displayed on a stand. Basically, this design is the Mustang 3-link, but heavier duty and with a Panhard bar that is adjustable. Adjustability allows centering the rear end after lowering. The factory Panhard bar is non-adjustable. Shelby Performance Part’s Skunkwerkes operation had already installed this new prototype 3-link on a 2006 Mustang and they were testing the car on the track alongside Team Shelby club participants.
The next day, Keith took the system off the car, reinstalled the factory 3-link, and then performed the step-by-step install. Readers who want to lower their Gen 5s can see how the job is done to align the suspension. Shelby Performance Parts also offers a lowering kit for the front end, which should be done at the same time as the rear end drop.
Here’s Shelby Performance Parts’ 3-link rear suspension on a display stand.
First, release the emergency brake and elevate the car on a lift.
The stock 3-link consists of a swap bar with links, a Panhard bar and a pair of lower control arms.
Remove the tension off the lower control arms by slightly elevating the rear end with a pair of “under-hoist” stands.
Remove the rear sway bar first. At each end remove the two bolts that secure the retaining bracket and “pillow blocks.”
Remove the sway bar links at each end.
Now you can remove the sway bar.
Remove the factory emergency brake cable on each side of this vehicle. This retaining clip holds the cable to the inside of the wheel.
Next, remove the lower control arms. Shane started with the back bolt on the driver’s side.
Next, he pulled the lower control arm’s front bolt.
For a starting point, adjust the new Shelby lower control arm to the same length as the factory bar. To adjust, loosen the jamb nut and turn the bar. Then, retighten the jamb nut.
The wider part of the end of Shelby’s lower control arm goes to the inside of the vehicle closest to the rear.
Install the Shelby lower control arms. Tighten, but do not torque.
Pull the stock Panhard bar next. Start with the bolt on the driver’s side.
Next, pull the nut on the passenger side while holding the Panhard bar so it doesn’t fall.
Pull the factory pressed-steel upper cross brace above the Panhard bar.
Replace the factory cross brace with this stronger Shelby brace. Tighten, but do not torque yet.
Elevate the hoists to simulate the load weight of the car on the ground.
Set the angle of the driveshaft to the differential housing from negative two to negative three degrees difference for manual shift Mustangs, and from negative one to negative two degrees for automatic shift Mustangs. Shane uses a special angle tool to measure. Negative means the housing is pointed down in relation to the driveshaft.
To set the angle of the driveshaft to the differential housing, loosen the jamb nuts on the lower control arms and turn.
Lower the axle back down off the under-hoist stands and torque the lower control arm bolts to 130 lb-ft. (NOTE: This is only true for spherical rod ends; not with polyurethane bushings.)
Install the new Shelby Panhard bar.
Install the new Shelby rear sway bar with the end links attached.
Notice the unique size and shape of the Shelby sway bar end links. The Rapid Prototyping Shop made them resemble a connecting rod for functionality. They are much stronger than stock.
Also part of the Shelby Performance Parts rear end is this differential upper control arm body mount, connecting the upper control arm to the body mount.
Tighten the connecting rod links.
To align the lowered rear end to spec’s, drop the car to the ground. Hold a plumb bob over the middle of each rear tire with the line over the center of the flat part of the fender. Measure the distance from the line to a fixed point on the wheel.
Adjust the Panhard bar until the distance from the plumb bob’s line to the wheel is the same (plus or minute an eighth of an inch) on each side of the rear end of the car. When the rear end is centered, tighten the jamb nuts. All jamb nuts should have blue Loctite applied before final tightening.
Shelby Performance Parts test-drove the lowered Mustang on the track during the January 2009 Shelby Bash.
The crew—four people, Rapid Prototyping (left to right: Keith Criswell, Tim Dunn, Shane Wagner, and Khris Kading.)