Muscle Mustangs & Fast FordsHow To Chassis Suspension
1993 Cobra Mustang Rear Suspension - All Torqued Up - Tech
We Infuse Our Fox-Body With A Modern Rear Mustang Suspension From Maximum Motorsports.
While many enthusiasts believe that late-model Mustangs are only good for drag racing, there is a strong opposition to that claim and one that regularly pushes our beloved ponycar around vigorous road courses in the pursuit of faster lap times. It's all about going fast in the end.
If you haven't followed MM&FF's project Stolen Goods, let us bring you up to date on our subject vehicle. Having come across a fantastic deal on a '93 Cobra, we set about rebuilding it, literally from the ground up, and started with a Maximum Motorsports Road and Track package for its suspension. For the rear suspension, we planned to use MM's Panhard bar/torque arm arrangement, but we wanted to get a comparison with and without the torque arm, and to do that, we had to complete the long build process and get the car up and running before we could flog it for testing purposes. Having put some 4,000 miles on the Snake, not to mention numerous track tests, we were ready to install the torque arm and convert the factory triangulated four-link to a three-link/Panhard bar design.
"The Mustang four-link came from the '78 Fairmont, and its design was fairly compromised to begin with," says Maximum Motorsports' Chuck Schwynock. "It doesn't do anything exceptionally well. In fact, body roll should be controlled by the springs and sway bars, not the control arms as is the case with this setup. The four-link has a tendency to bind up, and when it breaks loose the results can be unpredictable. The popularity of the Mustang showcases all of its deficiencies due to its old engineering."
The team at Maximum Motorsports set out to design a more current suspension setup for the Fox, and they ended up with a Panhard bar/torque arm setup in their shop car. Maximum actually has several torque arm options depending on your car's horsepower, subframe connectors, and the rear axle gear ratio.
To install the torque arm, we visited HP Performance in Orange Park, Florida, as it had the experience to perform such an installation, as well as a drive-on lift to facilitate it. Special tools like a MIG welder and angle finder are used, but many of you have these at home, so it is possible to do the job on a set of jackstands. The torque arm was installed in a few short hours and the results were immediately apparent. Straight-line traction, especially on our street tires, was much improved, which is quite helpful given our 430 hp powerplant's propensity for lighting up the rear tires. We did notice a slight increase in vibration through the floor, but that has either subsided or we have just gotten used to it because it doesn't seem to be present anymore.
We had previously run Stolen Goods at our local autocross without the torque arm, and one of the major issues we had was extreme brake dive and the subsequent rear lockup. With the torque arm installed, brake dive was reduced, which gave the rear tires more traction to perform braking duties with. We never had to change the brake bias as the reduced brake dive solved the issue.
During our post-install track session, we noticed that the rear tires were rubbing the inner fenders during hard cornering. After consulting Maximum Motorsports, we'll have to look into getting a better fitting wheel/tire setup out back. Now that the rear suspension is no longer binding, the body is rolling over more freely. While Maximum offers an increased spring rate to both compensate for that and the increased rear traction, it still allows for the body to move freely. The 10-inch wide rims and 275mm-wide tire combination just isn't going to cut it, but we see it as a good problem to have. We'll look to go back to a nine-inch wide wheel and a slightly smaller width tire and get back to the track to power out of the corners with confidence.
How To Determine Which MM Torque-Arm Is Best Suited For Your Application
1. Find your car's differential gear ratio in the Engine Torque Table.
2. On the same row as the gear ratio listing are the ratings for the maximum engine torque, and the maximum rear wheel torque, for the Standard Torque-arm.
3. If your car exceeds these ratings, then look at the next column for the maximum torque ratings for the Heavy Duty Torque-arm.
|Engine Torque Table|
|Standard TA||Heavy Duty TA|
| Max. |