Speed Tech Torque Arm Explained
Pro Touring cars do not need a lot of articulation, but one lesson learned is that a high horsepower, high traction car can do some REALLY funny things when you apply the throttle early in a corner. With a typical 3 or 4 link suspension, the instant center is a moving target and can easily cross over the 100% line, depending on static anti-squat and amount of travel. Also, on many early chassis, a 3 link is a somewhat difficult install as there was never much structure above the driveshaft tunnel. With high-anti squat percentage and short Instant Center lengths, heavy braking can cause rear wheel hop.
The torque arm has the advantage of a fixed Instant Center location, and a fairly long swing arm length. A torque arm doesn't allow anywhere near the amount of axle wrap we get with a short/long 3 or 4 link. There is very little pinion angle change or driveshaft slip. Also, it is typically a very easy install, requires minimal floor and frame modifications, and can even make use of existing front leaf spring mounts for the lower links. The tradeoff can be some increase in unsprung weight compared to the stock mono leaf springs, when compared to multi leafs there in virtually no difference.
The torque arm does require some sort of pivot or floating link at the front end, as the lower links define the travel arc of the axle housing; and rigid mounting the front will cause binding. Speed Tech uses a Delrin machined bushing that slides, rotates and pivots in the front mount. This also has the added benefit of locating the torque arm side to side.
The Speed Tech Torque arm is the ideal rear suspension set up for both street drivability and track performance, if you’re looking for the simplest install and easy set up with maximum performance the Speed Tech torque arm is your only choice