Generation 14 Severe Duty TorqueArm Kit 65-70 Mustang and Cougar w/8.8 Axle


A GR350 TorqueArm is the heart of the suspension system.

A TorqueArm greatly improves drivability and control at the limit of adhesion by applying loads consistently and evenly to both rear tires during acceleration cornering and braking.

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Many customers install an 8.8 rear axle when resto-modding their vintage Mustang or Cougar. The 8.8 has less hypoid offset than a 9 inch and that means less friction and better mileage, among other things. It also makes it little easier to install our TorqueArm rear suspensions system. (We do still make TorqueArms for 9 rears as well).

We have redesigned our 8.8 TorqueArm® Kits for all applications with 8.8 rear axle housings to keep up with the growing demands of our clientele to stay ahead of the ever increasing power and increased loads due to ever improving tires. This new series of TorqueArm® Kits kits utilize a unique Mid-Plate that bolts between the differential housing and carrier on 8.8 axles. For more information refer to this downloadable pdf.

TorqueArm Update

The GR40 or GR350 TorqueArm is the heart of the Rear suspension system. 

Griggs Racing was the first to fit TorqueArms® to Mustangs and has done so to thousands since 1979. As with all our products, we continually evaluate the needs of our customers, and upgrade the product as vehicle weight, power, brake and tire loads have increased, while endeavoring to keep cost of production of the best possible product within reach. And at the same time, continuing our policy of a lifetime warranty against breakage of most of our parts.

Our original production TorqueArm® for Mustangs with 8.8 inch rear axles were first offered in 1979 to accommodate the needs of drivers with Mustangs making 3-400 horsepower with drum rear brakes, and on tires of the day. Today, many of our customers are driving cars topping 2 tons, with tires producing 3 times the grip as in 1979, and with power adders as much as 1300 or more horsepower on which our newest design TorqueArm® is proving to be the standard of excellence. So we have discontinued all previous designs. (Legacy TorqueArms® are still available by special order).

Quick Facts

  • Improved strength. FEA and race tested.
  • Eliminates potential shuffle of differential cover precluding gear oil seepage/leaks.
  • Reduced resonance for quieter operation than any other unit on the market.
  • Provides easier TorqueArm® removal and re-installation during rear axle maintenance.
  • Mounts independent of Watts linkage.
  • Can be used with ANY differential cover or Girdle. (Some covers may require drilling of two 3/8 inch dowel pin holes. Tools available.)
  • Adjustable Pinion Angle.
  • Now only one part number per genre of GR40 or GR350 systems, each rated at 1300 hp capacity:
  • And the only TorqueArm on the market with a lifetime guarantee**.

How does it work? 

Basically a TorqueArm is one long traction bar that applies loads consistently to the two rear tires evenly by being mounted dead center on the axle and close to the vehicles center of gravity. Unlike most 3 link, 4 link, 5 link and leaf spring rear suspension systems, a properly designed TorqueArm system produces more total and consistent weight transfer to the center of the rear axle during acceleration and braking due to a non pivoting consistent load point on the chassis that is constant in relation to the center of gravity of the sprung mass of the vehicle. This results in a car that is easy to control at the limits of adhesion on wet or dry surfaces, and while cresting hills while turning, minimizing steering corrections required of the driver.

65-70 Applications. Leaf springs are heavy and prone to wheel hop, and a geometric compromise as they have to carry all acceleration loads, both longitudinal and lateral, and deliver engine and brake torque to the rear tires. In a performance application wheel hop is usually controlled by the addition of control arms and adding leafs to the springs. Though and improvement, this is a compromise at best, and in high performance cornering situations vehicle behavior is still not ideal. Addition of a TorqueArm removes the engine and brake torque from the springs, delivering consistent and predictable behaviour that is unparalleled by any other system. Further, installing a TorqueArm with a Watts link or Panhard bar, along with Ball pivot lower control arms, and either floating the springs on the axle with sliders or replacing them with coil overs provides a uniquely superior driving experience and perfects the rear portion of a formerly leaf spring suspended vehicle.

Other Applications. Beyond the above applications, we custom design and manufacture TorqueArms for 8.8 and 9 inch rear axles into any car for most any application.  If you have any specific questions regarding your particular application please contact us at (707) 939-2244, or email

** See Lifetime Warranty

For more information about how a Torquearm fits into a complete performance system Please review the following:
“Been There, Done It All” October 2004, 5.0 Mustang and Super Fords
“Extreme Winner” May 2005, 5.0 Mustang and Super Fords
What Are You Going To Do With Your Car
The GR40 Suspension System
“Vortech Mustang Mach 1” April 2004, Motor Trend