The GR40 TorqueArm is the heart of the Rear suspension system.
Griggs Racing was the first to fit TorqueArms® to Mustangs and has done so 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).
- Improved strength. FEA and race tested.
- Eliminates potential shuffle of differential cover precluding gear oil seepage/leaks.
- Quieter operation than any other unit on the market. Reduced resonance
- 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 K member on the market with a lifetime guarantee**.
How does it work?
Basically a TorqueArm is one big long Traction Bar that applies loads to the two rear tires evenly by being mounted dead center. Unlike most 3 link, 4 link, 5 link and leaf spring rear suspension systems, a properly designed TorqueArm system produces more total and more 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 vehicle 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 regardless of power available.
As delivered, the major limit in handling and overall performance of 79-04 Mustangs, and similar cars with like chassis is the "4 Link" rear suspension geometry. With the upper two control arms angled heavily outward to laterally locate the axle, the lower and upper rear control arms are not parallel, so as the suspension moves the upper arms are twisted in their bushings. During performance driving this quickly leads to a near total binding of the rear suspension, called "roll-bind." With the binding action as the body rolls, it acts like a giant progressive rear anti-roll bar, causing the rear roll stiffness to skyrocket and the overloaded rear tires to loose traction and spin. Further the layout locates the rear roll center far too high. This is why the rear end snaps into uncontrollable fishtailing when cornering, and it is also why the rear tires break loose at the drag strip once the body starts rising from the initial power hit. The TorqueArm along with a Panhard bar and lower control arms with a ball mount in at least one end is the best solution to completely eliminate bind, locate the roll center, and provide constant loading relative to the CG. This results in a very enjoyable high speed driving experience in a high powered car without the need of electronic driver aids.
Beyond this particular application, we custom design and manufacture TorqueArms for most any application. If you have any specific questions regarding your particular application please contact us at (707) 939-224, or email firstname.lastname@example.org
** See Life time 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