Heavy Duty, LR Torsion Arm, Straight, 600cc, 7/8" x 13" for X4, X6, & X7

Heavy duty 3/4" thick version of the standard version of the 40-175 torsion arm.

Depending on if your left rear rack is offset or not (we have changed this several times over the years) and which engine platform you use, you may or may not need the 40-176 offset left rear arm to get the optimal left rear bearing carrier position.

It is best to get the left rear bearing carrier out closer to the sprocket to allow the use of shorter chain guide block spacers (½" to ¾") is best. This will apply less force on the bearing carriers bearing from chain force also it will keep the chain block from flexing out of alignment. It will also increase the effective spring and shock rate for the left rear tire (this is much better).


Redesigned in 2017. The X4, X6, & X7 Hyper rear torsion arms are now designed with two shock mounting holes. The idea for the new hole, which is closer to the shackle mounting hole, was conceived when the R&D was being performed for the X7 chassis. More shock control was needed to control the rear axle when in the forward position (short wheelbase). In lieu of re-valving our shocks, we just added the new hole which adds 10% more effective shock rate to the dampening system thanks to the mechanical advantage change.

The new arm is also made a little stronger by increasing the relief pocket radius and increasing the web thickness in key areas.

The 40-401 Torsion Arm Standoff can also be used to allow the rear axle to drop further when the shock is fully extended. This is needed when using longer shackles or depending on shock brand as some shock types are shorter than other even though they are 7" stroke. The Standoff can be flipped to allow use for long or short wheelbase.

Machined from 2024 aluminum for superior strength. Rear torsion arms are measured from the center of the splined torsion bar hole to the center of the shackle mount hole. Squeeze bolt kit is included. Send us your old torsion arms or a sketch, and we will offset torsion arms to your specifications at no charge.