Differential Bushings

Differential bushings hold the differential housing to the subframe or body. They take the torque reaction of the final drive and keep gear noise out of the cabin. The part listed is a firmer rear differential mount bush, named by vehicle in its title.

When the driven wheels push the car, the differential housing tries to rotate the opposite way, and its mounts resist that twist. Soft or worn mounts let the housing wind up and spring back. That shows as a clunk on and off the throttle, wheel hop on hard launches or a lazy response to the throttle.

A firmer bush limits that movement, so drive is taken up sooner and more evenly. It also passes more gear whine and drivetrain vibration into the body, which is the trade to weigh on a car driven daily.

Two things to consider:

• Position: the bush is a rear differential mount. Check how many mounts the housing uses and whether the others are worn as well.
• Use: firmer mounts pay off with frequent launches, track days or added power, less so on a quiet daily car.

Support the differential on a jack before undoing its mounts, and do not let driveshafts or the propshaft hang at a steep angle. Press the bush in square, tighten the mount bolts to the specified torque, and check the driveshaft joints and the differential oil level while the car is up.