We manufacture the best engineered Billet rear covers for BMW differentials from T6 - 7075 aluminum.

Why to choose RacingDiffs Biller diff covers?

Our engineers spent months to develop the best possible inner design to speed up the oil flow and thus improve differential cooling. Each design is thoroughly tested, and not only as 3D model, but in real conditions on the car. We managed to lower the oil temperature by 15% (average).

Besides supreme inner profile, we have 3 holes for oil instead of 2 like oem covers. Lower one is for draining, but also for external pump inlet. The middle one is for filling and the upper one is for pump outlet. So with this cover you can mount external oil cooling system without any modifications. This is super important to keep your diff stable during any kind of endurance racing or long track days such as on Nürburgring. Holes are M16x1.5 adapted for AN connectors.

And at the very end, thanks to material supreme mechanical characteristics, you can say that this cover is unbreakable, which we also tested and proved.

Powerflex poly bushings comes as the standard option.