Want to tighten up the rear differential on your 2021+ G8X M3/M4, A9X Supra, G42 2 Series, or G2X BMW and eliminate unwanted differential movement during hard launches? VTT has you covered with our Rear Billet Differential Insert Kit.
This precision CNC-machined billet insert is designed to press into the factory rear differential bushing, filling the voids in the OEM rubber bushing to dramatically reduce differential movement under load. By reinforcing the factory bushing rather than replacing it, the kit maintains the majority of the stock ride quality and comfort while improving drivetrain stability, launch consistency, and power transfer.
Installation is simple. Support the differential, remove the factory rear differential bolt, and use the factory bolt to press the billet insert into place. Once installed, replace the factory hardware with the supplied upgraded bolt, washers, and lock nut.
Kit Includes
- One CNC-Machined Billet Differential Bushing Insert
- Two 49mm Hardened Steel Washers
- One Grade 12.9 M14 Bolt
- One M14 Lock Nut











Denzil Fernandes (verified owner) –
Without the whole bushing … it was a whole lotta bashing going on between the driveshaft and the factory bolt… Sure i shaved most of it… but having put all these bushings in … she’s holding nice and firm. I’d recommend to even do the transfer case bushing if xDrive