MMX Performance F2X / F3X Billet Differential Insert Set

The MMX Performance billet differential insert kit is the companion upgrade to the rear subframe insert set, and on a lot of F-chassis BMWs, the more impactful of the two for daily and track driving. The factory rear differential is rubber-mounted to the subframe for ride comfort, which under hard acceleration and braking lets the diff shift in its mounts. That movement translates to wheel hop, less consistent power delivery, and a less precise feel through the seat of your pants.

The MMX inserts are precision-machined from billet aluminum to fill the voids in the factory rubber differential mounts. They limit diff deflection under load while leaving enough rubber in place to retain refinement and prevent NVH issues. The result is a tighter, more direct connection between the engine, the diff and the rear wheels, without sacrificing day-to-day ride comfort.

Behind the wheel: noticeably reduced wheel hop on hard launches, cleaner power delivery on corner exit, and a more positive, predictable rear-end feel under both throttle and engine braking. It is one of the highest-return chassis tweaks on the F-chassis platform.

Installation is straightforward (under an hour with basic hand tools) and is completely reversible. No press required, no permanent modification, no need to drop the diff or subframe.

Product Details

• Precision-machined billet aluminum inserts
• Fills factory rubber diff-mount voids: does NOT replace the rubber
• Limits differential movement under throttle and braking loads
• Reduces wheel hop and improves power-delivery consistency
• Anodized finish
• SKU MMR12-6001

Vehicle Applications

• BMW 1 Series (F20 / F21)
• BMW 2 Series (F22 / F23)
• BMW 3 Series (F30 / F31)
• BMW 4 Series (F32 / F33)

Notes

• Includes a 1-year manufacturer warranty against defects in materials and workmanship
• Designed and tested in the United Kingdom