MMR Billet Subframe Inserts – BMW 420d

Designed and engineered in-house in the UK, the MMR rear subframe insert kit for the BMW F2x and F3x chassis is designed to limit movement in the factory rear subframe mounts to maintain proper suspension geometry when cornering and improve the responsiveness of the rear suspension and differential. Installation is very simple, can be performed in under an hour, and is completely reversible. By filling small voids in the four factory mounts as well as limiting vertical movement, the insert set eliminates the associated slop to ensure that you experience a more refined, connected driving experience, especially when driving at the limit. The billet aluminium parts will not wear over time and offer a lasting performance improvement. Worried about noise? NVH is a measurement of how much noise, vibration, & harshness gets transmitted into a vehicle’s cabin. Based on feedback, MMR inserts transfer little to none NVH into the cabin. NVH is subjective, so some users may find NVH to be increased or decreased from our rating. If you are experiencing higher than quoted NVH with this product, please evaluate the installation to ensure the components are installed correctly.

The BMW F2x and F3x series use rubber rear subframe mounts that deflect under load, causing the rear end to feel vague and loose, as well as leading to less-than-optimal suspension geometry and increased understeer. These precision-machined billet aluminium inserts are designed to fill voids in the factory rear subframe mounts, and limit subframe movement without sacrificing ride quality or introducing any perceivable additional noise, vibration, or harshness into the cabin. The result is a more refined, connected driving experience, as well as improved effectiveness of aftermarket rear sway bar upgrades and suspension components.

These inserts were tested extensively by MMR and independent BMW enthusiasts before release on multiple F2x and F3x vehicles. Our diff inserts fit diesel, petrol, manual and auto variants. • Billet CNC – machined 6061-T6 Aluminium body
• Fills void in OE Subframe rubber bushings
• Practically no additional NVH transfer inside vehicle
• Easy install with Subframe remaining in situ
• Reduces rear subframe movement during launches & acceleration
• Helps maintain correct suspension geometry under dynamic loading