X3M F97 X4M F98 Rear Differential Bush Bolt Collar Upgrade, Complete Diff Kit - Fj Motorwerkes

Latest revision is now UK made, using premium CNC machine engineering and stainless steel components only.

Proudly CNC-machined right here in the UK

Experience the enhanced performance of your X3M & X4M F97 F98 with the premium uprated differential bolt, bush & collar kit.

Common issues like diff bolt is no longer a concern. Whether you enjoy drifting, launching, or aggressive driving, our kit ensures a smooth and reliable experience.

This kit greatly reduces the risk of bolt failure, providing peace of mind for high-performance driving and power, bolts are known to deform on any level including stock. Whether your car is stock power or tuned this is the true complete kit to reduce potential failure causing ££££’s in damages (Diff failure, driveshafts etc etc).

Complete Kit in stainless steel includes:

Extreme strength, upgraded-sized bolt

Reinforced custom end solid bushing

Reinforced & strengthened CNC collar

Reinforced CNC front washer

Reinforced CNC crush washer

Reinforced CNC step down bushing

Grooved fast lock nut

Drill bit for installation

Full instructions

This upgraded bolt is over 39% stronger than the BMW revised bolt and significantly more durable than the original BMW part. To be precise the bolt can take 170,000 psi pressure (Extreme strength bolt). Paired with the solid end bushing to create seamless fix.

Full fitting instructions - Installation time 3hr

These are tested kits, not many owners know the true condition of their current bolt due to location, very high ratio who do remove confirm failure (Bent), whilst other vehicle’s make clunking sound or grinding/whining which reflects the bolt being nearer the end of it’s life - Do not wait around for sounds, this can cause pre mature wear on other components. We advise this fix.

Bmw are aware of issue, they revised bolt in late 2021 but unfortunately it’s proven unsuccessful.

While we recognise other offerings “solid bushings” or “lockdown braces”. Based on firsthand feedback on our test vehicles. Those solutions may create excessive noise and vibrations in the cabin at low speeds, making daily driving uncomfortable. Additionally, lack of flexibility, which can lead to component failure over time. Solid bushings or Braces are best suited for track vehicles.

NOTE: These bolts are tested on vehicles worldwide from stock, stage 1, stage 2 and stage 3 vehicles, sold 100’s units worldwide and proven highly successful.