Bmw X3M F97 X4M F98 Rear Differential Bush Bolt Collar Upgrade, Complete Diff Kit Exclusive Fj Motorwerkes - Supply & Fit service

The only ultimate complete kit on the market - Uprated Diff Bolt, End Bushing & collar kit, fix For Bmw X3M/X4M Exclusive to FJ Motorwerkes.

Our latest revision is now UK made 🇬🇧, using premium CNC machine engineering and stainless steel components only.  See image’s/video’s to see our manufacturing process.

Experience the enhanced performance of your X3M & X4M F97 F98 with our 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.

Our 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

Our upgraded FJ M Diff Bolt Kit is over +40% stronger than the BMW revised bolt and significantly more durable than the original BMW part. To be precise our bolt paired with our solid end bushing can handle 179,800 psi pressure (Extreme load). 

Ultimate breaking force:
1240 × 115 = ~142,600 N
= ~142 kN
= ~14.5 tonnes
1240 N/mm² = ~179,800 PSI
Safe Working Load (SWL)= 3 tonnes

Proven in real-world applications: X3M / X4M builds from 510 bhp up to 1000+ bhp — stock to Stage 3.

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

While we recognise competitor offerings such as "hollow bush" or "lockdown braces," firsthand testing on our vehicles, including our 850 bhp X3M Monster back in 2021 has shown that these options are often weak or problematic fixes. They tend to introduce excessive noise and vibrations (NVH) at low speeds, making everyday driving uncomfortable. Furthermore, their rigidity can lead to premature component wear or failure over time. For these reasons, those solutions maybe suited for dedicated track vehicles rather than daily drivers or fast road applications.

NOTE: These bolts have been tested on vehicles worldwide, from stock to Stage 1, Stage 2, and Stage 3 builds. Covering power levels from 510 bhp to 1000+ bhp. Hundreds of units have been sold globally, proving them highly successful. Due to this level of success, imitations exist, but they are limited in function and do not match the quality of the genuine FJ MotorWerkes product.

Full fitting instructions - Installation time 2/2.5hrs 

We also supply many of the UK’s, Europe’s, and worldwide leading tuners and garages. If you’d like to know whether a particular garage stocks our kits, simply ask us. Our products are the go-to choice for numerous influencers and YouTube content creators, who showcase the true performance and capability of our solutions.

Listing is for SUPPLY & FIT in UK only!