BMW Differential and Gearing Upgrades for BMW 3 Series E46 (1999-2005)

Hands down - one of the best performance upgrades you can make to an E46 M3, E60 M5 or E63/E64 M6! With almost no downside you can make your BMW much quicker by swapping in a new ring & pinion gear set. The gearing used to be overlooked when planning modifications but the 3.85, 3.91, and 4.10 gears are now one of our biggest selling upgrades for the E46 M3! With a rear end gear upgrade you get the effects of adding horsepower but without adding any more stress to the engine or drivetrain. It's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration. The R&P acts as a torque multiplier, putting the engine into the power band sooner for each gear. There is an 6% increase in torque at the wheels with the shorter R&P. Want to make your car faster off the line or out of corners? Or avoid a downshift to pass on the highway? This is what you need.

The R&P can be installed on its own but for cars that have more than 60,000 miles it would be a better idea to rebuild the whole diff. The factory viscous limited slip units have a typical lifespan of 50-70,000 miles. We offer diff rebuilding with 3.85 or other gear options and you get a fully-rebuilt and serviced limited slip unit at the same time. Click here for our diff rebuild options.

3.85 Gearing Example: 2004 M3, 6-speed manual, 275/35-19" rear tires

Gear RatioGearSpeedRPM

40 MPH in 4th
3.62 4th 40mph 2,250rpm
3.85 4th 40mph 2,350rpm

70 MPH Cruise
3.62 6th 70mph 2,650rpm
3.85 6th 70mph 2,800rpm

5th Gear Speed at Redline
3.62 5th 175mph 8,000rpm
3.85 5th 165mph 8,000rpm

Why 5th? Because 6th does not have the mechanical advantage to get past wind resistance at these speeds - it is more of a cruise/overdrive gear. Using 5th for comparison purposes is much more relevant than having to take into account wind direction, resistance, grade, elevation, tire sizing, etc. These numbers are for comparisons among gear ratios only, not to determine what your M3 will top out at.

This item is the genuine BMW part and the ring & pinion set only. You will need to have this professionally installed into your existing differential. BMW does not supply differential rebuild parts (bearings, shims, plates, etc.) so only a qualified shop that is experienced in BMW diff rebuilding should perform this installation. We also offer built differentials and exchanges, click here.

This item fits the following BMWs:
2001-2006 E46 BMW M3
2004-2010 E60 BMW M5
2004-2011 E63 BMW M6

OEM part number 33108311351

The Wavetrac® Torque Biasing Differential introduces an innovative solution for BMW enthusiasts. With its patented design, the Wavetrac® differential automatically enhances grip in low-traction conditions, setting it apart from conventional torque biasing differential designs.

Crafted with precision, the Wavetrac® differential features high-strength 9310 steel gears encased in case-hardened billet or forged steel bodies. ARP® fasteners are utilized throughout the differential, ensuring robustness and exceptional performance.

One of the defining features of the Wavetrac® differential is its maintenance-free design. Fresh from the factory, it's engineered to deliver a lifetime of service without the need for regular maintenance or rebuilds. To bolster the commitment to durability, all Wavetrac® differentials come with a transferable limited lifetime warranty.

For those seeking additional technical insights, comprehensive information on the Wavetrac® Differential can be found at this link: Wavetrac Technical Information.

It's important to note that the Wavetrac® differential is compatible with gear ratios of 3.15 and higher.

Important Note for Bolt Kits:

For vehicles equipped with a welded ring gear, the installation of this differential necessitates the removal, drilling, and installation of the welded ring gear from your stock differential. A Bolt Kit ES4368731 is an essential component for installing the ring gear onto the new differential. We strongly recommend consulting with a professional machine shop before purchasing this item and the necessary hardware kit. Please be aware that no technical drawings or instructions are provided, underscoring the importance of verifying compatibility and ensuring correct installation with your chosen machine shop.

It's crucial to be aware that no refunds or replacements will be offered if the differential has been installed or machined, or in the event of incorrect ring gear installation or differential failure due to improper installation.

The perfect upgrade for any E46, this finned differential cover increases cooling to the rear differential to prevent over heating and possible damage. This is a complete kit including fluid and drain plugs.

Includes the following

• Aluminum finned differential cover
• Drain & fill plug with sealing o-ring
• 2 Quarts of Redline 75w90

This kit includes Turner Motorsport solid aluminum differential race mounts pre installed in the differential cover for a quick install. These mounts where developed by Turner Motorsport for their Grand-Am Cup E46 M3 race cars, the advantages of solid aluminum mounts is increased suspension & drivetrain response, less drivetrain loss resulting in more wheel horsepower, and longevity - they effectively last forever. These CNC-machined mounts are a direct replacement for the stock rubber pieces, and have been lightened to remove excess weight.