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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 3.91 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 8% 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 3.91 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.
3.91 Gearing Example: 2004 M3, 6-speed manual, 275/35-19" rear tires
Gear RatioGearSpeedRPM
40 MPH in 4th
3.62 4th 40mph 2,250rpm
3.91 4th 40mph 2,450rpm
70 MPH Cruise
3.62 6th 70mph 2,650rpm
3.91 6th 70mph 2,900rpm
5th Gear Speed at Redline
3.62 5th 175mph 8,000rpm
3.91 5th 162mph 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 33127768525
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.
MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.