Diffsonline E46 M3 Racing Differential
$1,599.00
Premium racing limited slip differential for your M3 E46. Choose your gear ratio and limited slip.
Whether you demand performance on the street or the track, Diffsonline can provide you with the performance BMW differentials to suit your exact needs. Every differential is built to your exact specifications in shop, and shipped to your door.
Custom built to your specification, the Diffsonline-Spec Racing Differential is the best performing diff you can put in your car. Multiple options in gear ratio and limited slip units available.
Limited Slip Options:
Viscous Type Differential (M Variable): ThÂe viscous coupling is often found in all-wheel-drive vehicles. It is commonly used to link the back wheels to the front wheels so that when one set of wheels starts to slip, torque will be transferred to the other set.
The viscous coupling has two sets of plates inside a sealed housing that is filled with a thick fluid. One set of plates is connected to each output shaft. Under normal conditions, both sets of plates and the viscous fluid spin at the same speed. When one set of wheels tries to spin faster, perhaps because it is slipping, the set of plates corresponding to those wheels spins faster than the other. The viscous fluid, stuck between the plates, tries to catch up with the faster disks, dragging the slower disks along. This transfers more torque to the slower moving wheels — the wheels that are not slipping. When a car is turning, the difference in speed between the wheels is not as large as when one wheel is slipping. The faster the plates are spinning relative to each other, the more torque the viscous coupling transfers. The coupling does not interfere with turns because the amount of torque transferred during a turn is so small. However, this also highlights a disadvantage of the viscous coupling: No torque transfer will occur until a wheel actually starts slipping.
Diffsonline 3-clutch option: This is a BMW limited slip carrier with a third clutch pack. The unit is set to 40% static lock unless a different amount is requested by the customer, and it utilizes the stock ramp angles of 45/45 (acceleration/deceleration). This limited slip differential is much more durable than the factory M Variable unit and is well-suited for street and heavy track use. We recommend using Redline 75W110 gear oil for this application.
Diffsonline 3-clutch option with 30/90 ramps: This is a BMW limited slip carrier with 3 clutch packs and ramp angles which are modified from stock. The unit is set to 40% static lock unless a different amount is requested by the customer, and it uses ramps which are modified to 30/90 (acceleration/deceleration). This limited slip differential is much more durable than the factory M Variable unit and is well-suited for street and race use. Other ramp angles are available by request. We recommend using Redline 75W110 gear oil for this application.
Diffsonline 3-clutch option with 35/60 ramps: This is a BMW limited slip carrier with 3 clutch packs and ramp angles which are modified from stock. The unit is set to 40% static lock unless a different amount is requested by the customer, and it uses ramps which are modified to 35/60 (acceleration/deceleration). This limited slip differential is much more durable than the factory M Variable unit and is well-suited for street and race use. Other ramp angles are available by request. We recommend using Redline 75W110 gear oil for this application.
Diffsonline’s 210mm (large) Race Carrier: This unit weighs in at just 21 pounds while other options weigh 28lbs or more; the lower reciprocating mass helps to give you a competitive edge over the competition. The unit uses 10 clutches and single-driven ramps; making it the best working, most tunable limited slip on the market. The preload is controlled by coil springs so that preload is not lost as the unit wears. Since this is a Diffsonline exclusive product, we offer custom tuning assistance for your race team, and we can also cut any ramp and set preload anywhere you wish. We have a great baseline setting which covers 95% of cars running normal suspension setups. We recommend Redline 75W110, Motul Comp FF, or the Castrol SAF-XJ fluid for this differential.
This unit is a race carrier and is recommended for race/track applications only, and this is the go-to unit for the BMW M3 in any serious race environment.
Wavetrac: Wavetrac’s helical limited slip carrier. The beauty of the Wavetrac is that it is ideally suited to high performance road cars that see track use. It is very strong, yet transparent to both driver and traction control electronics during regular driving. On the track or in spirited road use, it provides two wheel drive without the handling issues that traditional clutch type diffs create (there is no tendency to push/understeer with a Wavetrac.) The Wavetrac outperforms other gear type diffs because unlike them, it won’t lost drive when one axle is unloaded (which happens more often than you’d think. Lastly, one of the most underrated benefits of the Wavetrac is its smooth delivery of the power near the limit. It’s patented design makes for a very predictable, smooth addition of power when you need it most- when things are at their limits: on the edge of traction mid corner and you’re using throttle to keep it there; or coming into a corner a little hot, but quickly back on it to maintain exit speed. These situations are often subjective to the driver, but the benefit can be felt. The Wavetrac makes you faster because it lets you drive with confidence.
QUAIFE ATB: This differential is QUAIFE’s Automatic Torque Biasing unit. QUAIFE does not specify bias ratio details and generally, does not use the term. The QUAIFE ATB differential is an all helical gear design. The angle and tooth form of the helix used, the number of pinions used, and many other factors (including the particular car fitted) all contribute to how the differential behaves and biases drive torque. Each QUAIFE differential application is designed to offer the best compromise between performance and durability. We recommend Redline 75W110 fluid for this application.
$1200 core charge will be refunded upon receipt of your rebuildable core*. Core MUST be received within two weeks of delivery of replacement unit!
*The ability to rebuild the returned differential will be decided by the differential builder.
Place a printed copy of your invoice in the box and return core to:
Diffsonline LLC
ATTN: MSW Core Return
190R Main St Unit 1
Wilmington, MA 01887
REM is a registered trademark of REM Chemicals Inc. registered in the U.S. Patent and Trademark Office.
BMW Fitments:
E46 M3
Differential Break-In Instructions
Fill your differential with the recommended fluid as described above. We recommend Red Line, Motul, and factory Castrol SAF XJ fluids for most differentials, but the OS Giken and Kaaz limited slip units require their own thicker fluid for proper operation. If you are experiencing chattering in your differential while cornering, you can add a limited slip additive from Red Line or GM. If you have a question about your specific application, email us, and we will get back to you with a recommendation.
All differentials built by Diffsonline LLC require a 1,200-mile break-in period. During this period, you should keep constant vehicle speeds under 80 mph and drive the vehicle moderately. This will allow the gears, bearings and limited slip parts to break in properly and without excessive heat. After 1,200 miles the fluid should be changed in your new differential with the same recommended fluid. After the initial flush, we recommend changing the fluid every 24K miles in a street driven car, or every 12K miles in a car that sees autocross and track day use.
For racing applications, one day of track use is recommended for break-in. Change the differential fluid after the one-day break-in procedure using the same recommended fluid. We recommend changing the differential fluid every other time you change the engine oil, or whenever the differential has gotten extremely warm.
Note: The differential fluid lubricates the ring and pinion gears, which transfer power from the driveshaft to the axles. The limited-slip unit requires fluid to keep all of the internal parts healthy and moving properly. Differential fluid changes areas imperative as changing the oil in the engine, and for the exact same reasons. Metal-to-metal contact wears down surfaces and creates heat from friction, which weakens parts and can lead to failure.
Normal Operations
During initial break-in, it is not uncommon for the rear end to have some chatter in the form of tire scrubbing or internal LSD noise depending on the vehicles limited slip choice. It is normal for some freshly rebuilt differentials to have a tight spot while turning by hand before break-in, as differentials are assembled and shipped dry except for some oil on the clutches and bearings during assembly. These conditions remedy themselves upon fluid fill and break-in process. Differentials with high levels of preload have difficulties unlocking depending on driving surfaces, such as rain, snow, gravel, etc.
| Series | Chassis | Model | Engine |
|---|---|---|---|
| Series | Chassis | Model | Engine |
| 3-Series | E46 | M3 | S54B32 3.2L I6 |
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