Diffsonline builds a wide variety of BMW differentials in house to accommodate the several different differential housings used in modern BMW’s. They start by cleaning the differential housing, then select the industry’s finest ring and pinion gears, apply the desired clutch packs and options, and finally carefully assemble the housing to be 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:
Diffsonline 4-clutch option with 35/60 ramps: This is a BMW limited slip carrier with 4 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 Compact (medium) Race Carrier: This unit weighs in at just 14 pounds while other options weigh 22 pounds or more; the lower reciprocating mass helps to give you a competitive edge over the competition. This unit uses 6 clutches and single-driven ramps; making it the best working and 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 Castrol SAF-XJ fluid for this differential.
Helical Type Differential: The helical type differential is a purely mechanical device; it has no electronics, clutches or viscous fluids. A helical differential works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular helical differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction. These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the helical type is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs. However, if one set of wheels loses traction completely, the helical type differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero.
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.
$500 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 323, 325, 328, 330
