Differentials

The purpose of a Limited Slip Differential is to gain traction at the rear wheels when cornering or under slippery conditions. A MM Variable Limited and Adjustable Limited differential is designed to maximize traction at the rear wheels without upsetting the handling, for increased cornering speed. MM differentials can take a 10% to 20% increase in torque.

Open Differentials
All Open or Limited Slip Metric Mechanic differentials are all blueprinted. Meticulously measuring the rolling torque of the pinion and carrier bearings. Along with measuring the back lash of the ring & pinion. All gears are cleared and peened with a mat finish for improved oil retention.

Variable Limited Slip Differentials (VLS)
The BMW factory 25% Limited Slip Differential is a Salisbury 2 Disc LSD with a 25% lock up. With the spider gear pins walking up 45° ramp angles for both acceleration and deceleration.
Metric Mechanic's Variable Limited Slip has a 35% lock up with 2 or 3 friction discs and uses a 30° ramp angle for acceleration with a 45° angle under deceleration. An MM VLSD will increase your cornering speed & exit acceleration out of a corner, over a conventional factory LSD.

Adjustable Limited Slip Differentials (ALS)
Metric Mechanic's Adjustable Limited Slip Differential converts an open BMW differential into an Adjustable Limited Slip differential. The limited slip is controlled by 4 preloaded friction discs.
The lockup is set up at 30% to minimize under steer. Increasing the lock up causes a car to drive straight and under steer. By simply removing the differential cover, adjustment to the limited slip can be made using an open end wrench and measuring the breakaway torque at the wheel. Simple!

M-GKN Visco-lok LSD
M models from 2001-on )except E39/M5)
This is a speed sensitive LSD used in the E46 and later M cars.
The stock BMW M-GKN Visco-lok 215mm LSD has 50lbs of breakaway torque that increases to 105lbs of rolling torque.
Metric Mechanic increases the breakaway torque to 65lbs and the rolling torque to 120lbs. These differentials use a long and short stub axle. The short stub axle, over time, will get loose with radial play in the carrier. We replace the failed short axle with a shortened and modified long stub axle to fix the radial play.

MM 168 Differentials

For models with 4 cylinder engines

MM 188 Differentials

For models with 6 cylinder engines

View all

MM 210 Differentials

For models with 6 cylinder & V8 engines

Terms and Costs
Once a customer order is written up, we require half down to get started.
The down payment can be done with a Visa / Mastercard / Discover / American Express credit card, PayPal, or certified check. There are 2 ways to purchase an MM differential
1. Metric Mechanic builds your ordered differential from a used differential core. It takes about 3-4 weeks to complete the build. The balance is paid before shipping plus the core deposit and shipping costs. Once the differential is installed, your old differential can be shipped back to MM in the same box for your core credit. Exchanging the differential minimizes down time and installation.
2. Or the customer sends in their differential to be built. It needs to be drained and we can tell you the best way to box it up for shipping. We take half down when we receive the differential and the other half prior to shipping. It takes about 3 to 4 weeks to complete the build. This method is commonly used when doing a restoration.
A core is a used engine, transmission, or differential that is rebuildable. Core deposits is not a set cost and is subject to change; based on availability, condition, and cost. The cores we need are for classic BMWs that are 15 to 50+ years old. BMWs this old are very scarce in salvage yards, many of the cores are too far gone to be rebuildable, and the rarer the core, the more the price goes up.
We buy used cores from suppliers or customers. Anymore, we will not waste a lot of time trying to find cores. We appreciate customers that are willing to supply their own cores.
After installation, the return differential core can be sent back in the same shipping box.
Returned cores must be rebuildable to get a full refund or pay a penalty for the damaged core.
If you'd like more details or would like to order, please call 573-765-1269 MM Shop number from 9am to 12pm and 2pm to 5pm CST. Or 573-836-4033 from 9am to 8pm CST.