If you race, autocross, rally, do BMW driving schools, or otherwise tend to push your car to the limit, let us convert your 25% limited slip differential to 50% or 75% limited slip. Wheel spin is reduced or eliminated, improving track times significantly. Additionally, the reduction in internal slippage lowers lubricant temperatures, helping prolong bearing life. The conversion requires special machining at our facility, making it necessary for you to ship your differential to us for modification. Your salesperson can help you decide which percentage is right for you.


  • 75% Limited Slip Conversion 33126375
  • 50% Limited Slip Conversion 33126350 (price when done with gear change or rebuild)

Korman Differential Rebuilds

Enhancing Traction and Durability

Differentials with normal wear don’t usually require the replacement of the ring and pinion gears. Our standard rebuild includes complete disassembly, thorough cleaning, close inspection of all parts, replacement of all bearings, seal gaskets, crush sleeve, and lock ring. Includes meticulous attention to correct gear lash, gear contact, precise pre-load of bearings, and exact torque specifications. Where applicable, rear covers are media blasted and clear coated, case repainted, and external hardware is replated for an as-new appearance.

If you have a limited-slip differential, we can also refurbish the limited slip carrier while rebuilding your differential (additional charges apply). As BMW limited slip units wear, the percentage of lock (25%, 40%, etc.) gradually drops off. We can restore your limited slip assembly to the original locking percentage (measured in lb/ft) or increase it depending on your needs. Korman is also able to supply limited slip differentials even if your car wasn’t originally equipped with one (inquire).


Changing to a quicker ratio provides faster acceleration in all gears at all RPMs. It does not affect engine emissions or idle speed and can make up for changes in tire diameter. Korman recommends a +/- 9% gear ratio change for most street driven cars. To obtain a percentage change, divide your original gear set ratio by your proposed new gear set. The resulting percentage also equals your RPM change at a given speed. Ask your salesperson for recommendations for your specific application.

Stock Differential Rebuilds

Small Case 168mm

E10 2002 Differential Rebuild 33124000

E21 320i 9/78> Differential Rebuild 33124001

E30 318 M10 Differential Rebuild 33124030

M42/M44 E30/E36/Z3 4 Cyl Rebuild 33126032


Medium Case 188mm

E30 325/M3/528e/Z3 Differential Rebuild 33126030    

E30 M3/325/E28 528e/Z3  Differential Rebuild with 50% Limited Slip Conversion (existing limited slip carrier)

E30 M3/325 Differential Rebuild with 75% Limited Slip Conversion (existing limited slip carrier) 33126475

E30 325 Spec E30 33126030SPEC

E24 10/81> 33126082

E36 325/328/M3, E34 525i, 530i, 535i Differential Rebuild  33126036

Spec E36 33126036SPEC

E46 323/325/328/330 33126046


Large Case 210mm

E24, E28 and E34 M5, M6 33126085

E46 M3 33126046M3


Side Loader

E3, E9, E24 >9/81 33126000