Limited Slip Differential
For a general description of Limited Slip Differentials, and how they work please see the External Links below.
Generally Limited Slip Differentials are referred to as "Slippers" or "LSDs". This contrasts to the normal differential fitted that is known as an Open Diff.
E30s with LSD as standard
- UK Spec 325i Sport
- M3
All other E30s has an LSD as an option.
LSD was *not* standard fit on the 318iS
E30 LSDs are clutch plate type and require special oil - see below.
Case sizes
E30s had two differential case sizes, they are interchangeable and the same width but will require adjustment of the prop length. Please see Fitting an E30 Differential.
E30s used either a Small Case or Medium Case differential. Other models used a Large Case which is not directly interchangeable but the internals can be swapped.
E30 LSD Ratios
Below is a list of ratio and cars in which they can be found.
- 3.64 -
- 3.73 -
- 3.91 -
- 4.10 - found optionally on UK spec 318i/318iS 2/4dr in Small Case, and on all US M3 models in Medium Case.
- 4.27 -
- 4.44 -
Please update the list of ratios and what cars they are found on and common case sizings.
How to identify and test an LSD
To identify and LSD one can first check for the presence of the tag on the rear casing. The ratio on this will be prefixed with an S for LSDs.
Alternatively one can jack up one rear wheel, ensure the car is out of gear and hand-brake is off then turn the raised wheel. Resistance on that wheel would usually indicate an LSD. An alternative method is to try to leave skid-marks pulling away on good tarmac, two tyre marks for more than a few inches would indicate a properly "locking" LSD. This won't work so well on grass or gravel as on loose surfaces both wheels can slip easier even for non-limited slip differential types.
What oil to use for your LSD
The BMW recommended oil is <Please update>
You can find supplies from <please update>
Durability, Rebuilds and Upgrades
<please update with details of rebuilders in various locations, recommended rebuild intervals etc>
External Links Wikipedia's Limited Slip Differential Entry How Stuff Works - Differentials
