BMW E34 rear axle, limited-slip differential and ratio: how to identify
How do I identify the E34's rear axle ratio and limited-slip differential?
The differential's metal ID plate is under a bolt on the rear cover, so brush it clean. The plate shows the ratio, and if it is preceded by the letter S, the axle has a limited-slip differential. If the plate is missing, there may be a painted S on top of the axle.
Is the limited-slip differential standard on the E34?
It is standard only on M cars, such as the M5. On other models, for example the 540i, the limited-slip differential is an option. The factory lock is 25 percent, which is enough for normal use.
Does the M5 rear axle fit other E34 models?
The M5 and 540i have the same TYP 210 axle, so the axle fits directly, but the ratios differ and should be checked. The number of bolts decides: an 8-bolt TYP 210 fits the 535i without changing the driveshafts, a 6-bolt TYP 188 does not. The E30's bolt-mounted TYP 188 does not fit the E34's cradle mounting.
Why does the rear axle whine or make noise?
If the noise is heard on engine braking, the cause may be wear in the driveshaft flange bearing, and the repair requires taking the axle apart. If the axle whines when pulling under throttle, check the axle bearings before replacing the whole axle. An intact used axle is often the cheaper option.