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The R107‘s rear differential is strong and usually trouble-free, but it is often overlooked when it comes to fluid changes. A whine or a leak are the common signs of trouble.
Which models have LSD
The US 560SL has a limited-slip differential as standard. Other R107 models usually have an open differential, though an LSD was available on some cars and markets. Check the data card or a tag on the differential.
Fluid type and capacity
Use hypoid gear oil to the Mercedes specification listed for your axle, typically a GL-5 rated 85W-90 or similar. A limited-slip differential needs an oil suitable for limited-slip use (often with a friction modifier). Capacity is around 1 liter or a little more depending on the axle; check the manual. Do not use ordinary manual-transmission gear oil.
Change steps
- Park on level ground and let the differential warm slightly after a drive.
- Remove the fill plug first (so you know you can refill).
- Remove the drain plug and let the old oil drain.
- Clean the plugs; many are magnetic, and fine metal paste is normal.
- Refit the drain plug with a new washer.
- Fill through the fill hole until oil begins to run out.
- Refit the fill plug.
Whine causes
- Low or wrong oil
- Worn pinion bearings or gear wear
- After a fluid change, a whine that appears suddenly suggests the wrong oil or missing friction modifier on an LSD
A whine that changes between acceleration and coasting is typical of differential wear. Wheel bearings can sound similar; see front wheel bearings.
Leaks
Check the pinion seal at the front of the differential, the side seals at each axle shaft and the cover. Wet seals spread oil onto the exhaust and the subframe. Replace leaking seals before the level drops.
Rebuild cost
A full differential rebuild is a specialist job. Used units are available, but check that the ratio matches your car; see axle ratios.
Quick answers
- How often should the oil be changed? Follow your maintenance booklet; on cars with unknown history, change it now.
- Can an LSD chatter in tight turns? Yes, if the oil lacks the correct friction properties.
- Is a clunk from the rear a diff problem? Often it is the rear subframe mounts or flex disc.
- How do I know if my car has an LSD? Check the data card, the differential tag, or lift both rear wheels and turn one: with an LSD, the other tends to turn the same way.
