Clutch Slipping

[Richard Madison]

4 Speed Manual 280SL:

Happens randomly when in 2nd going to 3rd or 3rd going to 4th, after the clutch is completely released, the revs go up but the speed does not increase...for example, going into 4th half way up a mild hill instead of lugging down a bit, the rpms increase with no significant change in speed...

Fluid is at proper level, pedal works fine, no recent work done on tranny. The clutch plate was recently inspected: "plenty of wear left" said the mechanic.

This is a new "happening" for this car, no past history of tranny problems.

I guess the clutch is slipping. Solution?
Richard M

[Benz Dr.]

Make sure your clutch is adjusted properly. The pressure plate may be broken or worn out as well. The actual thickness of the flywheel has a lot to do with how well the clutch works. I found this out the hard way with the Rocket car and had to find a better one.
You can't just go by the thickness of the clutch plate as there's several other things to consider.

Daniel G Caron

[Richard Madison]

Here's what the Haynes repair manual says about a slipping clutch on a manual transmission:

Symptom: Clutch Slip (increase in engine speed does not result in increase in vehicle road speed - particularly on gradients).

Reason: Incorrect release bearing to diaphragm spring finger clearance caused by incorrect pedal adjustment.

Question: Can the pedal adjustment described above be done by a non-professional with ordinary tools or is it a complicated job?

If it can be a "garage job", can anyone describe how to make the adjustment?

Richard M

[ja17]

Hello Richard,
You can adjust your clutch. If you look at the transmission bell housing on the bottom you will see the slave cylinder with a hose connected to it. It is held on by two nuts and studs. Pop the spring off and check to make sure you have a bit of free play at the fork (where the adjustable pin meets the fork comming out of the transmission). You must be able to wiggle the fork back and fourth (front to rear) just a bit. This free play indicates that the cluch is released completely. If you do not have about 3/16" to 1/8" play at the fork shorten the adjuster rod so you do. If you have too much lengthen it. Too much free play will not cause the clutch to slip. It may cause the shifting to be more difficult.

This system is hydraulic. Make sure your fluid level is up. If you have a lazy or slow acting clutch pedal, the rubber hose (like brake hoses) can restrict with age and cause a slow lazy clutch pedal.
Good luck!

Joe Alexander
Blacklick, Ohio