"Sloppy" Differential
 

I have a 1986 190E 2.3-16 valve with 80,000 miles. I have had noticeable looseness in the drivetrain for a long time that appears to be in the differential. When the car was up on my lift, I turned each section of the drive shaft and observed that with the rear wheels blocked, I could turn the differential input shaft perhaps 10 to 20 degrees of rotation (rough guess). At each end of the rotation there would be a "clunk" sound.

How much slop should I observe in the differential? It is annoying, because the car suffers from some driveability problems (light missing, surging) and the loose differential seems to magnify the problems.

How much trouble is it to tear down the differential and check the setup?? Is there an adjustment on gear mesh?

Thanks,

Tom

I've got the same thing on my '82 300D. I have the differential open now for an upcoming replacement of the two axle half-shafts it uses. There is some sort of floating gear in the differential that is on a shaft that moves back in forth within a slot. I'm sorry that this is not all that descriptive in words. I might be able to post a picture.

Anyway, my differential does the same thing - the clunk is probably that gear reaching the end of its "loose" travel. I'm going to spend some time in the manual to attempt to figure out what this design does.

Ken300D

The 16V has a limited slip diff & almost all other Benzs' have an OPEN diff, so there is somewhat a difference in the set-up. They both have side(pinion) gears. Possibly the 16V diff has worn out limited slip clutch discs!

If I remember correctly, MB differentials use a crush washer to set pinion clearance -- my 72 220D has the same problem, just worse.

I suspect that replacing this washer (it is really relatively soft hollow "donut" that can be complessed) will fix the excess backlash. The difficulty is getting the crush correct. The nut is tightened to get the correct rotating torque on the driveline, then straked in place.

Wear in the pinion bushing can allow it to move -- the crush washer is no longer "fat" enough to hold the pinoin gear in place.

Peter

Is this a DIY option?
 

I appreciate the replies on this. The question now, is could/should this problem be attacked by me (reasonably smart, but relatively inexperienced mechanic) and my mechanic (very experienced, but not on Mercedes)?

The manual shows a plethora of special tools needed.

What could it cost to have it professionally rebuilt?

Thanks for the help.

Tom Elerding

Tom:

The easy fix, if you can find one at a reasonable price, is to get a used differential and swap them. No setup, just remove the axles and swap. Take care, the diff is HEAVY! This is what my mechanic does, he isn't very good a trannys or diffs.

Otherwise, I'd find an indy mechanic familiar with this type of pinion adjustment (I think it is fairly common, reguardless of make) and talk to them. Other than getting the location correct this isn't a really big deal and can be done in the car.

Someone with experience can help you get the depth (ie turning torque) correct without risking excess backlash, etc. I'd not experiment without knowledgable assistance -- it's too easy to snap a tooth off the ring gear! Do not, under any cirucumstances, more the rear wheels with the pinion loose -- the weight of the car moving can break teeth off the ring or pinion gear.

Peter

Peter:

Since this is a 190E 2.3-16 Valve, finding a good used differential might be problematic, although I may check around.

I appreciate the advice to go to an experienced shop that repairs differentials. I live in a semi-rural town, but San Luis Obispo and Santa Barbara are close, so I might get lucky there.

Thanks

Tom