The W201 differential refresh thread

[spock505]

Thanks Stretch, that may well come in useful for future rebuild if needed.

I ended up getting a replacement differential which is the exact same match to my own. Believe me this was no easy task with one MB parts dealer listing a very used diff (once he knew I needed one) on eBay for £300 plus delivery and ..ouch!

The main problem is everyone lists second hand diffs using the number stamped on the cover, I searched using this too but couldn't make sense before finally realizing it's on the cast part.

Anyway, fitted the replacement diff only to find it made virtually no difference at all, by this time I had already replaced the front wheel bearings and center bearing. These parts needed replacing (center bearing rubber came away from surround, wheel bearings yellow with no play, over-tightened)

After this I was sure "it must be the diff" given the amount of oil leaked and then distributed around the underside. Unfortunately not, although I do now have a spare which can be worked on at leisure or sent away pending tools/difficulty level.

So onto the rear wheel bearings which can be a tad more difficult than standard W124 sedan (we are on a American forum - that said I have found a tool which should be okay for bearing removal but the **puck is too small (W124 small diameter bearing hole) to hold the back whilst pushing in flange plate.

I have the measurements so shouldn't be too hard to find additional **pucks.

Cheers for now.

** no idea what those bearing plates are called.

[spock505]

Stretch, sorry, I only saw the last post, you have covered the diff numbers thing although the actual EPC is cast into one side.

These are the part numbers, not exact match but seems to work okay.

Mine

124 350 51 98

replaced

124 350 58 14

[mb201]

Originally Posted by spock505

Unfortunately it has a whine between 35 - 60mph after which it seems to get a lot quieter.

Thanks

Had whine at 60km/t not 5 over or 5 under, it was the rear bearing. Not the easiest job i have done, one side was stuck as hell removing the hub.

[spock505]

Originally Posted by mb201

Had whine at 60km/t not 5 over or 5 under, it was the rear bearing. Not the easiest job i have done, one side was stuck as hell removing the hub.

Cheers, yup, sliding hammer arriving today - started a S124 rear bearing thread S124 rear bearing replacement - help needed

[spock505]

Originally Posted by Stretch

To fix the problem I had to strip the differential (in a hurry). I wasn't impressed.

Axial seals had to be chucked and replaced with new.



And this part of the differential had to be adjusted =>



I think the limit in the FSM for the torque needed to be applied to the side cogs =>



is rather confusing. To achieve the limit the cogs need to be set very tightly up against each other. I get the impression that it is pretty difficult to get the right torque with old used cogs. I did what I was told - and it didn't work.

I whacked back the old shims into the assembly and put the differential back together and I got rid of the dreaded tick - and the turning of the differential was much much smoother.

I'm going to re-visit this problem with some thicker shims later on in the year (when I have the time) and see if I can get the differential cogs to be more closely fitting together with some thicker shims. I think if these cogs are too loose you end up with a bit of drive line shunt (which isn't really the Mercedes experience I'm looking for).




#########




Still - other than that I am satisfied that the rest of the adjustments are good. The differential has done about 1000 miles since this fiasco and it is quiet and trouble free...

...well I say trouble free - it is probably trouble free(ish) now because the ABS sensor has now been refitted with RTV. The O ring failed and 0.2 litres of differential oil got sprayed over the back end of the car during a trip from Holland to Wales (about 500km) - the differential did sound a bit clunky on bumpy roads when this happened - since then a (differential oil) top up has cured the problem.

Stretch, setting the pinion pre-load requires some pretty delicate and precise measurement, how is this achieved with such high friction (40nm +) applied to the small side cogs?

Earlier on, you mention all the gubbins has to be back in the casing to do this.

Cheers,

[Stretch]

Originally Posted by spock505

Stretch, setting the pinion pre-load requires some pretty delicate and precise measurement, how is this achieved with such high friction (40nm +) applied to the small side cogs?

Earlier on, you mention all the gubbins has to be back in the casing to do this.

Cheers,

Don't forget

The side cogs move within the cage but only when one wheel is being "braked" by the effect of turning a corner for example. With these open differentials the wheel that is easiest to be turned gets turned first.

Also don't forget once it has been used this friction of the small cogs within the cage is almost gone. This is a factory fresh setting - not it should always be like this setting

#####

The main thing to remember for the purpose of this thread, however, is that most of what I've been droning on about is when the crown wheel is removed - so the pinion gets set up with out the crown wheel (and side cogs etc) fitted...

...if you are following the instructions in the FSM for refitting the pinion seal, however, then the parts are still assembled - in which case you set the friction to the value it was before you removed the pinion nut (so measure first - then disassemble!). You don't set the system to the factory values described in this thread (although I think there's a minimum value of friction specified in the FSM for the pinion seal change procedure) unless everything is in bits.