The W201 differential refresh thread

[suginami]

Originally Posted by chasinthesun

My puzzle skills are lacking but with the tortural technical teachings of your photo phindings are phantastic puzzle placers.

I can't figure out if "tortural" is a good thing or a bad thing.

It's not in my dictionary.

[fdanielson]

Did you ever put the diff back in service and if so was it as quiet as you hoped?

[Stretch]

Originally Posted by fdanielson

Did you ever put the diff back in service and if so was it as quiet as you hoped?

It is all fitted and ready to go - the rest of the car is almost done too. Some teething trouble with a radiator - and some other nonsense to overcome but I hope to have it all running soon.

Achtung - Das schweinhund baby benz thread

[fdanielson]

Thanks and good luck with the rest of the issues.

After re-reading your writeup a few times I was surprised at how much setup was needed in the differential since all you did was swap out the bearings. It was re-assuring to see that the original pinion depth shim worked. Do you suppose if I wanted to replace just the pinion bearings and the original side bearings were still in good shape I could get away with leaving the original shims and circlips in the rest of the differential?

[Stretch]

Originally Posted by fdanielson

Thanks and good luck with the rest of the issues.

After re-reading your writeup a few times I was surprised at how much setup was needed in the differential since all you did was swap out the bearings. It was re-assuring to see that the original pinion depth shim worked. Do you suppose if I wanted to replace just the pinion bearings and the original side bearings were still in good shape I could get away with leaving the original shims and circlips in the rest of the differential?

This is a bit of a dodgy rule of thumb but if you can remove the circlips on the axial / output bearings with out spreading the case then I reckon you need to add thicker shims to get that pre-load correct (assuming you keep the same bearings).

As soon as you change the bearings then you need to start the whole measuring and shimming procedure (whilst bearings are made to tight tolerances the chances of getting the right size to match your existing shims aren't so good).

[Stretch]

I've been meaning to update this thread for a while and finally have the time to do it.

In some ways the rebuild has worked out well - in other ways there has been a steep learning curve - in other ways I got to the jumping about the garden singing the "uckety uckety bastard wank **** ****" song...

Background information => I needed to get the car on the road in a hurry. As I'm sure most of you know when you are in a hurry things often go wrong.

I took the car to a local MOT (APK safety check) centre and on the way back I heard a weird ticking. I thought something was rubbing on the rear right wheel - wasn't that. Could it be the brake caliper? Nope. The parking brake? Nope.

I thought it was the rear wheel bearing - could I have got a bad one? Did I bugger up the fitting of the bearing? Nope.

It turned out that the differential was way too stiff.

This bit went wrong => Post 46

This meant I had to do this =>

[Stretch]

(Perhaps interesting to note?)

Although the differential had done less than 2 km in total driving distance; after draining the oil in a clean bucket



There was immediately evidence of "bits" in the oil



This is what I found in a totally clean casing with new bearings (but used cogs).

It isn't what I was expecting to see after such a short distance. This could of course be a result of the dreaded tick but I get the feeling that "bits" are almost always going to be in a differential so don't worry too too much when you see them too!

[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]

To try and solve the problems described in the last post with the rushed setting of the side cogs I'm refreshing the original differential so I can put that back on the car and keep myself driving something I own!

This is a pain in the arse to be perfectly honest but it does give the opportunity to learn. I can for example compare the heights of that dodgy pinion crush washer => New is on the left



The height difference is about 1.5mm - so that's how far you go when you apply 7 tons of force (see previous post - I'll say if I have to apply the same or more this time)

[Stretch]

Warning about pinion bearing shims

On the cheapo EPC on MB parts world the shim part numbers are mixed in with the W123 ones.

If you are setting the distance of the pinion bearing on a W201 differential make sure you don't order any shim with a 116 XXX XX XX style number!

It all sounds obvious (now). Two good examples are

1.65 mm thickness 124 353 21 52
1.7 mm thickness 124 353 23 52

[Stretch]

Playing about with a new special tool



(Gate hinge)

[Stretch]

Now the axial seals are in place you can fit the axle flanges. Make sure they go in and out of the side cogs smoothly before you fit the circlips.

The circlips need to fit really snugly.

Tapping the circlips in place with a bit of wood is a good start...



...before finishing them off with a narrower punch



Tap the eye in the circlip round so that it is positioned near to a land in the differential side cog to make it easier if you need to remove the circlip again.



Try to wobble the axle flange (black arrow) to see if you can see any movement in the side cog (red arrow).



If the side cogs wobble the circlip is not snug enough

Remove the circlip -and then fit a thicker shim between the axial bearing and the ends of the axle flange.

[Stretch]

Don't get too disappointed if the differential fluid doesn't stay clean (I was).

Even after completely cleaning out the casing and replacing the bearings and cleaning everything after 5000km the was like this opaque muck =>

[Maxbumpo]

Next stage: Fit a 124 differential?

[Stretch]

Originally Posted by Maxbumpo

Next stage: Fit a 124 differential?

I'm not sure if that would help for some of the W124 differentials I can get here - as in I think they are the same.

But I reckon there must be a wider W124 differential (need the width for a more rigid casing I guess) that can be used (as in something fitted to say the 500E!) but then I guess the gearing will be inappropriate for the engine I have...

...do you know if the 250D (as in W201 2.5 turbo) has a wider differential?

{Then of course I have a solution for the axles which would have to be shorter}