Currently working on rebuilding a 3.07 differential which will replace the 3.69 differential currently in the vehicle.

Had a pretty hard time finding correct bearings and races, but eventually I was able to at a place in Germany at cost of $300 for all 4 bearings needed.
I've had absolutely zero success finding pinion shims, or compensating washers.

At this point I have cleaned and painted the case. I even applied Glyptal to the inside of it because I had it close at hand.
I have pressed in the races for the pinion using the compensating washer and pinion spacer and washers that were fitted when I got it.
I have pressed the big bearing onto the pinion shaft then pressed the smaller bearing on with the pinion inserted through the case and supported.


I am now attempting to get the pinion bearing preload set. The factory manual (YES, I have a factory service manual) sets preload for new bearings at 140 Ncm which I am converting to 1.4Nm. I have the universal flange installed with a new nut that is fairly tight, however there is still no measurable preload on the bearings.


Do you just keep hammering that nut on until you get the reading you want?


I have not installed the pinion oil seal yet because I want to be sure I can get the correct preload with the spacer and shims as installed. I am also wanting to be able to install the differential into the case and check the pattern. As the compensating washer may need to be ground down, or additional shims added depending on what the pattern says. In a perfect world, the pattern will be OK and I will not need to pull everything back apart again.


Can I check my pattern before preload has been set??
Would be nice to know if that is at least good to go.
Obviously, I know that I cannot check preload with differential installed.


Any other insights are of course welcome.

The sort of story for me and bearings is I get the number from the bearing and the race if the race is separate. I go on the internet and find the interchange numbers to other bearing makers.

I go on eBay and find the bearing I want and email the seller as to what country the bearing is made in. If the seller resounds and the country is one, I deem suitable I buy the bearing. If the bearing arrives not made in the country the seller said it was, I file an 'item not as described' complaint and eventually get my money back.

I suggest you look to find some YouTube videos on rebuilding differentials and adjusting the wear pattern. If you are in luck they will have some Mercedes differentials. If not you can get an overall general idea on how it is done.

__________________
84 300D, 82 Volvo 244Gl Diesel

Thanks.
There are no markings on the diff carrier bearings that were originally fitted, only the races, and I did try a number of sources without success.
Anyway, I was eventually able to find correct replacement bearings, as previously stated.

I have successfully rebuilt a Ford 9" differential before.
It is obviously slightly different to the Mercedes Units fitted to W123s although the same principals apply.
I have also rebuilt a number of transmissions and transaxles, such as the 02J units fitted to later model VWs. So, I have some familiarity with setting preloads using shims.

My thought and hope was that I might find individuals on this forum with specialized knowledge and experience regarding these differentials in particular who might we willing to share those insights.


Thanks again.

Ks:

Re: Pinion bearing preload

1) Did you measure & record the pinion depth before removing it from the case?
If you did, you have a measurement to which you can return.
If not, because of the very small variances that are allowed in the manufacture of roller bearings, the odds are in your favor that the original compensating washer will be correct.
You can check the pattern without setting pinion bearing preload; just snug up the pinion nut.

2) Do you still have the original spacing sleeve (crush collar)? If you do, measure its length. Compare that length to the length of the new spacing sleeve. If the new spacing sleeve is more than ~.005" longer than the original, pre-crush the new sleeve, very carefully, in a press to within .005" of the original. Pre-crushing will make it much easier to continue the crushing with the pinion nut. Install the seal before finishing the crushing/preloading; you only get one shot at crushing a sleeve.

Thank you for this. Much appreciated.
Regarding the shims that were fitted on either side of the crush sleeve when the pinion was removed. Am I correct in assuming that these should be re installed on either side of the new sleeve??

Yes.

Regarding patterning: Install the pinion assembly into the case without the crush sleeve or seal. Snug up the pinion nut. Then the carrier & ring gear can be installed, the pattern checked, the tooth clearance checked, and the whole thing taken apart again!! Now the crush sleeve & seal can be installed, and the preload set.

The new crush sleeve measures 15.92mm
The old crush sleeve measures 14.61mm

Unfortunately, when I pre crushed the new sleeve it distorted slightly, so I am no longer comfortable using it. I'll need to get another crush sleeve before continuing which is annoying.

Interestingly, the site where I purchased the bearings and crush sleeve lists the part# as 108-353-00-42. Turns out there are varied opinions as to whether this sleeve "fits" a 1981 240D from site to site online. While it is slightly different visually from the sleeve originally fitted it seems to fit the pinion shaft OK.

If the distortion is such that the faces are a bit out of parallel it should be OK to use.
The function of the sleeve is to act as a spring that maintains a constant force against the inner races to compensate for temperature changes.

The distortion is such that one face has been compressed unevenly, and is no longer level.
When measuring the sleeve with calipers some areas and still thicker than the original sleeve and some are just under that thickness.
It also doesn't sit on the pinion shaft very well because the sleeve is no longer perfectly round.
I have tried filing the ID a bit in attempt to improve the fitment before resigning myself that I would need to get another one (or two) and try again.

I would like to have this project done, but also want it done correctly. Even though the delay is a bummer it's better than having problems further down the line when the differential is actually in service.

Thanks again for your continued guidance on this.

Well, I'm an idiot. But it seems that things may have turned out OK anyway.

Got the new crush sleeve. This time I managed to get greedy and crush it too far. I attempted to use it anyway and the pinion bearings locked up almost immediately. Not unexpected.

Removed the pinion shaft again and decided to attempt to make the other new crush sleeve work. I messed with it until I could get it fit decent on the pinion then I re installed the pinion and bearing with what I thought was the new sleeve.

I was able to torque the flange nut down a bit at time (I had to use a fairly large bar and a flange holding tool that I made) until I arrived in the neighborhood of 1.2 to 1.4 nm of turning torque on the flange.
Everything felt good when turning the pinion by hand.

Feeling pretty satisfied, I installed the differential and carrier bearings.
Pattern looks OK.

As I was cleaning up, I noticed the 2 new crush sleeves on the work bench.
I then realized that with so many crush sleeves floating around I had managed to pick up and use the crush sleeve that was originally fitted to the pinion.
Weirdly, I was still able to tighten the pinion nut and get to an appropriate preload. The preload amount was also observed to build as I slowly tightened the nut, as opposed the sleeve which was too short were the bearings just locked immediately.

While having the old crush sleeve installed if not ideal it does seem to have worked OK. I am planning to leave the differential as it is.