Differential Clunk Bushing

[Harry]

While I had my 230SL up on the lift, I noticed that this cylindrical bushing at the right front of the differential appeared to be spent. As best I could tell, the center part was laying against the outer part, as though the rubber bush was gone or useless.  I am not familiar with this particular part but it looks as though it controls rotation of the differential?
I have the common clunk noise although I did replace the trunk bearing years ago and would hope it is still good.  Can someone speak to this particular bearing - what it's function is and how difficult to replace?  I'm fortunate to have a lift so that makes most jobs a great deal more accessible.

Thanks,
Harry

[rwmastel]

I'm fortunate to have a lift ...

Harry,

Do you have a camera?  It would be great to see a pic or two that shows what you're talking about.

[David Robinson]

Is this the part you mean? https://www.sls-hh-shop.de/main/en/mercedes-230-280sl-w113-/35-rear-suspension/35-a-rear-suspension/rubber-bushing-axle-joint-german-repro-p-4600. if it is its not too difficult.

[Harry]

That is the part.  Is SLS a good vendor?  That price is better than Autohaus.  And I’ll follow with a picture.

Thanks,
Harry

[dirkbalter]

Harry,
IMO, SLS is as good or bad as all the other aftermarket vendors. Shipping will be more But crazy fast.
Sometimes these vendors sell original MB parts. If that’s the case, you can usually get it cheaper from MB direct.
I bought the bushing from SLS. My rear-end was out which made the change a lot easier. I am not sure if you can do it with the rear end installed. You will have to set and adjust the arm for perpendicularly and distance afterwards. (BBB).

[Harry]

Here are some poor photos but you can see thatit is resting on the lower part.  I’m thinking I need to jst replace it.  Are there any posts that address doing that?  With photos?  Seems like I am hit and miss with our Search function.

[Benz Dr.]

Axle must be removed in order to do this job.

[David Robinson]

Harry come to think of it my axle was on the bench when I changed mine. Sorry should have mentioned that.

[mauro12]

I’ve replaced this bushing  too and I bought from sls shop . Me and my friend mechanic have been able to replace without removing the entire axle . We used a puller and some hoist lift and we did it . It was quite labour intensive and difficult . But we managed to do it . Expect at least 4 hours of work .

[Harry]

Thanks everyone for your continued assistance.  I would REALLY like to not drop the rear ear end (obviously).  Is that necessary for access?  Does the BBB cover the operation?  (I haven't looked there yet.)

[merrill]

i ended up pulling my axle and replaced the rear clunk bushing as well as pinion seal, axle boot, re shoed the brakes and re lined the drums.
its not a hard job but took some patience and support from the group.

initially i asked an independent shop for a quote  to do this job , i think they quoted my just over $600 labor only and they were
going to try to replace the bushing while the rear axle was in the car.

after doing the job myself i cannot see how the busing can be replaced with the rear axle in place.

[Harry]

Thanks very much all!

[mauro12]

It is not necessary to drop the entire axle to replace this bushing . Dropping would make easier but it is not necessary

[Benz Dr.]

Anything can be done wrongly. Axle must come out to set up critical adjustments.

[Harry]

Is there any available guidance on how to do this?  I have the BBB so I'll look there tonight.  I also have a bunch of shop manuals that I can consult.

Harry

[dirkbalter]

Anything can be done wrongly. Axle must come out to set up critical adjustments.

I agree. The actual replacement is self explaining but you need to set up the arm at a set distance to the face of the drive shaft connection and insure perpendicularity to the axle tubes prior to reinstalling it. The dimensions are in the BBB. Contact me if you need a copy of the pages (in German though). If you go that route, I would also replace all the other rubber or wear components as described above.
Also, in order to get the bushing out, you need to remove the support bracket which requires the driveshaft flange to be removed. You will need a special socket to remove the nut. More important, you will have to tension the nut correctly afterwards in order to get the proper bearing clearance (crush washer). There is a torque value that needs to be maintained and stated in BBB. This is all doable but not a "quick job" IMO.
Hope that helps

[Benz Dr.]

We had to make a fixture to hold the pin socket in place when we replaced the crush sleeve on a 3.27 axle. The amount of force required to crush that sleeve while turning the pin nut is far more than you might imagine - it turns HARD.

Tighten the pin nut up to required torque and it should be good enough. I use a 1/2 impact gun set on high and really rattle that thing on tight.

[Harry]

So what is the special driveshaft flange socket (dirkbalter) and the fixture to hold the pinsocket (Benz Dr.)?  I’d like to he these ready when I start the job.
And maybe I should ask about changing the gear ratio?  Are the higher ratio gear sets readily available and priced “reasonably”?  If I were to change that, this would be the time.

Harry

[Benz Dr.]

I would find an axle with your desired gear ratio rather than trying to change to a higher ratio. You can change the diff seal with a pin socket that's readily available. 

[Harry]

Thanks Benz Dr.  where would you look and what ratio?  Mine is the “standard” US, I assume - 4:08?  Isn’t there also 3:27?

[rwmastel]

Your 230SL may have a 3.75:1 ratio.  You should check.  It's stamped on the side of the diff.

[Benz Dr.]

Yes, it's stamped on to the diff but in the case of 230SL it would be on the back bottom side of the central housing. On 250 and 280 it's on the front left, bottom side, of central housing.

[dirkbalter]

Harry,
I don’t know the proper name of the socket but SLS sells an expensive set. I made one myself out of a regular socket which I believe was discussed here once.
Like me, you should have a 3.75 ratio which is not as bad as the US 280’s (4.08).
My differential was ok. I did not touch the gearing. I only changed the lip seal and did not change the crush washer. In that case, you need to mark the nut and reinstall it into the same position to insure bearing fit or clearance. The required torque when rotating the rear end should be 26-30 cmkg with the tubes in a horizontal position and noting dragging (brakes).
Considering the small torque, I used a torque wrench for gun smith’s. (Amazon).

[Harry]

Thanks very much!

[Ed Riefstahl]

Hi Harry,
I have a trick for repairing your bushing at the risk of being laughed right off this list. I will add that I am almost 67 and have been working on these old MB's since I was 20. There's been a few times I've had to be creative and this was one of those times.

We also experienced the clunk in the rear of our 66 SL over 10 years ago. I've used this trick on many other applications to make nylon bushings etc. It sounds absurd, but actually works much better than you can possibly imagine and you really have nothing to loose by trying it.

Sounds like you have a lift which makes it much easier. Get some cotton string. Try to get something about 1/16" diameter. If you go too small like kite string, you will need to wrap it around the shaft too many times. Clean all remaining old bushing out of the gap. Wrap the string around and around the shaft until you have built up enough layers of string to fill the gap. Next take super glue (not gel) and from the top start to saturate the string until it's soaked and will not absorb any more glue. Be extremely careful not to allow the glue to drip on you.

When it dries, which is very quickly you will have a very durable bushing. My wife helped me do this (while on my back - no lift) at least 10 years ago and it is still in place. We've driven the car over 30,000 miles since doing that repair and had no issue or clunk.

You can start laughing now, but may want to wait until you've tried it first.

Kind regards,
Ed Riefstahl
Erie, PA