Some rear axle work

[mbzse]

I am refurbishing a 1:3.69 rear axle, to be fitted to my 280SL (which presently has a 3.92 axle fitted).
I have taken some pictures that I share with you here.
First the lid for the pinion axle, with its seal (1). Mount the lip seal with sealant and ensure it is flush (2) (if cantered, seal will leak!)
I exchanged the big rubber sleeve bushing - compare old and new in the picture (3).
To fit this bushing into the upright vertical support arm, expand the gap via M10 bolts in from other direction and a washer in the gap (4).

/Hans in Sweden
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[mbzse]

More images:
Slide the bushing in and place it, as good as you can approximate its position, in the car's front-aft direction (5).
After removing the "expansion help" hardware, fit the correct M10 bolts (6). Do not lock these down yet.
After mounting the pinion axle lid, and the 32mm hex head bolt that locks the bushing for the upright vertical support arm, time to position the upright correctly.
First check fore-aft position (158mm). I use a simple self-made measuring tool (7). You can see more info on this in this posting http://www.sl113.org/forums/index.php?topic=9060.0
In reply #3 of that posting, there is a sketch from the Workshop manual (BBB).
Then see to that axle shaft tube is horizontal (picture eight).

/Hans in Stockholm

[mbzse]

Next task, checking that upright is vertical (9). Now is the time to clamp down the two M10 bolts on the lower part of the upright.
Finally a picture of the whole axle, as it is nearly finished to be mounted into my car (10)

/Hans in Sweden
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[jameshoward]

Hans,

There's an easy way of putting the parts together in the correct order; I think I mentioned it here, but either way, get a wooden drift about the same size as the large pin and build the axle parts using that. When you're ready and have everything in the right place, simply tap in the pin from the rear.

Some of these threads contain some sage advice (some of it picked up the hard way...)

http://www.sl113.org/forums/index.php?topic=18228.0

http://www.sl113.org/forums/index.php?topic=18312.0

[jameshoward]

Hans,

Please note that you appear to have your boot circlips on upsidedown. The BBB (link enclosed to the relevant section) states that they should be at the bottom to allow for access. See page 35/5-2. The pdf is embedded in this thread.

http://www.sl113.org/forums/index.php?topic=18312.0

Note also that the rubber boot has a specific orientation ('oben' is stamped on it at the top). 

JH

[mbzse]

../.. There's an easy way of putting the parts together in the correct order; I think I mentioned it here

Yes James thanks for pointing that out. I did not disassemble the large pin out of this axle, but for sure it is a good thing to do when refurbishing one.
/Hans in Sweden
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[mbzse]

James,
Nope, nothing upside down here. I see now that in the Workshop manual of 1968, illustration 35-7/3 they do have the band screw clamps facing rear, and mention in text they should be accessible from rear/below.

But, on my original May 1968 axle, and illustration 35-4/3 of the 1959 edition (supplement March 1963) the clamps are mounted on top - see my pic here [and in reply #9]. Screw is facing rearwards. That is why I mounted them in such fashion.
BTW, these original type 9mm band clamps are hard to find - I had to search for them. They are no longer in the EPC, substituted there with the roll split pin type
/Hans in Sweden

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[jameshoward]

I'm just telling you what the book says, Hans, and it says they should be accessible from below, hence, they're upsidedown.

Even mercedes mechanics make mistakes...just trying to help.

[George Des]

Yes, that large pin can be a pain to install. The drift and build up is a big help. I also recommend the use of dry ice on the pin to lessen the amount of pounding you will need to get it back in. The end is easily flattened and ruined. Ideally you would press this back in but the shape of the axle not to mention its unwieldliness makes this very difficult to do with normal shop equipment. The dry ice is also helpful in installing those two hardened steel bearing surfaces that fit on the pin.

[mbzse]

../...Even mercedes mechanics make mistakes...just trying to help

Yes, I certainly realise that, and appreciate your help James. Thanks  
Some further illustrations:
Picture 35-4/3 from M-B workshop manual showing band screw clamp installed
Picture of hose clamp as presently installed in my original 280SL (60 000km), May 1968. "Grey stuff" all over is old bitumen spray on chassis

  /Hans in Sweden

[George Des]

Hans,

You can find the original style clamps here  <http://www.authenticclassics.com/Beru-9mm-Toggle-Hose-Clamp-S-9-N-284-p/auth-002422.htm>

George

[ja17]

For removal of the large hollow swing arm pin..........I slip a 1/2" extension into the pin and pound on the end of the extension instead of pounding on the pin directly. The small end of the extension slips into the hollow pin and the large end seats nicely against the end. No damage is done to the pin, but you may want to use an old 1/2" extension.

Attaching the trailing arm to the chassis...............
I have a drawer full of special rear diff. tools I made or bought over the years. Many are not absolutely necessary. But using them all on a job saves a lot of time.  Seems like I am doing a different rear axle every couple of months these days. Here is a picture of an alignment mandrel I made to help align and attach the front trailing arm. Keeping everything in place and aligned can be tedious without the tool.  In addition I temporarily use three  plastic wire ties to hold the rubber in the end of the trailing arm while it is being mounted to the chassis.

I saw a picture in one of the BBBs of a similar factory tool as my inspiration.   I used a 5" length of 1 1/2" diameter steel tube. I cut slots in the one end of the tube with my die grinder and a cutting disc. I closed the ends together and welded them to create the tapper. I welded a nut in both ends. The large end screws onto the threaded chassis stud, where the trailing arm mounts. As the trailing arm is raised it is easily slipped over the alignment tool. When the trailing arm is jacked tight against the chassis, the alignment tool is removed and the installation is completed. Just cut the plastic wire ties off when finished.

One of these days I will have a better one of these tools turned from billet aluminum on a lathe.

Here are pictures as requested....

[Eminent]

I have a question.
Is it possible to get the rubber mount (pic.3) out just by loosening the 6 bolts from the bracket in picture 1?

[George Des]

The short answer is no. The pin that holds the whole right axle assemby to the differential pumpkin runs through that and it is composed of a number of shims, bearing surfaces and rubber seals all in a specific sequence. This is what makes dissassembly such a chore and why MB developed the split boot to replace the one piece boot. I have done this job on two axles and it is one of those jobs that will challenge you to figure out the best little tools and methods to get it all back together correctly. A real good time to replace any other items in there that may go bad in the future like the boot, all the seals, and perhaps the bearings.

[Shvegel]

I actually believe I have the factory tool to do that job. It is a long steel pin with a removable cone shape on one end. It is meant to be slid through taper first as the axle is being assembled. The cone end is threaded to the pin and after you feed it through all the bushings and shims you remove the cone and thread the end of the permanent axle pin onto the threaded end of the tool. You then draw the tool back which pulls the permanent pin through the bushings etc.

I would post a picture but it's sitting in my toolbox in Cleveland and I am working in the Caribbean for the next 2 weeks.

[George Des]

That would be good to see. Sounds likeit would be simple to duplicate and a good toolbox item.

[George Des]

Joe. Thanks for posting the install tool. I took a look around and see where 1 1/2" alumium rounds are readily available. I may purchase a couple of short pieces and have them tapered and threaded to replicate the factory tool.

[Shvegel]

I have 6-5 gallon pails of old Mercedes tools I received from a friend in exchange for fixing the hydropneumatic suspension on a Citron SM(Loose internal bleeder screw).  Most are from a generation newer than our cars but there are a few gems that I have put aside including the proper slide hammer for removing the axle shaft.

I am hoping to dig out the tools that apply to our cars and bring them down to PUB.

[ja17]

Sounds great Pat!  I remember your posting back when  you got them. Can't wait to see all the goodies.

Joe

[Eminent]

I made a tool to measure the torque at the drive-pinion. The result is less than 1Nm.
The BBB says this must be 20-25 cmkp. This is 2-2.4Nm right?

[Dave H]

20-25 cmkp
1.96-2.45nm
1.44-1.8 ft/lb or 17.35-21.68 lbs force inch as measured on your nice little torque wrench ( would like that torque wrench myself.. It's a beauty! )

[Eminent]

It has Nm on the opposite side.
But my question. When i'm done with changing the oil seal, should the torque be the same as it is now (less than 1 Nm) or should it be between 1.96 and 2.54 Nm, the specs from the BBB?

[Shvegel]

As promised here are pictures of the tool from my box. It is indeed the factory tool for removing and installing the hinge pin in the split housing rear axle.  This is Mercedes special tool #180 589 08 39 00 It features a solid shaft with a removable nosecone. It is screwed onto the end of the pin and used as a mandrel to drive the pin out and then used with the cone screwed on to feed in all the parts and line it all up. The cone was unscrewed then the tool was drawn back through the axle dragging the pin through.

[George Des]

Thanks for posting. This looks like an easy enough to fabricate tool. Could you possibly provide the dimensions if you get a chance. Can see where this would really help a lot of members who would otherwise shy away from attempting any work on their own. Maybe we ought to start a separate topic area on tools as well where we can post pictures of tools that we have used to make jobs easier.

[Shvegel]

George,
The actual tool diameter of .980 inch is quite a bit smaller than the axle pin so breaking it down to the simplest to machine. 
17.5" of 1" shaft. Turn .750 of one end down and thread to 20mm X 1.5 pitch.  take 2.5 inches of the same 1" shaft, taper one end and bore the other to accept the 20mm X 1.5 end of the tool.  If I was making it and had it chucked in a lathe already I would bore the other end of the tool to 5/8" X 18 thread to accept a standard slide hammer in case you need to tap it a bit to draw the pin back in.