Yes, you will need full front and back access to the diff bushings to get them out and in. Probably beyond what could be accessible with out having the diff completely removed.

When I did mine those bushings where the first new part that was swapped into the striped subframe after I cleaned it and painted it getting it ready to go back together. It takes a bushing press tool to do it the easy way. I made one out of 2” black pipe, threaded rod and fittings.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Couple things:

To remove the stacked nut on the axle shaft without the benefit of an impact gun.

1) using a chisel and a hammer work the small staked portion of the 30 mm nut's collar out of the groove as best you can.

2) with rear jacked, blocked and on stands, the wheel/tire removed you can take a long pry bar or a section of rebar to counter hold the wheel hub from turning. Take a couple lug bolts and insert them into the respective holes in the hub. Now you can use the pry bar/rod inserted between the lug bolts and the hub center to brace the wheel hub from rotating. One end between the lugs and hub and the other end braced against the ground.

3) you'll need a 12 point 30 mm socket, the nut has a very short section that the socket interfaces with. This can make it easy for less than perfect interface between the nut and the tool. Most sockets have a rounded finish to their opening; in this case that rounded part will take up a bit of space when the socket is in place on the nut, thereby reducing the area of the socket that comes into actual contact with the nut. In the past I've taken a grinder to the socket and removed that rounded finished portion at the open end of the socket. That allows the socket to fit closer and more completely with its 30 mm 12 point interface area most completely on the shallow interface area of the axle nut.

4) Just before you tackle the axle nut use a propane or butane torch to heat the nut. It doesn't have to be red hot or even close but you should heat it top, bottom and sides to just a bit to hot to leave your finger on it. Temperature above 150 F will significantly soften and in turn loosen the blue threadlock that the axle nuts are treated with.

All that being done get your breaker bar and probably a section of black steel pipe as an extender, then while holding the socket straight and square on the axle nut on the braced wheel hub of the well blocked elevated rear you should be able to apply the pressure to unscrew the axle nut pretty easily once you break the initial bond free.

5) if you're planning on diff seals/bearings you'll need the diff dropped to get its back cover off in order to get access to the clips that secure the stub flanges the inboard axle ends bolt to.

Honestly if you're going that far and if you can somehow get a day or two with the car immobile I can't see how or why dropping the entire sub-frame isn't the best method. Only because once that's done you have infinately better access to every nut and bolt of the 10 bolts on each side you're going to be working on.

But everyone has his or her comfort level with that level of disassembly. Like R&R for the glow plugs, sometimes it's easier in the long run to remove the intake manifold to gain easier access than to spend much more time in multiples trying to work around things in order to get something accomplished. This is especially true when the R&R entails fooling around with things that can easily go wrong such as delicate parts or difficult parts like large strong suspension parts that might be 30 years in place.

You can get all the links replaced without disassembling the axle shaft from the diff, the axle stub usually pretty easy to drift out of the splined hub. If your determined to remove the axle from the diff I have found it easiest to do so when you can brace the hub and therefore the axle just like I've described for the axle nut removal. Brace the hub/axle, using a long extension you can reach into the axle/diff and after a thorough cleaning the bolt heads get that tool into the fastener and get it removed easier because the wheel hub/axle is counter-turn braced. You can usually reach at least one but maybe two of the axle/diff bolts before you have to unbrace-rotate-rebrace the hub/axle to get to the remaining of the six bolts connecting the axle and the hub. You have a later 124 so those six bolts might not be the original configuration XZM bolts and could be some variation of TORX head bolts that later 124 cars had originally.

If you disconnect the driveshaft at the diff mark the position of the drive shaft yoke to the diff yolk, keep track of the individual bolt/nut sets and where they where locked in relation to the yolks and the guibo. That way you can get everything back together the way it was. The 124 design can utilize a special heavier nut/s to help balance the drive shaft, if this part of the original installation you'll want to get all the parts and pieces back in the same place to avoid any potential mis-balance.

If you do work on the diff and need to drop it or pull it there won't be a better time to replace the two rear dif cover/sub-frame mounts and the single front diff mount. The front mount 8 mm Allen head bolt can be a bear and often rendered useless for reuse in the process. If you do drop the sub-frame of diff, get in behind the rear seat and unplug the ABS sensor wiring. Then you can pop the body seal, wiring and connector back through the hole and under the car. That avoids you having to remove the ABS sensor from the diff housing which can be a real bear sometimes, possibly resulting in damage to it in the process.

I've got a craftsman electric impact gun that I've used on this particular job in the past, and it got it done. I think Harbor Freight might have a ChiCom disposable version available. There should be some Sears Liquidation sale bargains available any day now as well!!!

The impact gun and a long extension is a very easy way to get the six axle/diff bolts removed as well, you don't have to get under the car, you can gain the access going in above the wheel carrier between the upper links.

@if6was9 - lots of useful info there! I'm probably going to go ahead and drop the sub frame. It's just been intimidating thinking about it but as I'm pecking away at it, I'm seeing how much easier it will be to access many of the connections - saying nothing about those rear diff bushings

Thanks!
Dale

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Dale

I've actually got one of those HF electric impact guns and just didn't think it had enough butt! But now that I've read that you've used one for this job - I'll give 'er a try

Dale

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Dale

Don't do it. HF will end up stripping your rear axle and then you'll need to replace the entire axle. I had to get axles from another member on the forum because one stripped and I could not get the collar nut torqued to spec and it ended up coming loose at some point and destroyed my rear wheel bearing. Use a breaker bar, 200 - 300 ft lbs isn't that hard to undo with a good breaker bar and some leverage....and I'm only 160 lbs and I did it with ease.

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1990 190E 3.0L

What part of the axle stripped? Are you referring to that 30mm axle nut? If that's what you're referring to, I'm not understanding why using a HF tool would be responsible. Just needing to have some clarity here

Dale

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Dale

The threads on the axle stripped. My guess is the combination of vibration and turning must've caused the nut to jump a thread or something, I don't know, but I wouldn't do it again. Break the nut loose first, then try it. I definitely wouldn't use it to put the nut back on

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1990 190E 3.0L

So I've gotten started with this deal, a couple or few hours here, an hour there, so it's not going to be a fast one for me. I'm needing to remove my driver's side brake dust shield to replace it with a new one that I bought two years ago. Long story! But now is the time.

Does the hub need to come off in order to change iout the shield? Does the hub simply pull off? I think I recall several years ago when I put new half shafts in my 300D, the shaft pulled in toward the diff - then compressed to pull it from the diff. Any help will be welcome and appreciated if course

Dale

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Dale

Unless you absolutely need to replace that dust shield and have all the proper tools and parts (i.e., another rear wheel bearing), then you are better off leaving that alone. In fact, I wouldn't even attempt it. I just replaced my rear wheel bearing not too long ago, and I had to have someone press it out for me. And even then it was sorta jury rigged to get it out. If I have to do the rear wheel bearing again, then I would end up spending the money on the MB special tool.

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1990 190E 3.0L

Crap! I was hoping I could do this while tearing into this rear end. I have a feeling that you know what you're talking about... Thanks

Dale

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Dale

Question...

(Ref the attached pic) New arm on left with the hardware that was packaged with it - old arm on right with orig hrdwr as removed. New hardware has a triangular washer type disc - old one did not. Is it to replace the 'cupped' washer on the bolt head side of the old?

Thanks
Dale

EDIT: Nevermind, it was easy to figure out since I had the printout of the FSM pages for this job...

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Dale

This job is getting closer to finished. I just did the passenger side this afternoon so now I'll likely do the parking brakes, rotors, and calipers tomorrow. It wasn't nearly as bad a job as I was fearing, especially since I didn't drop the subframe. I will need to do the subframe bushings soon though..

Now, those pesky diff bushings, not looking forward to those too much. Anyone have words of wisdom on that job? The seals on the output shafts appear to be bad as well as the rear plate. Sure wish I could have replaced the dust shield

Dale

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Dale

Looking good, how did your project turn out? I know I loved the feel of my 190 when I dropped the subframe and did poly mounts and 8 new Meyle arms. It got rid of the axle hop and the terrible tracking at high speeds

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97 e300d, 78 300Dt, 95 E300d, 94 E320 estate

It's still up in the air! Work and personal energy levels after working have slowed progress. I actually thought I'd mess around with trying to get those pesky wheel carrier bushings out this evening but I'm a bit whooped after work today

All the links have been replaced and torqued down to spec and have decided not to drop the SF at this time -saved for a summertime project perhaps!

Thanks for asking

Dale

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Dale