I need to change a rear hub on my 85 300SD, 126. I couldn't find any previous posts on this problem. I understand it is a sealed unit and cannot be adjusted or repaired. If the diff. has to be dropped or unbolted should I just change both? I plan on keeping the car for many years.
Any help is greatly appreciated

I'm about 99% sure the rear wheel hub and bearing assemblies are put together the same way as a W123. You probably need the first kit in this link:

1985 Mercedes-Benz 300SD Sedan - Axles, Bearings & Differential - Page 2

There's also a special socket and you'll need a dial indicator and magnetic base to set the bearing preload. The diff doesn't need to go anywhere. An alternate solution some have suggested is swapping a whole trailing arm instead of replacing bearings. I haven't tried that way.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I am pretty sure Skippy is correct. Instructions for the W123 will work on your year of W126.
In the Center of the Hub is the Bolt that retains the Axle in the Hub. You need to remove that and they say you will need new Washer for that Bolt (special one).

Push in the Axle and compress it being careful not to pinch the Axle Boot.

On the W123 you can raise and lower the Lower Control Arm (This means that side needs to be on a Jack Stand) and gently pry on the Axle to get it out.

Check Pelican Parts for the Special Pin Wrench to remove the Hub Nut.

I just remembered something; do not beat on the inside end of the Hub to get it out. it is thin and will only enlarge and make it harder to pull out.
The 2 methods in the DIY section for Beating the Hub out with a Slide Hammer or an old Brake Rotor damages the Bearings and they need to be replaced.

You did not say what happened to the Hub. If the Threads are stripped they can be Heilicoiled or perhaps Timecerted.

A new Hub is over $300 each and when you look at the parts they are right or left.
It is a lot of work to remove the Hub in the Junk Yard except that there will be a lot of old Brake Rotors for you to use.

You might consider getting a whole used Trailing Arm from. I don't have a figure as to how many People have done that have had bad Bearings in the New Used one

It worked for Me. I had an accident and Cracked My Trailing Arm and I bought 2 used ones. I put one on the Car about 3-4 Years ago with no Bearing issues.

Not too many ways to test one in the Junk Yard if you go to pull the whole Arm off. You can rotate it and listen and you could bring a Dial Indicator along so you can see if it has too Much end Paly.
After that all that is left is to decide if you want the Junk Yard Insurance on the Part or not.

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84 300D, 82 Volvo 244Gl Diesel

The Trailing Arms of other w123 will fit and the one`s off the W126 up to 85 will cross over to the W123.

Here is a DIY article n replacing the rear bearings.

PeachPartsWiki: Replacing the Rear Wheel Bearings


Charlie

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80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

On the rear hub of my 85 300SD I read somewhere that it was a sealed unit, hub with bearings and seals etc. D Morrison's illustrations on changing bearings cleared that up for me.
With rear end jacked up, right wheel has movement when tire is grasped at top and bottom and moved in and out alternately, not a lot but enough to be repaired.
I have all the tools illustrated to do the job so I will go this route.
No J.Y's around here that I know of that have MB parts.
Thanks for the help guys

Make it easy on yourself. Drop the diff, just two bolts and only takes a couple of minutes. Lower with a floor jack then slide it over an inch or two to get the axle out of the hub. No struggle.

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1984 300SD turbo 126
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So from what you say it sounds like you plan to replace the Rear Wheel Bearings.
If you pound out the Rear Hub from the inside to the out side you risk distorting the thin threaded area on the Hub and if you do the same from a little bit inside of the Hub you risk spreading out that end of the Hub.

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84 300D, 82 Volvo 244Gl Diesel

When I did it I used an old brake rotor for a slide hammer. No worry about damaging the bearings, since they were already toast. The problem there is in the event of overtightening the preload (which I did) is that you risk damaging the bearings if you take it apart again to change the crush sleeve. So I backed off a tiny bit and left it, figuring I'll put in new bearings if/when it goes to poo. That was several months ago and so far, so good.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Try assembling the new bearings without the seals and the original crush sleeve, unless of course it was damaged. Bearings are made to a standard dimension. If you get the end play you want, you're golden, disassemble it and install the inner seal. If not, you'll have to crush a new sleeve.

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'83 300D, 126K miles.

Wow - that's interesting. I was wondering what had happened...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

The purpose of the crush sleeve is to provide a surface for the retaining nut to be tightened against. With the nut loosened, all that is holding it is the locking tabs in the washer.

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'83 300D, 126K miles.

And if you look on the outer side of that washer you'll see that nothing is hold that bit in place!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!