Replacing the rear wheel bearings on a W123, W126

[dmorrison]

My son’s new 85 300D had the rear left wheel hub loose and required replacing. I was quoted $400-435 from 2 independent shops and $775 from the dealer. I wanted to learn how to do this job (35-130 ) The MB service manual calls for 11 specialty tools to complete this job. I had a good conversation with the old Mercedes specialist at the dealer and asked what “specialty” tools are really required. He said Just the Special castle socket . MB 115 589 02 07 00.
All the races can be removed and installed with conventional tool. So here is the write up of the job. The most difficult task was removing the outer bearing/race assembly off the hub. I destroyed the bearing holder and totaled the race. I would suggest bring the hub to an independent or the dealer and pay a few bucks to have then do this. They should not charge much. I figure $25-30. If it’s over $50 I would do it myself. I did not get a price for doing it.


Dave

[dmorrison]

Picture #1
Tools and parts needed for the job on a 1985 300D
˝ inch drive ratchet.
Special socket. MB tool 115 589 02 07 00
Brass drift.
Hammer
Dead blow hammer
3 jaw puller
Large flat washer or plate ( used with the 3 jaw puller over the hub opening)
Dial gauge, Metric preferred, SAE OK ( it's what I have)
Large flat screwdriver
Flat chisels, 2 small, 2 large
Dial gauge base holder
Wheel bearing kit MB part number 123 350 00 68 ( 1985 300D)
MB wheel grease MB part number 002 989 51 10

Picture #2
Remove the center bolt holding the axle to the hub. You may have to use the brass drift to remove the axle.
Unbolt the caliper.

Picture #3
Hang the axle and caliper with wire , out of the way. Do not
Allow the caliper to hang on its rubber hose. Do not allow the axle to drop.

Picture #4
Remove the rotor. Parking brake must be released to remove the rotor.

Picture #5
The slotted nut and inner bearings.

Dave

[dmorrison]

Picture #6
Purchase 2 lug bolts or 2 bolts to be sacrificial bolts for the job. M12 X 1.5 . Install them as shown

Picture #7
The “special” tool needed for this job on a ˝" drive ratchet.

Picture #8

I used a black pipe clamp since I have a wood shop. Any strong and long ( about 4 foot long ) bar will do. The setup shown will allow you to loosen the slotted nut.

Picture #9

Install the socket and ratchet as shown. This will allow you to loosen the nut on the outside with the back pipe.

Picture #10

Using the black pipe I loosened the slot nut.

Dave

[dmorrison]

Picture #11

Remove the seal on the inside of the hub from underneath the car. I used a large screwdriver.

Picture #12

I did not have a slide hammer to remove the hub. I did the
Following, I Used a brass drift to hammer out the hub from under the car. I hammered it out about ˝ inch. I then installed the rotor as shown and used it as a slide hammer to get the hub to release from the inner bearings.

Picture #13

This is the hub removed and attached to the rotor.

Picture #14

Now for the most difficult part, removing the outer bearings and race assembly. As you can see I destroyed the bearing cage in the process and tore up the inner race.
To do the job Use a wide flat chisel and force it between he inner race and the hub. ( I forgot to mark the picture, page 8 of the post has a photo of where to force the chisel ) ). As the race starts to separate from the seat you can use a 3 jaw puller
And a flat washer to pull the bearings/race assembly off the hub.
If you try to pound away at the bearing cage it will come apart, as shown. Then if you try and chisel at the lip that is left. It will break apart and fly everywhere ( wear safety glasses ).
So the solution is to use the flat chisel between the race and the hub shoulder.
Another suggestion would be to bring the hub and new bearings to an indy or the dealer and pay them a few bucks to do this part.

Picture #15

The wheel area needs to be cleaned of all grease and the races removed.

Dave

[dmorrison]

Picture #16

Use a BRASS drift to remove the outside and inside outer races. Using a steel drift will scar the metal and you don’t want that. This picture shows me removing the inside outer race. You remove the outside outer race from under the car

Picture #17

Clean the interior completely of all grease and brass bits that will come off the drift. Use a degreaser, dry it and then blow it out with compressed air.

Picture #18

A clean and dry wheel carrier section.

Picture #19

Another view.

Now install the new races. A technique to use is to use the old race to hit with the hammer as you are installing it. The old race will receive all the blows and the new one will have a solid matting against the old one eliminating damage to the new race. Drive them until they are seated completely.

Picture #20

Install the new outside bearing on the hub. I used a chisel as shown and ONLY strike the inner race not the bearing cage. Slowly drive it onto the hub until seated. Continuously tap the race rotating all around its circumference.

Grease the bearings as best you can, install grease into the wheel carrier. Total grease installed in the assembly is 50G. This is split between the outside and inside bearings.
Place the crush washer on the hub.
Install the hub into the wheel carrier.

Dave

[dmorrison]

Picture #21

Grease the inside bearings
To drive the inside bearings into position the MB service manual uses a press. I used the old spacer section and hammered the bearing onto the hub shaft. You will need to hold the hub against the wheel carrier as you hammer. It will not completely set the bearing on the hub shaft. But it allows you to then attach the slotted nut and then tighten the assembly.

Picture #22

Apply the remainder of the 50G’s of grease as shown..

Picture #23

Install the outer seal and new inner spacer. I then use a dead blow hammer ( its made out of rubber) and drove the seals into the carrier.

Picture #24

Driving the seals into the carrier.


Picture # 25

Attach the slotted nut and tighten.

Dave

[AMH]

Originally Posted by dmorrison

Install the new outside bearing on the hub. I used a chisel as shown and ONLY strike the inner race not the bearing cage. Slowly drive it onto the hub until seated. Continuously tap the race rotating all around its circumference.

Grease the bearings as best you can, install grease into the wheel carrier. Total grease installed in the assembly is 50G. This is split between the outside and inside bearings.
Place the crush washer on the hub.
Install the hub into the wheel carrier.
Dave

This is not a bad repair if you take your time and do it right.

[dmorrison]

I had to hammer the socket in because it was a very snug fit. If you allow the socket to work out the pins will sheer off and then your screwed.

Dave

[peachykeen]

Hi Dave, this is fantastic - so helpful that I am tempted to go for it myself...otherwise I've got a quote for $400 to $500 to have it done at a good German shop -- do you think that's pretty fair?

The noise I'm getting is a consistent propeller type at the rear -- couldn't be a CV joint could it?? The CV boots are both in good shape and no evidence of them having leaked their grease out...

Last question -- do you think it is OK to continue to keep driving the wagon in this state -- any chance of it damaging other parts??

Thanks for your time,

todd

[Alberta Luthier]

for both?, I was quoted $-500 per wheel
I've got too much play for sure and have been putting it off because I haven't worked up the nerve to do it yet and it hasn't made any strange sounds or anything forcing the issue.... yet! If I really had confidence that I would get first class work I still might hire it done, but alas, when you most need really good work is when you usually don't get it

[turbobenz]

Does a brass drift really work for this? I did the front bearings and had to get a used hub from pick n pull because i destroyed my hub with a hardened mini crowbar (perfect angle to get at the race). I bought a brass drift and couldn't get the races to even budge because the brass just deforms and absorbs all the force. I ended up carefully using the crow bar to tap them out.

[Diesel911]

Originally Posted by turbobenz

Does a brass drift really work for this? I did the front bearings and had to get a used hub from pick n pull because i destroyed my hub with a hardened mini crowbar (perfect angle to get at the race). I bought a brass drift and couldn't get the races to even budge because the brass just deforms and absorbs all the force. I ended up carefully using the crow bar to tap them out.

On the front some heat from a Propane Torch directed on the hub often helps when knocking out bearings.
I do not know if this is possible on the rear.

[dmorrison]

Originally Posted by Diesel911

On the front some heat from a Propane Torch directed on the hub often helps when knocking out bearings.
I do not know if this is possible on the rear.

Yes it is but a brass drift and a hammer will do the job. Just hit the beaing race along the circumference of the race and it will move out. If necessary heat the hub, not the race. After all the grease is removed

Dave

[Diesel911]

Originally Posted by dmorrison

Yes it is but a brass drift and a hammer will do the job. Just hit the beaing race along the circumference of the race and it will move out. If necessary heat the hub, not the race. After all the grease is removed

Dave

You are right; I have never seen one fall out of the hub just by using heat alone. But the careful use of heat seems to help with most jobs where something is stuck and the parts are metal.

Another thing I have found is that it is better to use a heavy hammer 2-3 pounds. You can control the slow short tap much better and the drift stays in place better. If you hit it fast and hard with a light weight hammer the drift just wants pops off what you are trying to knock out.

[bmonk]

I'm in the middle of this job right now, but my pin wrench socket cracked while tapping it into the lock nut. Here is the email I sent to the company that sold me the socket.

"I purchased Mercedes Tool, Pin Wrench Socket, M107, 114, 115, 116, 123, 126 (Technic Tool: model M915-0207) from your company about a week ago. The tool was not a perfect fit to the lock-flange nut that it was designed for. While tapping the tool into the flange, two of the teeth cracked. Please let me know what can be done at this point to get a replacement. Thanks very much."

Their reply is as follows.

"There are a couple of problems:

• This tool is not designed to be hammered or used with impact- “tapping”-that alone voids the warranty.

2. I also spoke to our Supplier, and they said that there is a locking plate behind that nut, and that it is supposed to be opened and then the M915-0207 fits in- if the locking plate was not opened enough- there was no way that the tool would fit in there"


Now does anyone know what they are talking about? I see no reason the tool would not fit other than poor design. It wasnt just a little tight either, there was no way it was going to fit in. I actually had to file the pins down quite a bit before it even came close. Am I missing something here? How do I open this "locking plate"?? Nothing I have read suggests there is such a thing. Please Help.