Replacing the rear wheel bearings on a W123, W126 - PeachParts Mercedes-Benz Forum

dmorrison · #1 12-01-2007, 10:59 PM

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 · #2 12-01-2007, 11:00 PM

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

dmorrison · #3 12-01-2007, 11:00 PM

Picture #26
Here the socket is installed and the ratchet attached. I found it necessary to use the dead blow hammer to seat the socket all the way in. I tightened them as much as I could without the black pipe pry bar.

Notes on tightening the assembly.

Hammer the socket into the nut after each tightening of the assembly. THIS IS VERY IMPORTANT or you can break the socket tabs, don’t ask how I know.
Now with the socket installed and the ratchet against the lower control arm. Use the black pipe and the 2 lug bolts to tighten the assembly about 1/8th of a turn.. Measure the tolerance of the hub with a dial set up on a base. Hammer in the socket again and then turn the assembly with the black pipe another 1/8th of a turn. Do this until you have tighten it to within limits.

The limits are 0.04-0.06 mm
SAE .0015-.0023Inch
Or 1 mark on my dial gauge is .001 Inch

If you over tighten the assembly. YOU MUST REMOVE THE CRUSH WASHER AND INSIDE SEAL AND START OVER AGAIN. You will have to buy a new crush washer and inner seal.

Picture #27

This shows the dial gauge tolerance I achieved. One is pushing on the hub and other is pulling on it. I have about a .0015 setting.

Picture #28

How to set up the dial gauge for your reading. I have the dial gauge and base I bought from Harbor Freight.

Dial
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=33675

Base

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=5645

Picture #29

After tightening the hub to tolerance. You “lock” the nut in position by punching the nut flange into the openings in the hub shaft.

Picture #30

Shows the nut flange punched.

Install the drive axle into the hub and tighten the nut to the specified torque for your type axle. ( M12- 95Nm, M8-30Nm )

Install the rotor on the hub.

Install the calipers over the rotor and bolt onto the wheel carrier using loctite.

Enjoy.

Dave

dmorrison · #4 12-01-2007, 11:28 PM

Here is the location to drive the chisel to remove the outer bearing assembly off the hub.

Dave

JimmyL · #5 12-02-2007, 01:25 AM

Dave, you are becoming the Gold standard of write-ups!
We are all going to be faced with this job on our cars at some point, and you have literally saved some of us hundreds of dollars if we DIY. Thanks so much!!
I'm not totally sure I understand the setting of the hub via the dial calipers. Is it .0015" of "wiggle"?
I guess I will be sure and pick up the dial guage and base at HF next time it's on sale.
Nice job Dave!

#6 12-02-2007, 05:11 AM

Excellent! I've bookmarked this for future reference.

SW · #7 12-02-2007, 08:41 AM

You DA MAN! Thanks for taking the time and effort to document your work.

dmorrison · #8 12-02-2007, 12:25 PM

Quote:

Originally Posted by JimmyL

Dave, you are becoming the Gold standard of write-ups!
We are all going to be faced with this job on our cars at some point, and you have literally saved some of us hundreds of dollars if we DIY. Thanks so much!!
I'm not totally sure I understand the setting of the hub via the dial calipers. Is it .0015" of "wiggle"?
I guess I will be sure and pick up the dial guage and base at HF next time it's on sale.
Nice job Dave!

Your looking for a movement in and out of the hub. It is very small and usually noticeable on the dial gauge not really by hand.
Place the dial gauge on the hub as pictured and pull it in and out and watch the movement of the dial gauge. As you start tightening it will rotate 1-2 complete revolutions. As you tighten it it will become a smaller and smaller rotation of the dial needle. To the point where you will get only a small arc of movement. On the dial gauge I have, your looking at the needle swinging 1.5 marks. If you go to tight then you start over.

R Leo

Symptoms??

I did not really have bearing failure there actually in fairly nice shape, except for the one I destroyed. I moved the hub against the outer bearings and rotated it, It was smooth. Then I pulled the hub against the inside bearings and again it was smooth. I found it difficult tightening it and actually broke the special socket tabs. So I figured I would just do the whole job so I could learn it, make this post and know that it was done right.
The initial problem was when I put the tire on the hub The whole tire moved in and out about 1/8th of an inch. Definitely not good.

Dave

Stevo · #9 12-02-2007, 06:02 PM

Thanks Dave, nice job, We all may face this job some day.

Eric Eliel · #10 12-02-2007, 08:54 PM

Dave,

Excellent write up and excellent photo's. I think you out did yourself this time, perhaps an even better write than your R&R evaporator A/C write up.
Well maybe.

Eric

hangit · #11 12-08-2007, 09:48 PM

Many thanks Dave for another great DIY article! Merry Christmas.

John

wegrow · #12 08-25-2008, 01:30 PM

Thanks for the superb write up. Any other sources for that pin socket? Some of those links didn't pan out. Did find one here for $68 bucks .
http://www.samstagsales.com/mercedes.htm

Any one have a spare?

rlh134 · #13 06-21-2011, 01:01 AM

dmorrison - many thanks for the hub rebuild procedure!! Nice job!

DeliveryValve · #14 12-02-2007, 10:05 AM

True to form, another great write up on a DIY Dave!

Quote:

Originally Posted by dmorrison

.....Picture #27

This shows the dial gauge tolerance I achieved. One is pushing on the hub and other is pulling on it. I have about a .0015 setting.....
Dave

I take it you are pushing and pulling with your hands (or with something else). I am always not sure how force to do this with. Can you elaborate on the technique a little.. i.e. hand placement and etc.

dmorrison · #15 12-02-2007, 12:41 PM

Quote:

Originally Posted by DeliveryValve

True to form, another great write up on a DIY Dave!
I take it you are pushing and pulling with your hands (or with something else). I am always not sure how force to do this with. Can you elaborate on the technique a little.. i.e. hand placement and etc.

The attached picture show how I pulled or pushed on the hub so that the movement in and out of the wheel carrier is within the tolerances specified in the Service Manual.

Dave