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1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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Discussion Starter #1
These steps were done on my 1986 420SEL. For much of my technique, I give credit to dmorission on PeachParts. However, his DIY was done on a w123 and there are a couple differences between that and my gen2 SEL.
PARTS:

2 Sets Mercedes Rear Wheel Bearing Repair Kit: 123 250 00 68



STEPS:

1. Jack up and properly support car with jack stand(s). I did just one side at a time. I also made sure to place the jack stand far toward the back of the car so as to have plenty of working room around the rear axle. I got it as high as my jack stand would go. Do not put on the emergency brake and put the car in neutral. Might use stop blocks for extra safety.

2. Remove wheel



3. Remove brake caliper (2 19mm bolts) and tie off. I used zip ties to secure it to the sway bar

4. Remove brake disk: remove hex screw, carefully wiggle off being careful not to damage e-brake shoes.



5. Using 13mm socket, remove bolt in end of axle. Put aside.





6. Using a drift or wooden dowel and a rubber or dead blow mallet, pop the axle out of the carrier with a solid tap. At this point, the axle won’t come out of the carrier, but it will slide in and out a bit.
Brass drift used to knock out the axle:



Next three steps are needed to make sure you get the trailing arm (TA) at its lowest position to facilitate axle removal:

7. Place jack under rear TA and lift an inch or so. This lets you remove the top 17mm nut to detach the sway bar link



8. Remove back seat and remove top 17mm shock nut. Lower jack at this time.





9. This got me very close but it still was not enough to remove the axle. On my Gen2 w126, I still needed the TA lower. To do this, I unscrewed the rear sub-frame bolt, using a 24mm socket, 3 and a HALF turns. It was still tight, but it was just enough for me to push in on the axle and use the heel of my hand to knock it free from the carrier. You should be able to go more than 3.5 turns, but I don’t know. You really don’t want that sub-frame bolt letting go and coming all the way out because it’s a bit of a pain to get back in.

24mm socket on sub-frame bolt:



NOTE: On gen2 SEL cars, there is a catch on the TA that will not let it drop such that the spring releases. Also, even if you went too far and accidentally released your sub-frame bolt, the spring with not fly out and kill/maim you. Unless you have non-standard springs or release the diff mount, you should be safe. I replaced my springs earlier this year and it required a spring compressor despite removing the shock and completely dropping one side of the sub-frame.

10. Now, as I mentioned above, you can grab the outermost axle joint, push in toward the diff, and wiggle the axle out of the carrier. Go toward the bottom to remove it as that is where the gap will be the greatest.

11. I used a zip tie again to hold the axle to the sway bar and keep it out of the way.

Axle and caliper held out of the way with zip ties:



Now it’s time to remove the hub flange.

12. On the back side of the hub there is a slot nut. This essentially holds in the hub. To remove the slot nut, the first step is to get a punch and “unbend” the slot nut’s collar. You’ll see that there are two indents on the hub. One of the last steps of re-assembly is to punch the slot nut collar into the indents on the hub. This keeps the nut from backing out. Before you try to remove the slot nut, you have to undo this procedure.
Before I “unbent” the detents:


My picture afterwards did not really turns out.

Removing the slot nut requires a Mercedes special tool (115 589 02 07 00). I got mine from the dealer for $120. I think parts.com has it for $70. There are some other sites that sell this tool as well as aftermarket special tools. However, the price is not all that different and if you search the internet, some people who used the aftermarket broke their socket or, it did not fit altogether because the tolerances were off. I don’t know if this information is true, but it is available on the internet for all to see for themselves.

13. The tough part about removing the slot nut is that it is torqued down really tight and you need to hold back on the hub to keep it from spinning while you loosen the nut. This is where dmorrison came up with an ingenious solution. First, you need either two sacrificial lug bolts or 2 M12x.150 80mm bolts. I got the two bolts at NAPA. Screw these into two opposite lug bolt holes on the hub. Put you ratchet with the special socket into the back of carrier and onto the slot nut. I had to tap mine to get it fully seated into the slots (I recommend this). Make sure the ratchet handle falls to the back of the TA. Do not let it push against your brake fluid hose! With it in this position, it will “hold back” on the ratchet while you use a cheater bar or a pry bar to turn the hub “counter-clockwise”…or “anti-clockwise” for you Brits. Once it “breaks” free, you can pretty much lose the bar and turn the hub by hand.

Special tool on slot nut. Note it is clear of the brake line resting against the TA:



Pry bar with bolt-in-flange-setup:



14. Once the slot nut is off, behind it there is a spacer that can be pulled off. Set this aside for later. You won’t be using it, but it will help in re-assembly.

Slot nut and spacer behind it removed:



15. Next, pry out the grease seal. I just used a screwdriver for this.



16. Now you need to pull the hub out of the carrier. The hub is now being held in by the pressed-in inner bearing. Again, another clever solution from dmorrison comes in handy here. Remove the bolts you used for leverage to turn the slot nut from the flange. Now, mount your brake disk backwards with the same bolts. Don’t screw the bolts all the way in…only enough that they are all the way through the flange. Now, you can pull on your brake disk and slam it against the top of the bolts. This action acts like a slide hammer and will release the inner bearing from the hub. I did not have to use a lot of force to do this. Maybe just 5 or 6 half-effort pulls. The bearing is not pressed on that tightly. Once this step is complete, you will be holding the hub in your hand still attached to the break disk. You can take them apart now.

Brake disc slide hammer setup:



Hub removed still attached to brake disk:



17. Next, I pried the grease seal from the outer end of the carrier.
Empty carrier:


18. Now time to get the races out. This step took a little patience but was not terribly difficult. I used a brass drift (from NAPA), inserted into the carrier, and pushed up against the lip of the race. Using a dead blow hammer, I pounded on the drift, working my way around the race. You should be able to peer into the carrier and see it separating as you do this. Eventually it will just pop out. Getting the outer race out was a little more difficult because you have to swing your mallet from the back of the carrier. You can either get under the car to do this, or, pretty much hug the carrier and reach around. I used the latter method because I don’t like getting under the car when I am pounding on things. This took a good 5-10 minutes per race but it got the job done. Using this method, you can pretty much bang on it all you want and you don’t have to worry about damage to the carrier. If you go the route of an air chisel or a steel drift, it might be another story.

19. Next is to deal with the hub itself. There is a crush washer that needs to come off. Mine was on pretty tight, I just used a screwdriver and a tack hammer to tap around the edges and work it off. This washer gets squeezed when you tighten the hub during assembly to help set your bearing run out. It does not get re-used. Your genuine MB bearing kit will come with a new one of these.

20. Now you have to get the outer bearing off of the hub. I had a little trouble with this. However, I think I was just not being aggressive enough. You can use a chisel to “pop” the bearing off. This is as indicated by dmorrisons recommendation. I was nervous about hitting the hub too hard and I was doing it against the floor instead of in a good vice. What I ended up doing was taking it to a Sears Automotive Center. A guy there just put it in a vice and hit with an air chisel and it was off in about ½ a second. I think that when I do the other side I will put it in a vice and smack it harder. Even with the air chisel there was barely a scratch on the hub. Methinks I just needed to man up.

21. Clean up the carrier of the old grease and any shavings from the drift. I just wiped it out and blew it out with compressed air. I did not want to use a de-greaser for fear of giving too clean a surface for rust to form since I was not going to start re-assembly till the next day and it was extremely damp here.
 

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1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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Discussion Starter #2
Okay, at this point, you are fully disassembled and ready to re-assemble.

22. First thing I did was drive in the new races. I bought a race driver kit from Harbor Freight. I am sure you can use the old race and hammer, but, for $20, this made it a piece of cake. The kit had two sizes that were a perfect fit for the Mercedes races. I used the driver to seat the inner and outer races.

Pics of putting races in:











23. Now time to pack the bearings with grease. Whether it matters or not, I weighed out the grease to 50g and applied it equally to each bearing as specified by MB. After packing each bearing, I spread the extra grease on the races and the hubs.

24. Slide the packed outer bearing onto the hub, and tap it into place using a chisel and a tack hammer. Do not hit the bearing cage. It does not take a lot of force when you work your way around the race. If you have a pipe of the correct diameter, that would be the safest way to do this. Either way, this way worked just fine. It didn’t even leave a mark on the race.

25. Slide the new crush washer onto the hub. Since it is not crushed, it should slide on easily.

26. Put the new outer grease seal on the carrier.

27. I put some grease on the inner race.

Pics:







28. Slide the hub into the carrier. The new grease seal should hold it in place.

29. Slide the inner bearing onto the back side of the hub.
Hub slid in with inner bearing on, packed with grease:



30. I put on the new inner grease seal at this time.

Getting ready to pound in new grease seal:



New seal seated:



31. This next part is a little tricky because it’s sort of a blind operation. You have to set the inner bearing on the hub and it’s a tight press fit. On top of that, you have to sort of trust that it gets seated. I imagine Mercedes has a tool that reaches through the center of the hub and grabs the race and pulls it tight. I didn’t have that tool and did not try to make one. I bet it could be done with the right size socket, some washers and a threaded rod. Nevertheless, the method described by dmorrison works pretty well.

After you have slid the inner bearing onto the hub, follow it with the rest of your grease and the old spacer. I had lots of grease left so the old spacer sort of “stuck” to the bearing race. The key with the spacer is that it rests on the inner race. Now, with all your strength, push in on the face of the hub and hit the spacer with your choice of soft mallet. Again, I used a dead blow. If you have everything lined up, it will drive the bearing onto the shaft enough so that enough threads are available for you to get the nut started. Basically, you will be able to pound the spacer in until it is flush with the back of the hub. Remove the old spacer and replace with the new one. The “hollow” side goes toward the diff. You should now be able to thread the new slotted nut on the hub.

This method actually worked pretty well and was pretty easy.
Here is a view of the bearing seated till the spacer is flush with the back of the hub. You can see there are just a few threads poking out from the hub…just enough to get the slot nut started…



Getting the slot nut “started” by hand:



32. Using the special slotted socket, I then used my hand to hold the hub flange and my rachet to tighten the nut and finish seating the bearing. It went in pretty easy. I was able to spin the hub by hand with no binding and I had about .030” of in/out movement.





33. Now, you need to get the same set up together that you used to loosen the slot nut, but, this time we will tighten it. The ratchet with rest on the other side of your TA. You will also use a dial gauge to measure the in/out “play” in the bearing as you tighten it.

The allowable in/out tolerance is:
Metric: .04mm-.06mm
SAE: .0015”-.0023”





34. Like I mentioned, my dial gauge started reading at about .030” (30 clicks). Using the pry bar on the flange, I tightened it by moving the bar about 10-15 degrees, then re-measured. This moved the dial about .003” at a time. Eventually, I got it down to somewhere just under .002” of play. I stopped there.

Pulled out:


Pushed in:



35. Once you are happy with your reading, you have to set the nut but punching the nut collar into the indents on the rear of the hub shaft. Basically, the reverse of what you did earlier.
Once I was done, my flange turned easily and smoothly. I could not “spin” it freely, per se, by hand without the brake disk or wheel on it but nor could I before I started this operation but it turned without much effort.
Now, you are pretty much done and ready to re-assemble.

I re-assembled in this order:

1. Put drive shaft back into hub.
2. Tighten sub-frame bolt back 3.5 turns.
3. Jack the TA closer to ride height.
4. Re-attached sway bar link.
5. Re-attached brake disk.
6. Re-attached caliper.
7. Re-attached top of shock.
8. Re-insert and tighten the drive shaft bolt using the new tension washer that came with your bearing to the correct torque. My car used the newer style M8 bolt and required 30nm of torque.
9. Put wheel back on.
10. Put rear seat back in.

I still have to do the other side. This whole thing probably took me a total of about 6 hours of real work time. However, since this was my first time, the total clock time was a couple days due to me running around for tools or when I had to go to Sears for them to pop off my outer bearing. When I do the other side, I fully believe I will have it done in one afternoon.
On another note, I have inspected my old bearings and races with my naked eye. I did not see any scoring or anything that “just didn’t look right”. Even before I tore the hub off, I did not detect any “play”. I wish I had the foresight to “pre-measure” with my dial gauge but I forgot.
I have already put about 6000 miles on the car since I finished this last November. At least nothing seems worse!!!
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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Thank you so much, foolio. This is a great write up.

What caused you to do the project? Was there a noise?
 

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1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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Discussion Starter #4
Yes, there was a noise. Of course, it turned out not to be the bearing, but, at least I learned how to do rear bearings!
 

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Two '87 570SECs, one '87 560SEL
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I used this absolutely marvelous write-up to put new bearings in the left rear hub of my '87 SEC. Thanks, Foolio2, for taking the time and effort to give us this!

I have a couple of suggestions to make this even better:
1. Removing the axle from the differential makes it much easier to get the axle out of the rear hub. That is a good idea only if the six amazingly hard to remove allen-headed bolts that hold the axle to the differential have been loosened at least one time in the last several years.
2. Don’t forget to use blue Loctite on the bolts during reassembly.
3. Beg, buy, borrow the tool to loosen and tighten the “special nut” on the back of the hub. You cannot do this job without it.
a. I used one like this: Ebay Item number 120927814808 - Mercedes Rear Axle Bearing Nut Socket Repair Tool
b. I used a 1/2" impact gun to tighten the Special Nut" to slowly get the proper runout by crushing the "crush spacer". It was a slow enough process that it was reasonably easy to get the 0.001 - 0.002" runout.
4. I tried to tap the front and rear grease seal in place with a hammer but couldn't get them properly started. I found a good solution in my desperation - a 6" long piece of a 4x4 that I use as a wheel chock. Hold the grease seal in place "kinda straight" with the 4x4 and then hit the 4x4 with a two-pound hammer! That popped the front and rear grease seals right into place.

Again, thanks Foolio2 for the great write-up and pictures!
 

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1985 500 SEC EURO AMG/LORINSER; 1988 560SEL, 1995 S500 Sonderschutz
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I used this absolutely marvelous write-up to put new bearings in the left rear hub of my '87 SEC. Thanks, Foolio2, for taking the time and effort to give us this!

I have a couple of suggestions to make this even better:
1. Removing the axle from the differential makes it much easier to get the axle out of the rear hub. That is a good idea only if the six amazingly hard to remove allen-headed bolts that hold the axle to the differential have been loosened at least one time in the last several years.
2. Don’t forget to use blue Loctite on the bolts during reassembly.
3. Beg, buy, borrow the tool to loosen and tighten the “special nut” on the back of the hub. You cannot do this job without it.
a. I used one like this: Ebay Item number 120927814808 - Mercedes Rear Axle Bearing Nut Socket Repair Tool
b. I used a 1/2" impact gun to tighten the Special Nut" to slowly get the proper runout by crushing the "crush spacer". It was a slow enough process that it was reasonably easy to get the 0.001 - 0.002" runout.
4. I tried to tap the front and rear grease seal in place with a hammer but couldn't get them properly started. I found a good solution in my desperation - a 6" long piece of a 4x4 that I use as a wheel chock. Hold the grease seal in place "kinda straight" with the 4x4 and then hit the 4x4 with a two-pound hammer! That popped the front and rear grease seals right into place.

Again, thanks Foolio2 for the great write-up and pictures!
What was this on peach parts I saw about not punching the axle with a drift as it may "mushroom" the ends and cause it to "swell"?
 

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Two '87 570SECs, one '87 560SEL
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Using a non-iron punch and you should be fine. Brass, hardwood, etc.

Once I got the six bolts out of the differential flange, the axle actually slid out of the hub without coercion. The driver's side axle was a pain to get out with the exhaust pipe in the way but it came.
 

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Proud owner of an Blue-Black (Charcol Gray) '91 420SEL
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You don't want to beat it into submission but when I took my right side bolt out my axle withdrew itself while I was knocking off my rear rotor. Take care to not damage the female threads on the axle shaft so that you can reinstall the retention bolt, washer, and spacer when the time comes.
Ideally a 3/4 inch diameter punch would be great to spread the load and help save the hole in the center of the shaft. Just use a brass or aluminum drift pin or punch. Unless it has been 10 years they should pop out without too much hassle.

Mercedes Source video stated that it is a good idea to rotate the drive axle shafts from one side of the car to the others side of the car when they are removed for greasing as it allows the other side of the drive mechanism to wear doubling the life of the shafts.

jimm1009
 

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1986 SEC500
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Images missing

Hi,

some of the images from this post are missing. Does everyone see this or is this a problem on my side? Has anyone got saved copy's? I plan to work on this over the next week or so and images help a lot. :|

Thanks guys,
DeepSub
 

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Two '87 570SECs, one '87 560SEL
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If this uploads, it's the 25 pages of instructions, with photos.
 

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1999 500SL, 1988 SEC
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Glad it was easy for you but when I tried to use the two wheel lug method of holding things I simply bent the studs. I also broke a couple of the cheap special sockets when I used a impact gun. So I built a 1/4 plate with all the lug bult holes in it, then welded a schedule 80 bar to it. I used that to tighten things and crush that crush washer. A tip. While you think you might have tightened it to the right amount of load I suggest you drive it for a week and recheck it. You might be surprised.
 

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1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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Discussion Starter #15
Glad to see My diy still living on. Thanks, mramay for saving a copy. Not sure why the pics disappeared. Hosted them at google hoping they would be permanent. Have not posted much on this site in years but my w126 is still kicking. Need to become active again. Happy to see some old regulars are still around. Maybe I should get around to finishing my hear rebuild thread that I left in purgatory 4 years ago. Lol �� still have all the pics.
 

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Two '87 570SECs, one '87 560SEL
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Foolio, I saved your write-up as a PDF so the pictures should have come through just fine this time. If I didn't thank you then for posting it, I'll thank you now!!

I saved that several years ago when I did an axle on my SEC so that this summer, when that axle had a little looseness and with your marvelous write-up (and an ebay axle nut tool and crush washer), it was simple to redo the thing.
 

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1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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1,026 Posts
Discussion Starter #18
Foolio, I saved your write-up as a PDF so the pictures should have come through just fine this time. If I didn't thank you then for posting it, I'll thank you now!!

I saved that several years ago when I did an axle on my SEC so that this summer, when that axle had a little looseness and with your marvelous write-up (and an ebay axle nut tool and crush washer), it was simple to redo the thing.
Yeah I remember that! Didn’t you rent my special axle nut socket from me?

Ha, it's the man himself. Good to see you posting Foolio.
Good to see you still around, Ian.

Chris..
 

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Two '87 570SECs, one '87 560SEL
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Yeah I remember that! Didn’t you rent my special axle nut socket from me?



Good to see you still around, Ian.

Chris..
Yep, think I did. It was instrumental in getting the job done!! Thanks one more time!
 

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1986 SEC500
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Glad to see My diy still living on. Thanks, mramay for saving a copy. Not sure why the pics disappeared. Hosted them at google hoping they would be permanent. Have not posted much on this site in years but my w126 is still kicking. Need to become active again. Happy to see some old regulars are still around. Maybe I should get around to finishing my hear rebuild thread that I left in purgatory 4 years ago. Lol �� still have all the pics.
Well that didn't go to plan! My car has anti-squat suspension which has significantly more components and a difference disassembly sequence.

Does anyone have instructions to replace all the rear bearings for the cars with anti-squat suspension? Things seems to get different from the normal cars when the axle has to be taken out.

To add to the above problem the previous mechanic that worked on the car had never heard of a torque wrench. Every nut and bolt is way over tightened! Two break with the touch of a spanner. Oh and that was after they got the steel brush cleaning and multiple soakings of WD40 over a long weekend. One of the brake caliber bolts needed a 1.5m extension to get it off. It's so annoying.

It's an ill wind that doesn't blow some good. With the brake caliber of the car, I took the opportunity to rebuild the caliber.

Here is the caliber split mid cleaning, with one of the new pistons, the new rubbers and rubber grease.


This is a close up of the caliber with new piston in place with rubber seals and securing spring.


Both sides of the caliber clean, refurbished and ready for joining.


Finished and painted caliber (front).


Finished and painted caliber (back).
 
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