300TE rear bearing removal. - PeachParts Mercedes-Benz Forum

MCallahan · #1 04-01-2018, 06:07 PM

I have no idea who did the writeup on Pelican for removing the rear wheel bearings, but they obviously never did a TE. The slide hammer is useless. There is no way on earth that slide will pull the bearing. I now have the entire knuckle off to take to the shop at work in hopes I can figure a way to get it off there. Of course, the brake backer plate and Ebrake backplate can't be removed until the hub is out. No idea how I am going to get this apart, but I have no choice now.

Hirnbeiss · #2 04-02-2018, 08:29 AM

I have also seen the approach of using bolts in the hub to push it out. Screw them all the way through the hub until they press on the wheel carrier (or backing plate), and then tighten uniformly to draw the hub out.

MCallahan · #3 04-02-2018, 08:45 AM

I'm going to take it to work today and weld up a fixture that bolts to the back side and see if I can press it out. I don't think the lug both threads are large enough to push it out without galling or stripping.

This was obviously designed with no forethought of service, only easy assembly. A slot in the hub for snap ring access would make it a 10minute job. Remove the snap ring, push the whole assembly out, cut the outer bearing race off the hub with a torch, heat the inner and remove. Would be a lot easier to put back together, too. Put snap ring on the hub shaft, press bearing on, install as a unit in the knuckle, install snap ring.

92-2.6 · #4 04-02-2018, 03:07 PM

It's terrible. I have a press and still couldn't figure out a way to get it mounted to be able to press the hub out.

I wound up taking mine to a machine shop.

MCallahan · #5 04-02-2018, 05:49 PM

SUCCESS!!!!

My ruminations above about the slot kept nagging at me, so that's exactly what I did... set the whole knuckle up on the big milling machine, cut a 3/8" wide x 1 1/4" long slot near the hub and there was the snap ring. Even at that, it was impossible to remove the snap ring with pliers, so the next trick was to rotate the hub while heating the snap ring with a torch through the slot until it got red hot and lost temper. At that point, a small screwdriver can be used to collapse the snap ring so it is out of the groove. With the snap ring released, a few whacks on the head of a large bolt put in the hub and the hub, with outboard inner race flew across the bench.

I am trying to post pics, but my drop box is being cantakerous and won't upload my phone pics to the laptop. The forum doesn't allow photos from the phone... catch 22.

NOW, here's why the wagon hub is impossible to remove with a slide hammer... On the sedans, the inner race and rollers are INSIDE the diameter of the snap ring. The wagon, with a bigger hub diameter, has a bearing that is larger in diameter. The rollers hang on the large section and the ears of the snap ring! Instead of trying to pull one side of the race, you are trying to pull both sides, and losing energy to the snap ring, and everything else flexing. If you can figure a way to press it, you are going to probably break or roll the snap ring groove out if you DO manage to press it out. There is NO WAY to pull the bearing and not tear something up without getting the snap ring out.

So, I wasted an entire day screwing with the slide hammer on the left side, as well as having to make two parts store runs, one to buy tri-square wrenches for the axle bolts to remove the axle. I destroyed one slide hammer and had to go get another, which ended up being useless. Today took me about two hours to figure everything, set the mill up and line up on the hub, and another 20 minutes to mill it out. Wasted a few minutes trying to get the snap ring out before I figured to just collapse it. Left at 12:30 and drove home to do the right side knuckle.

I got home and had the knuckle off in about 30 minutes. You DO NOT have to pull the axle from the differential. Take the axle nut off, take the knuckle loose and it slides off the axle. Including getting my tools out, turning on the compressor, removing the knuckle (that had a stubborned lower control arm bolt), turning off the compressor, washing my hands and the 20minute drive back to work, I walked back into the shop at 1:55. The second hub was set up in the mill, slotted and out in 20minutes. Hub was out, inner race dropped with a torch, outer race pressed out of the knuckle, backplate unbolted, control arm bushing out and the knuckle powder blasted by 3:00. Waiting on lower control arm bushings and I'll put it all back together tomorrow afternoon.

So, for you wagon owners... don't even screw with the slide hammer or the axles. Take the nut loose, take the knuckle off, slot the hub, heat the snap ring and collapse, knock it all apart. DONE.

The slot was cut with a 3/8" endmill centered .245" from the edge of the hub lip where the brake drum and wheel locates. There is one pair of lug holes with no access holes or locating studs or retaining screw holes between them. I centered it between those two lug bolt holes plunged straight down and moved .500" either direction to get my 1 1/4" slot. Taking .100" depth of cut at a time (taking light cuts due to the setup). Total thickness was about .450" and I had to remove a very small ledge at the bottom with a die grinder. Given this is supported by the brake disc and the wheel, I don't fear losing any structural integrity with the slot in the axle.

This is a MAJOR engineering oversight in terms of serviceability, first one I have encountered of this magnitude with Mercedes. I guess you were just supposed to by an entire new knuckle with the bearing in it? I hope I get another 143,000 miles out of the new bearings, but next swap will be easy and can be done in the car by heating and collapsing the O ring through the slot, then using the slide hammer to pull the hub and bearing, which will indeed work at that point.

lorainfurniture · #6 04-02-2018, 06:59 PM

I will say that the rear bearings are a real pain. Try doing it in a 4matic wagon. I needed to drop the entire subframe.

I look at it like this: the average lifespan of a car back in the early 90’s was about 10 years/ 100-150k miles. Domestic cars waaaaay less. So they (Mercedes) built a rear bearing that lasted beyond the expected life of the car. After 150k and 25 years I wasn’t really upset when I had to change my rear wheel bearings.

MCallahan · #7 04-02-2018, 08:38 PM

I was cautioned not to even consider a 4matic.

lorainfurniture · #8 04-02-2018, 10:11 PM

Quote:

Originally Posted by MCallahan

I was cautioned not to even consider a 4matic.

They are amazing. They get extremely frustrating when the 4matic system goes down. Nobody knows how to work on them. Some parts are NLA, like the front axles. I had to buy an entire 4matic car just to replace mine. Good thing I did as my transfer case just started leaking.

The car is amazing in the snow. With a set of snow tires I can go anywhere, at any speed with confidence.

Hirnbeiss · #9 04-03-2018, 06:06 AM

Thanks for the info.
I did some more googling focused on the wagon. No one seems to have approached the circlip removal like you did, but most agree on taking the carrier out and pressing the bearing out, often destroying the backing plate in the process.

MCallahan · #10 04-03-2018, 11:40 AM

Yes, you will absolutely destroy the backing plate and parking brake plate with any attwmp to press that way. I also considered welding up a fixture with hwavy angle rods that matched the suspension mount points and having a flat plate so you could sit a bottle jack in the fixture and press against the hub, but I really think it woild have bent or broken something before the bearing came out.

I'll post pics of the snap ring and bearing installed before the hub is pressed in, as well as pics of the dissected bearing, snap ring, rollers and bearing seals that came out of the knuckle, so everybody can see the problem.

MCallahan · #11 04-04-2018, 09:10 AM

Car is back on the road as of 8pm last night. Bearing installation was a breeze, even with my cheesy little HF press. I ground down the OD of the old bearing outer race and used it to push the new bearing in the knuckle. Found a scrap inner race that matched the diameter of the new inner race and used that to support the knuckle and bearing while pushing in the hub.

I am going to pull the rear wheels and inspect the hubs every month or so this year to make sure the slots are not causing cracking, but I really believe they are going to be fine. Car is superbly silent now.

Putting knuckles back on was quick and easy, except for catching a black oxide heavy wall 1/2" drive deep well impact socket in the face when it flew off my impact gun while installing the upper control arm bolt on the right side... 2" long cut from my upper lip to the left side of my nose. Ah well, chicks dig scars