123 Wheel bearing questions - PeachParts Mercedes-Benz Forum

coachgeo · #1 03-26-2004, 08:48 AM

I got a bad bearing (shavings are in it) so I need to replace it. Might as well do both fronts while Im at it. I have looked at the DIY about repacking bearings. It explains how to get one bearing out (inner most). Then the insructions just goes on like both bearings are out.

With my outer most bearing; the tapered bearing part, comes out just fine but the race (think that is the proper name?) is in there solid as a rock. The DIY does not explain how to get this out.

Any suggestions?

Kestas · #2 03-26-2004, 11:36 AM

Do you have the whole hub out? I'm not sure what it looks like, but some hubs let a bit of race protrude from the shoulder that allows you to use a hammer and drift to pound out the race. Ideally, the new race should be pressed in. If you hammer it in, be very gentle and don't nick it or kock it. Use wood wherever possible. Nicking the race will ruin it.

It's not really necessary to do the other wheel. But you should probably replace both inboard and outboard bearings from the one hub.

Be very clean with your work. Make absolutely sure there is no grit or burrs during the repair.

coachgeo · #3 03-26-2004, 11:41 AM

I had to take it to a machine shop. They were not as gentle as you suggested. They pounded them out with hammer and old hardened screw driver. Then they cleaned up all the burrs.

Wont the races press in along with the bearing? or do I have to go back to the machine shop and have them press them in?

engatwork · #4 03-26-2004, 12:48 PM

I think the race has to be pressed in. Personally, I would have left the races alone if they look ok.

Just for information the bearings (per wheel) are:

Timken brand
LM48548 at $7.24
M12649 at $4.16

These prices are from a bearing supply house that we purchase bearings from.

Rick Miley · #5 03-26-2004, 12:59 PM

Quote:

Originally posted by coachgeo
Wont the races press in along with the bearing?

Definitely not. You'll destroy the bearings that way.
The guys at the machine shop probably said to each other "He'll be back" when you left with that empty hub.

Kestas · #6 03-26-2004, 01:03 PM

I'm not sure what you're asking when you say, "Won't the races press in along with the bearing?"

Bearing sets are not meant to be pressed in all at once. The races must be pressed in individually. NEVER transmit a pressing force or hammering force across the contact surfaces of the bearing components.

coachgeo · #7 03-26-2004, 02:37 PM

Quote:

Originally posted by Kestas

Bearing sets are not meant to be pressed in all at once. The races must be pressed in individually. NEVER transmit a pressing force or hammering force across the contact surfaces of the bearing components.

Yeah that is what I assumed too so I didnt attempt it. The machine shop was not an automotive machine shop. They manufactured/machined medal products. There just up the road from me. I did not know they were not an automotive machine shop till I got there but I figured they were not dumb either. Our phone books list machine shops all under one catagory so their is no way to tell which one is auto machine etc.. Anyway, I told them if I needed to press in anything I will use a big socket and a hammer. They didnt wince a bit.

Socket and hammer is exactly what I have done now. On the outer bearing I just laid a 1" x 6" over the lubed race and used a rubber malet and drove it in. Worked just fine. Inner bearing I used a giant socket sorta tool my dad has. I'm guessing it was for his old Ford. Now Im trying to figure out how to measure out the grease best from this pack of 80grams

Kestas · #8 03-26-2004, 03:42 PM

The good automotive machine shops around here (and for the most part they are very good) are usually under one roof with an auto parts store. I've always had excellent work from our local shops. Try looking around. Get some referrals.

I believe the weight specification for grease is to keep mechanics from over-greasing the bearings. A lot of mechanics tend to overlube bearings by packing in as much grease as they can. I still read posts from people promoting this practise. This is not good for the bearing, it impedes heat transfer and promotes overheating of the assembly.

These are the steps to properly lube a bearing:

- First make sure all traces of old grease are gone. Bearing and hub must be clean and dry.
- Butter the entire hub cavity and spindle surfaces with a light slather of grease.
- Pack the roller/cage assembly by forcing grease between the rollers until filled. This is done by placing grease in the palm of one hand and scraping off the grease with the roller/cage assembly.
- After installing the roller/cage assembly, thickly butter the sides of the bearing races.
- Put a coating of grease on the new seal before installing the assembly. Never slip a dry seal over its mating surface, always lubricate with the parent lubricant.
- Properly set the bearing play (or preload) to specification. This is absolutely critical to bearing life.

I use either Mobil 1 synthetic grease or Exxon Infinitec. Both are superior greases for wheel bearings. Exxon Infinitec is not yet available over the counter.

coachgeo · #9 03-26-2004, 03:58 PM

Quote:

Originally posted by Kestas
....
- Pack the roller/cage assembly by forcing grease between the rollers until filled. This is done by placing grease in the palm of one hand and scraping off the grease with the roller/cage assembly.....

NOW you tell me LOL. Oh well other side will be done better.

BTW. THANKS folk for the help. I am as much of an amatuer as it sounds. Wait... is that what I meant to say.. LOL

coachgeo · #10 03-26-2004, 05:44 PM

On the front hubs got all the races in, bearings packed, Sheild on, and new brake disk bolted on (with lock tight). Put her back on the spindle annnnnnd Low and behold. GRRRRRRRRRR. apparently I didnt get the inner race deep enough into the hub cause there is no threads exposed to screw the spindle nut onto. Feeling in there with my finger verify's this. So does a closer study of the diagrahms.

Oh well. off to try to find new shields so I can try this again tommorow. Had to go to 4 places today to find two shields as it was.

coachgeo · #11 03-27-2004, 12:09 PM

Desperately need some help here before I fawk something up.

Wrong bearings maybe?

I just pulled from the hub the new the inner seal and bearing. Then rechecked the race for depth. I did install it all the way afterall.

I took the inner bearing I just pulled from the hub and tried to slide it over the spindle on the car. It does not fully slide over onto the part of the spindle I think it it rides on. (the inner most non tapered area of the spindle) It could be forced on I guess.

So my question is...... is this the wrong bearing? Should this bearing "easly" slide all the way back. If it should be real tight is it possible I need to just use a rubber malet and force the hub all the way back onto the spindle? I think not on that.

Any advice?

engatwork · #12 03-27-2004, 12:35 PM

Are they the Timken brgs that I put up the p/n for? Those are the ones I have used on the '85 300D without any issues. I've got to replace the rotors on the '81 and will tell you what I go through on it.

#13 03-27-2004, 02:30 PM

When installing a race that is supposed to be pressed in, it helps to cool it down, like in the freezer for an hour or so, to make it smaller.
Conversely, I have warmed up sealed bearings to be installed onto an axle shaft. Once on top of a
Coleman lantern beside the road halfway across Texas. Don't "warm" it too much, though...

wolf_walker · #14 03-27-2004, 05:30 PM

I've known correct bearings to not fit a shaft so well. Throughly clean both, heat the bearing or cool the shaft works sometimes. Others I've very, very slowly dressed one or the other, or both, with emery cloth. You really do not want to take off but a hair though. You'll sometimes find after the high/rough spot on the outer part, the bearing will slide the rest of the way on fine.

engatwork · #15 03-27-2004, 06:35 PM

They should slide on/off without alot of issues.