Main.TrailIndexPage | Wheels and Tires | WheelsTires.Bearings

Bearings

This component is part of Wheels and Tires.

Definition

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Function

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Maintenance

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  • Symptoms when it faults
  • How to test if it is faulty - what tools to use
  • How to fix / change

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You can generally tell the wheel bearings are bad in 2 ways. 1. They "groan" or rumble as you go around a corner. 2. Jack the wheel and push the top of the tire while simultaneously pulling the bottom and vice-versa. There shouldn't be any play. (Make sure its the wheel that has the play and not worn suspension components). If either of these 2 methods indicate bearing problems, you should first see if you can tighten the bearings. The manual should give you the procedure.

If tightening doesn't take out the noise or the slop, you need new bearings. The outer races are pressed into the hub. Unless you are replacing them, it's usually best to leave them be. A bearing press is best but you can usually push them out by using a drift and hammer around and around the edge to push it out. This can take some time and will probably damage the race, hence the advice to leave them in unless damaged (cracked, wavy, etc). Otherwise, most repair places should be able to do the job for you.

If you are putting in new outer races, you can use the old ones as drifts to press the new ones into place. I've never seen anyone recommend using solvents to clean old bearings that will be reused. The problem is remaining solvent which could dilute the new grease. The recommended way is to thoroughly wipe down the bearing with clean rags, removing as much of the old grease as possible. then, when repacking the bearing with fresh grease, the remaining old grease should be purged by the new.

Make sure you use grease that is formulated for disc brake hubs (higher temperatures). Modern cars get away from this by using sealed bearings. Those might now be available for this car. And always, always replace the seal with a new one.

I got my outer races pressed into the wheel. My MB shop manual specifies how many grams of grease to use when packing my front wheel bearings and in filling the cap. How do I measure this? Do I need to go buy a small metric scale? Is there some rule-of-thumb that will suffice?

When changing a flat tire on the right rear or passenger side I noticed there was some play in the bearing. At first I thought it was just that the lug nuts were loose but after tightening them there was still some play in what i think is the bearing. I just looked through my Haynes manual as well as the BBB and it seems that the job of replacing the bearing is quite involved. Has anyone out there tried to replace one of these? I have replaced bearings on many different vehicles over my time (I take them to a shop to have the bearing removed and new one pressed on)but I am not sure I should attempt this one. I will take the wheel off and inspect it more carefully but any advice would be appreciated.

This is not a simple job. If you read through the procedure in the Haynes manual you will find that the right side is the hard one to do. I had to replace a bent axel on that side and had to go through the process. It difficult but can be done in your garage.

This is not that difficult a job to do. I just did it on the passenger side of my 67 230SL. Slightly differerent procedure for your car since you have rear disks and the 230SL has drums. A couple of things though. Drain your differential first. You need to remove all your brakeware. Next remove the 4 small bolts holding the brake backplate. The manual calls for a special tool to extract the rear axle, but I carefully used a slide hammer--I know the manual says not to do that ! Actually you can--just don't be too forceful with it-- the axle shouldn't require a whole heck of a lot of pounding to get it out. A few light taps should get it out far enough where you can actually pull it out by hand. Once it is out you will need to pull the bearing from the axle. To do this, I made a set of long arms out of some flat 3/4" steel stock for a standard screw type puller. Put your wheel lug nuts back on and clamp the axle assembly upright by the lugs nuts in a vice. At this point you will need to bend back the tab on the bearing nut retainer. Using a drift and hammer carefully unscrew the bearing retainer nut by driving it counterclockwise. Once this is off, you can use your long arm puller to pull the bearing. The passenger side uses a self centering bearing which is quite different and consequently quite a bit more exepnsive than the driver side bearing--costs about $80-$90. Thy say you can use these interchangeably but MB used different bearings for a reason whatever that is! I think it is good practice though to replace with the same as you remove. Thoroughly clean the bearing mating surface of the axle and use a suitable length of pipe that bears on the inner race of the new bearing only to press it back on to the axle. Replace the nut locking tab making sure you put it on right side up--take a good look at the one you took off to understand what I mean here because you can get it backwards making it all but impossible to bend the tab up. Replace the bearing locking nut using the drift and hammer again making sure it is all the way home and then lock it into place by bedning the locking tab. From here assembly is the reverse of the dissassembly. Make sure you follow the Haynes instruction regarding the seals, packing with grease, the thread pattern on the bearing surface and of course the correct torque settings. This all sounds much more complicated than it really is.

I don't think the play you're feeling is the wheel bearing. Is the tire rotating (IE; top in, bottom out & visa versa?) rather than just up and down?. This is difficult to tell, due to the length of the axle. I thought I had a right wheel bearing going out, getting some vibration on this wheel. Then I pulled this axle only to find the wheel bearing was ok. (The bearing was a self centering roller bearing on this side.) Pulling the axle was not too big of a job. Of course I had to disassemble the brake (shoe brakes on my 67 230 SL). At this point I had to remove the entire differential, and remove the right axle tube. This was lengthy job as the pivot shaft was stuck. My problem was the sliding bearing, which is a part of the U-joint assembly connected to the righ side of the differential, under the rubber boot. This slider, which the splined axle end fits into, takes the lateral motion of the axle, as it pivots. The slider has three sets of 32 tiny rollers. This slider bearing surface had worn "rippled" allowing the axle to whip at certain speeds. Tom Hanson was very helpful in this repair. Unfortunately this slider is one of the few parts not commonly stocked in the US and had to be ordered from Germany. The parts were ordered a few days before "9 11", and my car was down about 6 weeks. By the way, I also replaced both wheel bearings with standard ball bearing.

Dan Caron: donít think so. There should be no play at all in the rear axel. No end play and no radial play. You will have to remove the brakes on that side to pull the axel out. Not a bad job but not all that much fun either. The bearing on the axel should be replaced in most cases and I usually install new seals too. On the RR axel you will find a barrel roller bearing. This is a special bearing and should NOT be replaced with a regular ball bearing. As the axel moves up and down it goes over center because of the way the hinged part is below the axel line. This causes the axel shaft to move in and out and this special bearing allows the shaft to float or pivot in the bearing. The sliding coupling on the other end of the shaft serves to allow for this in /out movement. These bearings are both expensive and sometimes hard to find. Make sure you have all the parts you need BEFORE you take it apart. DO NOT under any circumstances, pound on the end of the axle in an attempt to remove the bearing. This can only be done safely using a large shop press. Any marks on the splined end of the axle will keep it from going back into the differential. If you need help get back to us. You really should have a manual for jobs like this.

You donít need any special tools. To pull the axle, turn the brake drum (or disc) inside out and attach it LOOSELY with three lugs. This will serve as a slide hammer. To get the bearing off, remove the nut (a blunt chisel will due to unscrew it), then find a block of hardwood and repeatedly bang the axle vertically down onto it. The bearing will walk off. Put the new bearing on with a drift, tapping around it and hitting ONLY the inner race. Use the blunt chisel to tighten the bearing retainer nut.
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