Front wheel bearing torque?
 

Hello All,

I drive a 1993 300E 2.8 24V. I am looking to repace the front wheel nearings. Since, on a previous car, I already blew one axle by tightening the nearings to tight, I am looking to find out how I correctly tighten the nuts on the bearing. Are there any measurements in Torque that are to be followed or is there another way that I can do it correctly without all kinds of expensive or mercedes explicit tools?

Untill now I just leave a little play but that ofcourse is a pretty coarse method of adjustment.

Thanks and have fun,

marc

MB uses tapered roller bearings on the front of their cars, so no TORQUE value. You need to set bearing end-play with a dial indicator.

Hello Doc,

OUGH!! That sounds mighty complicated. I have read some threads on here and, depending on the thread, it sounds real easy or very complicated. But judging from your answer it is not really a DIY job.

I thought that I could adjust the tighening untill there is 0 play and then release a bit for tolerance and it should work. But I assume that I am mistaken here and better go for some new bearings and have them installed at the Benz shop.

Thanks and greets,

marc

The problem with this job is removing the shells from the hub.

There is almost no lip to catch on to, Mercedes have a special puller, most of us shadetree mechanics would use a punch and a hammer.

The inner shell is quite easy, the lip is enough to get hold of, but be careful about the outer shell.

If you do change them, don't overpack them with grease, and then tighten them up until you feel resistance to rotation, then back off enough to allow the thrust washer to just turn under finger pressure, ie. quite tight.

Check them after a week or two, because they will need retensioning as they tend to bed in a little.

Cheers,

Richard

Mercedes also have pre-packaged grease. It's exactly the right amount for two wheels and it's a special grease.

The part number is A 001 989 23 51 10. It's 150 g. Some of it goes in the caps and some in the bearings.

If properly adjusted, these bearings last a long time.

Hello Guys,

Thanks a lot for all the fast reactions. For now I have just tighened them a little. I left enough room so I can feel a little play in the wheel when it is off the ground. The sound is much better now. It sounded like driving on gravel when the road was not very smooth (and not gravel ofcourse). Now on one side i do think, but this may be my overfocusing ear, a little of the wining and rythmic hum that sounds like the start of a bad bearing. I will try this for a few weeks and if the bearing doesn´t burn itself on the axle I will see if decide to exchange them. I thinking of doing the brake disks anyway and maybe the fuseekogel (which is the Dutch word so it won´t mean too much to you).

Thanks and I will be back here by the time I decide to change the bearings with loads of new questions.

Thanks and greets,

Marc

Marc:

If you can feel play in the bearing (straight in and out on the hub!), it is too loose.

The Chilton's recommendation is to tighten the nut until the wheel is "impossible" to turn (way, way too tight!!!) then back off 1/3 turn. What I do, and this seems to work, it so tighten the nut until you feel some rotational resistance. You won't lock up the wheel, just tighten until it becomes noticably harder to turn. Back the nut off about 1/2 turn, or a little less. Pull in and out -- if you feel it "thump" tighten up a tiny bit, check again. Tighten lock screw.

Best is to set the bearing for 0.001-0.002" with a dial indicator, very easy and they aren't very expensive.

Peter

"Thanks a lot for all the fast reactions. For now I have just tighened them a little. I left
enough room so I can feel a little play in the wheel when it is off the ground. The sound is much better now. It sounded like driving on gravel when the road was not very smooth(and not gravel ofcourse). Now on one side i do think, but this may be my overfocusingear, a little of the wining and rythmic hum that sounds like the start of a bad bearing."

A properly adjusted and lubed bearing should make practically no noise, and no roughness at all when the wheel is spun. If you then preload the bearing, it should STILL make no noise. You have bad bearings.

When replacing tapered roller sets, I find it expedient to purposely preload the bearing while adjusting - above the recommended value. This will better insure the races are properly seated. Then I adjust as per spec. RECHECK after about 100 mi.

Steve

If I remember correctly, the way to do it if you aren't going to use the dial gauge is to tighten the nut and then back off until you can just turn the washer by hand.

With lesser cars, you would just tighten the castle nut and then back off enough to be able to insert a cotter key. It's worth doing it right because these wheel bearings will last a long time with repacking done about the same time you replace the rotors.

No load but no play
 

keep it simple....

tighten somewhere between no preload and not so tight as to have any play.

Good advice above. I would first check what preload (or tightening method) is recommended by the manufacturer.

Beyond that, bearing life tests shows maximum life for double-row taper automotive bearing designs is typically at 0.003 to 0.005" axial play. That is typically accomplished using the method Bud described.