Front wheel bearings, little questions - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 03-22-2009, 01:15 PM

This might be an unnecessary question ... but since it involves a part of the car that holds the wheel on ...

I replaced the rotor and repacked the bearing on one side yesterday (yes, I'm going to do the other side, just didn't have time before work). I repacked inner, outer bearing, installed new seal and tightened the nut down using dial gauge to determine play. I tightened the allen bolt down snug just using a plain old allen wrench, and for some reason that just doesn't seem adequate in my mind. It feels secure, but does the allen bolt need to be tightened to any spec? Everywhere I've read implies you just make it snug and that's enough. Just wanted to make sure hand tight is tight enough. Just to clarify, I'm talking about the allen that holds the nut down, not the nut.

Also ... I wasn't able to get the nut down tight enough to stop the hub from turning at all, I think due to tool inadequacy. It was close to not turning, but I didn't have a suitable wrench to really tighten it that hard (I hand tightened it with a little help from pliers). From the point where it almost wouldn't turn, I backed off 1/3 turn, then used the dial gauge to tweak it (FWIW, that guesstimate setting was WAY too loose). Since I was using the gauge to set the play, not the back-it-off estimate, I didn't think it mattered that I didn't start with it pinned to where the hub wouldn't move. Should I revisit that conclusion?

Sorry if I'm being anal ... I read a lot through searches (and manuals) but just wanted to clarify some little things.

Matt L · #2 03-22-2009, 02:48 PM

There is a torque spec on that bolt, just like everything else. I believe that it's 8NM on my 210, but would look it up before relying on my memory.

I think you'll be fine with the adjustment the way you did it. Tightening the assembly down at first helps seat all of the stuff, so you might want to pull the wheel and check the play again after a few miles.

snookwhaler · #3 03-22-2009, 02:55 PM

14 NM on the hex bolt in the clamping nut (123).

tangofox007 · #4 03-22-2009, 04:52 PM

Quote:

Originally Posted by BodhiBenz1987

Also ... I wasn't able to get the nut down tight enough to stop the hub from turning at all, I think due to tool inadequacy. It was close to not turning...

The objective is to seat the bearings and remove any burrs that might be present. Tightening to the point of almost not turning is reasonably adequate.

Quote:

Originally Posted by BodhiBenz1987

Since I was using the gauge to set the play, not the back-it-off estimate, I didn't think it mattered that I didn't start with it pinned to where the hub wouldn't move. Should I revisit that conclusion?

The method of adjustment is not a factor.

BodhiBenz1987 · #5 03-22-2009, 05:13 PM

Quote:

Originally Posted by tangofox007

The objective is to seat the bearings and remove any burrs that might be present. Tightening to the point of almost not turning is reasonably adequate.

The method of adjustment is not a factor.

I wasn't sure if the tightening to point-of-no-turn was to have a reference point for the 1/3 turn. I'll pop off the cap and re-adjust, doing it the way it's supposed to be done, then ... plus I'll torque the allen bolt to those specs. Doesn't hurt to be exact. Thanks, guys.

tangofox007 · #6 03-22-2009, 05:26 PM

Quote:

Originally Posted by BodhiBenz1987

I wasn't sure if the tightening to point-of-no-turn was to have a reference point for the 1/3 turn.

It is, of course. I meant to say that the "tightening" needs to be done regardless of the method of adjustment.

That said, I have had plenty of cases where I could not tighten to the point of no rotation even using a 16" adjustable wrench. Maybe that is an indication of high quality bearings and good grease!!!

I think that "almost no rotation" is adequate. But if you are loosing sleep over it, by all means recheck the bearing adjustment after a few hundred miles.