Wheel bearing adjustment question

[billabong132]

I'm doing the front bearings on my C280

I know they need to be adjusted to have play within a certain range.

I have a dial gauge and a magnetic base jig for it.

How do I measure the play?


Where should I put the dial? - how should I try and move it - just pull on it?

[donbryce]

Use the search button and read the many posts on this subject. There's at least 1/2 dozen ways to do this. I used the dial indicator technique, but as you'll see from the responses, I can't say with 100% certainty that I did it correctly, so use your own judgement here. Also, there may be another recommended method for the C280 (mine's a W126 380SE)
http://www.peachparts.com/shopforum/showthread.php?threadid=100590

As the job I did has only had a 500 mile drive for a 'test run', the proof in the pudding may not yet be evident. However, the bearing doesn't overheat, and no discernable noises to indicate a problem.

IMO, what I did is at least as good as trying to do the touchy-feely procedure by turning the hub until it's 'too tight to turn' or 'hard to turn' and backing off 1/2 or 1/3 turn on the nut, or rapping the mounted wheel until it 'sounds right' when the 'rattle' disappears.

It seems you either do it objectively with the dial indicator, or subjectively with the feel approach. Either way, it's a PITA to get it right by yourself with little or no prior experience.

[rsmcmahon]

I found the below text while searching for wheel bearing adjustment a while back. I think it was a post by Stevebfl who has posted great tips and information.

This is the "touchy feelly" approach to adjusting wheel bearing


As to the adjustment. . My German partner always showed the new guys this trick. Put the tire on and torque it. Take the spanner in one hand and use the other as a fist to lightly pound the tire. If you do this while loose you will distinctly notice a rattle sound that goes away when the nut is tight. The idea was to tap on the tire as one overtightens by a quarter turn to seat the bearing. One would then back off half a turn and do the tapping as one found the exact tention that cancels the rattle. Works pretty good. I always error loose, watch how much you are moving the pinch nut. If you can feel play with the tire on then its too loose. Doing this with the tire on improves ones sensitivity to the play whichever way one is observing it

[billabong132]

thanks guys

[elusive 190E]

For all of posterity...

Bearings too tight=

1.)Burned out bearings...

2.)Improper disc brake release...

Bearings too loose=

1.)High speed instability...

2.)Destroyed bearings...

Just my 2 cents... 30+ years automotive hobbyist...

[Kestas]

I work for the bearing industry in a technical capacity. Improper installation is the main reason bearings fail in automotive applications. When looking at warranty returns or failure rates in the field, there is always constant friction between the bearing manufacturer and auto (or truck) maker. The automaker is always saying "You make lousy bearings". The manufacturer replies "Your service departments don't know how to properly service bearings".... and the beat goes on. That's why the industry has trended toward preloaded, non-serviceable hub units, which cost ten times more to replace than the previous design.

Setting proper preload has the most important effect on bearing life. All this anecdotal shadetree advice of setting bearing preload followed by "... and never had a problem" probably didn't follow how long the bearing last beyond a couple years. Properly serviced bearings should outlive the car, and should definitely outlive the non-serviceable units that are commonly popular.

[Duke2.6]

I have to take issue with your use of the word "preload". Some anti-friction bearings are installed with "preload" and some are installed with clearance, which is zero preload, and this is the case with traditional front wheel bearing designs on RWD cars.

Use of the word "preload" for all installations causes a lot of confusion.

Duke

[Kestas]

Sometimes we call it negative clearance. But you're right, this term can be misleading. We use the word 'preload' at work a lot since >95% of our automotive product is nonserviceable hub units.

[Duke2.6]

I try to describe these bearing installations as "zero preload", and then add the caveat of recommended clearance, but this design type is becoming rarer on new cars, more of which are going to the non-serviceable sealed type, most of which I understand are assembled with preload similar to axle drive pinion and side bearings.

Duke