Wheel Bearing Adjustment - Page 2 - PeachParts Mercedes-Benz Forum

rivermasternc · #16 12-11-2007, 10:48 PM

Quote:

Originally Posted by rwthomas1

Do what works for you my friend. I have greased the MB wheel bearings twice in 50+K miles and they are just fine. Same ones that came with the car. No howling, no scoring, no heating up, nothing. While I understand the reason for procedures if the end result of another method provides satisfactory results then there is no issue.

RT

Quote:

Front Wheel Bearing W126
Stu Ritter
Tue Apr 15 16:17:04 MDT 2003
--------------------------------------------------------------

Wray Stanley wrote:

> Scott,
>
> The bearing tolerance is so small that I don't believe anyone who says they can "feel" when it is
> right. Dial indicator is mandatory.

Or, let's put it this way.
Every mechanic who has ever come to work for me, and in 25 years of
owning a shop I'd say I've had 8 or 9, has been put to the test because
none of them would believe me when I told them they couldn't set a wheel
bearing by hand. They would poopah me. OK, we would get a car, and
I would have them set the bearings. Both sides, so we could average their
mistakes. Then we would hook up a dial and measure it. None of them, not
a one of them got them to within 5 thou, much less the .01 - .02mm required.
All were set way to loose, as mechanics are wont to do. That was all it
took. After that, they all used the dial. It takes about 1 minute to hook it up
and put it away so they had no excuses.

Stu

That works for me!

Diesel911 · #17 12-12-2007, 01:09 PM

Quote:

Originally Posted by rivermasternc

That works for me!

I know that I did not get the "feel" for it correctly; all that nice thick grease covers it up.

K581RC · #18 12-12-2007, 02:42 PM

Hi everybody,
just following this discussion, very very interesting. One little problem, the pdf file given above in the fsm says 2mm endplay, but everyone here favors ~.02mm? I think the manual is too loose. which is correct?
Thanks!
Paul

K581RC · #19 12-12-2007, 02:51 PM

Never Mind!
the spec is in the first line of the pdf article! I mixed up preload with the actual endplay!
This is the scientific method, last time I did this on my fleetwood I did it by feel and I sure did not worry about what kind of grease was in there, boy is this stuff precise.
Paul

tangofox007 · #20 12-14-2007, 09:47 AM

Here is something that I don't understand. Some vehicles have a specified torque value for the axle nut. In some cases, that value is quite high. (I have a Jeep that calls for 175 ft/lbs.) Why is it that those bearings are not ground to pieces in short order? We are still dealing with tapered roller bearings. Not exactly the same design, but same concept, as far as I can tell.

winmutt · #21 12-14-2007, 11:32 AM

Quote:

Originally Posted by tangofox007

Here is something that I don't understand. Some vehicles have a specified torque value for the axle nut. In some cases, that value is quite high. (I have a Jeep that calls for 175 ft/lbs.) Why is it that those bearings are not ground to pieces in short order? We are still dealing with tapered roller bearings. Not exactly the same design, but same concept, as far as I can tell.

Are they sealed?

tangofox007 · #22 12-14-2007, 06:34 PM

Quote:

Originally Posted by winmutt

Are they sealed?

Yes.

leathermang · #23 12-14-2007, 08:08 PM

Good catch Winnmutt... I suspect that means they are not tapered...thus accounting for that very very high torque spec...

"SAE 0.00039-0.00078 inches"
Who on this forum.... or even anyone anyone knows.... owns a micrometer that will measure into the HUNDRED THOUSANDTHS ??????? Those are usually locked in the toolroom and used to measure the other mics actually used by the mechanics...
.. something seems askew...either what they expect of the mechanic ... or the conversion factors used .....( by someone somewhere ).

Corey · #24 12-14-2007, 11:05 PM

Quote:

Originally Posted by leathermang

Good catch Winnmutt... I suspect that means they are not tapered...thus accounting for that very very high torque spec...

"SAE 0.00039-0.00078 inches"
Who on this forum.... or even anyone anyone knows.... owns a micrometer that will measure into the HUNDRED THOUSANDTHS ??????? Those are usually locked in the toolroom and used to measure the other mics actually used by the mechanics...
.. something seems askew...either what they expect of the mechanic ... or the conversion factors used .....( by someone somewhere ).

Those are the correct lengths in inches for 0.01-0.02 mm. I'd say round up to 0.001 or try to get it just under the 0.001 mark. But I've yet to get to this job on my 240D.

Corey

tangofox007 · #25 12-15-2007, 12:00 AM

Quote:

Originally Posted by leathermang

Good catch Winnmutt... I suspect that means they are not tapered...

Here is a picture. Let me know if that doesn't fall within the definition of a tapered bearing.

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=SKF&MfrPartNumber=JLM603048F&PartType=184&PTSet=A

Quote:

Originally Posted by leathermang

Good catch Winnmutt... I suspect that means they are not tapered...thus accounting for that very very high torque spec...

"SAE 0.00039-0.00078 inches"
Who on this forum.... or even anyone anyone knows.... owns a micrometer that will measure into the HUNDRED THOUSANDTHS ??????? Those are usually locked in the toolroom and used to measure the other mics actually used by the mechanics...
.. something seems askew...either what they expect of the mechanic ... or the conversion factors used .....( by someone somewhere ).

Rounded off, that is .0004-.0008 inches. Which amounts to 40% to 80% needle deflection of one increment on the typical .001 increment on a dial indicator. Not unreasonable to visualize at all. For that matter, a deflection of half an increment is within tolerance.

leathermang · #26 12-15-2007, 11:54 AM

Quote:

Originally Posted by tangofox007

Here is something that I don't understand. Some vehicles have a specified torque value for the axle nut. In some cases, that value is quite high. (I have a Jeep that calls for 175 ft/lbs.) Why is it that those bearings are not ground to pieces in short order? We are still dealing with tapered roller bearings. Not exactly the same design, but same concept, as far as I can tell.

You are the one that said that... and I am agreeing with you.

Some factor is not being recognized in this situation. When you figure the mechanical advantage of the threads... then put 175 ft/lbs. of torque to the nut.. the pressure inward in a usual tapered bearing design would not let the wheel rotate. So something like a shoulder or something is keeping that force from being applied to the tapered bearing... more examination or research is needed.

I don't know what brand of dial indicator you guys are using...but most of them which read to one one thousandth only claim to be accurate to plus or minus one thousandth... so 'part of one increment deflection' should be taken with a grain of salt...

Chas H · #27 12-15-2007, 01:11 PM

Quote:

Originally Posted by tangofox007

Here is something that I don't understand. Some vehicles have a specified torque value for the axle nut. In some cases, that value is quite high. (I have a Jeep that calls for 175 ft/lbs.) Why is it that those bearings are not ground to pieces in short order? We are still dealing with tapered roller bearings. Not exactly the same design, but same concept, as far as I can tell.

The bearing used in this application is one piece with a split inner race to allow assembly. The internal clearance of the bearing is determined by the man'f and the high torque figure is neccessary to insure that clearance.
Comparing an adjusted tapered bearing set to the one piece -usuallly angular contact ball- bearing is apples to oranges.

tangofox007 · #28 12-15-2007, 01:37 PM

Quote:

Originally Posted by Chas H

Comparing an adjusted tapered bearing set to the one piece -usuallly angular contact ball- bearing is apples to oranges.

Apparently you missed the part that said that it is a tapered bearing set. I am sure that you will find your way out of the orange orchard once you get your bearings!!!

tangofox007 · #29 12-15-2007, 01:46 PM

Quote:

Originally Posted by leathermang

So something like a shoulder or something is keeping that force from being applied to the tapered bearing... more examination or research is needed.

On further examination, it does appear that the hub bottoms on the axle flange. So the torque is being applied primarily to the hub itself, and not the bearings.

Quote:

Originally Posted by leathermang

I don't know what brand of dial indicator you guys are using...but most of them which read to one one thousandth only claim to be accurate to plus or minus one thousandth... so 'part of one increment deflection' should be taken with a grain of salt...

I suspect that still beats the "alternative" methods by a mile.

leathermang · #30 12-15-2007, 02:26 PM

Quote:

Originally Posted by tangofox007

I suspect that still beats the "alternative" methods by a mile.

I am not at all suggesting using the alternative methods... the first time I did the rear of my 81 wagon I squeezed a tiny bit too hard... and had to wait till the Mercedes dealer opened up on Monday and do a 60 mile trip to get new ones... those shims are one time use only....

I am just saying in field conditions we would be kidding ourselves if we thought we could actually measure a chunk of iron hanging on a spindle with grease involved to Hundred Thousandths precision...