Dial Indicator Measurements For Front Wheel Bearing Question - Page 2 - PeachParts Mercedes-Benz Forum

Hit Man X · #16 03-23-2010, 09:16 PM

Quote:

Originally Posted by Chas H

Now we're getting some where. Considering the graduations are .001", what is the play in your wheel bearings and what is the play specified by Benz?

0.01-0.02mm is the spec per the FSM.

0.0059" is going to be about in the center of the measurements once converted from metric, as Tango pointed out.

TimFreeh · #17 03-23-2010, 09:26 PM

Quote:

Originally Posted by Hit Man X

0.0059" is going to be about in the center of the measurements once converted from metric, as Tango pointed out.

More like .000596, but who's counting?

Hit Man X · #18 03-23-2010, 09:38 PM

Whoops. That is the reason I purchased a dial indicator that reads in metric graduations, instead of having to dick with a calculator each time I need to do something on these cars. That extra zero makes a large difference.

I really wish the US was on the metric system.

Diesel911 · #19 03-23-2010, 10:57 PM

Quote:

Originally Posted by warmblood58

So I read the various posts on the dreaded front wheel bearing adjustments after rotor replacement and decided to purchase a dial indicator and magnetic mount at Harbor Freight. I set up the dial indicator so that the tip just came short of making contact with the wheel spindle end and using the fine adjustment, loaded the indicator to 2 and zeroed out when loaded. I checked clearance on both sides and found that on the passenger side (123 wagon) I was able to move the indicator through 1 line and on the driver side, maybe a half line. The bearings have been fine up to this point (no noises) and the grease did not look/smelled baked. I will try to create these same clearances when I actually pull rotors to replace and repack outer bearings tomorrow but I thought it would be a good idea to get a measurement frame of reference in advance of pulling the rotors given my front wheel bearings have been performing fine without overheating. Any thoughts?

The manual has that you should preload the Indicator 2mm. This means the Indicator plunger makes contact with the Axle/Spindle and you continue to push the Indicator towards the Axle/Spindle; compressing the Plunger in 2mm and locking it in that position.
After that is when you would set the Indicator to zero by rotating the outer Bezel so that the Zero mark aligns with the Indicator Pointer.

dannym · #20 03-24-2010, 08:07 AM

HUH?
He did preload it to 2. Read the red part you highlighted:

Quote:

loaded the indicator to 2

leathermang · #21 03-24-2010, 09:02 AM

For people who think these guys are being too picky..
wait until you are dealing with a rear wheel on some of these cars that requires the use of a ONE TIME USE crush washer to set the play... better keep an extra couple on hand since if you tighten it too much you have to pull it off and start over with new one... I know that is redundant in terms of description for most of you...

samiam44 · #22 03-24-2010, 09:56 AM

I think most ppl feel that measuring is picky-

But if you read Timken's guide on bearings, it appears MB is one of the only car companies following the guidelines!
Leatherman, rears are quite easy. The hard part is initiating the crushing- after that it moves quite well. Since displacement is proportional to angle due to the thread- it's a pretty easy.

Micheal

Diesel911 · #23 03-24-2010, 02:01 PM

Quote:

Originally Posted by dannym

HUH?
He did preload it to 2. Read the red part you highlighted:

2 thousands or 2mm? I also noted what was not there.

One of the reasons I wrote was because I do not recall that Harbor Freight sells a cheap Dial Indicator that measures in mm.

Also 2 thousands preload with that type of Indicator and the Magnetic Base setup is not enough to deal with the deflection of the setup.

warmblood58 · #24 03-24-2010, 03:33 PM

Quote:

Originally Posted by Diesel911

2 thousands or 2mm? I also noted what was not there.

One of the reasons I wrote was because I do not recall that Harbor Freight sells a cheap Dial Indicator that measures in mm.

Also 2 thousands preload with that type of Indicator and the Magnetic Base setup is not enough to deal with the deflection of the setup.

What would you preload with then?

Diesel911 · #25 03-24-2010, 04:59 PM

Quote:

Originally Posted by warmblood58

What would you preload with then?

The Factory Service Manual said to preload the Dial Indicator 2mm; I would go with at least the 2mm (0.0787").

But, you can preload your Indicator more than that.
It will to depend on how much of a range your Indicator has.
Somewhere near the middle of your Dial Idicator Range (travel) can be a good place to habitually start.

Just as a note; if you look in Factory Manual the Factory Magnetic base is simpler and more ridged than the Harbor Freight Magnetic Base (and the one I have is even slighly worse than the Harbor Freight one).

leathermang · #26 03-24-2010, 08:03 PM

" Preload " is just ' taking up the slack' so you get a good measurement .... the amount is not the point.. just that the needle starts to move when it is supposed to....

ak49er · #27 03-24-2010, 08:22 PM

There is some good advice here, but take amoment to ponder the really small distances we are talking about here, one thousandth of an inch, half a thou', tenth of a thousandth.

Temperature can really come into play here. Avoid direct sunlight, halogen shop lights, holding the indicator in your hand too long, etc. Probably not too much of consideration for this job, but good practice.

I am an Industrial Turbine Mechanic at a power plant, we align 30" diameter load couplings on 20-80mw machines, and have had to build sun shades, use generator space heaters and all sorts of other consdierations, to assure everything is at or near the same temperature.

When we use "tenth" indicators, or even Model "99" levels, we keep them in the wooden box, inside the cardboard slip cover, to keep the measuring instruments equal. Sometimes even storing our tools outside at night so everything is equal in the morning.

Just use some preload. For something like this I would load the indicator 50%, there is no way you could thrust it in or out too far out of range.

Some of our turbines are metric (ABB, BBC) some are American (GE, Westinghouse), talk about a pain going form overhaul to overhaul reaidng prints in metric, then American, and keeping all that stuff straight....