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1988 Mercedes 500 sec
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514 Posts
Discussion Starter #1
adjusted my new rear wheel bearings today using a digital dial gauge but not sure if I have done it correctly

when trying to zero the digital gauge it would not go to zero always -0.01 or a +figure
If I pulled the hub towards me id go up may be a few 0.01mm but the bigger increases were seen when pushing on the hub.

slowly tightened the hub until I was showing eg +0.03mm when pulling on the hub and -0.05 mm when pushing on the hub, I had to really apply some force when pulling or pushing to get these figures.
Although the figures were different on pulling and pushing im assuming the overall tolerance was set at 0.04mm either way, ie 0.03mm plus 0.05 mm =0.08mmdivide by 2 gives 0.04mm, when I spin the wheel it rotates approx. two and three quarters times before stopping, I can still feel a very feint play so feint sometimes its difficult to determine
not sure If I should adjust any further. as I am already at the max tolerance of 0.04mm

the other side is showing an overall of 0.035mm to 0.04mm, 0.035 mmis is slightly out of tolerance nut pshed an dpulled hard enough I can achieve 0.04mm , there is no play when holding this wheel at 12 and 6 oclock .
It rotates just slightly less than the other side ie two and and half rotations

does this seem correct or do I need to split the rear hubs again for new crush wshers and start over again,
 

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1988 Mercedes 500 sec
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514 Posts
Discussion Starter #3
Thanks i have that abd had a read but cant get my head around this digita dial l gauge as to if im measiring correctly
Its saying to pull in and out but also turn at the same time
Does 2.5 rotations on the wheel sound about right after having tightened the bearing to spec
 

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Moderator
1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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4,528 Posts
In my opinion, as a former auto tech on European cars, your 2.5 rotations technique sounds reasonable to me.

I've just not had hands-on experience in that area.

M
 

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1988 Mercedes 500 sec
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514 Posts
Discussion Starter #5
Thanks i will leave it then as it is
The digital dial gauge is hard to use
Im assuming if overall you have 0.08mm of play ie pushing and pulling on the hub then the final figure is approx set at 0.04mm either side of pushing and pulling on the hub.
Does that make sense its a little difficult to explain
The right wheel the adjustnent falls between 0.03mm and 0.04mm if you really push and pull on tbe rotor just concerned this may be a touch tight as it is 0.01mm tighter than what the mannual states
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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4,494 Posts
It's my understanding that we're measuring an overall amount of play, not an equal amount left and right of some center point. So I don't think it matters where you set the pointer on your gauge, you're just measuring overall play.

Further, I think you want a TOTAL of .04-.06, not those dimensions each direction when pushing/pulling for a total of .08-.12.
 

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Outstanding Contributor
350SDL, '17 GLS450, "Grandpa's Roadster" Project Car
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3,254 Posts
Correct! End play is measured by first pushing it all the way in one direction, noting the reading on the dial indicator, then pull it in the opposite direction and again note the measurement. The difference between the two is the end play. Ideally, push in and zero the gauge, then pull out and read the end play directly.
 

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Registered
1988 Mercedes 500 sec
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514 Posts
Discussion Starter #8
Thanks guys this has made it clearer maybee my digital dial gauge was fine in th end
it seems then my pasengeer side one needs a little further tightening

john as an eg if i pull them hub and get 0.02mm and then push on it and get -0.04mm does this mean my actual reading is 0.06mm which is in turn wit in the mannul spec of 0.04 to 0.06

if thus us the case i best check the front bearings the will need tightening a touch more
 

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Premium Member
1999 500SL, 1988 SEC
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1,281 Posts
Just an observation and this should not happen but it did on me twice. I used the procedure you did and tightened to specs. Drove the car for a couple of hundred miles and did a recheck. It was different and i had to tighten it some more. Thats a pain since you have to drop the 1/2 shaft. Again it should not do this but...... Of course it could have been me too.
 

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1988 Mercedes 500 sec
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514 Posts
Discussion Starter #11
stutz how much did it loosen by did you squash down the tabs to stop the nut working loose
 

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Premium Member
1999 500SL, 1988 SEC
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1,281 Posts
Oh yes the tabs were squashed down. It moved like .040 on me. I was furious since this was not an easy job. At least it was not on the drivers side which is more difficult due to the exhaust. It also could have been me being tentative since if you make them too tight you really need to use a new crush washer. You can’t simply back them off. I guess just take your time and really push It and out a lot . Then in a month or so check-it again
 

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1988 Mercedes 500 sec
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514 Posts
Discussion Starter #13
thats a lot of movement i understand your frustration its quite big job doing the rear wheel bearings
did you use the same method of pushing and pulling the hub and adding both readings as your final figure, what did you tighten to on the first attempt
 

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Premium Member
1999 500SL, 1988 SEC
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1,281 Posts
Yes, I used a dial indicator and did the push pull method. I tried to stay about .010 knowing a little loose might be better than tight. I devised a plate that attached to the wheel studs and connected a long 1 1/4 schedule 80 bar to use to slowly tighten that GD nut. That allowed me to sneak up on the readings. Other than that I can't tell you why it did what it did. Maybe I did not get one of the bearing races in enough, maybe I read it wrong, maybe I was impatient. The only thing I know is I had to take that damn axle out again, put a new lock nut on, and yes I had a new crush washer, and start tightening again. I wish I could tell you more, and it could have been a fluke, I just wanted you to measure it after a while. Shouldn't have to but,,,,,, just a precaution!
 
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