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Front wheel bearings

7K views 33 replies 14 participants last post by  RedLiner 
#1 · (Edited)
Hi front wheel bearings have a little play (they sound okay though)

I will adjust them, but should I repack them with grease at the same time? What size is the hub nut? (I hate having to go out for tools 1/2 way through a job) Any seals etc I should be replacing?
Do I need a puller for the hub, or will it "pop" off with the nut removed?

Thanking you all in advance.

Richard
 
#7 ·
Just remember. These are tapered roller bearings. They MUST have axial clearance (play). Most companies use a cotter pin system to set the freeplay. Mercedes uses a pinch bolt so you can set the play more accurately. If you grab the tire by the sides or top/bottom and "shake" you should be able to detect (feel) play. You will be able to feel it, but likely not see it. If it's enough to hear a clunk/click, probably to much play. If you can't "wiggle" the tire, to tight. I always use this a check after I've set the play by factory spec's as a second check.
 
#13 ·
Where to buy front wheel bearings

I had to take the front hubs off for another project and while at it decided to replace the rotors (silver arrow) and wheel bearings and seals. I can get the seals separately but who sells the bearings and races? All I see is the kit which includes the hub for $237. That can't be right. Can I simply find the timken number and get them that way?
 
#14 ·
I had to take the front hubs off for another project and while at it decided to replace the rotors (silver arrow) and wheel bearings and seals. I can get the seals separately but who sells the bearings and races? All I see is the kit which includes the hub for $237. That can't be right. Can I simply find the timken number and get them that way?
unless the bearings have been damaged there is really no reason to replace them, just repack them.

And I have yet to need to replace a tapered roller wheel bearing on any car I've owned. they last virtually forever.

But if you do replace them, you really need to replace the bearing and race. which means removing the race, fine as long as the race is easy to remove and install.
 
#17 ·
tapered wheel bearings are
1) an item that improperly adjusted (either to tight or to loose) can lead to major failure and damage.
2) are something that take a "knack" to get adjusted correctly, or lots of expensive tools and time. Once you know how to adjust them it is a piece of cake, but it's hard to describe.

The above procedure sounds like a good one. Another is tighten just over hand tight, then back off just enough to line up with the next cotter pin location. But Mercedes doesn't use a cotter pin system, they are a little more anal and uses a bolt with a side bolt that uses an allen bolt to turn the bolt into a pinch bolt, Very elegant.

But IMHO unless there is a reason to suspect they are misadjusted or obviously need greasing, don't mess with them.
 
#16 ·
If it ain't broke don't fix it I've known more than one person who decided to repack them and suddenly had problems because of a bad adjustment

I believe with a major service you're supposed to take the bearing cap off check the amount of grease but that's it.

When I got my SL three years ago I started to do that and the cap was on on so tight - I truly believe in 20 years it has never been off - I just decided to leave it alone.

So here I am three years and 40,000 miles later barreling through Utah and Arizona and the car, she's a happy.
 
#18 ·
Hi all :D

I adjusted my wheel bearings a couple of yrs ago but didn't repack with grease, the grease was black sticky stuff. As part of a major service I thought I'd revisit them.

I know I should use the MB green stuff and clean them thoroughly before repacking, but will I need a new seal for the back?

Any tips appreciated.

TIA
 
#19 ·
Thanks for the advice guys, and normally I do not replace parts just to replace them but since I did the control arms, struts, strut mounts, rear bearings, etc I simply thought well another few $ on something that does indeed see lots of service seems to make sense. Usually the bearings and raceways are in the $10.00 range, and while I agree they typically don't wear, I simply wanted to make sure. IT was lots of work getting all those things off and since I had to take the wheel off to get the backing plate off the front hub assembly I was already there with dis-assembly. I will defer though to you guys and will reuse them. They do spin awful fast though
 
#20 · (Edited)
Adjusting the bearings is easy and inexpensive to do correctly. Buy a magnetic base from HF for $10 and Metric dial indicator from amazon for another $10.

end play is .01 mm. This is so small there is no way you can guess it by hand or feel. Just spend the $20 and buy the tools needed and then never worry about it.

buy a tube of the good green high temp grease from MB and repack the bearings.
 
#21 ·
One thing you have to remember after repacking is to over tight the bearings, turn the wheel few times, then loosen the nut and do proper adjustment.
This way you know everything is seated.
Would I pull 20 years old seal for the job, I would rather put new one in.
Those seals are not working with pressure, so not really critical, but they are cheap enough to do the job to last another 20 years.
 
#22 ·
As I mentioned with AAM, Albert's advice, about just running on the grease, it's a feeling that you know if it's adjusted right or not.

If anything if you're not sure, err on the side of having the bearings slightly slacker than too tight.

I always tighten until the bearing binds then slacken off, I then continue until the bearing slightly binds then slightly back off. Finally I'll tighten until the bearing feels so very minutely tight, then back off just a touch so that the wheel spins freely with no play at all, or as Albert states 'Just on the grease' :wink
 
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#23 · (Edited)
I would be willing to bet that 90% of the people that say they can set the bearing by hand will be out of spec,and the rest will be lucky if they got it right.

.01mm is 10x smaller than the thickness of a piece of paper. You simply cannot feel that by hand.

Why not just spend $25 for the tools and know that it is correct?


Just my .02 c worth of opinion.
 

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#24 ·
that's one way and certainly a very good way to do it if you have the tools AND use them correctly to set the clearance.

the other is the very common way the mfg spec's setting clearance. Tighten to xx lb/ft while turning the wheel. loosen, tighten to yyy lb/ft (usually less than the first number). Then loosen to fit the first available cotter pin location. Guess what, that loosen to next cotter pin indicates a pretty wide acceptable tolerance range for adjustment.

Now I will admit, MB does use a pinch bolt so you could hit it exactly, but 20 million other cars made/year do just fine with the cotter pin method for usually the life of the vehicle w/o any wheel bearing issues.

the absolutely worst thing IMHO you can do with a tapered roller bearing is to adjust it to 0 or close to 0 clearance. They MUST have axial clearance to function properly and not destroy themselves. Your way better off being slightly loose vs. to tight.
 
#26 ·
The way that I have told members for 10 years is to jack the wheel, loosen the clamp, spin the wheel and tighten the nut till the wheel slows and you can feel some resistance, then back off the nut by 10 to 15 mins and that will be as close as you will get , and equal to a car with 5k miles. You cannot over tighten or do any harm at all this way.
 
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#31 ·
I did the old school by hand method for 40 years, until last year when I bought the correct equipment and did it per MB spec. I then realized then that there is absolutely NO way you can get it right any other way.

Grabbing the wheel on the car also shows looseness in the entire suspension, so that is invalid.

If you dont take the wheel off how would you be able to adjust it, unless you take the wheel off, remove grease cap, center cap from wheel and put it all back on again, and then do the opposite when you are done.

As far as backing off 10-15 minutes, or 45 degrees that will leave you @ 20x too loose. .01mm is equal to about a 2 degree turn of the clamping nut.


Good enough for a 1948 Ford isnt good enough for a Mercedes But is is your car to do with as you please.

"If it ain't broke don't fix it I've known more than one person who decided to repack them and suddenly had problems because of a bad adjustment "

that's because they did it wrong..

"tapered wheel bearings are
1) an item that improperly adjusted (either to tight or to loose) can lead to major failure and damage.
2) are something that take a "knack" to get adjusted correctly, or lots of expensive tools and time. Once you know how to adjust them it is a piece of cake, but it's hard to describe."

That is why you need to do it correctly. There is no "knack" if you just use the correct tools, and it is very easy to do that way. too many variables if you dont. Not expensive tools, $25 for everything you need.

REdliner, "I have a dial gauge in my workshop collection* but I wouldn't use it for setting up a wheel bearing! "
please go out an measure your work and report back.
 

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#33 ·
I did the old school by hand method for 40 years, until last year when I bought the correct equipment and did it per MB spec. I then realized then that there is absolutely NO way you can get it right any other way.

Grabbing the wheel on the car also shows looseness in the entire suspension, so that is invalid.

In my case I do not run cars that have play in any joints, there is a big difference in play in a wheel bearing to play elsewhere. The testing stations can all tell if play in bearings or in other components.

If you dont take the wheel off how would you be able to adjust it, unless you take the wheel off, remove grease cap, center cap from wheel and put it all back on again, and then do the opposite when you are done.
Yes I do remove then wheel and re fit minus the cap

As far as backing off 10-15 minutes, or 45 degrees that will leave you @ 20x too loose. .01mm is equal to about a 2 degree turn of the clamping nut.

I can feel that in my view it is too tight by backing off under 10 mins



Good enough for a 1948 Ford isnt good enough for a Mercedes But is is your car to do with as you please.

"If it ain't broke don't fix it I've known more than one person who decided to repack them and suddenly had problems because of a bad adjustment "

that's because they did it wrong..

"tapered wheel bearings are
1) an item that improperly adjusted (either to tight or to loose) can lead to major failure and damage.
2) are something that take a "knack" to get adjusted correctly, or lots of expensive tools and time. Once you know how to adjust them it is a piece of cake, but it's hard to describe."

That is why you need to do it correctly. There is no "knack" if you just use the correct tools, and it is very easy to do that way. too many variables if you dont. Not expensive tools, $25 for everything you need.

REdliner, "I have a dial gauge in my workshop collection* but I wouldn't use it for setting up a wheel bearing! "
please go out an measure your work and report back.
How long is the wheel going to stay your way, these things do wear, I reckon that my way is equal to about 5 to 10k miles of motoring and its safe.
 
#32 · (Edited)
The backing off method was used for 100 years and is still used on lot of other vehicles and trailers.
Point is that other vehicles are not expected to run million miles on factory wheel bearings
When there are lot of methods of adjusting by backing off, I think the one to tighten it with high torque, turning the wheel, than backing off and re-tightening with finger torque only is the best.
Than you can use 10 or 15 minutes back off.
15 minutes makes 1/4 turn btw
 
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