HHmmmm.....
Dang, how come the car is so fragile ?

At approx 24,000KM and 4th Oct 2020, I already set it nicely to 0.01mm. It was at 0.04mm and this tiny 0.02 "looser" than minimum specification, does make noise.


To test, hold tire at 12 and 6'oclock and do one hand a push and other hand a pull







========= Oct 2020 archive, first time freeplay adjustment, approx 24,000KM ===============================











=========================



Today, at no more than 36,000 KM or only 12,000KM of use, Its freeplay increased again, by sound (mild ) not as much as 0.04 mm like in 2020, but I think 0.030 mm.

I was doing my front right caliper overhaul today, preventive maintenance, 8 years old seals and dust boot, albeit 36,000 KM max.
So I tested my front RIGHT bearing freeplay by sound...DAMN, there is that sound.

I know I drive fast and my roads are not good, but 12,000KM...

 

Our W212 has 150k miles, over 30k under my ownership and never had to adjust it.
But good item to check when you lift the wheel.
That said, driving the brand for almost 30 years, with dozen models I bought for whole family, the only bearing I ever replaced on them was idler pulley on W211

 

I am sure you dont drive like me

 

Neither my wife. She is good driver, but she hesitate to common "left lane hugger" and merge in front of them with 50 cm to spare.

 

My estimate is correct, 0.03mm freeplay.









Managed to set RIGHT FRONT back to 0.01mm.
I am getting the hang of it now, since this is my 2nd time.

Tips :
Reading 0.01mm is no easy task,


The Clamp Nut is basically a big NUT, but it has a locking allan bolt of 5mm.


As with all bolts engagement to a nut, the thread themselves have tolerance.


Image Source : https://www.calqlata.com/productpages/00042-help.html


So if Clamp Nut loose and I set freeplay at 0.01mm, by the time I tightened the 5mm allan bolt, the clearance will be zero aka bearing will probably seize or be damage within short period of time. Sure wheel can spin still.
So when adjusting freeplay, a loose Clamp Nut , its own thread can contribute to freepay approx 0.01mm to 0.015mm, do remember this.
Make sure when you think you have achieved the target freeplay, once the clamp nut is tight ( using its allan bolt 5mm ), do test again to verify you are getting 0.01 to 0.02mm freeplay.
Its a bi-etch to pull and push 0.01mm...very tiring.
Take your time.

Placing the dial gauge is another art in itself. I hate it...... it is sooooooooo very slow to do.
Remember the dial gauge is placed on brake rotor and the rotor can spin.
Usually the component we measure is the one moving or spinning and the dial gauge stay put.,.... this is so much easier.

The measuring spot is the main wheel shaft, it has a shallow concave shape.

Above example of dial gauge needle not yet at concave's bulls eye and is only visible when zoomed. If by naked eye ....hhhmm, maybe 20 years ago I can tell

Me eyes not as good as a young man and since I can't raise my car as high as my eye level* ( *me sitting down on a super short stool) because Quick Jack maximum lift is approx 50cm only.
You have to make sure you hit the bull eye at the concave as accurate as possible, easier said than done. Need magnifying lens for me .
To verify that you dial gauge needle sit beautiful, at the concave bull's eye, spin the disc rotor 30 degrees LEFT and RIGHT and if your dial gauge move, that means the needle is not at the bull's eye yet.
All 3 axis aiming of your dial gauge needle must be spot on and 0.01mm spot on is tough. I wasted more time getting the dial gauge needle right than the freeplay adjustment itself.

That's all the tips I can share.


Will update with the LEFT FRONT wheel when done.

 

No wonder MB specified 0.01 to 0.02 mm.
The less loud click-click noise of LEFT FRONT was from a 0.025mm freeplay ...wow. Extra 0.005mm can make a sound....LOL







I can't do 0.01mm for the LEFT front. I got so worned out pullling and pushing so many times to generate the freeplay after adjusting the claw nut.
LEFT front I can only do 0.015mm.


I forgot to add, when using allen/hex tool, get the one with the L end having the ball type, so that it can be angled a bit.
If straight allen/hex tool, for my car it will get kinda obstructed by the lip of the bearing cavity. I marked red.
On my 1st time adjusting the freeplay in 2020, I was using straight one... not good at all, I was fighting friction not the bolt.




Okey.... this wrap up the maintenance. Done. Next 5,000 and 10,000 KM I will check again.

 

TIL you can adjust the play.

But the bearing on mine apparently failed without warning today. Thankfully the wheel does not come off!!! Suddenly on the highway (about 60kph) suddenly I feel the car hit something, then screeching sounds began to hear, then dash warning ABS/ESP inoperative. Pulled over but did not notice any liquid so I continue to drive slowly to the workshop. It made nasty scrheecing noise when turning.

At the shop it turns out the front right wheel has a lot of play :O and it has nasty marks on my rotor...




i plugged launch scanner and it does says front right wheel speed sensor malfunctioned.

Thankfully after bearing replacement (I replaced both front axle) the warning and strange sounds is gone. I do wonder whether the mechanic set the play adjustment correctly or not...

 

Wow, what hit the rotor ? Can' be brake pad edge, but can be brake pad metal body/base edge ?

 

The width and location matches what could be a brake pad rivet.

What brand are these pads... genuine MB ??

Perhaps someone stuck something through vent hole drillings.

 

I have no idea what hit the rotor, perhaps the metal part holding the brake pad? yesterday I took a photo but not clear enough because the wheel still installed and it was in a basement



The pads according to the shop genuine MB.

 

The front bearing for us RWD cars is sold as a set, hub set.
Only adjustment needed, no pain of removing bearing.



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Did the workshop inspected the shaft end, the taper ( knuckle) which held the bearing hub ?
Usualy when wobbling occured, this taper coul get damage too.

Below :

 

You may not be seating your wheel bearings properly initially. Can you feel play when you grab the wheel and try to rock it?
(Also you need a different tip on your indicator! Your accuracy is only as good as your setup. See pic)

When you “set” a tapered roller wheel bearing. The procedure is you have over tighten the nut, spin the rotor several times, THEN back it off to reach your clearance/play target. If you go the other way, try to tighten into the clearance, it’s much more difficult to achieve predictable results.

if you visualize how the two tapered roller bearings sit in the hub, you’ll understand why this makes sense.


The WIS procedure is correct, it’s just that you need to make sure you tighten the bearing, then loosen it to check clearance. Most techs I’ve seen have this problem haven’t tightened the bearings enough initially to get a proper/consistent reading. Or they are trying to set clearance while tightening the nut instead of loosening into the clearance/play.

Probably would have been helpful if they (MB/WIS) had given a torque spec, but they figure techs have been trained I guess….

Threads have play, bearings with freshly “packed “grease also can give you false readings if you don’t get that bearing properly seated by the method above.


Good Luck!