W219 front wheel bearing adjustment

[IFFY100]

Looking to adjust the bearings on the car and have been researching somewhat. It's the first I'll be doing them so would love any tips or advice in addition to what I have read on line. Also in terms of the 1 mm or so play allowance, do we pull the bearing in and out to assess this? And in terms of greasing the bearing, should I remove all the grease and try to insert the same amount that came out? Also in one clip I saw the mechanic remove the bearing itself and re grease, is this advisable?

 

[Bellow]

Looking to adjust the bearings on the car

Why? Is there discernable play?

Also in terms of the 1 mm or so play allowance, do we pull the bearing in and out to assess this?

If the play is 'axial' then yes, in and out and you will need a dial gauge and mount to measure it. Check your 1mm figure. That is ten to twenty times what I'd expect it to be.

And in terms of greasing the bearing, should I remove all the grease and try to insert the same amount that came out?

Best to clean the old grease off - wash in a solvent. Which requires....

Also in one clip I saw the mechanic remove the bearing itself and re grease, is this advisable?

..... which requires that the bearing be dismantled.
If you go this route, expect to have to re-adjust within 100 miles or so as invariable a freshly greased bearing 'settles' and needs to be nipped up a touch.

In summary:
If you are adjusting for excessive play, either do only that and monitor for further wear or, gain access to the bearing and look for wear.
If you are doing it as preventative maintenance - ie/eg, re-greasing - strip and clean thoroughly before re-greasing and be prepared to re-adjust later.
As a rule of thumb, if there's no lateral play discernable rocking the wheel and the wheel isn't 'tight' (to turn) it's very probably OK - and better left alone - unless re-greasing is your priority.

 

[ALFAitalia]

1mm at the bearing???.......seems a lot.....1mm of movement at the edge of the rim when rocking back and forth perhaps???!

 

[190]

MB spec for bearing clearance is .01 to .02 mm or in old money 0.4 thou to 0.8 thou. This is a very small clearance which is difficult to measure as most people don't have a dial gauge or the ability to set it up rigidly enough to measure such a small movement accurately. What I've done is tighten up the adjuster until there is zero clearance and then back off by an angle calculated from the thread pitch. As an example if the thread pitch is 1mm then the adjuster needs backing off by 0.02/1 x 360 which 7.2 degrees or a 50th of a turn.

MB at least have a infinitely variable clamping nut adjuster, you have to wonder how the old castellated nut adjustment was adequate when the increments were an order of magnitude bigger than the clearance we are talking about here. I think the answer is that the clearance is not as critical as is being made out. Obviously the 1mm that got mentioned is wildly excessive and would involve backing off by a full turn in the example above but I believe tightening to zero clearance and backing off by a 50th of a turn is safe enough.

Taper roller bearing life is actually optimised when there is a small amount of pre-load but that would effectively be impossible to measure on a car application. It's not on motorcycle though, my 44 year old BMW has a specified amount of pre-load on both front and rear wheels which is measured by wrapping a string around the wheel spindle and measuring the force required to rotate the bearing by pulling the string with a spring balance. Sums are involved to calculate the correct pre-load.

 

[IFFY100]

Why? Is there discernable play?

If the play is 'axial' then yes, in and out and you will need a dial gauge and mount to measure it. Check your 1mm figure. That is ten to twenty times what I'd expect it to be.

Best to clean the old grease off - wash in a solvent. Which requires....

..... which requires that the bearing be dismantled.
If you go this route, expect to have to re-adjust within 100 miles or so as invariable a freshly greased bearing 'settles' and needs to be nipped up a touch.

In summary:
If you are adjusting for excessive play, either do only that and monitor for further wear or, gain access to the bearing and look for wear.
If you are doing it as preventative maintenance - ie/eg, re-greasing - strip and clean thoroughly before re-greasing and be prepared to re-adjust later.
As a rule of thumb, if there's no lateral play discernable rocking the wheel and the wheel isn't 'tight' (to turn) it's very probably OK - and better left alone - unless re-greasing is your priority.

Basically the kwik fit guy for some silly reason decided to adjust the bearing. That's why I want to check it. Tbh, don't really trust they know how to adjust, as they don't usually do this type of stuff