Front wheel bearing issue

[Ian Comerford]

Longish story and a cautionary tale.  My car had a pre-MoT inspection last month and they noted my front wheel bearings needed adjusting.  I tried adjusting them but couldn’t achieve the light movement of the washer and little or no rim rock (if you have adjusted yours you will understand).  The assumption was that the bearings were worn.  Ordered new from Matthew and fitted them earlier this week.  Reassembled everything today and the same problem exists.  The hub isn’t worn, all of the races went in with a good snug fitting.  My only conclusion is that the inner spacer that is fitted to the spindle before the hub assembly goes on is worn.  I replaced this spacer in 2011 when I rebuilt all of my suspension.  The advice is to warm it up in the oven to 190 degrees for half an hour.  It worked and went on with a little extra persuasion to seat.  
The part of the process where I don’t think I paid enough attention is the bit that says to ensure that the inside of the inner race on each bearing (the bit that sits on the spindle) is free of grease.  This stops the inner race from spinning due to a small amount of friction.  I guess it also stops the spindle from wearing, which is the bit I am concerned about now.  I think the inner races ((the bigger of the two bearings) have been turning on the spindle and have worn the spacer, meaning the hub sits further into the spindle than it should.  
I dug the old bearings out of the bin and inspected the face that sits on the spacer, sure enough there are witness marks of wear.  I will order new spacers and o-rings but wonder whether the spindle might be worn from the inner bearing races rubbing as they rotate, which they aren’t supposed to do.  If the spindles are worn then it’s pointless putting new spacers on as the bearings won’t interact properly with the spindles…..which means new/used struts!! 

Has anyone experienced this? Thank you

[Chris_911]

I'm puzzled by this Ian.

I've just degreased and re-packed my front wheel bearings. Bentley advises lightly coating the bearing races and hub with grease.

Given the bearings are taper bearings I can't see how the inner race can rotate relative to the spindle, assuming all parts are in dimensional tolerance. 

Are you sure your spindle isn't worn?

[Ian Comerford]

Thanks Chris, it may be worn so guess I need to look for a measurement or tolerance.  Anyone have an idea of where to find this?  The point regarding removal of grease was at Fig 13 in this link, which sounds sensible.

https://www.pelicanparts.com/techarticles/Porsche_911/02-SUSPEN-Front_Wheel_Bearing_Replacement/02-SUSPEN-Front_Wheel_Bearing_Replacement.htm

[Ian Comerford]

Just thinking ahead on this one…if I strip everything off the spindle again, replace the spacer and refit this should allow me to adjust the bearings properly and at least get the last road trip of the year done.  Because if they are worn I need to buy new or used lower struts, this replacement will just delay that.  It could be a minefield buying used unless I have a set of tolerances for various key areas.  More thoughts welcomed

[Ian Comerford]

This is the extract from the Pelican article

Clean any grease that may be on the inner races of the bearings (red arrow) as you want the bearings to spin in the races not the races to spin on the spindles.

Makes sense to me

Edited August 23, 2025 by Ian Comerford

[Phill]

4 hours ago, Ian Comerford said:

This is the extract from the Pelican article

Clean any grease that may be on the inner races of the bearings (red arrow) as you want the bearings to spin in the races not the races to spin on the spindles.

Makes sense to me

Makes perfect sense. However, in my mind those races should be tight enough not to want to spin, after all they get pressed on pretty tight and generally need some persuasion to come off. Not the outer ones though.

[Ian Comerford]

It’s not those races Phill, not the ones that are pressed in, it’s the inner part of the bearing.  This is a snug push fit as part of the hub onto the spindle.  I suppose if it’s free of grease it is less likely to spin and wear the spindle and spacer

[Ian Comerford]

Does anyone know where I might get a measurement or tolerance (or both) for the spindle diameter under the bigger bearing?

[Chris_911]

I can measure one of mine? I don't have any bearing issues so might at least be a pointer?

Driver's side only has the hub mounted so needs to come back off to put a disc on.

[Ian Comerford]

Thanks Chris, it would be appreciated.  You should also consider ensuring there is no grease on the inner faces of the bearings, the surfaces that abut the spindle.

[Chris_911]

7 hours ago, Ian Comerford said:

Thanks Chris, it would be appreciated.  You should also consider ensuring there is no grease on the inner faces of the bearings, the surfaces that abut the spindle.

Have you seen this 'remove grease' advice elsewhere, or is it just this one Pelican 'guide'? I'm really struggling to get my head around the logic. It's the taper that holds the bearing - any grease on the spindle is simply there for corrosion resistance.

[Ian Comerford]

No I haven’t seen it elsewhere but it makes sense to me, especially with what I am seeing on my car.  The part of the inner race that sits against the spacer on the spindle has wear/witness marks so has obviously been turning, which isn’t advisable as it wears the spindle, the spacer and the inner race

[Chris_911]

33 minutes ago, Ian Comerford said:

No I haven’t seen it elsewhere but it makes sense to me, especially with what I am seeing on my car.  The part of the inner race that sits against the spacer on the spindle has wear/witness marks so has obviously been turning, which isn’t advisable as it wears the spindle, the spacer and the inner race

But I don't think what you are seeing is simply down to the presence of grease. Happy to be proved wrong as it increases my knowledge!

[Phill]

Ian, can you put up a diagram with some arrows to the bits you are talking about please?

[Ian Comerford]

Of course, hope this helps.  Item 24 is called a spacer and has to be fitted to the spindle using heat (I used our oven when I last did this, 20mins at 190 c from recollection).  There’s a small o-ring behind it to stop grease leaking past.  Item 29 is the grease seal and 27 is the larger of the two bearings.

[Phill]

Thank you.   

It's as I thought initially. The inner race could spin I suppose but I feel that it would be very unlikely due to the bearings themselves being that much more free to spin. Any inner bearings like that that I have dealt with have always needed a bit of oomph to get them off the spindle. Obviously the outer bearing tends to just fall out once the hub nut is off.

As Chris suggests, I think there is something else at play (pun not intended).

Also, (I can't remember, a while ago since I did the 911) do you not overtighten the hub nut for the very purpose of seating the bearing properly, and then back it off to tolerance?

[Chris_911]

Just been reading the SKF Bearing Maintenance Manual (as you do).

No mention of keeping the a bearing mating face free of grease. In fact, it indicates greasing all mating surfaces.

I think you have a wear issue.

If that inner race is spinning it cannot be transmitting load to the spindle. It simply cannot be in adequate contact with the hub spindle.

[Chris_911]

On 24/08/2025 at 07:22, Ian Comerford said:

Does anyone know where I might get a measurement or tolerance (or both) for the spindle diameter under the bigger bearing?

31.8mm according to my vernier.

[Ian Comerford]

4 hours ago, Chris_911 said:

31.8mm according to my vernier.

Thanks Chris, it will be interesting to see what mine measures tomorrow when I strip it (again…..)

[Ian Comerford]

A couple of decent photos in this link on the subject

https://forums.pelicanparts.com/porsche-911-technical-forum/599454-o-ring-front-wheel-spindle.html

[Ian Comerford]

I’ve just measured the inside dia of the old larger/inner bearing and both come up at 31.75 so we are in the same ball park Chris

[sopor]

Is the play different at 06:00 and 12:00 as compared to 09:00 and 03:00? That *might* suggest spindle wear.

[Ian Comerford]

Thanks Felix, I’ll check that once I strip it today

[Chris_911]

I measured my spindle with a vernier but a micrometer is really the right tool for the job.

[Ian Comerford]

Me too but I don’t have a micrometer of the right size.  Retail opportunity……

I’m still running over in my mind what else can be wrong and keep coming back to a worn spacer.  They are clearly a 'wear item' as they are replaceable, I’m just not totally clear on the relationship between a worn spacer and the inability to achieve the correct adjustment on the bearing.  I don’t believe that the hub is worn, all of the races were tight when being removed and the new ones were pressed in and not loose in any way.  A cross-sectional drawing of the assembly would be good to have.  Anyone?