Wheel bearings, warning/advice

T

Trig

Member
Well, had to do the wheel bearing on the shoe box the other weekend.

As you can imagine not as much fun as it sounds, and it really doesnt sound fun..

Ended up taking the hub assembly round the corner to a mate with a bit more kit than me to press the old bearing out and new one in.
However, the new kit didnt come with the bolt that goes thru the bearing and onto the drive shaft..
Noticed theres not really anything holding the whole thing together, no circlips, castle nuts etc
So I ended up reusing the old one with a bit of thread lock.

THIS DOESNT WORK!!!

2 weeks later and the bearing has started to come back out of the hub, luckily(!) I was checking the driverside brake's over as the passengerside are a due for replacement and figured I might as well check both sides and notice that the outside pad was starting to overhang the bit of the hub that holds the pads in, overhanging to the point that another 2/3mm and the pad would of come out. The bearing had come out of the hub a good 3/4 of an inch.

It appears all that holds the bearing in, other than the fact its pressed into the hub is the crappy, what can almost be described as pressed tin nut thing that goes on the end of the driveshaft...

So, if anyone ends up doing a bearing themselves or has had one done might I suggest you have a look and see if yours is moving too...
Perhaps someone might have a link to part numbers for the nut or a better "stop it falling out" alternative...
 
The pressed nut has been superceded for a number of years now by a cast, 12-point nut.

In any case, you should NEVER re-use hub nuts - they are single use items - take 'em off and bin them straight away!

Cheers,

Mike
 
Hi Trig
The centre nut only locks the driveshaft / CV joint to the hub. Even with this nut fully torqued, if the bearing comes loose, the driveshaft can extends so the hub assy will just start to creep out.

Bearing Installation
------------------
Audi recommend the bore in the bottom casting is dimensionally checked to ensure its within tolerance before replacing the bearing/hub assy.
Later Audi bearings incorporate a pressed spring steel cage with a locating lip which, I'm almost certain, engages in a groove in the housing bore to locks the bearing in place.
For installing the new bearing/hub assy you need to use a special split clamp service tool which goes round the hub flange and locates on the outer race of the bearing. If you don't use this type of service tool and just use a hydraulic press to push the hub/bearing assy into the housing, the several ton press load is applied through the ball races. In doing so, there is a great risk of indenting or Brinelling the bearing races which can lead to pitting and early failure of the bearings

Cheers Spike
 
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Cheers for the info guys.
The outside of the bearing did have a spring cage around the outside.
Anyone got the part number for the new style nut?
We just used a normal press with a few blocks of wood to push the new one in so shouldnt of done any damage, the cage thing tho was larger than the inside of the hub where the bearing goes so didnt lock into anything, perhaps it was the wrong type as mines an "X 1.4"..
 
Hi Trig
Checking dimensions for the housing bore are 71.922 to 71.952mm. Bore should be checked in several places and if any measurement is outside these limits the housing should be replaced.
The solid 12 point hub nut is p/n 6QO 407 396B (pressed 6 point version is obsolete)
Pics of the factory tool for installing the bearing / hub assy are attached. Note how the split collar part of the tool locates on the outer bearing race under the wheel hub flange.

Cheers Spike
 
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