1999 JAGUAR XJ8 3.2

Front wheel bearing replacement

    On the fresh MOT which came with the car there was an advisory regarding a slight amount of play in the off side front wheel bearing.  I can just feel it and thought I could hear a faint rumble from the off side at around 50mph - that could be an inherent noise or even a tyre.  I know that these cars are heavy on bearings and I've got to say that moving away from a pair of separate taper roller bearings with a good distance between them (as on the series and XJS cars) to this capsule type unit with ball bearings was a retrograde step.  The distance between the bearing races is very small so the loads are extremely high.  Some sources say this was because Jaguar had intended this setup to be used on 4wd cars - makes some sense when you see the space.  They probably did that to save some weight - and then put an electric motor in the seats to raise and lower the headrests!  True, there is a difference between sprung and un-sprung weight when it comes to handling.

    Anyway, there are all kinds of special tools required to do this job but apart from the rotor nut socket, most others can be got around with some ingenuity and a few bits made in the workshop. 

    I decided to source a second hand upright so that I could do this job at my leisure and even rust treat and paint said unit before fitting - yes, I know I ought to get out more!  Eurojag came to the rescue with an upright and I sourced a socket for the rotor nut as I had no sizes with which to make one from. 


This is the MDF template with pilot holes drilled

.....and the finished plate mounted in the vice



Removal of the upright. 

    The JTIS service info indicates the use of a spring compressor -  I do have a spring compressor from the XJS but wasn't sure if it would work on the XJ8.  In the event there was enough room at top and bottom to get my Sykes Pickavant separator in and free the pins from their tapers.  It's worth giving the exposed ends of the pins which stick through the nuts a really good clean and spray with penetrating fluid before trying to undo them - if the nuts bind up on the rust part way off, they can sometimes release the pin from the taper and then you have a real problem.  


Undoing the abs rotor nut

    I made up a pattern in MDF and took it round to the Smiddy in Sandwick and they cut one for me out of a piece of half inch plate -  it just needed the holes drilling on a 120.65mm PCD when I got back.  This can now be mounted in the vice and 3 wheel nuts to clamp it with.  It saves a lot of hassle trying to hold the hub while you undo the rotor nut - which is also the ABS ring.  There is a spring clip to prevent the nut from unscrewing and this has to be prised out before unscrewing the nut.

Soaked in penetrating fluid and then dropped in a tub of diesel for nearly a week before I got round to attacking the rotor nut - see why I decided to source a spare unit.


This is the spring loaded locking clip

...and the ABS sensor which is a push fit in the upright - be careful removing it they will break easily


This is the bolt which holds the sensor - weight saving at its extreme - the head is only 8mm across the flats instead of a more normal 12 or 13mm, which would provide a better spanner hold.  This area was soaked overnight in penetrating fluid so that I had a chance of removing and re-using the sensor as a spare if need be.  (Yorkshire born and bred tha knows!)

All sources suggest that this rotor nut is TIGHT - and they're not kidding -  I ended up on my arse a good few feet away from the bench when it finally let go and I thought at first I had broken the bar or the newly acquired socket - and I even got my overalls dirty!

Not really wishing to take anything from the excellent club tool hire scheme, I bought my rotor nut socket from the Tool Academy (www.thetoolacademy.com) for 21 plus 4 post and packing.  It's made by Laser Tools and is certainly up to the job.  How come the Jaguar one is 155?  It is imperative that you clean all the crud from the ABS ring to ensure that the socket seats fully down onto the ring.


The Rotor Nut removed from the hub centre



Once this nut has been removed, the hub centre needs to be pressed out from the bearing, so some form of safe support needs to be supplied as close to the centre as possible to prevent distorting the carrier.  You are now left with the upright and its centre bearing - this is held in with 2 fairly decent circlips which should have been fitted with the open ends at the bottom when on the car - it does matter, as any water can drain out instead of creeping into the bearing during service.  Now the bearing needs to be pressed out, so all those off-cuts of stout tubing under the bench that I've kept for years, once again came in handy.  These bearings have quite a large area of metal in contact with the inside wall of the upright and after many years of use they can be TIGHT!

It's very important when replacing the bearing (any bearing in fact) into the housing, that force is applied only to the outer race so whatever you use as a pusher must be relieved in the area of the inner race.  When pressing the hub back through the bearing, then only the inner race should be supported.  I walked into a repair workshop some time back and there was the 'mechanic' happily thumping hell out of a new bearing with a huge metal bar as a drift to put it back in the hub of a 4 year old van - now ask me why I'm sceptical about 'Full Service History' adverts!

When tightening the rotor nut - to 305 Nm (about 220 ft lbs) of torque, you have to make sure that the slots line up so that the spring clip can be refitted - don't be tempted to back off the nut a little, you MUST tighten it further to get the alignment.  Incidentally that torque figure is a bit like hanging a complete Mini engine/box/final drive at the end of a 12" long bar on your socket - tight innit?

    Being a sad old git, I now cleaned the upright and de-rusted it with Jenolite and gave it a couple of coats Bondaprimer and then two of satin black before reassembling the whole thing.  I gave the same treatment to the dust shield and treat the 3 torx headed bolts to copperslip before fitting.  Yes, I know I keep saying that this is just a disposable motorcar - but I'm getting to quite like it and think I would find it a struggle to source one as good for the money.

    The new bearing is quite easily fitted and pressed down to the first new circlip and fortunately the outer edge of the circlip groove is of a slightly larger diameter.  This allows the bearing to enter the bore squarely prior to pressing.  Once down to the circlip you should have a clear view of the other groove and the circlip should sit snugly up against the bearing - don't forget to position them with the gap to the bottom.  The newly painted dust shield was next to be fitted with the 3 Torx screws.  The wheel hub can now be pressed into place, making sure to support the inner  bearing race.  The rotor nut can now be fitted and torqued (305 Nm or 220 ft lbs) and then the spring locking clip fitted.  I decided to use the ABS sensor which was left in the upright from Eurojag, to see if it was actually worth keeping as a spare.


Torque settings (from the JTIS CD)


Top and Bottom ball Joint nuts 60 to 80 Nm  (45 to 60 ft lbs)

Track rod end 71 to 85 Nm  (52 to 62 ft lbs)

ABS sensor bolt 8 to 10 Nm   (6 to 8 ft lbs)


It has tidied up quite well and is ready for the ABS rotor nut to be screwed on.



The ABS rotor nut now fitted and the spring locking clip fitted.



     That's it then - time to re-fit the whole assembly to the car and road test - I noticed that the noise was getting a little worse on our recent trip South to Glencoe so it will be nice to have it back to how a Jaguar ought to be.


    Needless to say I will now fettle the original hub with a new bearing in the same way as a 'quick to fit' spare - someone else in Orkney might need one even if I don't.  I might even get a nearside knackered hub to do the same sometime.





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