Front stub axle change

[Dimdip]

Not sure if this belongs in here or steering but -
I've just had the "pleasure" of replacing the front discs and found both stub axles worn in the area of the inner bearing, not too unusual from what I hear.
While I'm waiting for the parts I thought I'd see if anyone has come across any unforseen difficulties doing this job?
Forewarned is forearmed as they say!!
Cheers

[poprivet]

There are many conflicting methods of setting wheel bearing play. The important thing to remember is that if the stub axle has worn the bearing has been turning on it when it should be static, only the rollers should roll!
Pop

[Mark_B]

If you haven't an appropriate extract tool, you wait till you try and remove the stubaxles, they'll be well and truley attached. It's a taper lock fit and very strong!

About the inner bearing... someone correct me if I'm wrong, but isn't the inner bearing race meant to do a 'harmonic vibration' thing around the stub axle, rather than be tightly fitted to it? If it does then any wear betwen the SA and inner race is not 'take-uppable' by adjusting the taper bearings, there's a slack that's always there. When you change the SA you'll want to do the bearing too.

And as PopRivet says, many different methods. My favourite is the JEC magazine 'simplified method', goes something like: adjust up to remove all slack, and slacken castle by 1/2 a flat.

Stubaxles and bearings well worth doing, the difference it makes to the straight-line stability.

[Dimdip]

Thanks for the replies,
The bearings are new with discs and only fitted to allow me to move the car while awaiting new stubs.
I'm also under the impression that the inner races on the XJS should "float" around the axle but haven't seen this anywhere else - every bearing I've met before is tight on the axle and the rollers/balls do their bearing stuff. It does result in brinelling but I'd rather have that then have to change stubs!

[poprivet]

I know this will open a minefield, but discussing wheel bearing clearances may be appropriate here! It's not difficult to set a bearing with the correct pre-load when cold (as Mark correctly describes) to ensure that the rollers do all the work, the difficulty comes about in agreeing how the entire assembly will behave when hot, after many miles in mid-summer with heavy braking involved.
No-one wants a tight bearing to fail due to overheating (it happened to me with a Ford Granada) but a slack assembly will also not perform correctly.
Open to discussion - ?

[Mark_B]

Too baggy is better than too tight, if over-tightened something will give like the inner race starts turning on the stubaxle rather than rolling round it, then after metal burns off you're left with a baggy(er) bearing again anyway. Something I'd noticed a few years ago when I was a teenager, my skateboard used to roll a lot better with sloppy bearings!

[nigel1]

I found removing the stub axle dead easy.

Disconnected brake flexi hose from calliper, plugged hose. Removed the two bolts securing the calliper. Be careful here as there are shims on the bolt between the calliper and the steering arm, so make a note of them.
Removed calliper.
Removed the bolt/nut securing lower end of shocker, lifted shocker up and secured out of way to give access to the nut securing the axle to the axle carrier. (3/4" AF)
Slacked backed this nut a few turns but do not remove completely.
Remove hub dust cap, split pin, hub bearing adjustment nut. Then screwed on a 5/8 UNF nut on to the axle, (did not want to risk damaging the adjustment nut at the next stage.
Tighten up the nut on the axle, forcing the thrust washer against the bearing. This has the effect of pulling the axle from the carrier. The axle came free at about 60Nm, so not to much weight needed.
Remove the nut and thrust washer, and pull hub/brake disc clear of axle. Fully remove the nut holding axle to carrier and pull axle clear.
Noted that the inner bearing had been turning on the axle, about 0.2mm wear on the lower side of the axle.

[Dimdip]

Thanks for all the replies and suggestions.
I've done the change and it was suprisingly easy - I made a tubular spacer to allow an old wheel hub nut to put some tension on the axle (a good nip up but nothing drastic!) applied some freeze spray to the back of the stub and gave it a sharp "tap" and it flew out. reassembly was, as they say, the reverse.
Both steering and braking control vastly improved

[nigel1]

If you dont mind me asking, how much did the new stub axles cost, and who supplied them

[Mark_B]

If it helps I gotten through 3 SA's so far, the first was a genuine Jag one cost over 100UKP the other 2 were pattern parts 30 each, sorry can't remember where I got the last 2 from. The pattern ones seem to be tighter tolerance than the jag one was.

[Dimdip]

Yes, I can confirm those prices, mine were around £95 +Vat each for Jag parts from my local dealer.

[Mark_B]

And you can mail order freezer spray from www.cpc.co.uk product code: SA01094 6UKP a can. The funny thing, freezer spray is actually R134a, intended for spraying into the atmosphere... In fact I'd used freezer spray for a few years in my airconditioning!

[mdelvis]

Stub axles can be found at www.lakelandjs.co.uk.these are copies.