Hello,
Hope you all don't mind me posting here as not really got a jaguar xjs, just the running gear in a cobra replica.
Uses xjs in board brakes but after advice please.
Rear hub bearing setup in the haynes manual shows 2 thou to 6 thou clearance...
have read on lots of forums that they should be -2 to +2 thou.....is this for xjs hubs outboard type...?

also I have a powerlock 3.54 diff which is whining ?on when get to coast speed very light throttle, whether that's 30, 40,50 or 60mph but more prominent at 60mph. Does this sound common for these and I suppose it's a full strip down required? Fresh oil is in and no change but only whines when warmed up.
Many thanks even if you kick me out lol.
regards
gavcob

 

You are welcome, at least by me!
The diff needs a rebuild.
The rear hub setup is quite demanding, be sure you 100% understand it. The thread link here may help, see post 5:
https://www.jaguarforums.com/forum/e...cement-244184/
The bronze shim needs to be anywhere between +2 thou endfloat or - 2 thou preload. If you are rebuilding the hubs, as long as you use Timken bearings (OEM) the shim already in there should be fine. New UJs are worth putting in if they are old; but only really good quality ones.
This is for an XJS, but the hub design is the same, and the steps identical.
https://www.jaguarforums.com/forum/x...ebuild-225834/

 

Hi, thanks for reply.
why does it say in haynes Manuel endfloat 2 to 6 thou?
I have already done hubs but could take some more off the shims to reduce tolerances
regards
gav

 

Try one more thing before you rebuild the diff. Jaguar calls for a positraction supplement to be added to the gear oil.
It’s not in the oil you buy, most parts places look at you with a blank stare. Go to the Chevy dealer and ask for the positraction supplement.
I would drain the gear lube in it and see if it has metal particles first if so that’s a very good warning the rebuild time is nigh. But if not too bad you might try fresh 90 wt with the supplement.
How is the rear ended mounted? Is it on the rubber mounts Jaguar uses? If solidly mounted you’re in trouble. The suspension only works if mounted on rubber.
Race cars that rigidly mount the rear end have to bring the trailing links into the inner pivot point in order for it to get the required compliance due to the conflict in the arcs.
If that sounds confusing please ask me to explain. Otherwise the rear end will be torn up. And you basically have a rigid rear end.

 

A lot of modern differential oils have the additive already in it. The Valvoline synthetic I use does.

 

As does Castrol LSD diff oil. Nevertheless, I have never come across a whining Jaguar diff yet that did not need rebuilding...
Castrol syntrax is the stuff, easily available in the UK:
https://www.amazon.fr/Castrol-SYNTRA.../dp/B004UBDGYW

 

Hi,
used 90 with diff additive in and then this which some cobra users use., no bits on drain plug
it is hard mounted but not a problem for other cobras with same setup.
other pictures show 2 to 6 thou for hubs in haynes manuel.
regards
gav

 

2 to 6 wil be fine.
As long as the radius arms have rubber bushes, so will the axle.

 

Hi, the kit doesn't use radius arms.
The cobra only weighs 1100kg btw.
regards
gav

 

FWIW my Jaguar ROMs show .001"-.003" end float as desired, and amounts exceeding .005" falling into "must be rectified" territory.

But these hubs seem to be quite forgiving. What seems (to me) to be excessive end float never seems to create a problem as far as driving characteristics go, nor create noise/bearing problems. Certainly there's a point of no return, so to speak, but it's quite a ways out there. Bearing failures, when they occur, are more likely due to lack of lubrication than anything else, IMO.

I think any of us would be happier with less end-float rather than more, and some insist that pre-load is actually the preferable set-up. I dunno. Maybe taking it just down to zero would allow everyone to sleep better ?

Cheers
DD

 

So are the drive shaft and bottom wishbone supported front/rear in any way? or is it just the bottom wishbone inner fulcrum bearings taking the acceleration and deceleration loads?
Have you got a photo of the setup?
As to hub endfloat, I on reflection agree with Doug, I reckon +6 thou is a bit too much.

 

Sigh, if you are counting the lower axles to keep the rear tires aligned, Tssk tssk.
I wish you good luck and I’d sure be gentle about acceleration. If you look at every used rear end you’ll find 3-4 worn out needle bearings. On each location.
There is a reason the rear end has drag links. Light weight XKE’s ( the race car version ) either had rubber mounts or the drag link came in at about a 45 degree angle to pivot at he inner pivot point.

Maybe you will enjoy the rear axle steering you around?

 

Just on the diff whine, if the diff seems fine under some load but whines on coast l would check the pinion preload before getting into a diff rebuild.
relatively easy to check and rectify, not much to lose.

 

Hi,
I didn't design the kit and there are 600hp versions around with no I'll effects...
're pinion preload check will have a look thanks.
regards
gav

 

I have the 3.54 diff in my 94 XJS and it whined. This was the state of the bearings when I got into it.

Don't be surprised if you need a rebuild!

 

Hi,
was yours whining on coasting as well? And which bearing, pinion?
regards
gav

 

Yes, mine was making noise everywhere. Actually, all the bearings looked like that, and the cross shafts in the limited slip had broken, filling everything with metal. The only thing I reused was the ring and pinion, I replaced everything else including the case. Mine was pretty extreme example though, I've not seen another Jaguar differential that beaten up

 

Ok thanks for reply.
regarding checking pinion preload as previously mentioned before complete overhaul, I remove prop shaft and check force required to move flange when in backlash correct? It's a last ditch attempt so nothing to lose. What inch pounds am I aiming for? Or is it to see if pinion nut has been previously marked and if so has it backed off?
regarding setup as a whole would a watts link setup on the LCA help as in here?

Regards
gav

 

The normal way to check the pinion preload is with nothing else in mesh, so the crown gear and axles have to be removed. Then you are measuring the drag on the pinion bearings only, and you're aiming for around 20 inch-lbs.

A second way is to mark the nut relative to the flange, loosen it off and then tighten to specification. I forget what it is, but plenty. You will need the flange holding tool and a long breaker bar to be able to exert enough force to tighten the nut.You have to do this by hand, you can't use an impact wrench. It should come back to the previous mark, but also there is a crush sleeve in there for generating the preload, so if you overtorque you can't back off the nut. The diff needs to be stripped and the crush sleeve replaced.

Yes, undoubtedly a Watts linkage would help. On the jag, the radius arms are there to prevent rear wheel steering caused by the whole IRS assembly moving under torque. It's amazing how much compliance there is in the mounts, so a way to control that motion is necessary.

My guess is your pinion mesh and/or backlash is incorrect, and that is what's causing the whine. It's possible that it's out of mesh because of bearing wear and a set of new bearings will cure everything, or it needs to be rebuilt. It's possible to rebuild it at home, as you have the manual. You must follow the instructions exactly, and make sure everything is in specification. You'll also need to be able to measure accurately to 0.001", and a vernier caliper isn't accurate enough.

Pinion depth is the critical first setup, if that is wrong, you'll never be able to get backlash and side to side carrier clearance set correctly - you'll only be able to set one, and not the other. The shims also go behind the carrier bearings, so you need a special bearing puller and a press. Anything other than the right clamshell type puller will destroy the new bearings. Expect to have to press the carrier bearings on and remove them several times to get the shims correct.

 

At last a photo! Your axle lower wishbone is not unsupported. You have a leading and a trailing link to take the acceleration and braking loads. It looks like it is located on the wishbone by a bolted fixing and I presume there is a bush somewhere to allow up and down movement of the axle, as the links look rose-jointed. A very nice setup that needs no improvement.
A watts link is only suitable for live (ie solid) rear axles and its function is to prevent side to side movement of the entire axle. It would therefore have no function on your solidly mounted setup.