I've got a few different questions about the rear half of the drivetrain/suspension, which are hopefully all related to one another, otherwise I've got even more problems. I'll start with symptoms and then list known issues and questions.

Symptoms:
-Took my car in for an alignment, was told the camber on the rear wheels measured fairly high negative (-1.6 deg RR, -1.1 deg LR), along with a disclaimer saying there is no rear camber adjustment. I'm assuming that came from Alldata or something, this was at a tire shop, not a Jag specific shop.

-Got new tires put on recently, on factory wheels, replacing the non-OEM wheels and defective tires that were on there. Low hum at highway speeds (around 65mph most noticeable). Very low frequency, in the 40hz range, and pulsing smoothly in and out with a cycle of 1.5 secs roughly. Seems to come from the rear, can very slightly feel it in the seat. Turning slowly doesn't seem to change the cycle, so I'm guessing it's only one side. It doesn't sound like wheel bearings that I've heard in that those always hum in a moderately higher pitch. Haven't got a chance to see if high turning load makes it more noticeable at one side or the other. Don't think I felt play in wheel bearings when I looked over before, but I could have missed something. Plan to grease U joints to see if that helps.

KNOWN ISSUES
-play in output shaft bearings. pushing inwards at 12 on both rear wheels results in some play. Looking under the car shows play in the diff output, not the U joints. RR is worse with maybe 1/8 inch of play at output shaft (guesstimated visually) and LR has less with maybe 1/16 in of play. I plan to replace those at some point when possible, but that's a task in itself...

-Coil spring isolator (the very big foam donut) maybe worn on both sides. Possible the pendulum upper bushes are worn, I'll know for sure about all that when I drop rear subframe to do fuel pump/line.


It seems real wordy, but I don't know any better way to explain everything without thoroughly explaining known, what's been done, etc...


Anyway, the questions.
-Anyone experienced a similar noise before? Would it be caused by the known bad output shaft bearings, or possibly/likely something else?

-Camber adjustment - is it actually possible? I've seen something about shims between the halfshaft/diff output flange. JTIS doesn't list a camber adjustment in the other rear suspension adjustments, but it does say "adjust camber" at the end of the output bearing R&I...

-Wanted to make sure I understood correctly and found the right part for said output shaft bearings. The part I found is JLM20337, part 17 in this diagram Differential Assembly - Parts For XJ Series from (V)812317 to (V)F59525 (X308 - Canada/Mexico/USA) | Jaguar Classic Parts UK and I'm guessing the retaining collar that gets pressed on is C2A1421, part 15 in same diagram.

 

Cambwr adjustment is achieved by replacing the discs between diff and drive shaft. The thicker the disc, the less negative camber you'll have...

 

That's what I thought when I saw those discs, wasn't sure. I'd assume the worn isolators and bushings, and play in the output shafts could influence camber as well.

 

What kind of tires are they?

 

Bridgestone Potenza RE970AS Pole Position Bridgestone Potenza RE970AS Pole Position

They only have maybe 75 miles on them so far, so there may still be a bit of break in to go. I have noticed that they noticeably flat spot even sitting overnight, but it works itself out after a few miles at highway speed.

 

You could make a more accurate assessment of the bearing play
by mounting a dial indicator either at the face of the output
flange or against the outer rim of the wheel.

In any case, I would think anything more than barely perceptible
movement is too much. After all, the shafts from the upper link
of the multi-link rear suspension and controls camber. All that
movement translates to unintended camber change.

Although it is the most difficult of the proposed fixes, changing
the bearings would be the most likely to yield results. The camber
spacers are easy to change but expensive and you have no fixed
point of reference as long as the shafts are moving around on
loose bearings.

 

Right. JTIS says 0.15mm is the limit for output shaft float, I figure if I can clearly see it moving it's already far beyond that. I suppose it's another one of those times I can't know what else is wrong until I fix the things that I know are wrong.

So I just need to source and install bearings... guess that means searching around to see if anyone ever found the factory bearing code to source the bearing directly from manufacturer. At $400 a side per bearing from dealers I think I might roll the dice with a replacement used diff.

 

When I did alignments at the dealer (when these cars were new), I found that 4mm shims were the most commonly installed from the factory. A 6mm shim usually corrected the camber after a few years of settling suspension.

I keep two 6mm shims in stock for customers that need rear camber adjustment because that is the likely size needed. At about $40+ each you need to determine the camber before buying a bunch. You might need the stub axle bearings but check for excessive play.

bob

 

Would the stub axle bearings be the part that I was looking at in the first post, JLM20337? Or is it a different bearing?

 

Yes, that is the correct part number for the output shaft bearing. As you suspected you also need the retaining collar, C2A1421. Check with our forum sponsors for better pricing. For example, SNG Barratt has the bearing kit for $120 per side which includes the snap ring and O-ring, and their price on the collar is around $30. Also check with Coventry West and Jagbits, and the other good independents. I think the original bearings were made by SKF, but I don't recall that anyone has found a cheap source for them like an industrial supply house. Apparently the bearings are rare and possibly unique to the X308/X100 application:

X308 Differential Output Shaft Bearing Kit

X308 Differential Output Shaft Bearing Retaining Collar

The output shaft bearings could definitely be contributing to the low hum you are hearing. 40Hz is very low, the fundamental of the E string on a double bass or bass guitar, but the bushings that isolate the rear suspension from the body may be filtering out higher harmonics.

Replacing the output shaft bearings is not as difficult as you might think. Do not remove the large aluminum collar with the notched/castelated rim - it's very important to leave it exactly where it is. Instead, just remove the snap ring and slide the stub axle out of the diff. Replace the bearing and collar and reinstall with the new outer O-ring and snap ring. I think there are photos somewhere on the forum.

On the XJ40/X300 you need to drill and cold chisel the old retaining collar to break it before pressing off the collar and bearing to reduce the pressure required to avoid stressing and possibly breaking the mounting flange, but I can't remember if the same is true on the X308/X100. I think you may be able to just support the back sides of the bearing and press both the bearing and collar off at the same time. Bob will tell us.

Cheers,

Don

 

Below is the only article I have ever seen on rebuilding the
V8 differential stub axles:

Jaguar V8 Axle Rebuild

edit: see cautions from Donb and Motorcarman below regarding the threaded collar!

 

That article gives some helpful photos, but unfortunately it begins with the ill-advised step of removing the threaded aluminum collar, which makes the job a lot harder than it needs to be because unless the position of the collar is somehow marked, the preload/gear mesh may be incorrect after reinstallation. Removing the snap ring with the stub axle in situ is a little fiddly due to the limited access, but if you have a pair of snap ring pliers it's not hard and is well worth the effort.

The article does seem to answer the question as to whether the collar must be drilled and weakened prior to pressing it and the bearing off, but drilling and splitting the collar is much easier if the threaded collar is left in the diff and just the stub axle has been removed.

I can't recall where I learned about leaving the threaded aluminum collar in the diff but I would bet it was either in this forum or at Jag-Lovers. It may have even been Bob (motorcarman) who shared this tip.

Cheers,

Don

 

The threaded aluminum collar sets the crownwheel 'side-to-side' as well as the preload on the carrier bearings. (LEAVE IT ALONE!!)

thanks Don B

bob

 

All good to know. The manual seems to show the same way as the mentioned method for the xj40/x300 diff with removing just the stub axle and drilling and chiseling the old retaining collar to loosen. Of course it's hard to know much from a few diagrams there.

I'll probably pull the xj8 diff from the junkyard tomorrow if it's still there, I've already mostly dropped that subframe for fuel lines, just need to undo calipers and driveshaft to free it. Not sure what they charge for a diff there, maybe I'll get lucky and the stubs have good bearings. At $180 a bearing it's still worth practicing pulling apart a scrap diff to practice on if I can.

 

The diff will likely have at least one good output stub axle. I'd get it if was reasonable.

bob

 

They wanted a bit more for a diff than I was willing to pay for it, but they gave me a reasonable price on the stubs. Naturally the nuts that hold the output flange to the half shafts were SAE and not metric... or if they were metric they were 18mm, but that may as well be SAE, I didn't have it in my junkyard tool bag. Will have to go back tomorrow with some penetrating oil and more wrenches...

Could feel a little bit of play when pushing on either rotor, think drive side has a good stub and the play is a worn U join, where the pass side may be play in the stub bearing, but significantly less than either one in my car. I'm guessing it's just like any other bearing, in that I'll be able to tell more when I pull it out and spin it in my hand?

 

The nuts are 11/16" as they have been since 1961.

bob

 

At the junkyard right now, managed to get one side apart all the way to getting the circlip out. Is there anything else I need to do to pull the stub out, or should it just come out now? Once I get the other side done I'll run to my car to grab my prybar, I'm hoping that's all it needs. Am I missing any more steps before I get prying?

update: got them out, passenger side just took a little bit more effort

 

A few updates. Found details on the bearing. It is made by SKF, part number BB1B1862021B. I can't find anything more about it except for some references to it in some jag threads. I'm guessing that it's one of those things like the x308 xjr harmonic balancer in that it's NLA and that's why prices are insanely high for it.

The sng barratt part seems to be an alternative replacement kit (as I'm guessing is denoted by the * at the end of the part no, they carry the OEM JLM20337 at that same cost. I remember reading somewhere that someone found replacement bearings that worked in every way except that they were 2mm thinner, and so would need a 2mm spacer to fit properly. I'm guessing the kit there is said bearing with a spacer kit, but I'm not sure.

I've found a newer noise to go along as well. This was actually happening occasionally before, but I'd never figured out how to replicate it until now. Driving along at between 20-30mph, a metal on metal knocking sound can be heard when coasting completely off throttle (and also noticeable under braking). It seems like it's coming from the back right of the car, but I'm not sure. It's definitely not engine noise, dropping into neutral doesn't affect the sound at all. I spun the rear wheels by hand in the air to see if I could notice anything, nothing. I'm hoping it's caused by the bad output shaft bearings, but I'll take a closer look around and check the propshaft as well when I have the rear subframe out.

Took a video, it's pretty hard to hear but it's there. It's almost impossible to hear when inside the car and windows are closed. https://drive.google.com/file/d/0B5f...ew?usp=sharing

 

More updates! Got the junkyard output shafts installed. While I was disconnecting the driveshaft to coupler bolts to drop the rear subframe, I found that one was loose, the nut wasn't coming off the bolt, but I could spin it in place by hand.

Anyway, new output shafts got installed, zero play on one side, and almost zero play on the other. Much better than the ones that used to be in there. I don't know about doing it in situ though, that seems like a difficult time. Maybe with power tools and proper snapring pliers... those snaprings are evil... Greased U joints while in there. My $10 grease gun blew a seal halfway through, and I'd never used it before then. At least it got the job done.

The low frequency hum seems to be gone, or at least greatly reduced. Feels more like the front now than just an all around noise like before. The knocking noise in my last post is gone. I haven't got an alignment check done yet to make sure toe is still good and camber hasn't worsened. I may wait until I replace the spring isolator foams to worry about swapping different shims unless the camber is very severe.

The bad bearings felt absolutely fine when I played with them out of the car. No play, notchiness, or roughness. I might try and take one off to pull the bearing apart at some point in the future.