I've got a noise that, with help, seems to have been isolated to the differential.

It has people scratching their heads though in that the noise appears only after driving the car for something on the order of 10 miles or so. (My trusted Indie could not hear anything with a stethoscope.) Once it appears, it has these characteristics ...

- coasting, no noise
- mild acceleration, maximum noise
- harder acceleration, less noise (I think ... not sure on that yet).
- rev motor in neutral, no noise
- seems to be coming from the right side or center, rear of the car.
- a "grinding" kind of sound.

We think all other possible sources in the back of the car (except maybe the drive shaft) have been eliminated. The fluid in the differential is full.


I'm hoping the experts here can give be some guidance. Questions:
- Is it OK to drive the car this way for a time under the idea ... "it will get worse so we can find it or it will go away"?
- Is it possible to say from the symptoms whether the cause is likely a bearing or something to do with the gears in the differential?
- If a bearing is the likely cause, is is possible to say which one(s) are most likely?


A little scary, this one. TIA for any help.

 

lol, don't panic man,

Jack the car up high, and supported.Disable traction control etc.

Have someone accelerate while you look or vise verse.

Common problems, are

1.Failed U-JOINT RIGHT REAR

2.Cracked coupling center of car-transmission.

Keep driving the car, it will not hurt nothing and eventually become more noticeable to find.

 

We've run the car through its gears while up on a lift, my Indie listening with the stethoscope. No joy yet.

Something happens when the car is driven for a while that we can't seem to duplicate on a lift.

My concern is that maybe I've got a failing bearing and by continuing to run it this way I'll mess up the pinion or some other gear in the differential ... turning a not-bad price tag into a big one.

 

I'd be checking the axle shaft u-joints. U-joints rarely make noise during coast, always (if bad) show up during acceleration. RR receives majority of torque and is the 'gutter wheel' (at least when driven on the proper side of the road ;-) ) which is more of a concern on Jag rear suspension as the axles also act as the upper lateral links.

 

Thanks for that. We've looked pretty hard at the axle u-joints. All seem good. But this is definitely a "wheel speed" noise, as opposed to something in the suspension.

I've got no feel for interpreting differential noises so I'm sort of flying blind here.

It's sort of ironic that my MGA diff has never been touched (far as I know) other than fluid changes. 52 years!

 

Just keep driving it, whatever is the issue, its going to have to be replaced anyway.

 

To be honest, I've got a similar noise. Sounds like a bearing but has little increase in noise when cornering. No increase in noise during coast, slight (maybe) during accel. No odd tire wear pattern(s). No perceptible play in u-joints but I've been suckered in by that a few times over the years. Not convinced enough to point a finger at the diff. Not the driveshaft or supporting parts, it's definitely wheel speed. Did a quick peek while spinning on the rack last fall, didn't come up with anything at that time. Too busy and already have a couple boxes of parts that need installed as it is. Maybe this fall I'll be able to get to it...

 

Restating my problem: I've got a noise that varies with wheel speed, comes on only after 10 to 15 minutes of driving, seems to emanate from somewhere behind the seats, center or right side.

I'm starting to think that maybe drive shaft components should be added to the list of suspects. I note there are 2 U-joints and a flex coupling there. I'm told the U-joints can't be lubed but have not confirmed this.

Questions: has anyone had any of these things go bad and, if so, what did it sound like?


I sure wish the damn thing would get worse so we could find it.

 

One thing to remember is if it's the driveshaft it will be three times faster than wheel speed.


My flex coupling was shot when I got the car but it made no noise whatsoever.

 

Yes indeed! This is what got me thinking about the driveshaft. The noise varies with road wheel speed, but the repetition rate is for sure more than once per rotation.

3x road wheel rotation might be about right. Of course this could also mean pinion bearing in the diff, right?

 

http://www.skf.com/binary/79-61924/TT08_024.pdf

 

Hey Dennis,


I got the same problem on my '98 XKR and now on my '03 XKR !
A couple of years, i found a thread about this on jagforum but I cant remember which one it was.... but I made a screen shot !
I did it on my 98--> no succes I have also changed the oïl (3 times!!), and noise was more or less present. I will try it on my 2003...
It seems to be an XK issue.....
I hope it can help you.
Here it is:

 

Here is the post for which you have a screenshot posted but could not find the actual post. https://www.jaguarforums.com/forum/x...se-read-73198/

 

Finally got around to replacing the RR wheel bearings today - noise is definitely gone. Over the past few weeks the noise increased but was still sending mixed signals - could be a tire or a bearing. Bearings generally make consistent growling noises, tires usually whoop-whoop... my noise was more like a tire but it showed no evidence of a problem. Rotating the wheel while on a hoist = no noise heard, also supporting a tire issue. However, today I was committed to changing the bearing and it finally did show up while spinning the wheel by hand.

On another note, the bearings were surprisingly easy to change considering their design. Typically wheel bearings assembled in this manner have tightly pressed hubs (interference fit.) Also typically that presents the biggest challenge - finding something suitable to support the hub carrier while pressing the hub out and not destroying the backing plate in the process. My Hub-Tamer wouldn't quite work in this particular situation yet once I devised a press fixture I found that the hub was relatively easy to press out. The next time I do one of these I'm going to use a slap-hammer and pop the hub out as soon as I remove the axle nut. By doing that one could leave the carrier attached at the lower pivot, change the bearings and seals and reassemble in-situ and not having to disassemble the parking brake, etc. (I'd still remove the ABS sensor rather than risking damaging it)

After inspecting the bearings I found the inner bearing to be the noise culprit and surprisingly found that it is the smaller bearing of the two. Typically when opposed taper bearings are used the inner is the larger as it is designed to carry the load and the outer stabilizes. Also noted that the cause of failure was insufficient lubrication. Obviously not much space to allow for much grease in the carrier yet there was/is space for much more than supplied. If I had the time I probably would have drilled a supply tube in the carrier and installed a zerk (with a relief valve to prevent blowing the seals out, ala S-cam tubes on heavy trucks) for periodic lubrication. Typically front wheel bearings on rear drive cars (which also employ opposed taper bearings) have a maintenance schedule of 30,000 miles.

 

A wealth of info there, Beav. Thanks.

Another of our brethren here is working through what may be the same issue ...
https://www.jaguarforums.com/forum/x...ration-120880/ .
It will be interesting to see what is found there.

The noise on my own car is still there at times, but maybe a little less so. We replaced the rear bearings recently (before the noise in question was heard) and I'm not sure if that makes those bearings more of a suspect, or less of one. Greased the u-joints twice now.

It occurred to me that an issue with a bearing might make some heat, so I've been looking for any difference in rear wheel temps after high speed running. Nothing so far.

I'm not even sure that the low rumble which can be heard rotating a rear wheel with the car on jacks is from the same source as the much louder noise that sometimes shows up on the road.

You think I'm OK driving it while waiting for it to clear or get worse?

 

"You think I'm OK driving it while waiting for it to clear or get worse? "


Some thoughts come to mind since replacing my bearings: Most hub and bearing assemblies have quite a bit of interference fit whereas these don't. When a bearing becomes rough enough it will impart enough reluctance to rotate as to cause the part(s) it's supporting to begin taking up it's slack. In this case that means the hub. Since it is, or at least is very close to, being a zero interference fit it could quite easily become damaged if it becomes easier to spin in the bearing than it is for the bearing itself to rotate. Then there is the possibility of the bearing's outer race becoming the easier part to rotate - damaging the hub carrier. I'm not trying to scare you but rather give you a couple 'coulds'. Being that I do this every day I'm possibly more attuned to the sounds a vehicle makes. I noticed the beginnings of a problem last summer yet could not duplicate them with the car in the air. I bought a bearing and seal set last year along with other parts (which I have yet to find time to install) figuring sooner or later they'd require replacement. It has been increasingly bothering me and I decided to commit to replacing the bearings and see what happened. Luckily it panned out and I once again have a silent car (until the belt tensioner decided to begin whirring... dammit!)


A low rumble could be the bearing(s) or just normal noise from hand-rotating a single wheel and causing the spider gears in the differential to rotate (normal - to an extent.) A really cheap stethoscope ($5?) would probably help. You'll need to have someone else spin the tire while you listen. I'm not too keen on recommending a DIYer to use the engine to spin the wheel to do this, especially if on anything but a hoist. Just waaaay to easy for something to happen and serious injury or worse to occur.

A failing bearing will create heat but I'm afraid a significant difference between wheels would only occur at or after the time collateral damages have occurred. At least, a non-contact thermometer aimed at the backside of the hubs (to differentiate) would be recommended, to avoid confusion of brake temperatures becoming involved (a little difference in braking between wheels could obscure any chance of determining bearing issues. And brake temps will be way in excess of the bearings.) Measuring at the wheel, it being a huge heat-sink, would mean very little.

 

For what it is worth a simple test that use to work fairly well on the rear wheels:
Noises when acceleration generally look at these two problem areas.
Jack up the rear to get the tires off the ground.
Grab the tire at the 12 and 6 position and try to rock it back and forth any appreciable play tend to point to the output bearing on the differential. There should be very minor play thousandth of an inch.
Grab the tires at the 3 and 9 position and try to rock it back and forth. Play in this direction points to the wheel bearings.


Whining noises after letting up on the accelerator usually point to the input bearing on the differential.


I've had both issue on my previous Jags which have similar systems. My 95 XJ6 had an input bearing to the differential go out. And my 88 XJ40 had the out put bearings of the differential go out.


Neither car ever had u joint issues with well over 160K miles on each of them. U joint problems seem to be rare from my prospective.


Hopefully this helps

 

There's a difference between the 'output' bearing, as you call it, and the side bearings (or carrier bearings.) The differential carrier bearings do not support the axle shaft and will never show play at the wheel end. However the carrier bearings can mimic a failing wheel bearing. The axle (half-shaft) inner support bearings (used primarily to locate the shafts as a lateral link for the suspension on Jaguars -12&6 positions) almost always show more than a thousandth of play yet not make any noise as a result of their clearance - up to a point. By the time the wheel shows play at the 9&3 positions it will probably have collateral damage to the hub and or hub carrier.

 

Thanks for the additional clarifications. I should have used "excessive" play. And I did have to replace one of the hub carriers on the 88 due to the wheel bearing failing. And hopefully avoided the other side because I replaced it's bearings at the same time. The 88 gave me the most problems with bearings. The 95 I just replace the differential with a new one since the input bearing went out. At that time there were new differentials available with slightly different ratios that were much more cost effective to replace than rebuild.

 

Thanks, guys, for the ideas and your interest.

We've done the stethoscope work with the rear wheels driven ... no joy. It seems there must be a load present for the noise to show up, and it tends to do so only after driving for at least 15 minutes or so ... especially after a period of highway-speed running.

Beav's comment about the spider gear makes me think that the rumble I was hearing when spinning a rear wheel by hand is not the problem. Of course that assembly is not spinning in the same way while on the road (unless I've gotten myself into a crazy situation).

The rear bearings were replaced recently (before this noise showed up) and my trusted indie feels that nothing seems amiss there. The noise did not appear immediately after the new bearings went in. Still, I wonder about them ...

Warning! pure rationalization follows: I do think the severity of the noise is decreasing somewhat. (Wishful thinking can't be ruled out here.) If we were to try replacing some component(s) at this point, it would be little more than a guess what to poke at. (Bearings again?) So I guess I'll drive it under the gets-worse-or-goes-away theory, hoping to dodge the bullet of creating new damage to some big-ticket component. Thing is, I just don't know what else to do.