I have a annoying rumbling/whining noise coming from the rear end that increases and decreases with road speed.
Even with someone sat in the rear seat they have been unable to say which side it is coming from. Could it be the Diff??
I have another 4 litre for spares and was thinking of just dropping the complete rear subframe from both cars and swapping them over.
How easy is it to remove the rear sub frame??
Apart from the calipers and prop shaft, I can't think of anything else.
Could anyone that has done this point me in the right direction.
Thanks Bill W.

 

Hi Bill,

I'm assuming your car is an X308 (it's always a good idea to add the year, model and engine displacement to your signature line so others don't have to ask). If the noise is low in frequency, I would first suspect the rear flexible coupling (also known as a Giubo after the inventor or a Jurid after a major manufacturer), Part 2 in the diagram below. The propshaft/driveshaft center bearing (unnumbered in the diagram but in the center of the shaft) is another potential source of noise:





If the noise is a higher pitched whine that varies with road speed but doesn't change when you let off the throttle, I would suspect a differential output shaft bearing, Part 17 in the diagram below. These can be replaced without having to drop the independent rear suspension. If the noise is a whine like a jet engine that rises and falls with road speed and changes depending on whether you are accelerating or decelerating, I would suspect either the differential pinion tail bearing, Part 9 in the diagram, or the large subframe or A-frame bushings (see the next diagram). Replacing the pinion bearing requires dropping the IRS for access to the differential internals.


Identifying a bad bearing is usually relatively easy using an inexpensive mechanic's stethoscope, with the rear end of the car raised safely on jack stands, the front tires securely chocked, the engine running, and the transmission in Drive so the rear wheels are turning. Just take care not to touch the probe of the stethoscope to any moving component. A bad diff output or pinion bearing or a rear wheel bearing will usually be obvious by the grinding noise heard in the stethoscope.

Another common source of rear end gear whine is failure of one or both large subframe mounting bushes, Part 13 in the diagram below. The bushes are supposed to isolate the differential carrier assembly from the body, but when they perish they allow metal-to-metal contact and normal differential gear noise is transferred directly into the passenger compartment. Replacing the bushes requires removing the lower A-frame, Part 12, but the differential and the rest of the rear suspension can remain in place.






Let us know which of these (if any) sounds most like what you're hearing and we'll go from there.

Cheers,

Don

 

Thanks Don B. I will get her in the air tomorrow, Monday , and have a look. The noise is Low frequency at start off and gets higher in pitch the higher the road speed. From what you say Don B it sounds like the jurid at the rear, I will let you know tomorrow. Thanks Bill W

 

Hi Bill,

The photos at the link below are of our '93 XJ40, but the Jurid is the same part as on the X308, CBC8996.

Welcome to Jag-lovers - Members Photo Viewing Page


Note that I had a bad experience trying to save money with an aftermarket Jurid from Uro Parts that wouldn't balance in any position. An OE part made by GKN balanced on the first try, so it was worth the higher price.

Please keep us informed, and let us know if you find the problem is something else.

Cheers,

Don

 

Hi Don,
I have just had a look at the rear jurid, and it seems from an external view to be OK. What is the best way to check it? My thought was just to replace it anyway!! While I had it up on axle stands I used 2 trolley jacked to lift up the rear suspension to a more normal level. I chocked the front wheels and started the engine. With the car in gear and the handbrake released I couldn't replicate the noise. I was a bit wary of taking the revs much above 2000rpm. I left the engine on tick-over and checked the rear wheels. I noticed that the left hand rear wheel ran true, but when I held that one still and checked the right hand wheel, it had an out of balance looking movement to the wheel itself, wheel bearing??. Once the engine was stopped I took hold of the Right hand wheel, but couldn't get any movement when holding the tyre at 9 and 3 or at 12 and 6. The only movement I get is about 1/2 in rotational movement. How much rotational movement is allowable in the drive shaft couplings? I am going to go and swap over the rear wheels and see if the out of balance stays with the tyre/wheel or the hub.
More comments later

 

Swapped front and rear wheels, nothing has changed, will order jurid and replace it anyway????

 

Check for a loose pinion nut. Mine was loose on mine. Found nut unstaked as well. someone may have did a yoak and seal kit replace on mine. My noise quit after retightening and staking nut.

 

How did you know how tight to make the pinion nut to set the bearing preload?

 

Bill,

The most obvious signs that a Jurid is past its prime are cracks in the rubber, which may only be visible when you stress the rubber a bit. See the 10th photo in the album at this link:

Welcome to Jag-lovers - Members Photo Viewing Page


Based on your examinations so far though, I'm wondering a couple of things. First, is your right rear wheel bent? It's not unheard of. The rotational movement you felt is probably normal driveline play.

The other thing I wonder about is the rear subframe bushes. Since the weight of the car has to be on the bushes in order for the subframe to contact the body, you won't be able to hear the gear noise with the rear end raised on jack stands and the subframe/suspension hanging down. With the car on the ground, take a close look at those large front subframe bushings, which are mount just ahead of the rear wheels. There should be some space between the subframe and body. If you can see any metal-to-metal contact, the bushes have perished and are allowing diff gear noise, road noise and other rear-end noises to pass directly into the passenger compartment.

See the 2nd photo in the album at the link below to see the subframe bushes separated from the body as I was reinstalling the IRS in our '93:

Welcome to Jag-lovers - Members Photo Viewing Page


Another thing to check while you're at it is the Driveshaft Center Bearing. Yours may mount a little differently than the one on our '93, but the principle is the same:

Welcome to Jag-lovers - Members Photo Viewing Page


Please keep us informed.

Cheers,

Don

 

This diff does not use a crush washer. It has a spacer. Tighten as if your where replacing a pinion seal/flange kit.

 

Don, Just got the car up on ramps at the rear. I managed to get a good look at the jurid, and there does seem to be some evidence of cracking. The nuts and bolts look as though they haven't been disturbed since manufacture, so have been given a good soaking in penetrating oil. A little more worrying was the fact that between the jurid and the diff I found a thin ring that is about the same diameter as the input flange area. It is about 3" in diameter. I have looked at the exploded diagram of the diff, and can find no reference to it. It is about the same diameter as the 'O' ring, Item19, but is made of thin flat metal, any ideas?? Another worry is that the area around the input is dirty and the dirt has oil soaked into it?????? If I can I think it means dropping the rear sub-frame and sorting it all out. Happy Days!!!!!!!!!


Bill W
2001 Jaguar XJ8 4.0 ltr LWB

 

Hi Bill,

Yep, it's time for a new Jurid. You might check the condition of the front one too while you're at it. If you find you need to replace both of them, I would recommend replacing one at a time in case you encouter any balancing problems, so you can make corrections to one end at a time. Hopefully, if you purchase OEM Jurids made by GKN, you won't have any problem.


Does the ring have bolt holes that match the diff input flange? I just checked the parts diagrams at jaguarclassicparts.com and the EPC, and like you I can't see anything like that on either the propshaft or diff parts diagrams. Could it be something that was originally part of the pinion oil seal but has become separated?


I'm fairly certain that on an X308 you can replace the pinion oil seal without dropping the rear end. I was able to do so on our '93 XJ40 earlier in its life before I ultimately rebuilt the entire diff. And since the X308 diff uses a rigid spacer and shims to establish pinion bearing preload instead of the crush sleeve/collapsible spacer used on the XJ40 and X300, I don't believe it's not as tricky to replace the pinion oil seal with the diff in place. As long as your pinion bearings are still okay, you probably don't need to drop the rear end. Search this forum or the X300 forum at Jag-Lovers for details.

Cheers,

Don

 

Hi Don,


Getting quite confused now !!! Looking at the exploded diagram of the diff earlier in this thread, it shows the input shaft, to the diff, to be a 3-armed spider with arms at 120 degree. It also shows that the area that the input shaft and bearing fit into, has 4 holes at each corner of the flange area of the diff. No bolts are shown and nor is any method shown of how the input shaft and input bearing are held in. There are definitely bolts in mine for some reason.

When looking at the same area, in the downloaded X308 workshop manual, it shows the aforementioned bolts, but it also shows a 4 hole circular input to the Diff?? How are we to sort these cars out when the information either isn't there or is missing or is just incorrect????????


The thin ring I mentioned is only 1/16 inchwide and completely circular.


The jurid has been replaced, and the old one was full of cracks and splits. Hopefully that will help with eliminating the rear end noise.
I will give it a run with the new jurid installed to see what effect it has had, and then I might have a go at replacing the input bearing, if I can fine the correct information on how it should be done?? Bill W.

 

***Update***


Rear jurid replaced, all torqued up etc and taken for a drive. Nothing has changed, still this noise from the rear.
I had originally thought it might be a rear wheel bearing, but even after a long run both the rear wheels have the same amount of heat coming off them, not very warm at all. This has led me to the rear diff, as my next part to change.
As I only have access to ramps, I will get it up in the air again and soak all the nuts etc in penetrating oil.
I would imagine a diff swap would be easier with the complete subframe removed???
All suggestions gratefully received.
I WILL BEAT THIS NOISE!!! At least, what I have done so far needed to be done, so I am happy with things so far.


Cheers


Bill W.