Driveshaft buckles under moderate acceleration, causing the Y-flange of the u-joint to make contact with the undercarriage, making a knocking sound. The differential unit, 2 jurid couplings, and center bearing where all replaced around 8 months ago, yet the rear jurid coupling is shot.

It seems like there is a lot of resistance between the transmission and the wheels, yet when I rotated the wheels by hand and rotated the driveshaft by hand, I didn't notice anything unusual, except that my right rear tire is more worn out than the left rear tire.

Could it be that the condition of the jurid coupling is causing the driveshaft to buckle under moderate acceleration?


Differential-end jurid coupling after 8 months of use

Differential-end jurid coupling after 8 months of use

Areas of the Y flange of the u-joint that make contact with the undercarriage when driveshaft buckles under moderate acceleration.

 

In my opinion, this is probably the weakest part of the XJR. I've had the most issue with the driveline, yet the engine and transmission are pretty solid components with the proper maintenance.

What this car really needs is a one-piece driveshaft with a beefed up limited slip differential.

 

You certainly need to replace the damaged coupling. Take care to install it in the correct rotational orientation, as shown on the pics below (note the arrows on the coupling and the thicker and thinner segments).

As for the increased wear of your right rear tyre, it could be due to a fault in the "Traction Control" which is actually an electronic LSD. When it is detected (by the ABS sensor) that a rear wheel is about to start spinning under harder acceleration, the ABS will start applying the brake on that wheel to prevent its spin. This is much like what the internal friction plates of a mechanical LSD do. It may be the case that your ABS system is unnecessarily applying the right rear brake. You should run an ABS diagnostics to see if there are any faults.

 

Yes, I agree. Hope you get it solved.

 

I mounted the guibo/jurid coupling the wrong way around and I can attest that when I changed it again, only after less than a year, it resulted in accelerated wear (cracking) and it causes a drive line vibration when taking off in the car at slow speeds.

Both issues totally resolved once I mounted it the correct way.

 

I developed my own beefed up rear end with an 85% Torsen. The difference is night and day. A friend of mine just fitted it to his XKR and he says the difference is amazing.

Unfortunately its not cheap and I don't sell a 'kit' because I make no money on it and am sick of all the whining (must be millennials who want everything for free!).

 

It seemed as if the old coupler was mounted correctly. Anyways, I swapped in the new one, making sure I marked all the bolts and lined up the shaft to the differential input shaft correctly. All is good now, and I can burn some rubber now. The problem was that the cracks in the coupler compromised the rigidity and allowed the driveshaft to flex and buckle.

I had check this same coupler a couple of weeks ago and didn't see anything out of the ordinary. I guess on one hard acceleration, it just decided to give out.

As for the worn tire, I rotated the differential input shaft clockwise and noticed that the right wheel would spin more freely than the left. Not sure why, maybe the left side hub assembly is a little more worn, or a warped rotor is causing some drag? I did swap the left and right tires and eased tension of the hand brake tire, so I will keep a close eye on this.

 

M. Stojanovic
Good suggestion. How would I go about performing an ABS diagnostics? There aren't any lights on the dashboard.


Count Iblis,
That's great. Don't know why people would complain if there's not many options for upgraded diffs--its either take what I have, or bugger off.

It seems like we have to go custom for any serious modifications on these cars--a shortage of aftermarket really. I have already fiddled around with swapping out the diff and it isnt something I would like to repeat, that's for sure.

 

Well, if you burn rubber this is what will happen:

 

Icarsoft i930 can read some ABS codes but, of course, the best would be to do a scan with the Jaguar diagnostic tool, VCM and IDS.

 

I may look into that when fundings allow. Right after I have to buy a new set of tires, and another broken coupler from having too much fun.

 

Perhaps one of your rear tyres worn more than the other was also a result of the burn-outs? In such a case, you don't need to bother with diagnosing the ABS and the Traction Control systems.

 

I think my differential may be on it's way out AGAIN. It is making the same sound as it did when my old diff was going out, and also the car slows down a lot when coasting. Like there is a lot of drag.

Anyone ever go through 2 differentials? I believe this is probably a driver problem for the most part, but are these 14 HU diffs really this problematic for other people, or is it just the way I drive? (I am okay with a little criticism here).

BTW, I don't do burnouts or doughnuts. I only do either accelerations from stops or rolling accelerations, with traction control on.

 

No experience with a bad diff, at least not yet. But if it does go bad, i'd put a diff from an x300 xjr.

 

The traction control applies left or right rear brakes (by the ABS pump) depending on which wheel is about to spin on hard acceleration or in the case of slippery surface. The open diff, together with this braking action by the ABS, acts practically as an LSD.

I don't think a diff, unless it has no oil and it is about to seize, can cause drag when coasting. Binding brakes (or the handbrake) can. Did you check for the drag while coasting with the traction control off?