Recently I developed a sound under my 1989 XJ40 that almost resembled a motor boat. It only happened around a range 25mph to 35mph. Not very loud but it had a harmonics that I could actual feel in my chest.
First thought was an exhaust issue but when I put it up on a lift it turned out to be a drive shaft problem. Everything nice and smooth except in that 10 mph range and then the front section of the drive shaft started really vibrating. Hmmm. Put in a new center carrier bearing item #3 (which I though strange because the old one was relatively new) and the problem was still there.
So after a process of elimination I determined it had to be coming from the front section of the drive shaft.
After making a few calls around the country I found out that Jaguar had a bit of a problem with that part in the past. As you can see in the diagram there are two tubes making up the forward drive shaft (yellow part in the diagram) and the space between those two tubes is filled with vulcanized rubber… BLIMEY ! While not that common it appears that if’s not that rare for that rubber to break down and allow the inner tube to moving around a bit.
Although I could get my hands on several used shaft, who knows what condition they would be in. So I opted to have that part remade into a solid shaft. Should be ready next week and fingers crossed !
Hi Groovman,hope your modification is a success,have you ever changed the rubber part numbered 10?, Just wondering as I have a little slop in my driveline, noticeable on cruise, could it be the rubber here deteriorated.
It’s called a “Jurid Coupling” and yes I have replaced it. Did it with the car up on jack stands with no real problem if I remember correctly. Usually it’s very obvious when they fail because the split.
Funny you should mention that coupling. The only reason I felt comfortable replacing the rubber isolated forward section of the drive shaft with a solid one is because that juried coupling is there to take up any sudden shock in the drive line (at least that my theory).
Thanks, I will get one, you’d be correct I’d say,a drive line shock absorber.Be interesting to know why Jaguar manufactured shaft in that way.maybe,fore/aft flex?
I believe any fore and aft (I love Navy talk) movement between the two sections of the drive line are taken up by the sliding splined joint that connects them. The rubber holding together the two tubes of the front shaft is hard as a rock, but somehow must have broken down enough to allow the shaft to flex, thereby producing the vibration.
The rubber coupling: if it is like the Guibo joints on various other cars, it may come with a steel band around its periphery: if it does, don’t remove that band till all 6 bolts and nuts are through and at least threaded.
The rubber “Jurid” coupling used on our cars doesn’t have any kind of steel band.
They are tough little customers though and even when they start to perish and split they usually still keep working … until they catastrophically fail !
That new drive shaft looks really nice. Was it expensive to have done? I’ve known many people to have this done for different cars, but never done it myself, so not sure on pricing.
VERY reasonable … $216.00 total. Took it in Friday afternoon and it was ready Tuesday morning. Very friendly people. This included balancing and a personal tour of their impressive facilities.
One nice thing about living in a place like Dallas/Ft Worth, if you can’t find whatever it is you’re looking for (probably in the color you want) it probably doesn’t exist in nature !
Thanks Grooveman for your insight, I to have that front driveshaft vibration, did anyone say to you to fill the cavity with Fiberglas resin or something similar? I was just thinking it would work.
Well I guess you could try something like that but I don’t think I would trust it in the long run. And you would still have to get the driveshaft balanced anyway. I think at a little over $200 it was excellent value for the money and it included the balancing.
True, I just dissembled the gearbox mount only to find no bushing left at all, this would misaligned the driveshaft and cause the vibration, on the hunt now for the foam bush, I think there was two MGH7566AA and something else.
I think that a failed transmission mount (complicated little devils aren’t they) would result more in a rattle or thumping noise when you drive over bumps rather than a vibration problem.
The foam donut (#7) that you mentioned and the two rubber gaskets (#11 and #3) are primarily for noise isolation, it’s the two springs that keep the rear of the transmission in place.
Try driving over a very smooth surface and see if you still have the vibration. if you do it’s probably not the transmission mount.
Another much more common cause of driveline vibration is a failed center carrier bearing (#3 in the below diagram) I would suspect this before the problem I had.
The only way I pinpointed my problem to the driveshaft itself was after I replaced the center carrier bearing and STILL had the vibration. Be advised that I couldn’t actually feel any physically movement
of the failed bonding of the driveshaft (colored yellow in diagram) so that’s won’t help in troubleshooting.
My gearbox mount is back together, I had to use a jack to force it back into place, it raised the box by about 2 inches.
Vibration still there, I’m going to target the front disks next as they are warped .
