A while ago I had a post regarding my car 'rumbling' after 50 mph, perfectly quiet and smooth before that speed. It never changes due to the UK climate, hot or cold, dry or wet, driven carefully or hard. From day 1 the car has done this, and after replacing every bush, joint, and bearing under the car - front & back I still have this rumbling at the same speed, gradually getting less up to 70 mph but, still there. I read other posts re changing out the diff bearings but, I'm not sure the right way to go. Are the diffs (and/or its bearings) known to be a problem, or the prop-shaft an issue, maybe the jurid couplings? I'm sure people will have different stories about their own experiences, but what I'm hoping to find is someone who has had a very similar issue with their car and how they cured it.

Having changed everything else under the car, and using the sometimes unreliable theory of elimination, I guess the only area(s) to look at must be from gearbox to rear drive axles (the output axles' U/J's have been renewed there too). Nothing, from the gearbox end jurid coupling towards (and including) the diff have been touched except the diff carrier has renewed bushes. So anyone experiencing similar problems please let me know if you cured the problem, and how?

Only other thing to mention, that may be totally unrelated, is braking hard at a decent speed... the car shudders, as if I had a warped disc, though they were renewed less than 3k miles ago. I'm just wondering if the hard braking is highlighting whatever it is causing the rumble, though it may be a totally different issue as said.

I did also mention in the previous post that it feels like a bad prop-shaft U/J problem I had years ago on an old Mk3 Ford Cortina (there's a blast from the past) which caused that car to rumble, but that 'eased off' when feathering the accelerator, on the Jag it's still there even if I knock it into Neutral? BTW, it stops immediately I drop below 50 mph and comes back if I accelerate again.

Whilst I accept it would be a rare sight to see one of these cars running completely problem free, this issue really is letting the car down after having so much done to it to keep it running as best as it can. Any help and advice is greatly appreciated as always.

P.

 

I have a similar vibration at the same speeds on my 98xj8. I have read somewhere in the forum that it could be the torque converter. It has something to due with the lock up clutch inside the converter. It on my list of things to do so I'm not sure if it is the problem until I change it, hopefully soon.

 

Wow! I hope not Bob, don't fancy the thought of having to tackle that one ...but needs must I guess, please let me know what you find. Wonder if anyone else can throw any light on this?
P.

 

Mine does the same thing - worse when just heading out, most noticeable at 55-60mph, sort of a periodic whrrum. Hard to tell where it's coming from, but I've got several suspension bits that need changing, so I'm going to wait on those before trying other things, but I'm betting I've got one, if not two wheel bearings that need replaced. I'm also thinking that the worse when cold is my tires flat-spotting, or just being straight up defective if I'm unlucky...

The diff output shaft bearings are easy to check, jack the rear of the car up and push in and out at 12 on the rear wheels, if there's some play it's probably those. After I did those I noticed a massive improvement in the vibration; where before it felt like the back end was going to vibrate apart, now it's a lot less pronounced.

 

In all the process of changing bushings, did you have a professional alignment done? I had very similar symptom as you describe but in a 1969 Corvette. It was a very recent restoration so all the parts were new. I put it on the lift and checked everything thoroughly but found nothing. So I drove it down to the tire shop to get the wheels balanced. That didn't fix it and I was stumped. But then looking at the car, standing 40-50 feet back, I noticed that the rear wheels leaned in a bit too much, like it had too much weight on the back. I got an alignment done and the rumble went away.

 

In my case I dont feel the vibration in the steering wheel, which would point to front suspension problem. I also had the alignment done about 6 months ago to rule that out. I feel the vibration mainly at my feet. And what is also pointing me at the torque converter is I can play with the throttle slightly and get the vibration to change or go away while maintaining roughly the same speed. If it were the tires or suspension it shouldn't change since I'm going at the same speed. It could be between the transmission and the differential, but I think I would feel that more in my butt or back. I plan to put the car on the lift with someone inside then maybe I can track down exactly where it is. I just got the wife to let me have it for a couple of days.

 

Thanks for the replies so far. In answer to pdupler, I see your point but yes, but I did have the front and rear alignments done immediately after the work was finished underneath, it was out considerably. However, as I said, the rumble was also present before I did all the work.

For BobRoy. I assume the Torque will drive at different speeds depending on which gear the car is in at any given time, but my car rumbles no matter what gear I'm in at exactly 50 mph. Again I'm assuming, that if it was the converter, the rumble would be prevalent at certain revs, rather than road speed? Maybe I'm wrong here or have missed your point?

Nilanium: I got hold of a dial Tool Indicator and checked the bearings, I found nothing on either side re any movement?

If any more description is needed, the rumbling is like going over a cobbled road at speed, very difficult to pinpoint the source as it rumbles through the whole car!

Thanks for the replies, please keep them coming if you have any thoughts.

 

two thoughts: grease the zerk fittings on both sides of the differential.

Probably a bad tire: if you feel it in the throttle or floor, rear; in the steering, front. Check the tire balance at the speed where you feel the problem; rotate the tires and see if the problem moves.

 

Hi Jim, thanks for the reply. I know what you mean, at first I thought wheel balance, very similar rumble and vibration. But I've had 4 tires put on just in case, when that didn't stop it I rotated the wheels at the same time, they have all been balanced but to no avail. I don't feel anything through the steering that I don't feel through the car/floor/seats, it's a rumble through the whole car?

Please forgive my ignorance --- zerk fittings?

Paul

 

Long shot - is one of the brake calipers sticking slightly so that at 50 mph the vibration is amplified through the drive train? Maybe go for a run round and then ask a tame tyre place or garage to check the turning resistance for each wheel.

 

Zerk are the fittings you connect the grease gun to to add grease.

Another thought. Maybe you can find a shop that has a set of chassis ears. You put sensors at different points of the car to hear sounds produced at that point. I know the vibration is not making a sound you can hear in the cabin but the ears will pick up the sound produced. If you find a sound that matches the vibration you probably found the location of the problem. Not a 100% it will pick up the problem but might be worth the shot instead of throwing parts at it. I have a set of ears but let my son take them with him when he moved to North Carolina or I would use them to diagnose my vibration.

 

My '99 VDP does this and has since I got it back in 2002. Seems to do in more out of Sport mode. IIRC, the resonance was strongest about about 52 MPH. Higher tire pressures helped it as well as leaving the car in Sport mode. I've got the trans out now and may do the converter. Put 100K miles on it and the symptoms of this have not changed.

My '03 XJR bought in 2006 has never done it.

-Mike

 

Hi all. Some very interesting ideas that I need to check, especially nigelmay and BobRoy. Now I know what zerk fittings are, yes, I have greased them. I did this when I put new U/J's in, and since running the car. I intend to check the brake calipers to see if they are sticking, I have noticed the car pulling ever so slightly to the right when hard braking along with the judder.

Very interesting too is the 'chassis ears' Bob, where would I look to obtain them from? I have a feeling they might well locate the source of the rumble at 50+ mph if anyone can help as to where I will get them, borrow them, in the UK?

All these ideas and experience are helping lots, even if I have already checked some of the ideas it does point out that I am looking in the right areas. I will come back after the weekend work and let everyone know any progress. keep the ideas coming please..

 

He is a link to a set here in US.

https://www.googleadservices.com/pag...Qwg8IGw&adurl=

Search UK for similar or call around and find a shop that may have them.

Today is the day I get the wifes XJ8 so I will put it on the lift and see if I can pinpoint the problem. I'll post my findings later on what I find.

 

So just to make sure I understand, a bad wheel bearing will be more noisy when it has less load (ex a bad bearing on the right side would be more noisy when turning right)? If so that explains why I couldn't ID the correct side worn bearing on my sister's car...

The chassis ears are something I didn't know existed in that kind of package, but will now be on my tools wishlist...

 

Hi nilanium. In my experience, little as it is, if the right side bearing has failed, it will be heard more when turning left, as turning left puts more weight on to the right side... and vice versa of course?

As for the 'Chassis Ears' I found a few websites by googling it, try this:
Steelman Chassis Ears from Direct Supply UK Ltd

 

Just to add to my previous post, the Chassis Ears that come up by clicking the link I put on, can be purchased a lot cheaper if you look around. It was a really good suggestion by BobRoy to add this tool to your list, the amount of posts I've read where this tool could be used is endless! Let me know if you decide to get one, I'm ordering one today when I track down the cheapest wireless one!

 

Just to add my experience from my wheel bearings I just did. In my case at least, it was definitely a case of right turn, bad right bearing. And likewise, it actually got worse with more load in the car, likely just due to the suspension compressing just that much more. And, I will also note that I also did experience braking shudder and initial pull to the right when applying, more pronounced if I was more aggressive. I imagine because the bearing was worn and allowing some play in the wheel, it was also "wobbling" the assembly causing the pads to grab differently.

That said, you might be able to just test for play with the car on stands, to see if that helps. The fact that yours does it only at certain speeds is slightly confusing, but I couldn't' say for sure it wouldn't cause it. But in my case, it was certainly bad, I could tell as soon as the wheel was off the ground - heck, even off the car, I could grab the hub and move it around. My bearing was beyond shot though.

That's all just speculation on it perhaps being yours. (if it makes you feel better, I've gotten the changing down to a 2 hour job with hand tools at this point lol)

 

Well, it's been a while since I posted anything as I've been busy with the car. The engine and gearbox are out and in the garage. Following talks and the reply post from BobRoy, I began to suspect the gearbox myself, and on changing the gearbox oil filter and finding shards of sharp metal attached to the magnets in the oil pan, I wasn't filled with confidence, so I decided to change the gearbox, and do the Oil Cooler pipe MODs all at the same time.

I contacted my local Jaguar breakers, EuroJag in Darlington UK, and asked them to look out for a good gearbox, and set about detailing the engine bay while I wait for a good gearbox. I got a call from them on Friday last, they just got in the same year and model as mine (1998 Sport, 3.2ltr ), and get this ... ONLY 34,773 miles with full service history!!! The car was hardly ever used, then a lorry backed into both driver's side doors, insurance wrote it off as beyond economical repair... what a find, I can hardly believe I got the gearbox for £400 plus VAT! I also noted with interest nilanium's comment on the back diff, so I nicked that out of it for £120 as well, just to try and make sure I've covered everything drive-line to get rid of the rumbling. Adding two new Jurid couplings and I should be good to go

Once all finished I will put up some pictures

So, now I'm detailing the engine, picking up the box tomorrow, and fit it all back at the weekend. I am so fortunate I live very close to this breakers, the quality 2nd hand parts have helped keep my car on the road with (nearly) all original parts for 'affordable' money. A less than 35k miles gearbox for £400? still can't believe it, apart from the driver's doors this car is mint! All the leather, the interior finish (less the rubber mats I also got) and the engine purrs exactly like it should. Anyone in the UK looking for some great parts you know where to contact, mind, I noticed they also ship overseas!

Be happy to put up the pics when done