XJ XJ6 / XJR6 ( X300 ) 1995-1997

X300 vibrations when accelerating slowly

 
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Old 05-04-2019, 07:30 AM
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Default X300 vibrations when accelerating slowly

Hi everyone,

I'm a new member and unfortunately not a terribly technically gifted one (although I'm learning). I recently bought a 1997 Jaguar XJR X300 supercharged with only 145 000 kms. Overall I'm very happy with the car, but I noticed that when I accelerate slowly there are distinct vibrations to be felt that only stop either by accelerating more forcefully, or by releasing the throttle. It seems to be happening more continuously and mostly when the engine is warm. I was told it could be the 'donut', but at the garage they thought it was fine. Does anyone know of other causes for these very annoying (and possibly harmful?) vibrations?

Thank you
David
 
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Old 05-12-2019, 02:21 AM
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Sorry for the delayed response. Did you make any more progress on this?

Driveline vibrations as you describe could be caused by trouble (meaning wear-out) with any of these:

Driveshaft Center Bearing (#3)
Transmission mount
Engine mounts
U-joints (2 on driveshaft, 4 on rear axles)
The "donut" (Jurid coupling rubber, #5)


If any of these components were replaced in the past, vibration could happen due to incorrect installation. The driveshaft has to be aligned very carefully. If the donut was replaced, it could cause the driveshaft to be out of balance.
 
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Old 05-12-2019, 03:08 AM
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Hello Richard,

Thank you for your reply, it is very helpful!
I wasn't getting anywhere really. The donut was replaced only recently by the previous owner's garage, so that seemed unlikely.
But as you say, it could very well have been installed incorrectly which is hard for me to assess.

Since there aren't that many mechanics nearby that are familiar with this type of car, the scheme you've added could prove very useful too.
I've looked up a nearly retired mechanic that hasn't worked a lot on Jaguar before, but with this info at least he should know where to look and what to check.
Appointment on 22nd May. I'l keep you posted!

Thanks again and have a nice weekend
 
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Old 05-12-2019, 04:05 AM
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Jaguar recommends that the coupling donut not ever be removed from the driveshaft because of the balancing done at the factory. Of course if it is worn out, it must be replaced. So many years down the road, that leaves the job open to some possibly questionable work due to inexperience or unfamiliarity. Look for evidence along the drivetrain if the center bearing or transmission mount have also been moved from their original positions.

While it is possible to have the driveshaft with donut balanced again, you may do just as well to simply re-orient the donut, while checking for proper fit and correct torque on the bolts. Of course those other items of concern should be ruled out first. The center bearing is a likely suspect too.

Be sure to have the mechanic check those things, and the wheel bearings too. The rear wheel bearings should have no play in them whatsoever.

Good luck, please let us know what happens. And you are welcome!
 
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Old 05-12-2019, 04:27 AM
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Will do!
I just hope the mechanic's many years of experience on other cars will allow him to do the job properly.
Your guidelines will certainly help!
 
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Old 05-12-2019, 06:09 AM
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Also get your mechanic to check the rear Driveshaft Universal Joints. Greasing these joints is a service item that is often missed leading to failure.

Also, the Rear Hub Pivot Bearings are a known issue as they never see lubrication and can seize and disintegrate.
 
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Old 05-12-2019, 07:46 AM
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Hi Brendan,

Thank you for that additional piece of advice!

I bought the car only recently and the seller's paperwork with regard to maintenance wasn't complete.
Although a mechanic had a quick look at it before I bought it, some things only show up later, like the vibrations.
Better to put in some extra care now than be sorry later

Thanks again and I'll keep you posted through this thread!
 
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Old 05-23-2019, 01:11 PM
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Hello Richard,

I got a call from the garage earlier today. As I told you they are not familiar with Jaguar. They say they saw a rubber part of about 10cms with about 0.7cms slack to the side, situated somewhere near where the drive chain and transmission meet.
They suspect that slack is causing the vibrations.

But they cannot find any serial number, brand name or other references on it, and based on their unclear description I cannot determine what part they could be referring to. Do you maybe have an idea, or even a technical drawing like the one you sent me earlier? They say the part is not on that drawing.

Thanks,
David
 
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Old 05-24-2019, 01:07 AM
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Maybe they are referring to a part of the transmission mount. Bushing #13 MMC7553AA is well known for wearing out. It is made out of a spongy material. I don't think that alone would be responsible for so much vibration, but I could be wrong. I think the previous work done on the drivetrain has caused this vibration.





Jaguar Classic Parts UK

Diagrams complements of JCP. That site is your friend.

Looks like you and the shop have to educate yourselves about this car. There are downloads for service manuals in the stickies section here. The shop should have access to lots of service information too.

Thanks for getting back to us right on time! Good luck.
 
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Old 05-24-2019, 12:43 PM
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Thanks for this interesting piece of info.
I went to the garage after work with the drawing and took a look underneath.

When I pushed upwards against the drive chain, it went up and down at least 1cm, maybe more.
And you could see a space between to bottom bolt (n15 on sketch) and the metal 'holder' (n1).
The mechanic thought that not to be normal, so if he's right it could be any of the parts from n6 to 15 that is causing it.

I took some pictures, hoping this will clarify the situation:




parts n15, 14 and 13 from the sketch

Or should he look elsewhere for the problem?
 
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Old 05-24-2019, 12:50 PM
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And thanks for the 'stickies' tip
As a non-native speaker I wasn't familiar with the term and it took some figuring out, but I found some really interesting downloads on the forum.
Also with thanks to all the Jag lovers that put them there!
 
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Old 06-12-2019, 04:45 AM
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Hi,

At the garage they dismantled the group of parts from the drawing and turned out that bushing nr 13 was slightly bent.
Replaced it and already the car is suffering noticably less from the vibrations. So thanks a lot for pointing this area out!

Still not completely resolved though. We are wondering if the play on parts 15 to 13 isn't too big, but as it seems we cannot decrease it by further tightening bolts or anything... Is there any reference to the allowed play on these parts to be found somewhere? I haven't been able to find it so far.

If it is not the play that is the problem there must be another part or configuration that is causing vibrations.
I'm going to try and figure out together with the garage where the rest of the problem could be.
We will be changing the front shock absorbers soon, so maybe that is an opportunity to look further

Any suggestions are still welcome!

Thanks for the support already
David
 
 
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