Jaguar World Monthly Forum - XJ40 Rear Scraping

JCWatson

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XJ40 Rear Scraping
16.04.2012 at 20:33:07

Hey folks,

My XJ6 Gold has developed a scraping sound coming from the rear offside, when accelerating the sound is non existant, as soon as i take my foot off the accelerator it appears.

Since the sound started it's passed an MOT and i've done the test of jacking it up and grabbing the wheel at 12 and 6 o'clock, and 9 and 3 o'clock and there is only slight movement at 12 and 6. The exhaust had been shunted forward at some point so i thought it may be that but i've got it back into place and the sound is still there.
The sound also goes if i go over a hump in the road.

Any help would be much appreciated before i take it to the garage.

Thanks

JC

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covkid

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Re: XJ40 Rear Scraping
Reply #1 - 16.04.2012 at 22:16:48

JCWatson wrote on 16.04.2012 at 20:33:07:

Hey folks,

My XJ6 Gold has developed a scraping sound coming from the rear offside, when accelerating the sound is non existant, as soon as i take my foot off the accelerator it appears.

Since the sound started it's passed an MOT and i've done the test of jacking it up and grabbing the wheel at 12 and 6 o'clock, and 9 and 3 o'clock and there is only slight movement at 12 and 6. The exhaust had been shunted forward at some point so i thought it may be that but i've got it back into place and the sound is still there.
The sound also goes if i go over a hump in the road.

Any help would be much appreciated before i take it to the garage.

Thanks

JC

Sounds as if it could be transmission / driveline related if it comes and goes with acceleration / deceleration.

Could be something to do with the prop-shaft centre bearing or even the diff pinion bearings. Collapsed forward mounting bushes on the rear sub-frame can sometimes amplify diff noises in the cabin through metal-to-metal contact between the sub-frame and body.

I heard such 'scraping' noise once coming from the mechanical cooling fan rubbing on the fan shroud caused by a collapsed rear engine/tranny mount allowing the engine to 'nod during acceleration/deceleration - but you don't mention the year of your car so perhaps it is a later model with the twin electric fans and not the mechanical one on earlier cars?

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JCWatson

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Re: XJ40 Rear Scraping
Reply #2 - 17.04.2012 at 13:08:32

Ouch all sounds rather expensive.

Thanks for the help,

It's a 94 model so I would assume it's not the fan thing. It certainly seems to be coming from the one side as opposed to the middle, could that still be the prop shaft bearing or the diff pin bearings?

I was also thinking whether scraping is the correct term, it's maybe not that severe, more as if two metal plates were rubbing together without any lubricant, if that makes any sense at all?

Also if the sub frame bushes had collapsed would that not have been noticed on the MOT?

Thanks again

JC Smiley

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XJ40S Senior Member Offline Posts: 1908 Sheffield Gender:	Re: XJ40 Rear Scraping Reply #3 - 17.04.2012 at 15:54:45 Brake back plate rubbing on disk or a pebble on caliper rubbing the disk? Brake shoe lining coming away from shoe? Cheers
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Rolys mk10

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Re: XJ40 Rear Scraping
Reply #4 - 17.04.2012 at 15:56:51

JCWatson wrote on 17.04.2012 at 13:08:32:

Ouch all sounds rather expensive.

Thanks for the help,

It's a 94 model so I would assume it's not the fan thing. It certainly seems to be coming from the one side as opposed to the middle, could that still be the prop shaft bearing or the diff pin bearings?

I was also thinking whether scraping is the correct term, it's maybe not that severe, more as if two metal plates were rubbing together without any lubricant, if that makes any sense at all?

Also if the sub frame bushes had collapsed would that not have been noticed on the MOT?

Thanks again

JC Smiley

all depends how they jack up the car to show sunframe bushes are duff. dobt they jacked car up so they could see subframe bushes were duff.. front and back Shocked

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JCWatson

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Re: XJ40 Rear Scraping
Reply #5 - 17.04.2012 at 19:02:10

Cheers guys, going to have the brake off etc when I get some nice weather. So hopefully it isn't anything too serious.
The odd thing was that after I took the wheel off to get the exhaust into back into place the sound went off a bit, but after a run it came back again. Fingers crossed that it is only something to do with the brake.

Thanks again,

JC

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covkid

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Re: XJ40 Rear Scraping
Reply #6 - 17.04.2012 at 19:15:40

JCWatson wrote on 17.04.2012 at 19:02:10:

Cheers guys, going to have the brake off etc when I get some nice weather. So hopefully it isn't anything too serious.
The odd thing was that after I took the wheel off to get the exhaust into back into place the sound went off a bit, but after a run it came back again. Fingers crossed that it is only something to do with the brake.

Thanks again,

JC

I would have suggested a brake rubbing problem had you not said that it came and went with acceleration /deceleration. If it is the brake, it would be consistent at road speed, not vary in the manner you have described.

I think you need to do a little more analysis - perhaps raising the rear of the car on jack-stands and running the car in 'D' at simulated road speeds to see if you can reproduce the problem. If you do that, make sure that the front wheels are well and truly chocked and put some wheel ramps under the body sills between the wheels just in case it falls off the jack-stands!

BTW, it is a good idea to include the model and year of your car when posing a question so that the answer is appropriate to the build standard / model year of your car.

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covkid

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Re: XJ40 Rear Scraping
Reply #7 - 18.04.2012 at 08:21:25

JCWatson wrote on 17.04.2012 at 19:02:10:

The odd thing was that after I took the wheel off to get the exhaust into back into place the sound went off a bit, but after a run it came back again. Fingers crossed that it is only something to do with the brake.

Thanks again,

JC

That comment stirred my memory. You wrote :-

"when accelerating the sound is non existant, as soon as i take my foot off the accelerator it appears."

I remembered reading of a guy who experienced something similar to that who wrote :-

"at any speed above 70 mph, when taking my foot off the accelerator, a nasty vibration arose from the back end which disappeared as soon as I started to accelerate again but came back with a vengeance on deceleration."

Admittedly his was a different car but he found the problem to be loose wheel bolts.

Are your wheel nuts correctly torqued?

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JCWatson I've just arrived Offline Posts: 9	Re: XJ40 Rear Scraping Reply #8 - 18.04.2012 at 13:07:42 Just had two new tyres and the garage did correctly torque them but I've just thought, one of the washer nuts was missing when I put it back, could it possibly be that simple? Jc
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covkid

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Re: XJ40 Rear Scraping
Reply #9 - 18.04.2012 at 14:21:00

JCWatson wrote on 18.04.2012 at 13:07:42:

Just had two new tyres and the garage did correctly torque them but I've just thought, one of the washer nuts was missing when I put it back, could it possibly be that simple?

Jc

I have known wheels to be improperly fitted by our friends at the tyre shop - usually it is over-torquing the wheel nuts - but if the wheel is not correctly located over the spigot on the hub, in effect, the wheel nuts can come loose when the car is driven and the wheel 'beds down'.

The guy I mentioned above had lost three of the five wheel bolts IIRC, so the wheel was 'waggling' around a bit, hence the noise on the over-run.

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JCWatson I've just arrived Offline Posts: 9	Re: XJ40 Rear Scraping Reply #10 - 18.04.2012 at 15:14:13 Hmmm possibly not as it would be from the other wheel too and I've had it off (ahem) since and the sound is still there. As long at the weather is okay on friday I'll have a full investigation and see if I can find anything. Thanks again, JC
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