Knocking from rear

[MPG]

Hoping for some advise please.I have a '99 XJR which I've done 6500 miles (the car has done 64k) but just recently I've noticed a knocking noise when going over bumpy roads.It appears to be from behind the rear seats. Its not particularly loud and on good A roads and m'ways not noticable at all.Sleeping policemen don't do it also it just seems to be on poor surface roads. Any ideas please.

[GavinPearson]

The busings could have slipped out of the A frame.

[MPG]

Is that something a good garage could do or is it main dealer thing. And I guess it'll be pricey!

[groomi]

MPG said:

Is that something a good garage could do or is it main dealer thing. And I guess it'll be pricey!

Any Jaguar specialist should be able to do this. I had them replaced on my XJR recently at approximately £400.

However, I do still have a very faint knocking similar to your discription. I am guessing it is worn CV joints as virtually every other drivetrain component in my car has been replaced.

For the record, my car has covered 105,000 miles.

[GavinPearson]

X300s and XK8s, plus all previous models with IRS use Universal jointed driveshafts as the upper link of the rear suspension. So it isn't going to be a cv joint.

[MJK]

MPG, for what it's worth, your description of knocking noise from rear matches exactly what I have now with my 2000 XJR. I was going to point it out at next service at 50K. As always though, before been shafted by main dealer it would be nice if you guys out there could be more certain for us with the diagnosis of the problem. Previous info on this forum has saved me thousands with nikasil and tensioner problems.
Thanks.

[thesilverfox]

jags have a lot of problems with the bottom bush on the rear shock absorbers, you can buy the bush by itself and carefully press it in

[milesj]

Having spent most of the day trying to resolve a problem as you describe, I can reveal my experience.

Jacked car up, took hold north and south of wheel, play found whilst rocking, tried east west. no play found, not wheel bearing! held drive shaft whilst rocking, no play! "drive shaft goosed" loads of money, bastard!! checked Hardy Spicers (U J's that is )noticed grease nipples, pumped new grease in cured rocking, GREAT!! PROBLEM SOLVED.
Road test, STILL RATLING, back on jack, pulled everything in sight, found metal shroud on damper loose, this is without a doubt the problem, as I got the girlfriend to shake it whilst I was in the car.

looks like a bit of a bitch to repair, will let you know soon.

May I just point out that my car has a full jag service history, yet the U.J's, in my opinion have never been greased?

>> Edited by milesj on Sunday 26th June 11:00

[milesj]

Problem sorted! removed nsr damper, nut on top required no less than four turns to tighten! Not as difficult as first thought! Estimate, no more than an hour for a reasanably equiped gararge, i.e. air tools and a little bit of tech abillity.

DIY
Make sure you disconnect the CAT lead before trying to remove the strut. Use good quality spring compressers, (essential to avoid lost fingers,as the spring has to be compressed in-situ) accuratly mark the lower pivot before undoing the bolt, (or pay for a geometry realignment) apart from that, a piece of piss.
miles.

[MPG]

Thanks milesj I'll pop along to my garage armed with your info and at worst if its not that it shouldn't be too expensive1

[MJK]

2000XJR 50K service,MOT and 2 new rear shocks. £1100 at main dealer. Ouch! but it now runs smooth again.

[simon t]

HI,

My 98 XJR seems to have a similar problem. Lots of play in rear wheels top to bottom. no play from side to side. Also getting a lot of wheel wobble. anyone know if this a common or known problem?
Simon

[GavinPearson]

simon t said:

HI, My 98 XJR seems to have a similar problem. Lots of play in rear wheels top to bottom. no play from side to side. Also getting a lot of wheel wobble. anyone know if this a common or known problem? Simon

You need to check the diff output shaft bearing / tapered circlip assembly.

If it was wheel bearings or lower bearings you'd get side to side.

Keep us updated.

[simon t]

Found the knocking noise, it was the rear exhaust mounting bushes, just above the tail pipes, the hole had gone oval and the mount bar was rattling, that was the easy fix, still got the wobble/judder though

Simon

[jtp57]

If the knocking is happening on high frequency small bumps rather than smoother undulations on the road,then as posted by Thesilverfox on this forum, the problem may well be that the lower damper bushes are shot. These are of the Rose Jointed type on the XJ8 and others. All it needs is for them to have a small amount of wear or endplay and it results in a noise very similar to metal to metal knocking. This is exactly what happened to my own 1999 XJ8 3.2 recently. After months of headscratching and a complete stripdown and rebuild of the nearside rear suspension, guess whar happened?. The noise abated but didn't completely go away. A few weeks later it came back with a vengence (time to turn up the radio and CD player again!). Having had enough, I put the car into a recommended local independent garage with Jag knowledge, short road test, immediate diagnosis, £230 paid, both Rose bushes pulled out and new one's pressed in, problem solved, car back to running as quiet as a church the way it should be, happy Jag owner, great!!.

[mpp]

milesj said:

Problem sorted! removed nsr damper, nut on top required no less than four turns to tighten! Not as difficult as first thought! Estimate, no more than an hour for a reasanably equiped gararge, i.e. air tools and a little bit of tech abillity.

DIY
Make sure you disconnect the CAT lead before trying to remove the strut. Use good quality spring compressers, (essential to avoid lost fingers,as the spring has to be compressed in-situ) accuratly mark the lower pivot before undoing the bolt, (or pay for a geometry realignment) apart from that, a piece of piss.
miles.

[mpp]

milesj said:

Problem sorted! removed nsr damper, nut on top required no less than four turns to tighten! Not as difficult as first thought! Estimate, no more than an hour for a reasanably equiped gararge, i.e. air tools and a little bit of tech abillity.

DIY
Make sure you disconnect the CAT lead before trying to remove the strut. Use good quality spring compressers, (essential to avoid lost fingers,as the spring has to be compressed in-situ) accuratly mark the lower pivot before undoing the bolt, (or pay for a geometry realignment) apart from that, a piece of piss.
miles.

Hi, can you tell me how i get access to the top nut of the rear shock? I will be attempting to establish if i have the same problem this weekend and can not find my workshop manual!!!

Thanks,

Mel

[mpp]

mpp said:

milesj said:

Problem sorted! removed nsr damper, nut on top required no less than four turns to tighten! Not as difficult as first thought! Estimate, no more than an hour for a reasanably equiped gararge, i.e. air tools and a little bit of tech abillity.

DIY
Make sure you disconnect the CAT lead before trying to remove the strut. Use good quality spring compressers, (essential to avoid lost fingers,as the spring has to be compressed in-situ) accuratly mark the lower pivot before undoing the bolt, (or pay for a geometry realignment) apart from that, a piece of piss.
miles.

Hi, can you tell me how i get access to the top nut of the rear shock? I will be attempting to establish if i have the same problem this weekend and can not find my workshop manual!!!

Thanks,

Mel

[mpp]

mpp said:

milesj said:

Problem sorted! removed nsr damper, nut on top required no less than four turns to tighten! Not as difficult as first thought! Estimate, no more than an hour for a reasanably equiped gararge, i.e. air tools and a little bit of tech abillity.

DIY
Make sure you disconnect the CAT lead before trying to remove the strut. Use good quality spring compressers, (essential to avoid lost fingers,as the spring has to be compressed in-situ) accuratly mark the lower pivot before undoing the bolt, (or pay for a geometry realignment) apart from that, a piece of piss.
miles.

Hi, can you tell me how i get access to the top nut of the rear shock? I will be attempting to establish if i have the same problem this weekend and can not find my workshop manual!!!

Thanks,

How do i get to the top nut????

Mel