Slight knocking sound from rear??

[sparky35uk]

Careful listening has revealed a slight knocking sounds at very low speed (5-15mph) from the rear end. It's almost like a loose exhaust mounting type of noise, but they seem firm enough.

Am going to have a closer inspection tomorrow, but was just wondering if anyone might have any clues or encountered same or similar?

This is on an X308 (2002) lwb model.

Cheers guys.

[Jaguar steve]

Most likley cause is the rear shockabsorber. They usualy do this over low speed speed humps or potholes. Often the wheel on the other side of the car from the noisy shock hitting a hump or hole will cause the noise. There's nothing visible to see if the shock has failed, so a good look round the rear suspension with a pry bar checking for worn bushes, trapped stones and loose bolts before you condem the shocks is worth doing just in case.

Big Nige described the noise as "Snogglebock" - which is a perfect decsription of what a worn shock sounds like.

[BigNige]

Yup, mine does it as well Sparky, just as Steve describes.

If yours is anything like mine, the noise goes away on warmer days.
I can only think tolerances change enough to negate it in some way.

[sparky35uk]

Cheers for the advice, will have a look later today - too busy enjoying the sun yesterday!

Yes,Nige; seems more audible on warm days and can't hear it at all once the cars fully warmed up and been out for a bit.

Will have a poke around like Steve suggests first

[Simon T]

Make sure you check the lower damper mount, It's a spherical joint and is prone to wear

Simon

[sparky35uk]

Well, i've had a crawl about underneath and I can't see anything obvious at all, nothing loose, nothing visible in the way of 'shiny metal'; all exhaust mounts are firm & secure, it's most strange and has, if anything, become slighly more audible, particually 1st thing in the morning.

Confused.....

[Jaguar steve]

I believe it's the internal valves in the shock that fail and cause that particular rattle. If that's the case with your car there will of course be nothing to see. As you've now had a look and found nothing obvious wrong with the rear suspension my best guess is that's the problem.

[Pettsie]

Yup, that's what it sounds like - mine is doing it! I have been quoted £450 but seeking better.

[Tame Technician]

To locate the fault, Hold the bottom of the rear damper while someone else bounces the car. You should be able to tell if its the lower damper spherical bush or the damper its self.

Of course that said, if you going to go through the aggro of removing the damper, you might not want to press a new bush on and replace it anyway.

[XKRacer]

Tame Technician said:

To locate the fault, Hold the bottom of the rear damper while someone else bounces the car. You should be able to tell if its the lower damper spherical bush or the damper its self.

Of course that said, if you going to go through the aggro of removing the damper, you might not want to press a new bush on and replace it anyway.

That would be my first check, the bushes are far more prone to failing than the shock itself and a shedlaod cheaper to sort, a bush only costs £15 a shock considerably more.

As TT says just hold a finger on the bottom of the shock and get someone to bounce the car (without squashing your head ) and you will feel if it is the bush, otherwise it will be shocks.

[sparky35uk]

Sounds good XK....I assume the bushes are easy to locate?

I've always thought it sounds like a bush failure somewhere, but difficult to locate on your own.

[XKRacer]

I would go here for the parts http://www.britishparts.co.uk/.sc/ms/cat/Jaguar%20...

Removing the bush can be done in situ but you would need special tooling (I made mine myself!) but you can remove the whole damper and do it on the bench.

You can see this bush very easily from under the car I will take a pic if you want and post it up.

[sparky35uk]

Cheers XK....if you wouldn't mind, just to be sure what i'm looking at!

:-)

[XKRacer]

sparky35uk said:

Cheers XK....if you wouldn't mind, just to be sure what i'm looking at!

:-)

Assuming you are in the UK! This is looking from he offside (drivers). Circled in red is the bottom of the damper, this is what you need to press your fingers onto and have someone bounce the car for you, if you feel knocking that's your problem.

[sparky35uk]

Great stuff, that's tomorrows task then! Yes, in the UK, in Worcestershire.

[sparky35uk]

Have ordered some new spherical bushes from www.britishparts.co.uk on the pre text that this is the problem. Will be looking tomorrow, but at the relativley cheap price (£19) they're worth having 'in stock' anyway.

It has become most annoying and need to get it sorted now.

Pic is a great help XK

[XKRacer]

Happy to be of help.....They can be a pain to fix. If you are planning on doing this in situ you will need something like this




I borrowed this pic from the XKEC forum....damn good place for info if you intend to look after your XK yourself.

[Simon T]

Just as an FYI, I tried to do it in situ but the bearing was too tight. I hsad to take the damper off and get it in a 10 ton press to get the bugger out...
S

[sparky35uk]

Blimey, thanks for the 'tip off'

[XKRacer]

Simon T said:

Just as an FYI, I tried to do it in situ but the bearing was too tight. I hsad to take the damper off and get it in a 10 ton press to get the bugger out...
S

If you dont have the tool don't even attempt to do it in situ. As a minimum you will need some appropiate sized sockets and a vice to get the bush out.....As Simon says, it is damn tight!

Good luck