'Clunk' from back over bumps?

[zcacogp]

Chaps,

A long shot, but I'll try.

My (beloved) S2 has started to make a dull, heavy "clunk" noise when going over bumps. Seems to be coming from the nearside rear. They need to be fairly agressive bumps, and attacked pretty hard, but it is a new noise and I haven't heard it before. It seems to happen most on potholes (of which there are plenty around here!) and is getting annoying. To describe it, I'd say it sounds like a bushing noise, as if there is a bush damaged or crumbled somewhere, but they are powerflex items with only about 20k miles on them.

It sounds most like something knocking in the boot. But I have taken everything out, and it still does it. ('Taken everything out' includes the carpet and - blimey! - it's noisy without the rear carpet in it!)

I've jacked it up in the air and there is nothing obviously wrong. That's to say that the ARB bushes all look intact and the plates holding them on are screwed in correctly. The ARB drop links are attached as they should be and not broken. The bushes themselves are all intact. There is nothing loose (caliper/pads/CV-something), and the dampers themselves are still bolted in as they should be.

Does anyone have any suggestions? Would a blown shock absorber sound like this? Is there something to do with the swing arm that could cause this noise? (A bush in the main hinge bit of it, for instance.) Rear wheel bearing? What else could it be?

All suggestions more than welcome - thanks!


Oli.

ETA: A good wobble of the exhaust failed to produce a similar noise either. So I doubt it's that. And the rear trim all seems to be held on OK too.

 

[John Sims]

I know exactly what you mean. Mine does to. Mine only seems to do it on the first hard right hand turn (as I go around the mini roundabout at the end of my road) and seems to settle down after that.

It may do it on bumps but I try to avoid them.

I think it could be the torsion bar/trailing link bush but I don't know for sure. - see the torsion bar delete thread (until some of the yobos hijacked it to talk about antiquated MAF kits and (not so antiquated) AFR gauges [])

 

[Fen]

I was going to suggest maybe your turbo had fallen off, but John's hasn't so it can't be that...[][]

 

[gemmerson]

I had and in fact have a similar noise on my S2. Eventually my local indie recons it is slight play in the bearing for the drive shafts into the gearbox. As you say only really does it on hard cornering or going over speed bumps. His recommendation was to do nothing until the noise gets worse and......... not to do any donuts !!!. New bearings etc aint cheap. I have had the noise for a few years now and it isnt getting worse and now I know what it is, it doesnt bother me anymore !!

Hope that helps


George

 

[cococola]

Ive had this type of noise for a few months now and I put it down to driveshaft bearings(hard rh lock turning) at first it seemed like suspension type knockIt hasnt bothered me too much

ORIGINAL: gemmerson

I had and in fact have a similar noise on my S2. Eventually my local indie recons it is slight play in the bearing for the drive shafts into the gearbox. As you say only really does it on hard cornering or going over speed bumps. His recommendation was to do nothing until the noise gets worse and......... not to do any donuts !!!. New bearings etc aint cheap. I have had the noise for a few years now and it isnt getting worse and now I know what it is, it doesnt bother me anymore !!

Hope that helps


George

 

[Elliot]

Jack your car up at the back and check the rubber joint on the spring plate, sometimes these become detacted and wear which will then cause noise on excessive jolts.

may be sticking cv joint, are they quietish on normal driving and if you corner one way then the other is the noise more pronounced on one side.

 

[zcacogp]

Chaps,

Thanks for your answers. Sounds like there are a lot of people out there with interesting 'clunks' coming from the back of their 944's!

And the overwhelming concensus seems to be 'live with it'. Hmmm. []

I have a few more symptoms from mine - which may make it a different noise to those that others are experiencing. It is not associated with drive or cornering at all. I'd be slightly surprised if it is gearbox-bearing related, as it has started very suddenly and seems to be coming quite definitely from the nearside. It seems to be associated with unloading (as opposed to loading), so it makes the noise when the suspension is suddenly extended - going into a pothole, as opposed to going over a bump (but this is hard to tell, as the forces change from unloading to loading very quickly in such a scenario).

The noise itself almost sounds like a load of glass bottles being rattled together in a box. The sort of noise that comes from a box of empty wine bottles when you take them to the recycling centre after a party. In fact, it sounds very like that. (But it isn't, before anyone asks - I have ensured that I removed the empties from the boot after the last sesh!)

If it had a normal coil spring, I'd be strongly suspecting that it is a loose spring platform or similar. Should I be thinking about torsion bar mountings?

Elliot - the rubber joint on the spring plate - that sounds hopeful. Erm ... what is it and where do I find it? (There are no springs on the back! It's torsion bars ... )


Oli.

ETA: John, mine doesn't seem to settle down with time, but it doesn't make the noise when sometimes I think it should, so it could be something loose which is occasionally jamming. (This is only a very vague notion.) Fen, go straight to the top of the list for unhelpful comments! []

 

[cococola]

If it is a sticking joint do you know what the best repair would be?

ORIGINAL: Porkaparts

Jack your car up at the back and check the rubber joint on the spring plate, sometimes these become detacted and wear which will then cause noise on excessive jolts.

may be sticking cv joint, are they quietish on normal driving and if you corner one way then the other is the noise more pronounced on one side.

 

[Hilux]

The noise itself almost sounds like a load of glass bottles being rattled together in a box. The sort of noise that comes from a box of empty wine bottles when you take them to the recycling centre after a party. In fact, it sounds very like that. (But it isn't, before anyone asks - I have ensured that I removed the empties from the boot after the last sesh!)

It sounds like a `ping` I had from the rear damper when it was knackered, the shock reverberated into the top cover which acted like a `bell` so could be the damper is u/s or the damper mounts have collapsed?

 

[zcacogp]

Paul,

Thanks for your comments. It sounds possible ... not 100% convinced but worth a look.

Dampers were changed at the same time as the bushes - 20k miles ago. And are Koni, so I'd expect a fair bit more life out of them than that.

They seemed to be still bolted on OK, when I looked underneath last night (with an inspection light, lying on the road in the rain!) Could well be worth a closer look. Or unbolt them and make sure that they are still 'damping' OK.

Elliot - still interested in the idea of the rubber being detached from the spring. Any more details?


Oli.

 

[petrolhead944]

hi oli i was getting a noise from the ns rear on my s2 i found a old spanner and the battery bracket was loose so the battery was banging.that was driving me mad.sorted now..hope you find the problem soon..carl

 

[sawood12]

The only clunk I get from mine is from the nearside rear and it is the exhaust. The rear-most hangar is very close to the rear underside edge of the car and when I go round a small roundabout I sometimes get a clunk, or bumping noise. In my case it is definitely the exhaust.

 

[zcacogp]

Chaps,

It seems to be getting worse ... coming back this evening with three in the car (Mrs zcacogp in the rear near-side seat), it thumped alarmingly over bumps. Interestingly, it also seemed to be dragging at the same time - the car slowed down, as if there was something catching on something.

First suspect was the exhaust hitting the floor, but everything is at the right height (i.e. the exhaust isn't hanging off) and there are no obvious scuff marks anywhere.

There is nothing loose in the boot, and nothing seems to be amiss below the car. I haven't yet had the shock off, but the car responds as you'd expect if you bounce it when stationary (i.e. the shock seems to be doing it's job - it's not blown, although this is not a test of the rubbers at the ends of it.)

All suggestions welcome. If the worst comes to the worst, it'll all be up in the air (and in pieces) doing the clutch in a couple of weeks time so I'll see if that changes anything, or if there is anything to see then.


Oli.

 

[DivineE]

Sounds a little bit like when my gearbox mounts were failing on my lux and it was jumping around a bit over bumps independant of the car. If it is then its a cheap and easy fix which is nice but try lightly holding the gearstick as you go over said bumps when its in gear. If its that I seem to remember feeling a jolt quite substantially through the gear stick as it bounced.

 

[zcacogp]

Ben,

Thanks - another good thing to try.

I'm not quite sure where to go with this one - I can't think of a good way of diagnosing it. I think I'll keep a close eye out for things which are amiss when I do the clutch, and quite possibly buy a new gearbox mount to swap when the 'box is off. Then, if the problem is still happening I'll try something else. Possibly removing the ARB and seeing if it makes the noise without that (it sounds very bush-esque, although the dragging would suggest otherwise) and going from there.

Either way, I'm a bit hacked off about it.


Oli.

 

[zcacogp]

OK. An update (for anyone still interested. Hands up if you are. Thanks. That'll be no-one then! I wonder why I bother ... )

Had the back all up in the air again last night. (Yes, it was drizzling. Yes, it was dark. Yes, I was working on the side of the road.) Everything still looked as right as rain. I had a theory that it could be the camber or toe adjustments coming loose, but they were all done up as tight as ever. I took the nearside (the noise comes from the nearside) shock off and it was fine. Examined the bushes and compressed it a couple of times. All was well. Put it back on and did it up nice and tightly.

Then took the ARB off. And left it off. And have driven to work today without it attached. And it seems to have perhaps cured the problem. I'm not 100% convinced as the problem came and went a little anyway, but I drove it briskly over a broken bit of road and a couple of potholes, and it seemed to make no more than the usual tyre noise.

So, if this is the case, I need to identify why the ARB makes a clonking noise. Any suggestions? The obvious candidate is the drop links, but those looked fine (rubber didn't seem perished, wasn't detatching, bolts weren't loose.) And I think they are expensive to replace ...

Any other suggestions? All welcome!

(Thanks to Ben and Elliot for the suggestions. The rubber blocks seemed fine, and the gearbox mounts didn't allow the gearbox to wiggle any much more than usual. Good suggestions tho'.)


Oli.

 

[sawood12]

Has anything around the ARB become detached and might be fouling with it? Handbrake cable?, earth strap? brake pipe?

 

[zcacogp]

Scott,

Thanks, it was a good idea. But a false alarm. The noise came back on the way home. So it wasn't ARB related, and is unpredictable (i.e. it comes and it goes.)

Very annoyed. I then refitted the ARB when I got home, and remembered why I hate them so much. They are stressed most of the time, so simply don't fit, unless you force them. And applying force when lying on your back with the car above you is a sure-fire recipie for sore arms.

Essentially, I am out of ideas. I don't know what it is. My big fear is that it is (as Mr Sims suggested) one of the big bushes which the whole of the back axle hinges off. I really really hope it isn't, as that will be a back-axle-off job to replace them, but I am running out of other ideas at the moment ...

Thanks for your input anyway chaps. It's appreciated.


Oli.

 

[James_G]

I'm still interested Oli so don't feel you are writing for writing's sake.[]

Happy to report that I'm just back in one piece from the track day we discussed - had a great time, shame you couldn't make it.

 

[Neil Haughey]

I am interested as well since I haven't had this problem, well occasionally something loose in the boot but nothing like this.

The spring plate bushes could well be shot. My own pretty much fell of the car when the torsion bar tube was dropped a couple of years back, they take a lot of cornering strain which distorts them. Then add in nearly 20 yr old rubber which is likely cracked and falling apart by now. Thing that annoys me no end though is I asked the OPC about new spring plates (bush not supplied seperately which ISTR is how they are made anyway) and the quote was something like 450 quid, just as crazy as the front top mounts.