Rear end clunk - have done the usual suspects

[8Jb9]

Crossing mountain roads with rutted ice take their toll on the poor 16 year old suspension, and I've gone through most of the usual suspects to get rid of clunks in the rear, and it has indeed gradually become better. Now there's only one annoying noise left.

Noise is linked to rear left wheel (driver's side), and occurs as distinct subdued clunks or short burst of clunks. It doesn't rattle like the top-link. Noise comes when there is sudden strong acceleration in Z (vertical), such as a shallow pothole or a change in road surface with slight height difference. I don't really notice it on cobblestone. The noise can be heard under favourable conditions up to at least 60 and a bit kph. On the other end of the scale it can occur down to very slow rolling, but it requires a step, not rough surface (cobblestone).

In the rear I have replaced:
L+R ARB linkage and bush
L+R tie rods
L+R trailing arm bush and hinge bushes
L+R dampers
Fuel tank jammed with foam

At the moment I suspect the rear exhaust, but it looks good and I haven't really detected any play in it when trying to shake it by hand. Some months ago I rebuilt the joint between the intermediate pipe and rear muffler. I think I used a new exhaust clamp at the time.

I have access to a pit (and a lift, but for this a pit is better) and have had friends trying to shake the car. I finally identified play in the old ARB linkage and tie rods this way, but there's still that one clunk left I can't find....

Have I missed any common points?

[GingerMagic]

Spare wheel loose, jack in the wheel making a noise..??

I'm not sure whats left to look at and replace.....

[steve_earwig]

God yeah. you changed everything already. I'm going to go for the spare wheel as well, don't mess about, take the whole lot out and take it for a spin. Try not to get a puncture...

[jasper5]

I would be inclined to check the front suspension....won't be the first time a rear end noise turned out to be front

[8Jb9]

I should have mentioned, but I emptied everything - spare wheel, tool kit, even the little plastic box on the LHS.... it made no difference to the sound. Also, didn't have a puncture.

I'll have to check the front as well for lack of better ideas. It's just a bit surreal that when I slowly run over those shopping mall speed bumps the sound comes exactly as the rear wheels are jolted across, and not the front (several seconds between them). How about something like engine mounts? If the exhaust system gets jolted around and pushed on it?

[GingerMagic]

Oh...

I did have a rattle in my old Hdi90, which with help from my friends driving it and me sat in the boot, it turned out to be the fuel flap release cable hitting the inside of the bodywork.....

Maybe you could try the same thing, sit in the boot while a mate drives over speed bumps, obviously very slowly, and see what you can find.

Do you have a towbar?

[8Jb9]

We tried that some time ago, but didn't really find the location of the fault - same sensation as in the cabin. Maybe I need friends with better spatial awareness ;-)

I do have a tow bar, it's removable and not currently fitted. OEM from what I can tell.

Noise not linked to acceleration, and I can't provoke it in any other way than bumps.

[8Jb9]

I keep hunting down manholes and other inconsistencies in the road without getting wiser. Just that it happens when the rear L wheel hits something... It sounds like a quick series of little clunks.

The big problem is reproducing it while stationary since it requires such a little jolt to start. I've never managed to trigger it when pumping the car by jumping on it in the back. Any ideas on it? I was thinking about maybe lifting it up a bit on a jack and trying to open the valve as sudden as I can, but don't know if it will do the trick.

Also... what's left to look at.


[*]Lower suspension arm bush, #17
[*]What's going on in the suspension arm - #1? Are there any bushes integral to it?
[*]Bearing is new and does not have play
[*]Lower ball joint, #7


[*]Subframe joints, #6


[*]Spring rubber parts, #4 and #5
Inspected, couldn't see anything out of the ordinary.

Anyone had to replace any of these parts? How did it sound, and how to reproduce?

[steve_earwig]

My only experience is this upper tie rod thing (#6 in the first pic), I know you already replaced yours but there is a point, I promise. For a long time my D9 was making a light clunk going over just the sort of thing you describe. It was up on the 2-poster a few times with Krešo the mechanic checking it over and giving me a "you imagined it" look. Then it went on the ramps and was imminently obvious, just grabbing the arm and giving it a twitch made the noise I'd heard. Problem was up on the 2-poster the suspension is just hanging and not where it is when the weight is on it.

[8Jb9]

Yes, I get your point with the 2-post. That's why I roll it in over the pit instead of the lift when I try to provoke it. The tie rod was immediately obvious last time when I grabbed the wheel at 10 and 2 on the ground and yanked it towards me - now it's firm. I'll keep at it though...

[ally406]

Any play in the wheel at 12-6? Lower rose joint bushes can develop some play, but would result in play at the wheel. Might be better jacking the suspension arm up a bit to a neutral position before checking.

[8Jb9]

I'll try to have a look for it, but no - I haven't detected any play. Not since I replaced the tie rods at least. I'll try with wheels off the ground and suspension loaded to see if it makes a difference.

Right now I think I've been able to reproduce it and will take it on a lift tomorrow to have a closer look. By vigorously jolting the exhaust around while leaning inside the boot I think I could hear the sound, so I'll be inspecting the LHS rear silencer mount that might be bad.

[GingerMagic]

Strap the exhaust nice and tight to the bodywork, then drive down some steps....

If the noise has gone, or changed note then hopefully you've found the little beggar.....