Loud clunking sound over bumps

[Rom]

Hi all,

My 99 2.5L is making some weird loud clunking sounds over bumps, which sounds like the rear passenger side. I’ve lifted the car and inspected everything, tried moving the wheel up and down, checked for any loose suspension bolts, but nothing apparent.

I know the control/caster arm bushing sometimes wears right under where the passenger door ends and causes weird noises, but the sound does seem to be coming from much further back. Driving on a smooth road is quiet - just any bump clunks loudly. Handling does not appear to be compromised at all.

The car does have PSS9 coil overs and Tarett drop links, as well as adjustable toe control arms, but all that has been checked and appears tight (at first I thought the suspension top mount had come loose).

Anyway, any other ideas as to what it could be? I thought maybe the anti roll bar bushings, but they seem okay. I might disconnect the drop links and drive around to see if it changes.

Any ideas appreciated!

Thanks!

S.

[Luckyed]

That sounds like the situation I had before I changed my rear control arms. Clunk went away after that.

[Anker]

A very simple test to verify that it is the read control/trailing arms is to either brake or accelerate over a bump. If the rattle diminishes greatly or disappears than it is confirmed. If not, it must be some other suspension component.

If it is the trailing arms they are easy to replace yourself as long as you have a good set of sockets, a breaker bar and a big torque wrench. The bolts take a lot of torque, up to 118 ft lbs.

[Rom]

Thanks guys, especially Anker as I've been looking for a way to confirm the issue. I'll see if that works for me. If anyone knows any other positive tests I can do to confirm, would be much appreciated!

S.

[DWBOX2000]

Does the noise go away when the car warms up?

[Rom]

Originally Posted by DWBOX2000

Does the noise go away when the car warms up?

Nope - temperature does not seem to affect it at all...

Thanks!

S.

[Rom]

I wanted to close the loop on this thread in case anyone looked at it (annoys me when I see threads with no solution posted!). The sound ended up being the rear passenger side top mount - the rubber has sheared completely so the suspension was moving freely up and down over bumps, knocking loudly. It didn't fall out because of the large washer on top of the damper, but was surprised how the rubber completely failed.

It was a brand new OEM top mount when the suspension went in, but of course the suspension being much stiffer put a much higher load on it.

Thanks!

S.

[Starter986]

Originally Posted by Rom

I wanted to close the loop on this thread in case anyone looked at it (annoys me when I see threads with no solution posted!).

Thank you. Welcome, new person. Se ya around.

[Ciao]

Check engine cover and rear storage container to see if all screws are tightened

[dbear61]

Does this occur over all bumps at all speeds? Or do you only experience this on rough roads, not bumps, at low speeds (i.e. <30mph)?

My 2001 S has been doing this at low speeds on rough roads since I bought it in 2012. Seemingly same location, rear passenger side.

I had my mechanic do a thorough inspection, and he could not find any cause. So I just endure it.

DBear

[piper6909]

Originally Posted by dbear61

Does this occur over all bumps at all speeds? Or do you only experience this on rough roads, not bumps, at low speeds (i.e. <30mph)?

My 2001 S has been doing this at low speeds on rough roads since I bought it in 2012. Seemingly same location, rear passenger side.

I had my mechanic do a thorough inspection, and he could not find any cause. So I just endure it.

DBear

dbear61, your issue is most likely the rear track arms (the tuning forks):

https://www.pelicanparts.com/catalog/SuperCat/1049/POR_1049_SUSSHK_pg4.htm

They're very hard, if not impossible to diagnose while on the car because of the type of joint. Mine had the exact same issue as yours. I changed them and no more clicking/clunking noise. They're easy to change.

This could be the same issue for the OP, if his symptoms are the same.

[pilot4fn]

Originally Posted by piper6909

dbear61, your issue is most likely the rear track arms (the tuning forks):

They're very hard, if not impossible to diagnose while on the car because of the type of joint. Mine had the exact same issue as yours. I changed them and no more clicking/clunking noise. They're easy to change.

This could be the same issue for the OP, if his symptoms are the same.

I had on my 2001 986 the loud bang(s) over the bumps and for that reason changed all control arms front and rear as well as the dog bones on the sway bars. Almost all the noise ended, but still sometimes on 'right kind' of bumps i hear the fairly loud bang from rear that sounds like coming from close to my ears. I do believe the reson for the final bang to be the rear shocks upper bushings or bump stops. Those are next on the list to be be changed...

[steved0x]

Originally Posted by Rom

I wanted to close the loop on this thread in case anyone looked at it (annoys me when I see threads with no solution posted!). The sound ended up being the rear passenger side top mount - the rubber has sheared completely so the suspension was moving freely up and down over bumps, knocking loudly. It didn't fall out because of the large washer on top of the damper, but was surprised how the rubber completely failed.

It was a brand new OEM top mount when the suspension went in, but of course the suspension being much stiffer put a much higher load on it.

Thanks!

S.

I've seen this happen twice now, but only in cases where the lower cupped washer was failed/forgotten to be installed - the OEM strut top mounts require both the upper and lower cup washers to hold in the rubber bushing and give it something to push against for compression and rebound loads. If the failure looked like this, it is from a missing lower cup washer, you can see the top washer in this photo.