The dreaded CLUNK! Insights appreciated.

[emw525E34]

Most of our E34 had this problem of sorts but trying to trouble-shoot a particular clunk sound can be a real challenge. Here is my situation:

Car E34 95 Touring, Euro model with M50TU motor and 5spd.

Symptoms: From cold or after parking for some hours. Reversing out of a parking bay or garage, I will get a large CLUNK on the driver side, then a small clunk of the passenger side. Definitely coming from the wheels/suspension or steering link areas.
Things already replaced: Pair of new upper control arms. (This was the first suspect as the driver side had a leaking balljoint. Not it!)
Next was the steering link tie-rod end. Driver-side had one replaced as it balljoint was in bad shape and nut was threaded. (Actually clunk worsen now!!!). The 22mm nut of the shocks are also tightened. (Not it as well!!)
Upper and Lower spring pad was also new but shock absorbers will be next in line for replacement. I also found that the front is a bit mushy as I could sit on the fender and get a dip of about 2-3 inches. Shocks done ?.

Could the shocks be over-extending themselves?. Pls advise as I strongly suspect that replace the shocks will eliminate this clunk syndrome. Thanks.

[Kalevera]

I'd get the car up on ramps and shake the sway bar links. You'd hear them when going over bumps if they were done or the ends were loose.

What about the collar nuts on the struthousings? Tightening the top nut is one thing, but if the collar nut is loose, the insert will bounce around in the housing and, probably, eventually destroy it as mine were when I got the car. Once again, it'd be more of a BUMP problem than anything else.

My other idea is strut mounts. Does "upper spring pad" = strut mount? I don't know, but I'd check 'em out.

best, whit

[Karl]

Sometimes the brake pads can stick to rotor, so it lets go with a jerk when you first start to move. Not common, but I've heard of it...
If it's a shock absorber, you'll hear a clunk every time you hit a bump in the road. Likewise if it's a bad bushing or ball joint it will happen all the time, not just the first time you move it.

[Mobius]

Tighten your front subframe mounting bolts, and steering box mounting bolts. They won't be loose; but if you can just get them a little tighter, the noise will go away.

At least, it did on my car.

..after I replaced all my control arms and tie rods..

[darron525]

I would do like Lowel said, if its when you go over something its probably sway bar links. I had the same problem about 3 weeks ago. Changed the thrust arms and the shimmy went away, changed rotors and pads and the vibration under braking was gone, changed the lower control arms, but still got clunking. Got the car up on ramps and noticed that the pass side sway link had play. Although the drivers side had no play it still clunked when giong over bumps. Put new sway bar links on and the clunk is gone.

darron

[jplacson]

Could be rear subframe mounts. Sometimes it just 'sounds' like a front end noise from the cabin.

Try and have someone else back it out while you stand outside and listen for the source.

[emw525E34]

Hi Whit,

I had my car up the ramps and shaked the daylights of all the joints without much success. Almost got crushed since the car was violently shaking sideways. All joints were tight!.
Collar nut very tight already. There seemed to be some bearing below the 22mm nut ?. I am not sure how to tell if this are worn. ANy tips on how ti inspect it ?. Or should I take off the 3 supporting nuts ?.
Upper spring pad is the 3mm thick spring mount. My shorts seemed "over extended" when the car is unladen, it does not look normal becuase the wheel arch looks like a 5-6inch gap between top of tire and the fender walls!.
I would replace the shocks right away, if that could rid the clunk noise once and for all. Its strange that the clunk is load only once and is when it is stationary. No the brale caliper were not sticking to the rotor at all.

Also, when I jack up one front wheel, I do get the same clunk but not as loud!. Lower control arms in very good condition and tight. Swaybar links 2 yrs old and tight as well.
Steering links I have not quite check. I will re-check the steering box connections and subframe bolts re-tighten as well.

PS: also when I replaced the "loose" inner ball-joint in the tie-rod end. The passenger side clunk seems louder now! Driver side still loudest. And only once. Across speed bumps, only a very small clunk heard with windows down.

[Kalevera]

HMMMmmm... Don't get crushed, it's not a good way to go :O !!

http://www.realoem.com/bmw/showparts...28&hg=31&fg=10

Have a look at that. A week or two ago, Bidoli and some of them were talking about *missing* parts of that sequence (and the sequence has to be correct) and having weird handling/sounds/voodoo magic **** going down.

I'm surprised that the tie rods weren't just completely replaced -- they tend to be cheap as one whole shebang...at least in the US. I just replaced the entire thing and had the alignment shop tighten and set them for me.

Are the upper control (thrust) arm bushings properly torqued? The latter's bushing -- specifically the center part (green on 750 bushings/white on stock/red when replaced with Bruno's delrin inserts) - should "lock" at an angle corresponding with normal ride height, which is why it's important to tighten it with the weight of the car on the suspension (so it gets normal ride height and not suspension-bottomed-out height). If the car's being jacked up in the air, I can imagine a loose bushing "snapping" in it's mount, giving that sound. Quick and easy way to check is to visually inspect it when the car is up on jackstands and see if the bushing is "stressed" (it should be -- with the front end up in the air, it's fighting the weight of the struthousing/wheel/tire/rotor).

As others have said, it could also easily be a subframe or steering box mounting bolt that's just not tight enough. Also, I've noticed that my springs themselves can sometimes be loud for no apparent reason. EDIT #2: ...especially if the car has been sitting in one spot for a while (maybe because my Kumho 712's grow flat spots really easily).

...actually, just re-read the message...Given the messed up ride height, I really think the control or thrust arm bushings just weren't properly set. Get the car up on ramps (or put old rotors under the wheels or something) and loosen the bolts at the four bushing points. May even have to remove and reset the arms in the mounting locations, then torque when the car is definitely at normal ride height.

edit: also, I would be sure to carefully inspect the control arm bushings. Riding around with improperly set bushings is a quick 'n dirty way to destroy them, as some have found out. While I think they'd probably deliver more than 500 miles, best check them out while the part's out, or partially out, again instead of having to do it all over another time around a few months (or weeks!) down the road.

best, whit

[emw525E34]

Hi Darron,

Yes, I shall check the sway bar link. thought they are only 2 years old, , one side looked like it is under some pressure. Since these are cheap parts, they are expendable then. Thanks for the tip. This would explain the clunk when I jack up the driver side of the front wheel!. Its the only part I assume would be OK but did not check fully. The upper control arms are new, and lower control arms are real solid and clean ball-joints and very tight to the wheel base. Caliper is not sticking at all.
JP, certainly not rear noise, it is very clearly from the front end. Nothing in the rear is loose at all. Most parts there are already new including the dogbones!.

[emw525E34]

Guys, FOUND the source of the dreaded clunk!. You might not believe this!. My passenger side spring actually was moving around when I put a gloved hand on the spring and shake it!. It is so simple, I kicked my self for using ramps etc and shaking things under the car.

Seems that the 22MM nut was tight and I put a hex on the rod and tried to tighten to no avail. It has exposed almost 1 cm of thread already. Also seems that top bearing mount is loose. SO this probably needs to be replaced as well. My worn front shocks are over-extending to the stage that the front spring barely had any weight on it when car was unladen.

Man, its a relief that I don't have to bother with lower steering or suspension parts. So when the new bilsteiin HDs come in the suspected parts will be renewed. At least for now, the trouble spot has been identified.
Many thanks for the tips here and the encouragement (plus bits of humour here and there).
You guys are cool!.