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Front End Clunk

89K views 415 replies 60 participants last post by  bmw blue 
#1 ·
My driver's side front suspension has an intermittent but audible and tactile clunk. I usually feel and hear the clunk at slow speed after sharp braking (going on and off the brake), and as I drive along a bumpy road. I removed both front tires expecting to find a loose strut, tie rod, sway bar, or other suspension component. Instead, everything is tight. Calipers as well. But something is definitely loose or worn because I can actually feel the clunk...clunk. Another irritant is the front brakes are very grabby. When I roll to a stop under braking, they grab and make the stop not exactly passenger friendly. I wonder if my clunk is related.
Can anyone suggest a diagnosis of the clunk? It's a weird one.
Thanks,
CL
 
#2 ·
I just had the thrust arm bushings replaced at my dealer. This was to prevent the well known violent shaking problem while braking on a rough surface. The thrust arm bushings looked fine visually but the dealer said they are definitely the problem with the shaking from hell. So, new thrust arm bushings in and the clunk is basically gone. Go figure.
 
#5 · (Edited)
It would really help if you posted up the mileage of your car.

That said, we have the same car and mine is exhibiting the same behavior as yours. I can hear it from the driver's side, and most likely it is coming from the passenger's side as well. However, it is very faint and probably just cannot hear it from the driver's seatIn my case I have ruled out the thrust arms and sway bar links because they are brand new. My car brakes excellent because they were replaced a month ago. It rides and brakes as smooth as glass.

My car has 65K on the clock and my problem is coming from worn out struts/shocks. I can hear a knocking coming from the strut tower just as you describe when I brake, bumpy roads, and when I accelerate. I am in the process of shopping around for shocks and strut mounts. if your mileage is similar or more than mine, then chances are you have the same problem. My car spent most of its life in DC and the roads are not that great so I am sure that has contributed to the worn out shocks tremendously. I would imagine that you are in a similar situation due to Mass. not having the best roads as well.

Gut feeling tells me your brakes just need to be flushed and bled.

Addition: Just realized I missed your second post. When you say "basically", I am assuming you mean there is still a faint knock? Is this correct?
 
#6 ·
Open the hood and pull off the shock covers, the black plastic ones. Then push up and down on the car and watch the shock end. Even put your fingers on the end of the shock assy to see if you can feel the clunk.

Check both sides as it happens often what sounds like from one side can be the other side.
 
#8 ·
Had a similar problem on my 65K miles 528i.

Brakes would shudder when applied and cause a real noticeable "shimmy" on the steering wheel.

Thought it was a bad steering rack, but it turned out to be bad tie rods ends.

Replaced the drop links also at that time as they had play in them.

Cured the problem.
 
#10 ·
Sorry all. Hadn't been back here for awhile.
2002 525i. 103,000 miles. Road conditions are basically average to below average. Frost heaves and pot holes. Otherwise, decent. Normal New England.
 
#11 ·
Update:
The 525 was in the BMW shop today for "clunk" repair. Here's the verdict: The non-BMW shop who installed the Bilsteins installed the "lock ring" washer just below the Upper Strut Mount upside down. According to the tech, this washer is slightly conical in shape and needs to be installed wide side up. He replaced the washer and reinstalled. On the drive home, the clunk seems to be gone. Also, and not insignificantly, he found the tie rods on both sides to be in bad shape. He thought they were significantly damaged when removed by the first shop during the Bilstein install. So, now with new tie rod assemblies, reinstalled struts with the washer correctly positioned, and an alignment, I am poorer, smarter, and ready to move on.
Lessons learned: Do not under any circumstances trust the sensitive front suspension of your BMW to a generalist shop. No substitute for experience.
Also, Frank nailed the diagnosis with the top of strut test while pushing down. "clunk... clunk". Strut mis-installed. Oh well.....
 
#12 ·
Update...
The clunk is back in force. The BMW mechanic believes the source is the shock tower bearing. He also did not replace the conical washer first time around and instead "repaired" the original. So, the 525 is going back in for a new washer and new strut bearing. Of interest is that the clunk was gone last week after the mech "repaired" and correctly installed that upper washer.
I am interested in other things to check/do so we can ge this fixed for once and for all.
Currently on the car:
New tie rods
New thrust rod bushings
Tight sway bar links (but not new)
New Bilstein HDs
New spring plate

Thanks.
 
#13 ·
I had the annoying clunk also when hitting even the smallest lip in a driveway, etc. Problem completely gone after replacing upper control arm bushings and the lower control arms (thrust arms) including bushings. I see you replaced the thrust bushings already; I'm surprised you didn't do the uppers as well. These things definitely will wear out. May not be your problem, but with over 100k miles and if you haven't had the upper CA bushings replaced, this may be something to consider before doing anything more pricey....
 
#14 ·
Chris,

When you initially posted about a clunk you were also describing the association of that clunk with the brakes being "grabby". I think you should take the caliper off and inspect the piston, brake pads, also looking at the wear on the rotor. Sounds like you could possibly have a piston that is not moving freely. When this happens the pads do not stay seated properly. When the brakes are depressed, the the ears clanging on the pad rails might be what you are hearing. This can happen when you depress and release the brakes. Also, it would explain why your brakes might be grabbing. Old fluid or a leaking piston could be a potential problem, or both. A piston not moving freely can also exhibit signs of shimmy at various speeds, additionally adding to the possibility of premature rotor warping.

My feeling is that once the caliper was remounted the piston was able to move, then after a few days it is "stuck in the same groove", so to speak. This might also explain when everything was torn down and put back together the clunk came back.

The good thing about doing this exploration is that it is free and does not require you to keep paying for more parts and unnecessary labor. Give it a shot - I am always amazed that when I am chasing something down, plenty of times it ends up being something way out in left field.

Good Luck
 
#15 ·
Michel,
Leave it to me to be a little short of full disclosure and accuracy.
A month or two ago, I came the same conclusion as you per the grabby brakes and possible link to the veritable clunk. So, I replaced my rotors, pads and did a full pressure bleed. I then seated the pads properly and feel like the brakes are in good shape.
I also took to heart Waveho's note above suggesting upper and lower control arm bushing possibilities by calling my BMW shop and suggesting this possible culprit. His answer was that all the control arm and control arm bushings are fine on both sides, top and bottom.
So, he said "I know where the problem is which is at the top of the strut mount. I am certain when I change the strut bearing and replace the washer hardware, you will be all set".
That remains to be seen but I love his confidence.
I'll let you know and am very grateful for the many responses.
 
#16 ·
Cool. I hope it all works out. I will be getting rid of my clunk later on today when my shocks and strut mounts get delivered by the big brown brick. The knocking that I first suspected was my shocks will most likely turn out to be my tie rods as well. I have two distinct knocks coming from my suspension and they are the only tings that have not been replaced. The newer, stronger stuff is making the weaker stuff more apparent as time goes on.
 
#17 ·
I don't think that tie rod ends knock when worn.

I just had everything on the front end replaced including my Bilstein HDs. Now I've got the new Bilstein Sports which are supposed to have the same valving as the old HDs

Well don't believe that. The new Sports are not super stiff but they are stiffer than the HDs I had. And they are definitely stiffer than OEM sport.

However they are not too stiff for me but I can see how they would be for others.
 
#18 ·
I don't think that tie rod ends knock when worn.

I just had everything on the front end replaced including my Bilstein HDs. Now I've got the new Bilstein Sports which are supposed to have the same valving as the old HDs

Well don't believe that. The new Sports are not super stiff but they are stiffer than the HDs I had. And they are definitely stiffer than OEM sport.

However they are not too stiff for me but I can see how they would be for others.
I would imagine if the ball joint portion has worn out it could exhibit a knocking sound (ofcourse, it may very well not be in my case), but you might be right. I will do a good inspection on the old ones to see how they fared after 70K miles.

It is good to hear your feedback on the difference between the HD and Sport valving. Theory would tell me that the valving would be different since they are tuned to accommodate the different spring rates between the Sport and standard springs - this supports your findings. However, if you speak with Bilstein they will tell you they are the same. Well, I will take your word for it since you have first hand experience with both since all other parameters are the same. Much better than believing one of their techs that is reading it off of a sheet of paper.
 
#19 ·
I have close to 200K miles on my front end compoments and the tech that did the work said I could have gone longer on the tie rod ends.

My car got hit on the right front wheel and that slightly bent the shock so that is why I got shocks. Otherwise my HDs were good and going strong.

It was the other guys fault so his insurance paid for one of the pair of shocks plus everything else.
 
#21 ·
Solo1,
Your point is made. I
P
R
O
M
I
S
E
I will insist the BMW tech check the sway bar links on this hopefully final trip to the shop. I really do appreciate all the help for all of you.
 
#72 ·
Center link applies to the 540, not the OP's 525i. Unless it's a steering rack issue, of course.
 
#24 ·
540ispdSprt, how much was it to replace the center link?
 
#26 ·
Please excuse my ignorance, but where is the center link? And how does it play into the suspension?
 
#27 · (Edited)
The center link (#9), or center tie rod, connects the two outer tie rods (#10 & #11) together. The center link is then connected to the steering box via a Pitman arm (#1). Pic 1

The I6 E39's do not have a center link, steering box, or Pitman arm - they are replaced with a steering rack (rack & pinion). Pic 2
 

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#28 ·
Thanks for the info. Looks like another component that I may need to replace in the future. : )
 
#30 ·
Today, new strut top cap and bearing installed. The clunk is gone for now. I am guardedly optimistic the clunk was due to worn/damaged shock bearings. If not that, I'll be back to post round 3. Everything including the center link seems perfect. My mechanic says if the clunk returns, the only thing left is the strut itself.
 
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