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Discussion Starter #1
I installed a pair of rear coilover shocks on my 99 Cobra. These are Koni Series 30 shocks with a coilover tube and spring perch:



I get a terrible sounding clunk when I drive over small bumps at low speeds of 10-30MPH:

CLICK HERE FOR HORRIBLE CLUNK NOISE

In my mind this clunking sound can only be coming from the following locations:

1. The top or bottom mounting point. I’m using a QA1 poly bushing and metal sleeve on the bottom. The bolt is torqued down pretty good. Very unlikely to be coming from the bottom. The top mounting point is similar to a stock shock with bushings on the top and bottom. Unlikely to be coming from this. I am using washers to ensure that the shock body does not come in contact with the lower arm.




2. The coilover spring hitting the swaybar or something else. I have about ¼” or more of clearance (spring to swaybar) when the car is at level. I also used some duct tape to see if it is rubbing. It’s not. I also removed the coilover spring and reinstalled the original springs using this Koni Series 30 shock. It made the same clunk noise. So that confirms that it is not the spring hitting something.

3. The shock itself. I have never heard a shock make this kind of noise. These Koni shocks have 3 click adjustments for rebound. Compression is unadjustable. At the low and medium setting for rebound it makes this clunk noise. When I adjust the rebound to the high setting the clunk noise is 95% gone. But the car doesn’t handle so well with the rear shock at full rebound. Lots of push. I bought these Koni shocks used from someone that heavily road raced his 99 Cobra. Can worn out shocks make this kind of noise?

I’m hoping some of you have had similar experiences with shocks that could help me pinpoint and eliminate this annoying clunk. I think I have just about run out of options short of buying new Koni's and trying them.

Thanks for your help!
 

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Try adding a little more preload on the upper shock mount bushings - maybe another turn or so. I had a cluncking sound when I first installed my rear coil over kit and it ended up being too little preload on the upper mount bushing.
 

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Discussion Starter #3
Those upper bushings are already sandwiched pretty darn good - to the point that they are bulging. I also had this noise when I had solid upper mounts (metal to metal) with the torque of God applied.
 

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How much clearance do you have between the lower end of the shock body and the control arm (just above the mounting bolt)? In one of the pictures, there is what looks to be a wear mark on the shock body just above the 'Made in Holland' stamp.

Also, it looks like you need to shave a little material off the poly bushings. In one of the pics, it looks as if the poly bushing is widerthan the crush sleeve.

If you have the noise on one side of the car more than the other, take the shocks off and static cycle them to get a feel for whethter they respond the same. If one shock is different (compresses easieer/extends faster, you may have a problem with one of the shocks. Switch the shocks to opposite sides of the car. If the noise follows the shock, this supports the possibility of one shock being bad.
 

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How much clearance do you have between the lower end of the shock body and the control arm (just above the mounting bolt)? In one of the pictures, there is what looks to be a wear mark on the shock body just above the 'Made in Holland' stamp.

Also, it looks like you need to shave a little material off the poly bushings. In one of the pics, it looks as if the poly bushing is widerthan the crush sleeve.

If you have the noise on one side of the car more than the other, take the shocks off and static cycle them to get a feel for whethter they respond the same. If one shock is different (difference in compression/rebound) for the same setting, you may have a problem with one of the shocks. Switch the shocks to opposite sides of the car. If the noise follows the shock, this supports the possibility of one shock being bad.
 

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Discussion Starter #6
Blown46Cobra - both sides make the clunking noise. There is enough gap between the lower control arm and the shock. The rubbing is from a previous use. The sleeve is slightly recessed because I kept torqueing it down. It would clunk, I would l tighten it, it would keep clunking so I kept tigtening. The sleeves is starting to compress on itself. I have since repaced that sleeve with a much thicker sleeve that should be less prone to crush. It is extremely tight yet it still makes that clunk noise as bad as ever.
 

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Discussion Starter #7
BUMP
 
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