Koni Swapped Strut clunking sound

[Claw]

I did a Koni swap to my OEM struts about 2-3 years ago.  They've been great for a while but this spring a clunk developed and I'm having a hard time pinpointing the source of it.

It seems to occur on decompression of the strut.  I've checked my mounting bolts top and bottom and it's all there and tightened to spec.  I thought it might have been the M12 bolt underneath pulling the insert into the body, but that too is tightened and rusted in place.

I took it to a mechanic to check out my suspension and they said everything looks solid, no loose joints, connections.  Also fellow forum member had a look and a test drive and thought that was also strange.  My aluminum Mevotech LCA's from Rock Auto and their bushings are all still good.  I sent an inquiry to Koni and this is what they had to say:

"A clunking noise is very rarely related to the working function or internal compression/rebound damping force of a shocks absorber. That is unless the damper has lost a considerable amount of oil. If the inserts have developed leaks where you are seeing large collections of oil in or around the upper strut mount, or leaking down the strut body, it’s possibly that the clunk is related to the lack of oil inside the shocks. Though if that were the case you would also notice a considerable degrade in the handling/performance of the dampers, not just a clunking noise. Clunks especially in colder weather can become more prominent as the temperature drop and the rubber isolators in mounts, bushings throughout the suspension system become much harder, almost plastic like and less susceptible to movement."

Lastly, I changed from full stiff minus half a turn to full soft minus half a turn, and the clunk seems to be less when the strut extends after I hit a bump.

Thoughts on what it could be?  I know my passenger side strut has a leaky seal so I'll be sending that one in to Koni for warranty replacement, but the clunk is a lot more apparent on the drivers side.

[BoozeRS05]

Seems a couple members are having issues with their Koni struts lately.

I had a full set for 8 years and 80k miles that were removed 3 years ago bc one of my rear springs actually snapped, but the struts were still working great. I’d assume it’s the upper mount before the strut, but maybe Koni quality control is going down hill. Also check your sway bar endlinks and bushings, they’ll clunk very quickly if they’re old or dry

[Claw]

Sure - I'll check the upper mount too.  Also endlinks, the car is almost 18 years old so that's a valid point.

It's odd that if I turn the dial down to full soft the clunk mostly goes away.  Went for a drive up a short 1km road this morning in full stiff and full soft, there's a lot more clunking going on in the full stiff.

[Pleides]

I'm curious what exact date you purchased your Konis? My suspicion is that Konis as of pandemic era have declined in quality. Both my fronts had some sort of severe failure by 30K miles. I'm driving the car with them right now having warrantied the right front, but the left front doesn't rebound much anymore. 

 

There's the potential that you didn't cut the strut housing correctly. I had a shop install mine, so I would have assumed that they did that job correctly, but who knows. If the housing is cut too short then that will cause issues. I actually suspect this is why my front right failed so quickly. For the front left, I think she's just defective. The thing isn't blown. The right front was leaking. 

 

See if you can take the strut off and watch the actual strut move up and down in its housing. if it's not moving completely straight (perhaps it shimmies a bit or has side-to-side movement like mine both have had), then that'll cause noises and premature failure. For me, the front left squeaked for about 10K miles before it just stopped rebounding. 

[Claw]

I bought them in 2011, but didn't get around to installing them until 10 years later when my stock struts started feeling bouncy.

I had followed the writeup here about the Swift Springs/Koni insert DIY, did the exact measurements and cut.  I had suspected that I didn't locktite the attaching screw enough, but on a few occasions I took the tire off, tried to move it up and down with a jack and it didn't shimmy or move funny.  The screws at the bottom are solidly rusted (ie. secure) to the strut body.

The telling moment is when I dialed the strut (both of them) to full "comfort mode" and the clunk went away.  I've done a few long(er) distant drives and on country roads/fire roads taking my kid to camp and the clunk never came back.  But as soon as I twist the dial towards the sportier setting and back half a turn from full, the clunk comes back.

I messaged Koni warranty with this finding and they said:

Quote

A clunking noise is very rarely related to the working function or internal compression/rebound damping force of a shocks absorber. That is unless the damper has lost a considerable amount of oil. If the inserts have developed leaks where you are seeing large collections of oil in or around the upper strut mount, or leaking down the strut body, it’s possibly that the clunk is related to the lack of oil inside the shocks. Though if that were the case you would also notice a considerable degrade in the handling/performance of the dampers, not just a clunking noise. Clunks especially in colder weather can become more prominent as the temperature drop and the rubber isolators in mounts, bushings throughout the suspension system become much harder, almost plastic like and less susceptible to movement.

Where I'm at it's cold (below freezing) 6 months out of the year.. while the lifetime replacement is nice, I'd rather not be swapping struts every time it fails.  The right front strut is leaking from the top and the other is clunking.  It's like I'd need a spare pair of struts ready to swap in.