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John W. Tilford

I know it doesn't happen on the forums too often, lol, but I wanted to update everyone on what it turned out to be for any future mystery clunk sufferers:

Drum roll....

It was the left front shock.

My instincts were kind of right. My final thought was perhaps the shock had prematurely worn out internally after just 15,000 miles. It was indeed the shock making the noise but it wasn't that it had worn out. What it actually was, was the upper mounting nut had come loose somehow. I know it wasn't loose when I installed it or the clunking would have been there from right after I installed it and I would have immediately checked into that; but since it showed up 5000 miles later, I didn't directly connect the two.

So after spending at least a dozen hours changing ball joints twice, spindle, checking and tightening bolts, etc. it turned out to be literally a 3 minute fix.

So why didn't I notice it before when I was banging/prying on everything with the wheel off? The play in the upper mount only showed up when the car was on the ground (shock compressed). When I jacked it up the shock was mounted nice and tight since it was being pulled by the suspension.

I figured it out because I started thinking it might be the two bottom mounting bolts were slightly loose allowing a slight amount of metal to metal contact when the suspension moved through its paces (even though I had already checked it like 5 times). So since I was only going to quickly check those couple of bolts, I just drove the Fiero up on the curb and shimmied underneath. The bolts were tight. Then I got the thought maybe I should reach up and see if there's any play in the third mounting point. When I did voila, I could feel the gap between the crossmember tower and the rubber insulator.




Because of the big rubber insulator when brainstorming, I wouldn't have thought that even if loose it would make a clunking noise, but then I realized the entire upped part of the shock could move sideways and that the mounting shaft was banging on the crossmember hole the shaft goes through.




Case closed.

[This message has been edited by reinhart (edited 01-26-2023).]