88GT LF Clunking Noise Mystery (Page 1/2)
reinhart JUL 20, 10:13 AM
88 GT: factory springs and stock ride height

I've had a mystery clunking noise in the front left when I go over bumps that I can't find for about the last 5000 miles.

What I've changed:
- I've got poly bushings all around (don't see any wear or metal to metal possibilities where the bushings are)
- replaced lower ball joint twice
- replaced the LF spindle
- checked all bolts for tightness (suspension and rack bolts are tight) (also UCA alignment bolts are tight).
- rack has been personally rebuilt with all new bearings and a new factory plastic bushing about 20,000 miles ago

Can't find any play in anything. Tried using a breaker bar in between any area that should move. The sound is just like when I had a bad lower ball joint in a different Fiero years ago. However, after 2 ball joints replacements, I'm pretty sure that's not it.

I cannot recreate the noise when the car suspension is jacked up.

What else could cause that clunking noise?

So could it be front shock absorber? (I replaced them about 20,000 miles ago). Would that make a clunking noise or just not absorb the suspension travel if bad?
Could a bad wheel bearing cause that noise? I don't hear what I would think would be any bearing noise when driving on a flat surface (i.e. no whining or humming).

What could I be missing?

[This message has been edited by reinhart (edited 07-20-2022).]

theogre JUL 20, 10:56 AM
Brake pad(s) etc can make noise going over bumps.

May not be on LF but sounds like is to you.
Or may not be suspension but other things broken and moving.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

John W. Tilford JUL 20, 06:29 PM
I had a VERY similar mysterious clunk/clank problem from the front for several months a couple years ago. (1988 GT, 3.4L, 4T60 trans). Nobody could diagnose. I couldn't even detect a reliable pattern. Sometimes clank over a mild bump, then none over a bigger one. Once made it 40 miles with no clunk at all. Then over a slanted lane in town a bunch over a few blocks. I got first one side up high enough I could wiggle under and tap everything I could see with a rubber hammer, listening for the clank sound, then the other side. No luck. Finally Meineke in Ellettsville, Indiana found it. Turns out no other shop had bothered to take the front wheels actually off the car. (Warning, poor terminology follows.) The guy called me out into the shop so he could show me while the car was up on the lift. As he turned the steering wheel back and forth the outer tie rod would sometimes rub against the anti-sway bar. Sometime along the long and winding road of parts being replaced on the car the spacers between the suspension proper and the anti-sway bar had been replaced with a too short version. Easy fix. Put the correct length spacer in. Think I had to buy another set of threaded rods, nuts, and spacers but not a big deal. They changed for me on the spot. Was a real pleasure to drive without the frightening noises.

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John W. Tilford

[This message has been edited by John W. Tilford (edited 07-20-2022).]

fieroguru JUL 20, 07:02 PM
Check the caliper sliders. They can wear (more of an issue on the 88s) and allow the caliper body and bridge to bounce.
The tie rod to sway bar can interfere depending on state of lowering, caster adjustment and length of sway bar end link.
Sometimes the bolts holding the upper a-arm will not be properly tightened and the pivot shaft will move around.
Depending on amount of lowering, you could be bottoming out the shock - especially if you are running KYB shocks (longer than stock).
reinhart JUL 22, 10:18 AM

quote
Originally posted by John W. Tilford:

I had a VERY similar mysterious clunk/clank problem from the front for several months a couple years ago. (1988 GT, 3.4L, 4T60 trans). Nobody could diagnose. I couldn't even detect a reliable pattern. Sometimes clank over a mild bump, then none over a bigger one. Once made it 40 miles with no clunk at all. Then over a slanted lane in town a bunch over a few blocks. I got first one side up high enough I could wiggle under and tap everything I could see with a rubber hammer, listening for the clank sound, then the other side. No luck. Finally Meineke in Ellettsville, Indiana found it. Turns out no other shop had bothered to take the front wheels actually off the car. (Warning, poor terminology follows.) The guy called me out into the shop so he could show me while the car was up on the lift. As he turned the steering wheel back and forth the outer tie rod would sometimes rub against the anti-sway bar. Sometime along the long and winding road of parts being replaced on the car the spacers between the suspension proper and the anti-sway bar had been replaced with a too short version. Easy fix. Put the correct length spacer in. Think I had to buy another set of threaded rods, nuts, and spacers but not a big deal. They changed for me on the spot. Was a real pleasure to drive without the frightening noises.



Thanks for the ideas. I did all the work myself on this car (bought with 19K on it 15 years ago) and it all started all of a sudden (no correlation to any repair). But good idea to check to tie rod and sway bar clearance. When yours was rubbing was it with the suspension hanging down? I feel like mine is on the compression cycle. I suppose it's possible the sway bar shifted to the left or right side a half inch which could make it rub so I'll check that too.

Guru, I've checked those upper arm bolts as I had the same thought you did. Also I am the only one that has done the alignments so wasn't abused by some shop and I have the Rodney nut reinforcement pads. The alignment is amazing by the way.

Forgot to mention I replaced both inner and outer tie rods when I rebuilt the rack. Everything on the front suspension and steering has been replaced in the last 20-30Kmi except the upper ball joint. I didn't feel any play there either loaded or with the control arm loose and manually moving the ball joint. I am hesitant to replace them due to the need to drill and weld new ones in and I've never seen an upper go bad and can't find any play there.

I'll jack it up again and check the sway bar and tie rod. If I don't see any sign of rubbing, I'm almost tempted to either remove the front left shock or to swap left and right shocks and see if that eliminates the clunking on the left. If that doesn't fix it then I suppose the only thing left is the upper ball joint or the wheel bearing. Unless someone else has another idea for me to check.
ninedriver JUL 23, 10:44 AM
Maybe a long shot, but when I first got my car I had a clunk from the left front end as well. Turns out it was coming from the left front headlight assembly. Give it a good shake down. And operate it with the hood open and shake it down again. Mine only made noise going over bumps and I thought for sure it was suspension related. Who knows, worth a look.

[This message has been edited by ninedriver (edited 07-27-2022).]

reinhart JUL 25, 05:02 AM

quote
Originally posted by ninedriver:

Maybe a long shot, but when I first got my car I had a clunk from the left front end as well. Turns out it was coming from the thief front headlight assembly. Give it a good shake down. And operate it with the hood open and shake it down again. Mine only made noise going over bumps and I thought for sure it was suspension related. Who knows, worth a look.



Wow good thought. I haven't had a chance to work on this problem yet because I've had a friend visiting from out of state, but this will be the first thing I check since it won't require jacking the car up. Will report back on this in the next week!
ninedriver JUL 27, 11:50 AM
Good deal. Let us know what you find out. I just looked at my post and there was an obvious typo / autocorrect. “Left” headlight , not “thief”…
Larryinkc JUL 28, 07:34 AM
I had a similar issue on the passenger side of my 88. It turned out to be the coolant pipe banging against the front frame rail. It had moved forward a bit over the years and on some bumps would hit the frame. I moved it back and no more banging.
kendell JUL 31, 11:20 PM

quote
Originally posted by John W. Tilford:

I had a VERY similar mysterious clunk/clank problem from the front for several months a couple years ago. (1988 GT, 3.4L, 4T60 trans). Nobody could diagnose. I couldn't even detect a reliable pattern. Sometimes clank over a mild bump, then none over a bigger one. Once made it 40 miles with no clunk at all. Then over a slanted lane in town a bunch over a few blocks. I got first one side up high enough I could wiggle under and tap everything I could see with a rubber hammer, listening for the clank sound, then the other side. No luck. Finally Meineke in Ellettsville, Indiana found it. Turns out no other shop had bothered to take the front wheels actually off the car. (Warning, poor terminology follows.) The guy called me out into the shop so he could show me while the car was up on the lift. As he turned the steering wheel back and forth the outer tie rod would sometimes rub against the anti-sway bar. Sometime along the long and winding road of parts being replaced on the car the spacers between the suspension proper and the anti-sway bar had been replaced with a too short version. Easy fix. Put the correct length spacer in. Think I had to buy another set of threaded rods, nuts, and spacers but not a big deal. They changed for me on the spot. Was a real pleasure to drive without the frightening noises.



Good tips. We might deal with a similar issue on my uncle's new GT 3.4L. It's been sitting for a year and the previous owner wasn't able to solve the intermittent clunk. Got to finish installing the rotors, tire and wheel packages on the Silverado this week before we can clear the garage and take a closer look.