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Mystery clunk in front suspension.....solved by 86fierofun
Started on: 04-21-2008 02:12 PM
Replies: 4
Last post by: sjmaye on 04-23-2008 08:30 PM
86fierofun
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Report this Post04-21-2008 02:12 PM Click Here to See the Profile for 86fierofunSend a Private Message to 86fierofunDirect Link to This Post
I thought I would this post here, so others can learn from my blunders.

History:
About 2 maybe 3 years ago, I rebuilt a lot of my front suspension, mostly on the passenger side. What was replaced:
Upper and lower ball joints (pass. side)
Inner and outer tie rod ends (both sides)
Steering rack
upper and lower control arm bushings (pass. side)
shocks (both sides)
sway bar bushings/endlinks
brake pads

As is typical, Mr. Rust would not play nice. The control arm bolts siezed to the inside sleeve of the bushings, and I could not remove the bolts. I could not get any of my cut off wheels to fit in the area to chop out the bolts. So I had someone come over to burn them out with a torch. BIG mistake. He basically put the torch in there and turned his head (So he could fit, he is rather large). Needless to say, on 3 of the 4 mounting location he burned out the hole on the frame in an oblong shape, no longer circular. Dang. So I tacked in some grade 8 washers onto the frame to make the hole true again. I wasn't sure how well this would work.

Shortly thereafter, I developed a bit of suspension noise, rattling throughout the front end. I immediately thought my welds broke loose, but I checked them all, and they were in great shape still, and there wasn't evidence of shifting. Huh. So I check all the play, none in the bushings, none in the ball joint, nothing anywhere. So I give up. I revisit it later and give up again. This would cycle for about two years untill now. It has developed into a regular noise and is just too dang loud to ignor. It sounds like something is going to fall off. "What the heck" I thought, as there is no way it can make this much noise and not be obvious what the sound is. I couldn't find it. I invited a fellow Fiero owner who is a body shop guy and have him look it over. He can't find it, but from what he could tell, he strongly suspected something hitting the frame. Well shoot, I am going to find this. With a fine tooth comb I look over the suspension. The K frame mounting bolts are fine, braces are fine (well one was loose, but tightening it didn't help the noise). Finally I see on the lower control arm on the passenger side, where it bolts to the space frame, rust disturbance. It looks like the bolt has been rotating. Further inspection and removal of the nut reveals that the only hole that didn't get burned out of round has now wallowed! I hadn't looked at it well before, because I knew it was the only one un-torched. How did this happend? Well, It appears that the frame mounting had been bent out, meaning that the bushing was not sandwhiched inbetween the flanges, there was travel for the bushing to go on parrallel to the mounting bolt. This also meant that the bolt must NOT have been all the way tight (otherwise it would have bent the flanges back) and the bolt was allowed to rotate with vibrations. this wallowd out the hole and caused my control arm to move and create that clunking that was driving me crazy. I will have to now tack on another washer to that side because of my horrible error when I first installed the control arms. If memory serves, I was needing to get my car back on the road, so I hurried the job tward the end. Stupid mistake.

Untill I can get my hands on a welder I took a grade 5 nut on the outside and tightened the crap out of it, which allowed the nut to squish into the wollowed out hole taking up the slack. This obviously wont last long, but the noise is now gone, and I am not perplexed by the mystery clunk.

Lesson learned.
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86fierofun
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Report this Post04-23-2008 01:26 AM Click Here to See the Profile for 86fierofunSend a Private Message to 86fierofunDirect Link to This Post
bump for those who may find this helpful.
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sjmaye
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Report this Post04-23-2008 04:16 AM Click Here to See the Profile for sjmayeSend a Private Message to sjmayeDirect Link to This Post
 
quote
Originally posted by 86fierofun:
Finally I see on the lower control arm on the passenger side, where it bolts to the space frame, rust disturbance.


Exactly which bolt is this? You mention the lower control arm, but it does not bolt to the space frame? If you mean the bolt going through the sub-frame and a-arm bushing I understand and had a similar problem in the rear of my car. Misery loves company

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86fierofun
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Report this Post04-23-2008 02:19 PM Click Here to See the Profile for 86fierofunSend a Private Message to 86fierofunDirect Link to This Post
Do you have an 88?

84-87 the rearward bolt of the lower control arm on the front suspension bolted to a mount welded directly to the space frame.

on the 88 it bolts to the front subassembly.
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sjmaye
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Report this Post04-23-2008 08:30 PM Click Here to See the Profile for sjmayeSend a Private Message to sjmayeDirect Link to This Post
I actually have an 87GT and an 88GT, but I was referring to my 88 whose front end I just went through last year.
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