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Discussion Starter #1
Hello, please help a newbie diagnose a mysterious noise!

I have a strange thumping noise that seems to be coming from the front suspension of my 2001 Spyder GT with manual transmission. I have 165,000 miles so there are many things that might be worn out. This car is new to me and it has no maintenance history.

The noise is a rattling thump, kind of a rapid duh-duh-duh-duh noise that occurs when I go over average sized bumps in the road at 30+ MPH. A manhole cover or some patched uneven pavement will usually do it. A speed bump won't trigger it. I can't seem to get it to occur reliably at low speeds.

The noise seems to come from the passenger footwell area. The thumping is severe enough to shake the windshield and rear view mirrors. You can feel it in the steering as well. It's most noticeable with the convertible top down.

The noise can't be triggered by doing things with the gas pedal, brakes, clutch or steering. Rapid acceleration, deceleration, and fast turning don't trigger the noise. Driving over a section of rough pavement will do it pretty much every time. Smooth pavement is fine.

My mechanic (with 20 years experience) has had no luck tracking it down. With the car up on a lift, nothing appears to be loose or in questionable condition.

So far, we have replaced the front struts and strut mounts with GR2s and KYB mounts. The rubber boots on the sway bar end links had failed, so I went ahead and installed new end links. Sadly, no luck. The new parts didn't change the noise at all. It really seemed like the strut mount should have been the problem, but that didn't fix it.

Has anyone else experienced something similar? I'm thinking either ball joints, steering rack, or something weird going on with the rear end. Could the old rear struts be making a noise that sounds like it's coming from the front?

Any ideas would be greatly appreciated!


Tim
 

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CreepnIn The Shadows
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4,426 Posts
Was the front end shaken down? Sway bar bushings checked, control arm bushings?
 

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I had similar problem with the rear a loud thumping only caused by bumps but not speed bumps or things like that.

After about five months of just dealing with the thumping and having various mechanics look at it. It was simply a loose suspension bolt. Jack up the car, put several jack stands down, and then try wiggling different suspension parts from the area you hear the noise. If you can move them with your hands giving a decent tug or pull then try tightening the bolts.

I suggest to try it soon. I mean it takes what 5min to jack up the car and set down stands. Maybe 10min looking for loose parts. Let us know how that goes, I am curious as to what the problem is
 

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Discussion Starter #4
Noise in Front Suspension

My mechanic did another hunt through the front suspension on Friday and came up empty. Nothing appears to be lose or worn.

I'm leaning toward the sway bar bushing theory. The car has 165,000 miles and there's a high probability that the original bushings are still there.

I was getting ready to order some Energy Suspension bushings and then I got stuck. What is the size of a stock 2001 Spyder GT front sway bar? I've seen many different numbers pop up: 16mm, 18mm, 19mm, and 20mm.

Does anyone know what the size actually is? I'm leaning toward 19mm, but I'm not certain.


Tim
 

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Discussion Starter #5
It turns out that my swaybar was actually 16mm. Sadly, replacing the bushings had no effect on the clunking.

Then, I got lucky. My mechanic spotted the problem! One of my motor mounts was badly worn. He installed a new mount and that was definitely the issue. No more clunking. Problem solved! It's like having a totally new car. Everything is noticeably much smoother, quieter and more stable.

For future reference, a bad motor mount can cause symptoms that seem like a bad suspension problem. The noises only occured over bumps. It sounded almost like a guy with a hammer banging around in the passenger foot well.

If you have weird clunks, definitely check your motor mounts!


Tim
 
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