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Discussion Starter · #1 ·
ZMasters: I have a mysterious, bad, loud rattle from under the car when I decelerate. The rattle occurs only as the rpm's descend in the range from 3000 to 2000 with the clutch out and wheels rolling. This occurs in any gear, no difference. I can stop the noise by pushing in the clutch. If I'm sitting still and rev the engine up and down, the noise does not occur regardless of clutch in or out. The noise sounds like an exhaust pipe rattle or some other loose part that is rattling because of resonance with the exhaust. However, I've checked under the car and found nothing loose.
Since it occurs only when rolling and decelerating with the clutch out, I'm perplexed. Could this be a tranny or clutch problem? Driveshaft? U-joint? Gremlins? Any advice will be much appreciated. Thanks.
Alfa Georgia
 

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well it could be an axle rattle. i know i had that problem and then they fixed it, but it could be a tranny issue as well. if i were you i would take it to the dealer for futher inspection.

make sure that you ride in the car and show them the noise
 

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i have a very minor rattle noise as well. but its only while i am driving on the highway. it feels like its coming from the front dash board
what might that be??
 

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i have this rattle. it's on the passenger side. my guess is that it's the torque from the engine (it will rock one way on the gas and the opposite way off the gas). i got it when i installed a set of test pipes. i haven't looked under to see where clearances might allow for it, but keep in mind, with your engine sitting static, you won't have the same conditions, so the clearances won't be there to show you where it's touching. if i figure out my problem, i'll let you know what's up, though.
 

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How many miles do you have? Do you drive your Z really hard? It might be a worn out throw out bearing. If it is, you might as well replace the throw out bearing, clutch, and pressure plate.
 

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BTW, do you have a lightened flywheel? These rattles are common in cars with a fair amount of hp/tq (...like the Z) with a lightened flywheel. I bet you only hear it when the clutch is disengaged (in idle), huh?
 

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Discussion Starter · #9 ·
Thanks to all for the ideas. I think I found the issue: the Stillen cat-back exhaust is rattling against the cross brace in the middle of the car. A pad to isolate the two tubes from the brace seems to fix the issue.
 

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ZMasters: I have a mysterious, bad, loud rattle from under the car when I decelerate. The rattle occurs only as the rpm's descend in the range from 3000 to 2000 with the clutch out and wheels rolling. This occurs in any gear, no difference. I can stop the noise by pushing in the clutch. If I'm sitting still and rev the engine up and down, the noise does not occur regardless of clutch in or out. The noise sounds like an exhaust pipe rattle or some other loose part that is rattling because of resonance with the exhaust. However, I've checked under the car and found nothing loose.
Since it occurs only when rolling and decelerating with the clutch out, I'm perplexed. Could this be a tranny or clutch problem? Driveshaft? U-joint? Gremlins? Any advice will be much appreciated. Thanks.
Alfa Georgia

Just a guess. Flywheel or throw out bearing. Flywheel only if aftermarket.
 

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Thanks to all for the ideas. I think I found the issue: the Stillen cat-back exhaust is rattling against the cross brace in the middle of the car. A pad to isolate the two tubes from the brace seems to fix the issue.
++

I used to have a rattle like that on another car.. I should have guessed that first..
 

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Thanks to all for the ideas. I think I found the issue: the Stillen cat-back exhaust is rattling against the cross brace in the middle of the car. A pad to isolate the two tubes from the brace seems to fix the issue.

Just curious, what kind of pad did you use to fix this? I think I have a similar problem with my borla and was wondering what to use to fix it.
 
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