need help w/ drive train clunking
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3rd Gear
Joined: Jun 2005
Posts: 3
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need help w/ drive train clunking
1990 c-4 convertable w/ zf s6-40 tranny and 55K miles. Owned since new and I only beat on it very rarely.
When there is no load on the drive train and I feather the throttle, I get a single clunk as if I had a bad u-joint. When the car is at full opertrating temp, parked in nuetral, clutch in or out, I get continous non linear clunking. The sound appears to originate from the tranny but is diffucult to tell for sure. Most novices say I may have a bad throw out bearing. I removed the tranny and inspected all u-joints w no discrepencies noted. The clutch assembly (disk, press plate, TO bearing) appears fine less normal wear. The shop manual tells me to inspect the dual mass fly wheel but does not say what to look for to determine if it's good or bad. I can get a couple of degrees of rotation of the outer fly wheel which seems like normal dampening to me. When I grasp the tranny main drive gear (shaft) and quickly rotate back and fourth, I get a similar clunking in the tranny and it is obviousley not as loud as when operating, and seems as if it's normal gear lash noise. I purhased a new clutch kit, but I'd hate to put the whole thing back together only to find the same syptoms and I'd hate to have the tranny overhauled if it's not the problem. Any thoughts, comments or advice would be greatly appreciated. Thanks
When there is no load on the drive train and I feather the throttle, I get a single clunk as if I had a bad u-joint. When the car is at full opertrating temp, parked in nuetral, clutch in or out, I get continous non linear clunking. The sound appears to originate from the tranny but is diffucult to tell for sure. Most novices say I may have a bad throw out bearing. I removed the tranny and inspected all u-joints w no discrepencies noted. The clutch assembly (disk, press plate, TO bearing) appears fine less normal wear. The shop manual tells me to inspect the dual mass fly wheel but does not say what to look for to determine if it's good or bad. I can get a couple of degrees of rotation of the outer fly wheel which seems like normal dampening to me. When I grasp the tranny main drive gear (shaft) and quickly rotate back and fourth, I get a similar clunking in the tranny and it is obviousley not as loud as when operating, and seems as if it's normal gear lash noise. I purhased a new clutch kit, but I'd hate to put the whole thing back together only to find the same syptoms and I'd hate to have the tranny overhauled if it's not the problem. Any thoughts, comments or advice would be greatly appreciated. Thanks
Burning Brakes
Joined: Sep 2001
Posts: 981
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From: Anderson South Carolina
As I recall, if you can rotate the Dual-Mass Flywheel by hand it may be worn out.
For a ZF to be the problem with only 55K and no real hard driving would be strange.
With everything out, I would replace all of the u-joints just because.
vettmike
For a ZF to be the problem with only 55K and no real hard driving would be strange.
With everything out, I would replace all of the u-joints just because.
vettmike
Instructor
Joined: May 2005
Posts: 218
Likes: 0
From: Gaithersburg Maryland
Mike's response resonates true. I don't know anything about the dual mass flywheel, but it sound like you might have some free motion available in the drive train somewhere, and from his comment, and your description of what is happening, I would investigate that. I would also change the u-joints just on GP's. Checking the mounts is just one of those "I hope it is that simple" kind of things to investigate. wishfull thinking, so to speak.
Instructor
Joined: Mar 2003
Posts: 118
Likes: 0
From: Shrewsbury MA
Originally Posted by metalbutt
1990 c-4 convertable w/ zf s6-40 tranny and 55K miles. Owned since new and I only beat on it very rarely.
When there is no load on the drive train and I feather the throttle, I get a single clunk as if I had a bad u-joint. When the car is at full opertrating temp, parked in nuetral, clutch in or out, I get continous non linear clunking. The sound appears to originate from the tranny but is diffucult to tell for sure. Most novices say I may have a bad throw out bearing. I removed the tranny and inspected all u-joints w no discrepencies noted. The clutch assembly (disk, press plate, TO bearing) appears fine less normal wear. The shop manual tells me to inspect the dual mass fly wheel but does not say what to look for to determine if it's good or bad. I can get a couple of degrees of rotation of the outer fly wheel which seems like normal dampening to me. When I grasp the tranny main drive gear (shaft) and quickly rotate back and fourth, I get a similar clunking in the tranny and it is obviousley not as loud as when operating, and seems as if it's normal gear lash noise. I purhased a new clutch kit, but I'd hate to put the whole thing back together only to find the same syptoms and I'd hate to have the tranny overhauled if it's not the problem. Any thoughts, comments or advice would be greatly appreciated. Thanks
When there is no load on the drive train and I feather the throttle, I get a single clunk as if I had a bad u-joint. When the car is at full opertrating temp, parked in nuetral, clutch in or out, I get continous non linear clunking. The sound appears to originate from the tranny but is diffucult to tell for sure. Most novices say I may have a bad throw out bearing. I removed the tranny and inspected all u-joints w no discrepencies noted. The clutch assembly (disk, press plate, TO bearing) appears fine less normal wear. The shop manual tells me to inspect the dual mass fly wheel but does not say what to look for to determine if it's good or bad. I can get a couple of degrees of rotation of the outer fly wheel which seems like normal dampening to me. When I grasp the tranny main drive gear (shaft) and quickly rotate back and fourth, I get a similar clunking in the tranny and it is obviousley not as loud as when operating, and seems as if it's normal gear lash noise. I purhased a new clutch kit, but I'd hate to put the whole thing back together only to find the same syptoms and I'd hate to have the tranny overhauled if it's not the problem. Any thoughts, comments or advice would be greatly appreciated. Thanks
Any help appreciated.
Last edited by chb88; Jul 4, 2005 at 09:28 AM.
