vibration help
10-19-05, 01:17 PM
#1
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vibration help
my 88 NA has developed a vibration. Its getting worse. The whole thing started with a Racingbeat metal 4 puch clutch disk with a stock N/A pressure plate. the chassis will vibrate, I can feel it through the seat, when I rev in neutral above 4,500rpms and when I push in the clutch pedal at anything over 60 mph. dry rev vibrations are hardly noticable, but when I clutch to neutral at highway speed the windows, doors, glass, mirror, seat and gear selector stick vibrate. As speed increases to say 80 MPH, I can feel sort or galoping vibration kinda like a tire out of balance, but it is comming through my seat. All of the interior trim vibrates with it. I know I torqued the bolts holding the presure plate down and I know I torqued the drive shaft bolts too. Just replaced transmission mounts with solid aluminum, vibration got worse, as expected. Motor mounts are solid plastic and stiff as bricks. I doubt it could be the mounts. Transmission shifts great, better than ever due to Pennzoil Syncromesh, GREAT STUFF! If the transmission doesn't leak, could the imput shaft bearing be bad? Drive shaft seems to be solid and does not have any cracks or visible problems. Any ideas?
10-19-05, 01:35 PM
#4
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I thought so, but it could have gotten messed up when you re-installed the transmission. For example, sometimes people can't get the transmission to mate back up to the motor, so they use the transmission mounting bolts to pull the two components back together. If there's misalignment, the new pilot bearing can be destroyed (I confess...I know from personal experience).
10-19-05, 01:44 PM
#5
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When you say that it vibrates above 4500 in neutral, do you have the clutch pushed in? That might be a good test, since the pilot bearing would have the most effect when the motor and transmission input shaft are not engaged, and are rotating at different speeds.
10-19-05, 02:00 PM
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That may just be it. We did have massive problems mating the transmission back to the input shaft. Perhaps that is it. Thanks for the idea. I will pull it next week at.
10-19-05, 02:20 PM
#7
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Originally Posted by JamesWade2002
I will pull it next week at.
That's a hateful job. Maybe another member will weigh in with an easier fix before you have to do it.
Good luck!
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10-19-05, 03:11 PM
#8
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yeah I would hate to have to do that, but I feel like I can't rev it with that crappy vibrations going on, and what good is a rotary if you can't rev it?
10-19-05, 03:45 PM
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I had to change out several things at once but here my .02. I changed the motor mounts, transmission mounts, replaced the u-joints (yes they are replaceable)on the propeller (drive) shaft but I had to replace the differential mount also. It had broken. I don't know if you checked that or not but it was causing a pretty good vibration.
10-20-05, 11:16 AM
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yeah I shook everything under the car repeatedly. I could not find anything that was loose. If the pilot bearing was bad, wouldn't the car try to lurch forward when the clutch was in(pedal depressed) and the transmission in gear? Mine does not do that.
10-24-05, 11:06 AM
#12
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Originally Posted by JamesWade2002
If the pilot bearing was bad, wouldn't the car try to lurch forward when the clutch was in(pedal depressed) and the transmission in gear? Mine does not do that.
By the way, I'm just suggesting it MAY be the pilot bearing--I think you're smart to get as many suggestions as you can, and remove the transmission as a LAST resort.
Sureshot, I thought they made throwout bearings flat on one side, so that they don't roll away when you set them on the workbench! (sorry...bad joke)
10-25-05, 07:32 PM
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found the problem. Driveshaft U-joint @ the transmission was frozen on one axis. like it would not move. It was awsome. Don't buy a metal puck clutch and put it behind a 200hp motor and sticky tires, the rest of your car won't live long. learned my lesson.
10-26-05, 07:11 AM
#14
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Glad you found the problem!
Edit: I was wondering why the driveshaft was causing the vibration when you revved in neutral above 4500 RPMs... it never occurred to me that the car might have been moving when you did that!
Edit: I was wondering why the driveshaft was causing the vibration when you revved in neutral above 4500 RPMs... it never occurred to me that the car might have been moving when you did that!
Last edited by buttsjim; 10-26-05 at 07:14 AM.
10-26-05, 09:05 AM
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hey 02,i have an88 gxl sunroof problem one side goes up the other does not, 7heaven told me it is the tract need to replace,my problem is i don't know how to get to it. can you help me? if not thanks anyway, but glad you got your problem solved. one2rx. i also don't know how you would respond back? so this is my e-address-- ritch2real@yahoo.com
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