[HELP]Drivetrain vibrations....what's causing it???
Thread Starter
Melting Slicks
Joined: May 2000
Posts: 2,974
Likes: 5
From: CenTex Texas
[HELP]Drivetrain vibrations....what's causing it???
I've had a drivetrain vibration for a few years now (just seems to be getting a little worse each year). Anyway it started about a year after my H/C install and occurs most noticably between 2500 and 4000 rpms...and only when in gear. In neutral there's zero vibrations across the rpm range.
I've had a new clutch, pp, pilot bearing, slave cyl, and flywheel installed, and still get the same vibration. So i think it's the motor mounts and possible the tranny mounts......What does CF say?
I've had a new clutch, pp, pilot bearing, slave cyl, and flywheel installed, and still get the same vibration. So i think it's the motor mounts and possible the tranny mounts......What does CF say?
Race Director
Joined: Sep 1999
Posts: 12,439
Likes: 921
From: CONCORD NC
is it speed related, or rpm related. If it is rpm related, it could likely be the torque tube. If it is speed related, then it is likely a wheel, halfshaft, diff, etc.
The torque tube, unlike traditional drive shafts, spins at engine speed. Do you feel it when the car is in neutral with the clutch out, or when the clutch is dis-engaged? In neutral, the torque tube still spins. In gear, but with the clutch pressed, it doesn't.
The torque tube, unlike traditional drive shafts, spins at engine speed. Do you feel it when the car is in neutral with the clutch out, or when the clutch is dis-engaged? In neutral, the torque tube still spins. In gear, but with the clutch pressed, it doesn't.
Thread Starter
Melting Slicks
Joined: May 2000
Posts: 2,974
Likes: 5
From: CenTex Texas
It's rpm related. I can drive at any speed and not feel it, but once i get the rpm's over 2500 (in any gear) i feel it. I've only tried running the rpms up in neutral with the clutch engaged (pedal released).
It very well might be the torque tube bushings....i mainly feel the vibrations (and first noticed it) in the shifter.
It very well might be the torque tube bushings....i mainly feel the vibrations (and first noticed it) in the shifter.
Team Owner
Joined: Mar 2001
Posts: 25,889
Likes: 7
From: Virginia Beach
CI 3-5-6-7-8 Veteran
Not all LSX motors are truly zero balanced. At final assembly if it is off GM will compensate w/ an off-balanced flywheel/pressure plate combo to bring it in spec.
If you have one of these motors and install a new zero-balanced clutch/flywheel assembly you will induce a vibration. I did... and it took a lot of research and lots of calls to tuners to figure it all out.
I had to re-do the clutch and match balance it to my oem parts. My stock setup was 8 grams out of balance and had 2 balance weights in the back of the stock flywheel. After having the new setup match exactly to that and reinstalling all is now perfect.
The problem is the only way to find this out is to pull the stock clutch setup and take it to a machine shop.
You won't get any help from GM. The early C5 service manuals tell you to mark the location of balance weights on the back of the flywheel and transfer them in the same orientation to the new one. Then, later service manuals tell you that the clutch/flywheel come as a balanced assembly and to not touch it.
So... you could have a motor balance issue fom the new clutch.
If you have one of these motors and install a new zero-balanced clutch/flywheel assembly you will induce a vibration. I did... and it took a lot of research and lots of calls to tuners to figure it all out.
I had to re-do the clutch and match balance it to my oem parts. My stock setup was 8 grams out of balance and had 2 balance weights in the back of the stock flywheel. After having the new setup match exactly to that and reinstalling all is now perfect.
The problem is the only way to find this out is to pull the stock clutch setup and take it to a machine shop.
You won't get any help from GM. The early C5 service manuals tell you to mark the location of balance weights on the back of the flywheel and transfer them in the same orientation to the new one. Then, later service manuals tell you that the clutch/flywheel come as a balanced assembly and to not touch it.
So... you could have a motor balance issue fom the new clutch.
Thread Starter
Melting Slicks
Joined: May 2000
Posts: 2,974
Likes: 5
From: CenTex Texas
Cobra4B - The vibration started up about a year after my H/C install.......but long before the clutch/flywheel install.
BTW LGM did the clutch/flywheel install last year so i would assume they would have known about any flywheel weights needing transfered.
BTW LGM did the clutch/flywheel install last year so i would assume they would have known about any flywheel weights needing transfered.
Team Owner
Joined: Mar 2001
Posts: 25,889
Likes: 7
From: Virginia Beach
CI 3-5-6-7-8 Veteran
^ Not normally... most tuners just slap them in out of the box... then if there's a vibration they'll pull it out and match balance it. Most of the time slapping it in works... sometimes it doesn't.
Pro
Joined: Jun 2005
Posts: 734
Likes: 0
From: Austin TX
How many miles did you have when the vibration started?
How many miles now?
Could be any number of things. I guess i would have to experience the vibration to help much further. Maybe try gettin under it and prying some of the bushings and mounts to see if any of them have extreme visable weakness or damage.
BTW, thanks for replying in my other thread.
How many miles now?
Could be any number of things. I guess i would have to experience the vibration to help much further. Maybe try gettin under it and prying some of the bushings and mounts to see if any of them have extreme visable weakness or damage.
BTW, thanks for replying in my other thread.
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