Bad vibration , help needed
03-17-2015, 10:31 AM
#1
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Join Date: Mar 2015
Posts: 5
Bad vibration , help needed
Hi all I am new here and new to the LT1 world. I just purchase a 97 Z28 with a Lt1 383 stroker with Callies crank and rods Weisco pistons. 1500miles on build. it has March underdrive pulleys which I believe were installed incorrectly. weather in gear (6Speed) or in neutral free reving I get a harsh vibration that gradually gets worse with increasing rpm. seams to peak at 4000RPM. prev. owner seems to think it's due to poly trans and motor mounts. attache is a picture of the March crank pulley and also a picture of the instructions from March website. I assume I need to find a balancer ? thanks. well sorry no way to browse and select image. if possible i'll try to add to photos in my album
Last edited by Rde Bandit; 03-17-2015 at 12:07 PM.
03-17-2015, 04:16 PM
#2
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,648
Re: Bad vibration , help needed
The stock piece is not a "balancer" per se. It is a harmonic damper. The damper is there to minimize crankshaft "whip" as the cylinders fire. Would be unusual for it's absence to provide severe vibration, but it may be noticeable. Excessive crank whip can lead to fatigue and premature failure.
Certainly looks like they installed a "sandwich" style U/D pulley, and failed to reinstall the factory damper.
Here's what you are looking for, courtesy of Shoebox:
http://shbox.com/ci/balancer_hub.jpg
http://shbox.com/1/pull_pulley.jpg
I would replace it, and see if it helps reduce vibration.
Certainly looks like they installed a "sandwich" style U/D pulley, and failed to reinstall the factory damper.
Here's what you are looking for, courtesy of Shoebox:
http://shbox.com/ci/balancer_hub.jpg
http://shbox.com/1/pull_pulley.jpg
I would replace it, and see if it helps reduce vibration.
03-17-2015, 04:35 PM
#3
Registered User
Thread Starter
Join Date: Mar 2015
Posts: 5
Re: Bad vibration , help needed
The stock piece is not a "balancer" per se. It is a harmonic damper. The damper is there to minimize crankshaft "whip" as the cylinders fire. Would be unusual for it's absence to provide severe vibration, but it may be noticeable. Excessive crank whip can lead to fatigue and premature failure.
Certainly looks like they installed a "sandwich" style U/D pulley, and failed to reinstall the factory damper.
Here's what you are looking for, courtesy of Shoebox:
http://shbox.com/ci/balancer_hub.jpg
http://shbox.com/1/pull_pulley.jpg
I would replace it, and see if it helps reduce vibration.
Certainly looks like they installed a "sandwich" style U/D pulley, and failed to reinstall the factory damper.
Here's what you are looking for, courtesy of Shoebox:
http://shbox.com/ci/balancer_hub.jpg
http://shbox.com/1/pull_pulley.jpg
I would replace it, and see if it helps reduce vibration.
03-21-2015, 10:17 PM
#4
Registered User
Join Date: Jun 2003
Posts: 1,083
Re: Bad vibration , help needed
OP
you need to have a damper on the front vs. just a pulley
your 383, is it internal balance?
if so is the flywheel for the M6 neutral balance or stock one?
it will shake like a dog shiating razor blades if you have a internal balance motor running a stock external balance FW
you need to have a damper on the front vs. just a pulley
your 383, is it internal balance?
if so is the flywheel for the M6 neutral balance or stock one?
it will shake like a dog shiating razor blades if you have a internal balance motor running a stock external balance FW
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