Dampner Movement
Thread Starter
Le Mans Master
Joined: Jan 2002
Posts: 8,913
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Dampner Movement
One of my buddies stopped over tonight, and when timing the car, I noticed the balancer thrusting forward about 1/8"-1/4" when the motor was revved. Returned back when the RPM decreased.
Is that normal, I guess I never noticed it before on anything else.
Mark
Is that normal, I guess I never noticed it before on anything else.
Mark
Team Owner
Joined: Mar 2003
Posts: 26,118
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From: Greenville, Indiana
Originally Posted by ghostrider20
That's what I thought, to the rear, so what would make it thrust forward???
Mark
Mark
Sounds like your buddy's engine is about to go on a weight diet. Is the whole damper moving forward or just the outer ring?
Burning Brakes
Joined: Aug 2001
Posts: 1,104
Likes: 1
From: Frederick Md
Good question
Originally Posted by ghostrider20
That's what I thought, to the rear, so what would make it thrust forward???
Mark
Mark
Put a pry bar behind the damper and pull or push it and see if that makes it move more than the normal amount, .003 to like .012. If it moves load the thrust on the crank or the thust bearing or both has checked out and it's time to pull the motor and repair the problem
Safety Car
Joined: Feb 2003
Posts: 4,068
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From: St. Joseph Mo
I noticed the balancer thrusting forward about 1/8"-1/4" when the motor was revved.
Le Mans Master
Joined: Apr 2005
Posts: 6,359
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From: Seattle Area WA
Dampner
It isn't all that uncommon for the outer dampner ring to come off and do some serious damage underhood. Some engine builders drill and countersink three bolts in a new dampner at 120 degree intervals to prevent it from coming apart at high revs.
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Burning Brakes
Joined: Aug 2001
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From: Frederick Md
Originally Posted by Scott Marzahl
It isn't all that uncommon for the outer dampner ring to come off and do some serious damage underhood. Some engine builders drill and countersink three bolts in a new dampner at 120 degree intervals to prevent it from coming apart at high revs.
Le Mans Master
Joined: Apr 2005
Posts: 6,359
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From: Seattle Area WA
Dampner
The dampner on my 383 that I ran with NOS had that done and there were never any problems. I used the Chevy 8" modular iron dampner with the bolts not torqued down, just snugged with nylocs nuts.
Instructor
Joined: Dec 2004
Posts: 171
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From: Ontario
dampener
Hello
I would replace the dampener. Not only will you get false readings for the timing on one that has the outer ring slip, but it can come apart.
This is why you drag cars replace them, for the same reason you replace bellhousings and cast flywheels
take care
Tom
I would replace the dampener. Not only will you get false readings for the timing on one that has the outer ring slip, but it can come apart.
This is why you drag cars replace them, for the same reason you replace bellhousings and cast flywheels
take care
Tom
Team Owner
Joined: Mar 2003
Posts: 26,118
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From: Greenville, Indiana
Ya' better pull it 'fore it flys apart.
Originally Posted by ghostrider20
The whole dampner is moving. You can noticably see it thrusting forward with revs. I doubt you would notive .003-.011 movement.
Motor sounds good, runs good.
Mark
Motor sounds good, runs good.
Mark
Instructor
Joined: Aug 2003
Posts: 216
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From: west coast fl
I'm assuming your running a small block and most likely the balancer is not bolted but pressed on. I had one come off awhile back doing 70mph,
lucky me no damage. Anyway pull the belts and and inspect the balancer if it moves replace it and by all means drill, tap and bolt it on. I did and have had no problems since. If you do a search on this you should find allot of info. good luck.
lucky me no damage. Anyway pull the belts and and inspect the balancer if it moves replace it and by all means drill, tap and bolt it on. I did and have had no problems since. If you do a search on this you should find allot of info. good luck.
Le Mans Master
Joined: Jul 2003
Posts: 6,808
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From: Westport CT
"whole dampner is moving" means it is migrating out along the snout.
give it the SHP treatment and drill / tap for a bolt, such bolts are available since they were done for the SHPs. Discussion Threads exist on doing this with engine in car, rad removed. Center punch already exists in snout.
here ya go, parts and pictures:
http://forums.corvetteforum.com/show...um_id=4&arch=1
would seem that Mark - Coves4me did this and might be able to offer some advice
Last edited by ctjackster; Sep 22, 2005 at 10:00 AM.
Safety Car
Joined: Feb 1999
Posts: 3,504
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From: Mexico Beach FL
Sounds like the "thrust" flanges on the thrust main bearing are worn.
I saw one like this, it was caused by the clutch being held in too long and too often -- wore the thrust bearing out.
Tom Piper
I saw one like this, it was caused by the clutch being held in too long and too often -- wore the thrust bearing out.
Tom Piper
Le Mans Master
Joined: Apr 1999
Posts: 6,134
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From: Raleigh North Carolina
Originally Posted by Tom Piper
Sounds like the "thrust" flanges on the thrust main bearing are worn.
I saw one like this, it was caused by the clutch being held in too long and too often -- wore the thrust bearing out.
Tom Piper
I saw one like this, it was caused by the clutch being held in too long and too often -- wore the thrust bearing out.
Tom Piper
Unless the damper is loose on the crank... and is just following the belt tension as RPM changes. Grab hold of the damper & wiggle it... if it's worn bad enough to move in & out when spinning, then it will probably wiggle when it's not running. Otherwise, I'd go with the thrust bearing theory... which you can easily check by putting the tranny in neutral and forcing the crank forward/rearward (engine off).
Didn't catch which engine you have.... but the early 327's had press-on dampers and un-threaded crank snouts. I think Fluidampers require a threaded snout.
Guest
Posts: n/a
Reading this thread reminded me of the same thing concerning my '67 L-79 small block harmonic balancer. Ordered the correct new one #3817173 yesterday from http://www.gmpartsdirect.com/ .It cost $76.oo + S&H. I'm not going to flirt with disaster. Here is intersting article on balancers.....http://www.chevyhiperformance.com/techarticles/4402/
Team Owner
Joined: Oct 2000
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From: Washington Michigan
Good article on what "balancers" (dampers) really do, but I'm continually amazed at all the recent articles that say the pre-'69 timing index line is offset 2* from the keyway centerline. I guess they just copied what the other magazines said, and never bothered to look at the GM damper drawings to get the correct information; the index line is dead-centered on the keyway slot and pulley bolt hole center, +/- 1/4 of a degree tolerance.