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harmonic balancer?

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Old 01-23-2003, 10:57 PM
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jimsmith
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Default harmonic balancer?

It's been about 20 degrees lately and I decided to start the old 85 C4 up. I let it run for about 15 minutes. When I went back outside I noticed a vibration at 12-1300 rpms. I could feel the vibration come and go about 2 seconds apart. Any ideas ? How could I check the balancer? thanks...Jim
Old 01-23-2003, 11:16 PM
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Shawn's 78
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Default Re: harmonic balancer? (jimsmith)

Jim,
Hook up a timing light to see if you can get a mark (and see if your mark is moving up and down).
To quickly check, grab the outer ring and see if you can turn it. I just replaced mine and that's what I did to determine it was bad. I was lucky to replace it when I did, once it was off, I could turn the outer ring with little effort.
If you replace it, get a good puller/installer (non jaw type). That will make your life alot easier (on/off took me about 35 minutes).
Changing out the HB was and is only part of my vibration problem. Next is having the clutch balanced to the flywheel.
good luck!:cool:
Shawn
PS - also check our motor and tranny mounts. I replaced all and found out the left side motor mount was broken. :eek:
Old 01-23-2003, 11:32 PM
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lyonsh
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Default Re: harmonic balancer? (Shawn's 78)

Jim,
Hook up a timing light to see if you can get a mark (and see if your mark is moving up and down).
To quickly check, grab the outer ring and see if you can turn it. I just replaced mine and that's what I did to determine it was bad. I was lucky to replace it when I did, once it was off, I could turn the outer ring with little effort.
If you replace it, get a good puller/installer (non jaw type). That will make your life alot easier (on/off took me about 35 minutes).
Changing out the HB was and is only part of my vibration problem. Next is having the clutch balanced to the flywheel.
good luck!:cool:
Shawn
PS - also check our motor and tranny mounts. I replaced all and found out the left side motor mount was broken. :eek:
:iagree: Well said, Shawn. If the rubber ring in the balancer was already weak, the cold may have put it "over the edge." That could give you the vibration. Or it could be an engine mount (or, as we-all call 'em down here in the south, a MOTOR mount :lol: ).

Follow Shawn's advice to the letter, and you should be able to zero in on it.

:cheers:
Old 01-24-2003, 11:52 AM
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Default Re: harmonic balancer? (jimsmith)

Just a visual inspection can reveal a lot. You may see the balancer is crooked or loose. Removing the crank pulley may be a good idea so you can see it well. Placing a stripe on the outer ring and on the pulley will let you know if the ring is slipping. Mark it, then run the engine, then check the mark.

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