That's sort of like saying that you don't need to balance your tires.
Half Shaft's different OD
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Half Shaft's different OD
Had bad vibration in my 73. The output shaft on the Muncie had some play in it. So went and installed a TKO 600 so I could have a overdrive gear. Then rebuilt trailing arm's laid out half shaft's and discovered one is about 2 1/2" OD and the other is 3" OD. Is it possible that the different weight's of the shafts caused some of the vibration even if they were both in balance? I am having the 3" shaft balanced and a new 3" built to match the other. My thought is that if they both are in balance then it shouldn't matter or add vibration to the drive train. Therefor the vibration should of been coming from output shaft or bad angle on driveline? All u joints were in good condition.
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From: Shamong, NJ
I doubt that the two different diameter half shafts, are causing your vibration. I've seen quite a few Corvettes with two different size shafts, I don't recall any of their owners complaining about a vibration.
Chevrolet switched to the larger diameter half shafts (and drive shafts too) in 1975. At that point, the smaller diameter shafts were discontinued, and only the larger ones were available from Chevrolet. Since only the larger shafts were available as service replacements, this caused more than a few Corvettes, to end up with different size half shafts.
Supposedly, the larger shafts aren't any stronger than the small ones. I was told GM reduced the wall thickness of the material used for the shafts, and the diameter was increased, to offset the loss in strength caused by the thinner shaft material.
Chevrolet switched to the larger diameter half shafts (and drive shafts too) in 1975. At that point, the smaller diameter shafts were discontinued, and only the larger ones were available from Chevrolet. Since only the larger shafts were available as service replacements, this caused more than a few Corvettes, to end up with different size half shafts.
Supposedly, the larger shafts aren't any stronger than the small ones. I was told GM reduced the wall thickness of the material used for the shafts, and the diameter was increased, to offset the loss in strength caused by the thinner shaft material.
Racer
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From: NJ
Le Mans Master
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From: McHenry Illinois
One half shaft being heavier than the other won't have any effect on the drivetrain. Also the diameter is so small compared to the speed they turn, one would have to be out of balance really bad to feel it in the car.
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From: Charlotte NC
If the half shafts are NOT DENTED...and/or have a super heavy coat of undercoating on ONE SIDE (half of it)....the half shafts DO NOT need balancing.
I HAVE NEVER seen balancing weights on the half shaft...and truthfully....the company that balances my drive shafts told me 30 years ago that they can not balance the half shafts and that they do not require it.
DUB
I HAVE NEVER seen balancing weights on the half shaft...and truthfully....the company that balances my drive shafts told me 30 years ago that they can not balance the half shafts and that they do not require it.
DUB
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Racer
Joined: Jun 2013
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From: NJ
If the half shafts are NOT DENTED...and/or have a super heavy coat of undercoating on ONE SIDE (half of it)....the half shafts DO NOT need balancing.
I HAVE NEVER seen balancing weights on the half shaft...and truthfully....the company that balances my drive shafts told me 30 years ago that they can not balance the half shafts and that they do not require it.
DUB
I HAVE NEVER seen balancing weights on the half shaft...and truthfully....the company that balances my drive shafts told me 30 years ago that they can not balance the half shafts and that they do not require it.
DUB
In my book balancing is a must if you plan on driving your corvette over 40mph. There would be 80% less threads on these forums about vibrations if everyone took the time and spent the money to balance their drive shafts and half shafts.I would be willing to bet that your 40 year old half shafts are way out of balance. We all know rust never affects steel drive shafts after 40 years, nor the fact that bubba beat the crap out of your driveshaft and flanges when he installed your discount u-joints. trying to save you money.
I HAVE NEVER seen balancing weights on the half shaft
Race Director
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And yet with somewhere around a half million C2 and C3s built, not one case of vibration has been attributed to half shafts being out of balance.
High speed balancing machines have been around for 60+ years. Nothing new.
High speed balancing machines have been around for 60+ years. Nothing new.
Racer
Joined: Jun 2013
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From: NJ
Do you seriously believe that there has never been a vibration problem due to half shafts being out of whack? 
You didn't drink the Koolaid that GM sent you, did you? 
I wonder why any of the performance guys even balance their shafts. We should let them know that they are doing it wrong.
Race Director
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From: Charlotte NC
But turning about 1/3 the speed of the drive shaft....you do as you wish.
Vibration issues I look somewhere else....IF the half shafts pass the visual inspection.
Wheels( true and not warped), tires (balanced and not to badly 'out of round' which can cause them to be balanced and shaved on the car), clutch( including all related measurements to make sure it is correct), differential crossmember and related and drive shaft balancing and u-joints are what I would look at.
People can do whatever they want to make them happy.....and when 'whatever' is done does not fix the problem...at least they know it is NOT that ...that is causing the problem.
DUB
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Safety Car
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From: Seattle Washington
Getting back to the Vibration Issue do You think it is the same one before and after the new Trans ? Or something new ? Maybe some more info on when it Vibrates all the time or just at certain speeds. Engine RPM related or Speed related ?
Sounds like somebody replaced a 1/2 shaft at one point, and that's why the newer 3" on one side. But Why ? Did they break it and screw up a Yoke or an Axle Flange. Is there Fiberglass damage on that side showing its exit path.
Sounds like somebody replaced a 1/2 shaft at one point, and that's why the newer 3" on one side. But Why ? Did they break it and screw up a Yoke or an Axle Flange. Is there Fiberglass damage on that side showing its exit path.
Safety Car
Joined: Jan 2009
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From: New York
You could have an alignment issue under load so check all mounting points in the drive train for bad bushings or damage. Did pressure plate get replaced or ground ?
Check rear wheel bearings .
I just ordered (2) 3" half shafts with 1350 yokes and joints . These shafts have weights for balance on them. I ca not speak for oem or other makes of the half shaft but the place I got mine has made these for 35 years and balances every one.
Check rear wheel bearings .
I just ordered (2) 3" half shafts with 1350 yokes and joints . These shafts have weights for balance on them. I ca not speak for oem or other makes of the half shaft but the place I got mine has made these for 35 years and balances every one.
Race Director
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From: Chino CA
Race Director
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From: Charlotte NC
Getting back to the Vibration Issue do You think it is the same one before and after the new Trans ? Or something new ? Maybe some more info on when it Vibrates all the time or just at certain speeds. Engine RPM related or Speed related ?
Sounds like somebody replaced a 1/2 shaft at one point, and that's why the newer 3" on one side. But Why ? Did they break it and screw up a Yoke or an Axle Flange. Is there Fiberglass damage on that side showing its exit path.
Sounds like somebody replaced a 1/2 shaft at one point, and that's why the newer 3" on one side. But Why ? Did they break it and screw up a Yoke or an Axle Flange. Is there Fiberglass damage on that side showing its exit path.
and also what I wrote in a the above post. But with not one reply from the original poster....we do not know if it is gone ore not.
DUB
Last edited by DUB; Jan 16, 2015 at 06:19 PM.