GM Drivetrain & Suspension Chassis | Transmission| Driveshaft | Gears/Rear End/Differential | Traction Aids

Drivetrain loss 2-piece v 1-piece Driveshaft?

Old Nov 3, 2006 | 05:47 PM
  #11  
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Originally Posted by 93ChevExt5.7
Thanks for the feedback - I'll admit, I was a doubter, but I got to thinking about the SS now that its not just AWD and another guy told me too! I wonder why Denny's Driveshaft and others won't build an aluminum one for me?

Great setup by the way - what kind of power do you put to the wheels?
Never had it on a dyno but, going off my times and weight it should be about 530fwhp or so.

The other guys are right about the 1 pc driveshafts being too long which creates problems with the critical speed. That made me think that the Dmax revs out in the mid 3000rpm range so it's never gonna get close to the critical speed of the driveshaft.

I guess it's a bad idea to try and keep a 1pc driveshaft in a ECSB with more power and rpm than stock.
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Old Nov 7, 2006 | 12:43 AM
  #12  
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from what i have seen the one piece aluminum shaft isnt any where as strong. the place i usually dyno my truck has half of an aluminum one sticking out of the wall about 15 feet up. It came out of a tahoe with a 5.3 and stock radix. I bet that was a fun dyno session!
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Old Nov 7, 2006 | 08:18 AM
  #13  
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A 2 piece will most likely be a lot more quiet too. Two shorter and smaller driveshafts are easier to balance than one gigantic long one. If I were to go to a 1 piece, it sure as hell wouldn't be aluminum. Chrome moly would be a better choice IMO. I'll find out if it's possible since I might be doing a TH400 swap in the near future.
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Old Nov 7, 2006 | 10:31 PM
  #14  
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It;s really not an issue of strength. It's a critical speed issue, the length of the driveshaft is prohibitive. No one will make a 72" driveshaft and gaurantee it. I was told by Denny's that anyone who would make you one should be seriously questions. It's not just the strength of the material at that point, it's the mass that drives that critical speed. Higher the mass, the lower the critical speed, hence the AL ones.
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Old Nov 8, 2006 | 07:43 AM
  #15  
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Yeah, but with slicks a stick shift and power shifting, an aluminum driveshaft will fatigue sooner and more easily while banging gears, even before the critical speed is reached.

Oh yeah, is 72" really the length it would need to be?
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Old Nov 8, 2006 | 07:10 PM
  #16  
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If harmaonic vibrations suddenly go through an aluminum driveshaft at high rpms, the results of an exploded driveshaft will be seen. If the pinion angle goes beyound it's normal operating range under load (which can happen if pinion angle is not preset for higher hp/tq applications), that will send a high pitch vibration through the driveshaft causing the aluminum to distort and fatigue. Then catastrophic results of course will follow.
The "long" aluminum driveshaft really should not be a choice for high hp/tq applications.

Jim
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