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Drive shaft ---- Aluminum VS Chrome Moly
#919540
02/02/11 10:43 AM
02/02/11 10:43 AM
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Joined: Jul 2009
Posts: 694
Michigan
Super Scamp
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mopar
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OP
mopar
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Posts: 694
Michigan
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Well after looking and hunting down a drive shaft, with the help from Dean at Mancini Racing,he hooked me up with Dyna-tech. The problem I had was my lenght of my shaft  55 1/2 center to center so Aluminum 3.5 dia.1350 ends was the order. Motor 518" 2500lb car dana60 with powerglide in a "A" body. What are you guys running in your A body with glide?
Just One Man's Opinion
Mopar Mafia Racing
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: 408strokerdart]
#919542
02/02/11 11:27 AM
02/02/11 11:27 AM
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Joined: Jul 2009
Posts: 694
Michigan
Super Scamp
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mopar
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OP
mopar
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Posts: 694
Michigan
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I guess that us A body guys have a length issue running a glide  I'm pushing about 800hp any more I would have to go with a 4"..Or should I change it to 4" now??
Just One Man's Opinion
Mopar Mafia Racing
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: Super Scamp]
#919543
02/02/11 11:40 AM
02/02/11 11:40 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I guess that us A body guys have a length issue running a glide I'm pushing about 800hp any more I would have to go with a 4"..Or should I change it to 4" now??
Did you ask them about the weight difference between
a 3.5" moly and a 4" alum and what each will handle
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: Super Scamp]
#919546
02/02/11 05:26 PM
02/02/11 05:26 PM
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Joined: Jul 2009
Posts: 694
Michigan
Super Scamp
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mopar
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OP
mopar
Joined: Jul 2009
Posts: 694
Michigan
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How many of Moparts Members have a drive shaft longer than 52" and run in the hp range of 800hp?
Just One Man's Opinion
Mopar Mafia Racing
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: Super Scamp]
#919547
02/02/11 06:01 PM
02/02/11 06:01 PM
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Joined: Jun 2009
Posts: 1,212
QLD Australia
Keith Black®
pro stock
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pro stock
Joined: Jun 2009
Posts: 1,212
QLD Australia
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not sure of length, but close to standard length B Body. Mark Williams chrome moly. told it will handle 1000hp. although i'm making much more will never see that load given tires etc.
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Darren Beale
Keith Black Racing Engines®
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: Dunnuck Racing]
#919550
02/02/11 08:51 PM
02/02/11 08:51 PM
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Joined: Oct 2007
Posts: 4,213
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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That sounds backwards - aluminum stays stretched (rods), steel relaxes back.
Boffin Emeritus
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: Super Scamp]
#919552
02/02/11 09:38 PM
02/02/11 09:38 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Did you ask them about the weight difference between
a 3.5" moly and a 4" alum and what each will handle
The shop that did mine told me to use aluminum because it had better "memory",and would flex and relax back to it's original state.And that moly steel would take more of a hit without twisting,but would not relax back.
Keith
Dyna-teck said they would guarantee my drive shaft not to break ,but I was to inspect the shaft and the welds offen. 
I went with a moly shaft... got it from dynotech...
it still has the original U-joints in it and still
feel like new
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: polyspheric]
#919553
02/02/11 10:26 PM
02/02/11 10:26 PM
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Joined: Jan 2003
Posts: 16,932
NC
440Jim
I Live Here
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I Live Here
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Posts: 16,932
NC
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Quote:
That sounds backwards - aluminum stays stretched (rods), steel relaxes back.
Wall thickness and diameter are the design parameters for torque. If designed to stay under the fatique limit, the steel will have unlimited life. Aluminum has no fatique limit, it will always fatigue at any stress; it is just a matter of time.
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: 440Jim]
#919554
02/02/11 10:35 PM
02/02/11 10:35 PM
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Joined: Jun 2007
Posts: 2,646
Plymouth Meeting, PA
bigtimeauto
Trophy Winner
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Trophy Winner
Joined: Jun 2007
Posts: 2,646
Plymouth Meeting, PA
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Ok, here is my info from one of my last logs. I run a 56" X 3" mild steel shaft. I don't know the wall thickness but at 7189 driveshaft rpm I am past *critical speed* and make more HP than you have posted.
I also do something that is text book wrong but tried it this year and have no issues. I run the rear pinion perfectly in line with the driveshaft and have angle in the trans side only.
BB, TT5,Procharged 3300lb Street Car 4.79/154
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: ALKYW5DART]
#919556
02/02/11 10:49 PM
02/02/11 10:49 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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What is being used in 2000 +HP cars? Just asken.
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Re: Drive shaft ---- Aluminum VS Chrome Moly
[Re: 440Jim]
#919559
02/02/11 11:57 PM
02/02/11 11:57 PM
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Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
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New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
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Quote:
Quote:
That sounds backwards - aluminum stays stretched (rods), steel relaxes back.
Wall thickness and diameter are the design parameters for torque. If designed to stay under the fatique limit, the steel will have unlimited life. Aluminum has no fatique limit, it will always fatigue at any stress; it is just a matter of time.
Aluminum has higher elasticity so, all else equal, an alum. shaft will flex more than steel. However, aluminum shafts are thicker so you'll need to do a bunch of math for a real comparison. Either will permanently deform if stressed beyond the yield point.
The Mark Williams critical speed chart has a safety factor built in and is very conservative. Both Wikipedia and Wallace Racing have info on critical speed if you want to see how your shaft shapes up. The short course is that the longer the shaft and/or the faster it spins the larger the diameter needs to be to stay straight while spinning. If it starts to flex too much it becomes unstable both physically and mathematically.
I have a shortened OE 7290 shaft about 50" long and it's been 1.40 60' at around 3300lbs and I've had it over 6500rpm.
http://en.wikipedia.org/wiki/Critical_speed
http://www.wallaceracing.com/driveshaftspeed.htm
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, BobR, what do you guys use 
