Is this Driveshaft guy smoking crack or what?
Feb 29, 2012 | 08:46 PM
#24
TECH Resident
Joined: Aug 2008
Posts: 927
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From: Dubai
the 5" .125 thick will prob be stronger then a 3.5" .065 thick 4130 DS. but given my lenth which i know is over a foot longer then the OP's the steel absolutely will not hold the rpm i turn which is prob why they recommended the alum. Brent the owner of driveshaft specialists prob heard truck and said the aluminum since thats what most of us need.
about the money in their pocket, when i got mine i looked up the part numbers of the components used to build it and purely material alone is over $400 for someone to buy. that 5" tube is over $200 itself for 80" long. they already built mine and sent it and never even had my credit card info.
i always figure by engine rpm because we would be going through traps in 3rd gear 1:1 ratio. any drag car you see even a pro mod doing 240mph doesnt have overdrive so they will only be turning engine rpm through the traps.
about the money in their pocket, when i got mine i looked up the part numbers of the components used to build it and purely material alone is over $400 for someone to buy. that 5" tube is over $200 itself for 80" long. they already built mine and sent it and never even had my credit card info.
i always figure by engine rpm because we would be going through traps in 3rd gear 1:1 ratio. any drag car you see even a pro mod doing 240mph doesnt have overdrive so they will only be turning engine rpm through the traps.
Feb 29, 2012 | 08:48 PM
#25
TECH Resident
Joined: Aug 2008
Posts: 927
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From: Dubai
Feb 29, 2012 | 11:17 PM
#30
Joined: Jan 2006
Posts: 16,282
Likes: 438
From: Huntsville, AL
Ive had a 4" AL, a 5" AL, and a 3.5" steel from them, all quality parts.
Steel has a higher critical speed due to the much higher modulus of elasticity of the material; thats why they can afford to be a smaller diameter for the same application. AL is lighter, so it saves you a few hp, but you need a larger diameter. The weight of the shaft does not matter as far as critical speed is concerned. The only thing that matters for critical speed is modulus of elasticity, diameter (inner and outer), and length.
Steel has a higher critical speed due to the much higher modulus of elasticity of the material; thats why they can afford to be a smaller diameter for the same application. AL is lighter, so it saves you a few hp, but you need a larger diameter. The weight of the shaft does not matter as far as critical speed is concerned. The only thing that matters for critical speed is modulus of elasticity, diameter (inner and outer), and length.