Twins with Twins, Anyone?

kidturbo

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Jul 20, 2010
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I can get a closer pic today. That rust line in there makes me think it likely cracked some time before Friday. My guess, cracked in that video above, and we washed down the bilge directly after.

When searching for options, that looks to be called a 16 spline midship stub shaft. Commonly used on Ford front driveshafts.

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2004LB7

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Dec 15, 2010
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Just a thought if you can't find billet shafts maybe have some rifle bored. It makes axles much stronger.
I think that is only true when comparing them by weight. A hollow driveshaft of equal weight to a solid shaft will usually be quite a bit larger in diameter and thus stronger. But two equally sized shafts, the solid one will be stronger
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Gun drilled is usually reserved for 300m to allow it to twist more before breakage.

When you run 37s or 39’s with even just 4-500 hp, you can snap solid 300m shafts after 1000-2000 miles of racing in the dirt. Gun drilled lengthens that mileage substantially.

That said, gun drilling weaker material won’t benefit him nor do I think he really has enough material to take advantage of its purpose (to allow twist and return with no deformation).



Ken, I’d call Currie, speedway engineering, or possibly even Tom woods driveshaft. Probably going to be custom either way and at that point, get 300m
 
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2004LB7

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Ken, Taking another look at the pictures and it seems it broke right at the splines. For your design, wouldn't it be better to slightly neck down the shaft on the unsplined portion to allow it to absorb the shock better? Basically better spring ability spread out over the whole smooth part of the shaft so as to reduce the concentration of stress on the weaker splines

And maybe 300M or 4340 at a fraction of the cost for probably 99% of the strength of 300M
 

56taskforce

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Mar 30, 2014
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They gun drill axles for strength. We have done it in circle track cars for years. In a twisting force it's the surface area that creates the strength. Gun boring an axle gives it a another surface, it doesn't seem like removing material would add strength but it does.
 
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THEFERMANATOR

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There's Florida Powertrain on 60 in Tampa that builds shafts as well as Spicer, and other driveline stuff. It's probably worth a call to Mastry Marine in St Pete, they specialize in Yanmar diesel repowers, and have done just about anything you can imagine including building jackshafts for high HP diesels.
 

kidturbo

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Thanks for the info. I plan to run up Tampa way tomorrow, so will give them a call. One of my buddies here told me to check Precision Shaft Technologies in Clearwater also. Guess they have done a few marine setups also.

We got both drives off today, and one gear box out. Other shaft looks fine..
 

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