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Discussion Starter #1
2003 GT
2.1L Kenne Bell
Coilovers
Torque Arm
Panhard Bar
3.73:1 Gearing

I am considering getting a TrueTrac for my mustang. I will never drag race the car. It is just set up for open track. I am making right about 400HP and about 450 torque. But, knowing that I will not be doing hard dragstrip launches, is there any particular reason that I would HAVE to have the 31 spline axles? I think that the ~$300 could be better spent elsewhere.

What do you think?
 

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31 spline axles have a larger diameter over most of their length than 28 spline axles. This gives them better bending stiffness, which is very important to maintain camber under high cornering loads. Some axle vendors may be willing to machine an axle with the diameter of a 31 spline unit down to the root of the splines.
 

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Discussion Starter #3
Thanks Jack. That is an interesting thought but I am certain that the cost to do that would far exceed the cost of the 31 spline differential + new axles.
 

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31 spline axles have a larger diameter over most of their length than 28 spline axles. This gives them better bending stiffness, which is very important to maintain camber under high cornering loads. Some axle vendors may be willing to machine an axle with the diameter of a 31 spline unit down to the root of the splines.
Moser did EXACTLY this for me a couple years ago........I don't remember them charging any extra for it either. If so, it was minimal


(FWIW: I'm running a SN95 with 260 RWHP and I've bent these but not so bad that I'm changing them yet)
 

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Yes, it is actually less work for the axle vendor to do this since they are removing less material when machining the axle. I'm sure that some vendors won't want to do this, because they aren't actually machining the axles at all.
 

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Discussion Starter #6
I was unaware that in open track applications there is enough load on the axle to bend it. I thought that this would really be an issue in drag race application where you are seeing a monster amount of torque in an instant.
 

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The axles are flexing, not bending. Bending means that after the load is removed, they do not return to their original shape. Flexing means that they do return to their original shape.

Anything with a load applied to it flexes. The amount of deflection may be really small, but it is still there. A factory 8.8" axle housing assembly has enough axle flex under a 1g corner with a 3,200lbs car for the camber angle to change over 1 degree. It is visible.
 
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