CGT axle questions

[steinbru at vnet.ibm.com]

Ref:  Alan's note of Wed, 22 Aug 2001 09:19:46 -0400
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<steinbru at vnet.ibm.com> wrote:
>>I thought equal length axles was the key to banishing the
>>torque steer of driven front wheels.  What's the real story?

"Alan Kramer" <ackramer at hotmail.com> replied:
>It's not really length, but the moment of inertia of the driveshaft that
>matters. The difference on the CGT shafts is around 24mm from what I
>remember.  That's not much compared to their 520+/- mm individual lengths.
>So if the diameter (which is proportional to the mass of the shaft which
>would be proportional to the intertia) of one is different it's almost
>indistinguishable from the other.  Contrast that to my '97 Jetta where one
>driveshaft is over 2x as long as the other.  The shorter one is *much*
>fatter than the longer one, giving it the same amount of inertia.  If they
>were the same diameter shaft, just shorter or longer then the short one
>would be easier to spin than the longer... resulting in torque steer.

Alan,
I don't think we're to the bottom of this yet.  When you figure in the
wheel and tire, the axle and joints don't count for diddly in the
angular moment.  Also, differences in axle diameter probably have much
more to do with stiffness than anything else.  The moment arm IS
proportional to length though, and when acted on through that
length, the force on the axle from the road (due to the torque
required to accelerate) tries to turn the car --at least that was my
(probably oversimplified) mental picture.  I know Hondas do it and
Audis don't.  If my Rabbit did it it was not objectionable or even
very noticable, but maybe because of the low torque.

I copy the list, maybe we'll get some clarification.  You might be
right, but I'm still confused.

I'll be checking the outers from the '86 this weekend to see if they
can swap to the 87.5 --after I clean up the inner to
see if the whole thing is worth it!
--Gary