Walt is right . . .

As understand it, in a torque tube setup the axle cannot be afixed to the springs - nor can the propeller shaft be afixed to the transmission - because both the driveline angle and length vary.

The pinion angle is dictated by the geometry within the tube. But as the axle rides up and down through spring travel the angle of the tube itself changes. This is why the universal joint is enclosed in a spherical coupling. This holds the distance between the transmission tail case and the rearend pumpkin constant - allowing the angle to change, and also allowing the propeller shaft to slide in-and-out on its splines as the axle moves up and down on the springs (end play).

With an open driveline the pinion angle is dictated by the perches. Driveline length is constant with universal joints at both ends.

As Steppenwood points out in his website - the torque tube spring perches are unsuitable for use with an open driveline - because they allow the axle to rotate which would change the pinion angle.

regards
stock49

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