I'm getting ready to shorten the torque tube on my Model A. I'm not going to bore you with the specifics of the build but what I would like to know how much end play should be on the drive shaft after I cut it. There would be no reason for the splines if it didn't move back and forth a little bit. I'm talking drive shaft , not the torque tube.
The snap ring position for the bearing/speedometer gear is critical. I measured few rear ends and settled with .080 clearance. The driveshaft is pinned if 33 up and tapered if 28-32. Either way the driveshaft does not move relative to the rear end.
Not very scientific, but here's how I've always done it. If you look at the front end of the shaft, the splines have a beveled end, about an 1/8". Now look at a shaft in a torque tube, set a straight edge across the bell and you will see that 1/8" bevel is whats longer than the tube. theres your length.
I know that on the pinion shaft at the rear end but where it goes into the u joint on the tranny, it can't be too long or it would bottom out. I guess I should of said it's going onto a 40 pinion shaft at the rear.
The only thing you should worry about is the position the bearing and speedo gear. If they are in the right place, you have no problem about the length of engagement in the U-joint.
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