I'm putting together an altered chassis with a solidly mounted rear axle and I'm looking for some input regarding the rear axle install. The axle is a 9" Ford that will be narrowed. The motor/trans assembly will also be solidly mounted. I prefer the way the axle looks mounted with the housing centered rather than the pinion centered, but it seems like centering the pinion would make the pinion angle issue simpler. So my questions are as follows: 1. If I run the setup pinion centered, should I go with 2-3 degrees down on the trans and 2-3 degrees up on the pinion to get the cups in the u-joints moving properly? 2. With a rigid setup, can I get away with more than 3 degrees? 3. If I run the setup with the housing centered, should I run the output and pinion in a straight line (looking at it from the side) and rely on the offset (looking at it from above) to make the u-joints work properly?
If you are running a solidly mounted rear axle why would you run u-jonts? Run a solid drive shaft with a centered pinion.
Honestly, I've never seen that kind of setup. I've seen the couplers used on front engine dragsters, but never a solid shaft (outside of a torque tube setup).
Is the engine mounted with a motor plate? If so, nothing moves. I have a local buddy who builds FED chassis and he just makes a slug for the front and rear engine mains and runs a solid bar through them to the pinion bearing. If your trans output is abit higher or lower than the pinion, than u-joints and yoke would be fine, with centered or off-set pinion they just need to be square to each other.
If you run a driveshaft with u-joints you need at least 1 degree difference just so the needles in the u-joint don't ride in the same spot and dig into the cap and cross. Up or down I don't see what difference it would make with a solid mounted axle and engine. I'd run a shft with joints just because solid mount might not be solid enough. Amazing how much flex is in frames under load.
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