I'm building my first T-bucket. I've looked over the many suspension options. I've come up with one I'd like to use but want to run it by more experienced guys. I would like to put my rear model T type spring in front of the axle. What would be wrong with making batwings with spring mounting holes to mount the spring between the radius rod holes? Any added stress or weakness? Something like this front one but designed for the rear.
Something to consider, and this is the Suspension Validation Engineer in me talking, and I am used to working with Heavy Truck Suspensions that are designed to go a 1,000,000 miles, so small grain of salt. With that batwing design, you are going to start and stop a weld at the top and bottom of the axle tube. The top and bottom is where the axle tube is stressed the highest in bending and the weld start / stop at those locations is the worst possible place to start a weld. It creates a large stress riser that will lead to failure much sooner than if the batwing mount was designed with a flange that is welded to the axle tube horizontally (lengthwise) along it's mid plane. It get that an 1,800 lb T-bucket is completely different than a 34,000 lb tandem axle, but the same engineering rules apply.
Most rear ladder bar mounts have a full circle around the tube. More important than your concern about the spring mount twisting, should be a concern for the arms to point together at the front, forming a triangular section. It will prevent the whole rear axle acting as a giant sway bar. Extending the lifespan of the axle and bars.
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