Hot Rods Cheap Hot Rod axle

Just a thought, but why not use the twin I beam axles and adapt the coil spring mount to fit the double leaf springs found on most trailers. Adjust them to the appropriate width, and mount the pivot end where needed. Make a mount to the axle for the tierod end making the alignment adjustable. It would be a lot of work compared to just buying axles, but you could have disc brakes on it if you used a tongue with surge brakes.
The comment on riding smoother comes from personal experience. I was raised on a ranch, we always drove Fords because they wouldn't break your neck on the ceiling when you hit a cow trail.

 

I had a '73 F100 that drove like I was drunk all the time. Seriously, you couldn't keep that thing in its own lane over 50 MPH. Threw parts at that sucker 'til I finally gave up and sold it off. The father of the fellow I sold it to had it put on a frame rack, come to find out one of the frame horns was bent in very insignificantly. They straightened the frame and that thing is still running up and down the road.

I think on the two wheel drives that twin I-beam is pretty sweet because of the quality of ride factor all ready mentioned. A lot of folks don't care for it in four wheel drives (myself included) because they're a bit less durable when abused in extreme situations. That said, I have a '89 Bronco with twin I-beam and she's a great mild off roader.

Enough of my threadjack, to the OP: it's probably not a good idea to use this setup when building a hot rod. Check around, there are still cheap straight axles to be found. I found a Model A axle, complete from spindle to spindle, with the wishbone, for $20. It's a little pitted, but with some elbow grease she'll look just fine.

 

Check this out, it may shed some light for you... This guy has done this at least twice.
http://www.hotrodders.com/forum/journal.php?action=view&journalid=17166&page=8&perpage=5&reverse=1

 

It's a bit ugly, but he did do a good job doing it