Thread: Spring question.

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At the risk of fanning the flames of discontent I'll add an item or two.

From '35-48 Ford did in fact mount the spring other than on top of the axle, see pic below. The rationale as I've read it in the past was to have a wider spring for a more compliant ride without being constricted by the width of the axle. Also it lowered the ride height, which afterall is a big part of what we do as rodders. Of course the hardware pictured here is a nice forged assemblage, of particular note that the attachment to the axle is both top and bottom. Which leads me to my personal suspicion (for want of a better word) of the design you've proposed that would be a single shear mount. If you allowed for enough rotation in the radius arm pivots you might not put too much stress on the mounting point, but I'd be mindful of that. Keep in mind, with the original Ford design the wishbone bracket pretty much moved in the same arc as the axle due to the single mounting point under the transmission. When we "split the bones" and mount them out to the frame sides we limit the amount of rotation which translates to stress at the axle mounting, particularly with a single mounting point on each side at the rear. You get higher stress from both rotational movement of the axle on the spring center point, as well as straight up and down movement at the axle mounting points. That's partly why four bar arrangements became so popular years back, having two mounting points front and rear lowered the stress at the axle mounting in verticle movement, and was somewhat more tolerant of rotational movement.

My other "objection" to the axle you've got is how wide it is..........this is mostly an aesthetic issue. The Ford axles had 48" kingpin centers, you're 6 inches beyond that. Couple that with how narrow the frame will be, and a fenderless body, and it all gets a bit gawkish. Too bad you're about as far away from me as the lower 48 allows, I've got a nice '39 axle just lying fallow out in the shop.