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My friend to whom I go with all questions specifically Cummins-Dodge had a 1st Gen Std. Cab that he had Deaver build a set of springs for, but he never got rid of the Rancho's that came on the truck. The plan was a set of 7100's. He sold it before that could happen because suddenly he need room for a tricycle motor. I've long felt that was a missed opportunity.
Hot-rodders for years have been putting a low friction liner between the leaves of leaf springs to make the springs more supple & ride better. GM did them one or more better by putting shims between the leaves in the region of the U-Bolts and low friction tip sliders on the tips of each leaf thereby creating an air gap between the leaves for most of their length. Air is frictionless so a lot of the internal friction in a leaf spring was lost just by that act.
The internal friction in a leaf spring also acts a bit to dampen the spring. Reducing the friction in the spring requires an increase in damping rates. It is a sure way to tell that you've reduced the internal friction. Bilstein rates their damper shim stacks by Newton-Meters of force required to move the damper's shaft at some specific velocity. Normal Bilstein valve shims for leaf springs are 255/70 (Rebound/Jounce). Moving to the GM springs required going to Bilstein's 275/78 shim stack to regain proper damping.
I mention all of this because I think that if you can find a spring mfg willing to make your some springs with tip sliders and air-gap shims that it will be well worth the effort; and also that if you do succeed in that that the std valving in a 5100 or 7100 will be a bit light. It is possible to order the dampers with any of their catalog damping rates. The set that I've ordered that way took a little longer to get, but didn't cost any different.
Hot-rodders for years have been putting a low friction liner between the leaves of leaf springs to make the springs more supple & ride better. GM did them one or more better by putting shims between the leaves in the region of the U-Bolts and low friction tip sliders on the tips of each leaf thereby creating an air gap between the leaves for most of their length. Air is frictionless so a lot of the internal friction in a leaf spring was lost just by that act.
The internal friction in a leaf spring also acts a bit to dampen the spring. Reducing the friction in the spring requires an increase in damping rates. It is a sure way to tell that you've reduced the internal friction. Bilstein rates their damper shim stacks by Newton-Meters of force required to move the damper's shaft at some specific velocity. Normal Bilstein valve shims for leaf springs are 255/70 (Rebound/Jounce). Moving to the GM springs required going to Bilstein's 275/78 shim stack to regain proper damping.
I mention all of this because I think that if you can find a spring mfg willing to make your some springs with tip sliders and air-gap shims that it will be well worth the effort; and also that if you do succeed in that that the std valving in a 5100 or 7100 will be a bit light. It is possible to order the dampers with any of their catalog damping rates. The set that I've ordered that way took a little longer to get, but didn't cost any different.