[Floyd]

So true. A leaf spring is really a constant strength (stress) plate of roughly diamond shape and cut into strips and stacked together to make practical sized assembly for use. It is nothing more than that. Now with the strips stacked together we get some form of friction between the slightly sliding plates. This provides a bit of damping (hysteresis) to the assembly which is going to be needed somewhere in a spring mass assembly. This small amount is acknowledged in the design of the real damping device that we call shock absorber. The lube that is added is to prevent squeaks and to provide a constant amount of friction over the life of the assembly. The lube is not there to eliminate the friction, only to try to keep it constant in spite of rain, salt , rust and corrosion trying to change the characteristics over time. As Ted alludes to above, in time without maintaining the lube of the springs (probably no one did it anyway ,even with the wrapped deluxe models), the friction level rises, increasing damping. At the same time the shocks are wearing and their damping rate is decreasing. The spring increase in damping factor however is not enough to fully offset the loss in the shocks, but given a spring surface ugly and rough enough, it certainly helps.
We have a spring-mass-damper system on all cars and they should sing in harmony and in the same key.
This is why I am fully opposed to the teflon spring insets besides the fact that they look stupid.
Every time my '32 stops on a dime, I say "thanks Ted"