> I love the look of my old NR calipers. However, >
compared to current modern
> anything, the amt of lever pressure required > is........tiring.
> Does anyone know of a readily available replacement
> spring that will make the
> NR caliper easier to close?
I made new return springs for a set of old cantilevers (the originals could have powered a siege machine). I bought spring wire at Orchard Supply that was about 60% as thick as the original. Used the shaft of a 3/8" drill bit as a bending mandrel for the coil, clamping the wire and mandrel in a bench vise. Anything round will work as a mandrel, and it helps if there's a flat spot on the mandrel for clamping the wire between it and the vise jaw.
It took me 5 attempts per side to get 2 return springs with nice coils and all the other little bends in the right place. This was not hard, just tedious and fussy. Some attempts looked right, but didn't work when installed.
Sidepull return springs should be a little easier to duplicate. You may need to shim the thinner wire where it goes through the notch in the bolt.
You might also check if Dia-compe BRS or later RGC springs will fit your calipers. These may still need a shim.