Posted by Vince on January 02, 2003 at 22:17:11:
In Reply to: Hirsbrunner "nylon" rotors posted by Steve on January 02, 2003 at 09:38:28:
My 1978 HB-2 CC has the tryplen rotors. I honestly don't know when they stopped making them. Only part of the valve is nylon; if you look at it from the top (or bottom,) the core (spindle) and the outside of the rotor are brass, with a layer of nylon surrounding the core. I had to have mine lapped because of the tendency of these valves to expand more than usual when they get warm, like when playing outside in the summertime.
-Vince Humphrey