Those of you who have my book can find this stuff in the
Suspension chapter...
Steel bushings make a steel-on-steel bearing surface, which is a huge no-no in the world of rotating bearings. Machinery's Handbook covers this is painful detail. Why Honda has chosen, since the 1990s, to provide steel bushings is beyond me, but they do: the result is about 5000 miles of collar life in these arms. I get many arms for rebuild that have these bushings and ravaged collars.
Phenolic was Honda's primary choice, once they quit using the terrible Zamac plastic composite in the K0/K1/K2 750 and the CB500. It is easy to machine, but gets squishy-soft over time from the grease and makes the bike handle loosely.
Bearing bronze like SAE660 (this is the kind you find for sale now and then) is nice and hard, and easy to machine. But, it requires lube at the same 3000 mile interval that the phenolic does, and does not forgive you if you stretch that interval very far. Racers often use this stuff.
Oilite (841 bronze) is very hard (for improved handling), and fairly easy to machine. It was created to run on steel shafts (like the Honda collars) with either oil for high-speed use (like in fan bearings) or grease in lower-speed, impact use (like our swingarms). It contains oil in the metal (it's a metal powder material, fused in high heat, porous) that comes to the surface if the bearing gets above 150 degrees F or so. This allows some forgiveness in our situations, where we might be on a long tour and are stretching the grease interval on the arm. Once the oil has started to ooze out, it softens the nearby grease again and helps us out. When you regrease and ride, the heat lets the oil from the new grease soak back into the matrix for the next time.
