Rebuiulding master cylinder on 48 Chevy 2dr Fleetmaster Coupe.
MC piston from Chevs of 40s looks alot different than the old one. (Old one fairly matches the one in 42-48 shop manual). The new piston has an extra 3/16" thick "rib" as part of the casting, approx. 1/2" from outer end. On the other end of new piston, the 6 small holes are covered by a very thin spring-steel disk secured to the piston at its center. The disk has 6 holes, each approx 1/8" dia, arranged in a circle. These holes do not reveal the 6 holes in the end of piston.
Should I use the new piston, or re-use the old?
The rubber on old piston is not bad; have not tried removing the rubber from new piston to put on old piston, but will do so if you think I should re-use the old piston.
