I working on a resto-mod of a '55 1st Series Chevy Pickup. I replaced the original master cylinder with a dual master cylinder and the new system has disc brakes in the front and drums in the rear. Several years ago when I first got the master cylinder I used some Dot 3 brake fluid to bench bleed it. It was a few years later when I finally got all the lines done and was ready to fill the system with fluid. I decided at that time to use Dot 5 fluid, having forgotten for the moment that I had put Dot 3 in the master cylinder previously. After filing the system I noticed the color of the fluid changed and remembered I had put some Dot 3 fluid in the master cylinder several years ago. The master cylinder also started leaking at the front where the push rod goes into it. I am going to either replace or rebuild the master cylinder. I also plan to flush or blow out all the lines before I put the new master cylinder back on. Should I be worried about the wheel cylinders or disc calipers? If I clean out the master cylinder and rebuild it and clean all the fluid out of the lines and wheel cylinders/calipers, should I be good to go with refilling the system with Dot 5? If not, what all needs to be done to make sure the new fluid doesn't get contaminated again?
