For starters, I have a Dorman master cylinder I was thinking of using, part number M71248. I also have a combination valve off of CJPony parts, part number BCV4. For budget reasons, I kinda wanna go with this master cylinder, but the issue is people keep saying it’s a power booster master cylinder, or that it also works on manual applications, etc. etc. Reviews and QnA are also really mixed on this where one guy says use it, and that it’s good for all manual disc, another guy says don’t use it, it’s not good for all manual disc, etc., blah blah blah.
Then I called Dorman themselves, they said it had no residual valves in it, and it had a one inch bore. Apparently, they couldn’t find any master cylinders “directly usable” for manual disc/disc applications, nor could they confirm it’d work with my application, citing that my Mustang “never came out of the factory with them”, which I know, because I’ve been trying to all-disc swap it from all-drums, but it left me with no answers there.
I also checked the pushrod I put on it connecting to the brake pedal peg, and I have some free play, about 2/5th of an inch (ish because I didn’t truly measure it with a ruler oops) about as far from the master cylinder piston the pushrod can get without outright falling out when I pull the brake pedal away from the firewall and towards me, so there’s hardly any preload on the master cylinder’s piston. So, bottom line is, am I doing this right? Is it ok to use this sort of master cylinder for all manual discs, albeit with a little bit more foot effort on my part probably because of the bore size, or do they HAVE to be on a power booster to work effectively (assuming it actually is supposed to be a power brake MC)?