72 master cylinder
Thread Starter
Melting Slicks
Joined: Apr 2013
Posts: 3,483
Likes: 1,823
From: McCloud CA
C2 of Year Finalist (appearance mods) 2019
72 master cylinder
I need to rebuild my master cylinder on my 72 manual brake car. All the kits I see only have one piston isn't there two?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Well, yes & no. One piston, two seals or "O" rings. Front and rear.
I don't know your reasoning for wanting to rebuild it yourself. To save money or just because. But the potential for something to go wrong here should scare the hell out of you.
If a brake hose fails you lose one brake. If a brake line fails you lose two brakes. If a caliper fails, one brake. But if a Master fails, you have lost everything! Its something to think about when that deer runs out in front of you or that little girl chasing a ball in the street.
Rebuilt Masters are not cheap. But piece of mind for safety sakes, let someone else rebuild it for you.
I don't know your reasoning for wanting to rebuild it yourself. To save money or just because. But the potential for something to go wrong here should scare the hell out of you.
If a brake hose fails you lose one brake. If a brake line fails you lose two brakes. If a caliper fails, one brake. But if a Master fails, you have lost everything! Its something to think about when that deer runs out in front of you or that little girl chasing a ball in the street.
Rebuilt Masters are not cheap. But piece of mind for safety sakes, let someone else rebuild it for you.
Last edited by HeadsU.P.; Sep 15, 2019 at 02:05 PM.
Race Director
Joined: May 2006
Posts: 18,692
Likes: 2,572
Yes there are two, primary and secondary, but one of them only requires the seals to be replaced and those should be in the kit. see the generic diagram link below
https://keen.ipower.com/pages/Catalo...50063&year=ALL
https://keen.ipower.com/pages/Catalo...50063&year=ALL
Last edited by MelWff; Sep 15, 2019 at 02:49 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Some designs (GM, included) have one piston with two sections/piston lands/seals. Some have "nested" pistons. There is only one piston in a 1972 master cylinder.
It is a simple rebuild and inexspensive, to boot! Get a quality kit from NAPA, etc. IMO, you should stay away from most of the national chain stores. If NAPA offers more than one option for that rebuild kit, DO NOT buy the cheapest one. Just sayin'...........
You must 'bench bleed' the master cylinder after rebuild and before hooking up the brake lines. You can do it "on the bench"; or you can assemble it to the booster and bleed it (with plastic fittings and hoses) on the car. But, it MUST be bled completely free of air bubbles before hooking up the steel lines. THEN you get to bleed the rest of the system.
P.S. While you are at it, push enough fluid thru the lines to completely clear out any old fluid. DOT 2 &3 can absorb water and turn dark with age. Get the old stuff OUT!
It is a simple rebuild and inexspensive, to boot! Get a quality kit from NAPA, etc. IMO, you should stay away from most of the national chain stores. If NAPA offers more than one option for that rebuild kit, DO NOT buy the cheapest one. Just sayin'...........
You must 'bench bleed' the master cylinder after rebuild and before hooking up the brake lines. You can do it "on the bench"; or you can assemble it to the booster and bleed it (with plastic fittings and hoses) on the car. But, it MUST be bled completely free of air bubbles before hooking up the steel lines. THEN you get to bleed the rest of the system.
P.S. While you are at it, push enough fluid thru the lines to completely clear out any old fluid. DOT 2 &3 can absorb water and turn dark with age. Get the old stuff OUT!
Burning Brakes
Joined: Sep 2009
Posts: 1,124
Likes: 140
From: Western New York
As 7T1vette has said, it's a simple rebuild and nothing to be afraid of doing yourself. In fact, I feel more confident and safe with my MC rebuild than with a rebuilt unit that you know nothing about the materials used, or the goofball who rebuilt it south of the border or who knows where. It is a piece of cake. And if you have your original MC like I did, you don't lose it on a trade in for the core. Your 72 should have the bleeders in the MC body which makes for easy bench bleeding. Good luck.
Duane
Duane
Race Director
Joined: May 2006
Posts: 18,692
Likes: 2,572
Number of pistons in master cylinder
Not to be argumentative but the master has two pistons primary and secondary. See the rebuild procedure in the link below.
https://www.capitalcorvetteclub.ca/i...aster-cylinder
https://www.capitalcorvetteclub.ca/i...aster-cylinder
