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master cylinder install

20K views 16 replies 6 participants last post by  twistedaase 
#1 ·
Does anyone have a good write up on brake master cylinder install on a 1983 cj7? I thought it was going to be bolt off bolt on but looks like there might have to be a rod removed from old to new. Thanks.
 
#2 ·
Where did you get it? Is it a factory replacement? Power or manual? How many bolts at the firewall? The rod you are talking about, I'm thinking, is the rod that connects to your brake pedal? It should have come with it. Did you bench-bleed it first?
 
#6 ·
thats funny i always thought about this.... so finally i did it on my last mc swap. turns out its a good way to bench bleed unless..... you get a bad mc to start with, ask me how i know , lol. i think the benifit is if you do get a bad one at least its not installed. Maybe other reasons but this is the most reasonable difference i see.
 
#8 ·
It's worth the effort/time to get the bleeder kit. The tubes bend back into each reservoir eliminating any chance of inadvertently pumping air back into the system. Otherwise, you'd have to connect your brake lines and you'd end up pumping the trapped air in the MC right into your lines. You could bleed it mounted to the firewall using the brake pedal. Bleeding Jeep brakes is pain enough without pumping extra air into the system... IMO!
 
#15 ·
It's worth the effort/time to get the bleeder kit. The tubes bend back into each reservoir eliminating any chance of inadvertently pumping air back into the system. Otherwise, you'd have to connect your brake lines and you'd end up pumping the trapped air in the MC right into your lines. You could bleed it mounted to the firewall using the brake pedal. Bleeding Jeep brakes is pain enough without pumping extra air into the system... IMO!
Thank, Mike, for the correction. I will be careful not to give out bad advise!! :thumbsup:
 
#9 ·
It came with 2 plastic bleeder screws and 2 clear hoses that i attached and put the tubes into bottle of fluid i tried pumping the brakes and no fluid is coming out of the tubes , i do notice air bubble very very slowy coming out of the first hole in the reservoir closed to the booster.
 
#10 ·
Should be a plastic clip that fastens over the divider between the two reservoirs. The tubes attach to the clip. It holds the tubes in each reservoir. The idea is to keep the fluid level over the ends of the tubes. Each time you make a stroke it moves the fluid, in or out. It would work in the bottle but it will make it harder to see the bubbles, again, IMO. You can see it easily when the tubes are in plain sight.
 
#14 ·
That is because you didn't bench bleed it.

It has to sit perfectly level to get the air out or you just pump air down the line and mess up the combo valve, you are nowhere close to level on the booster. Even a set of steps will work usually, it gives something to push against and they are usually level.

If they are the kind that need full throws to bench bleed, the brake pedal also won't do that when it is installed, you need a screwdriver or rod for that.

You also have now tripped the combination valve from the sounds of it and may have to have someone pump it up hard, hold the pedal and then crack open a front bleeder screw to switch the combo valve back to center. It thinks there is a leak there and has shut down the circuit.
 
#16 ·
Okay when you say combination valve are you talking about in the master cylinder itself. I now have the master cylinder off and i am trying to bench bleed it. When I push the the cylinder in with a little pressure it pushes fluid up the small reservoir hole inside the small reservoir as if it would squirt up in the air with more pressure but does not do that in the larger reservoir.
 
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