Thread: quick master cylinder question

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I have seen diagrams where the brake line going to the rear is connected to the front of the master cylinder and the line going to the front is connected to the rear of the master cylinder and i've seen it the other way around also. does it matter?

Some master cylinders are set up for discs on the front and drums on the back, so in that case I think you need to hook it up in the correct ports. But on ones that are set up for drums, and if you are using drums, I don't think it makes a whole lot of difference. It could be that certain master cylinders have different sized bores too.

On my T I ran the master cylinder facing the opposite direction, and simply hooked up the lines so they ran conveniently, without regard to front or back, and it seems to work fine.

Don

Generally it is front chamber to rear brakes and rear to front.

Generally, the bigger chamber is for the fronts.... Must take a bit more volume to make discs work then drums???? When I use dual master cylinders and a balance bar I use the same size reservoirs.... Maybe a safety thing or something the factory built into them?????

If there is a bigger inside reservoir, then that one is to the front brakes due to the usual 60/40 (or whatever) brake bias, front vs rear. The thought was that you need more fluid for the front to maintain that difference. In a real world, I doubt that it really makes a difference

The larger reservoir for discs has nothing to do with brake bias or stopping force required. Disc brakes require more volume than drums, and as the brake linings wear the pistons are pushed out of the calipers farther and farther so more fluid is required. Next time you need to change front pads check the fluid level in the master before you squeeze the piston back into the caliper, it gets pretty low

Originally Posted by ceh383

The larger reservoir for discs has nothing to do with brake bias or stopping force required. Disc brakes require more volume than drums, and as the brake linings wear the pistons are pushed out of the calipers farther and farther so more fluid is required. Next time you need to change front pads check the fluid level in the master before you squeeze the piston back into the caliper, it gets pretty low

I think that's really what I said!!
Bias = the fact that there is additional wear on the front DUE to that difference in braking effort = the additional reservoir capacity needed to keep that fluid chamber and lines full. This is true regardless of whether you have drum or disk brakes

I am running 4 wheel discs and the two reservoirs are the same size, but the cap has a rubber insullator on one side that takes up half the reservoir . That could easily be flipped around though if needed I guess. I think I will run the front to back and back to front.

Originally Posted by 35fordcoupe

I am running 4 wheel discs and the two reservoirs are the same size, but the cap has a rubber insullator on one side that takes up half the reservoir . That could easily be flipped around though if needed I guess. I think I will run the front to back and back to front.

Can that rubber seal be pushed back up? They usually extend when the fluid is low. You should be able to hold the cap in your hands and use your thumbs to push it back in place - it should fold back to the original size. Is it a Corvette style MC?

Originally Posted by IC2

Can that rubber seal be pushed back up? They usually extend when the fluid is low. You should be able to hold the cap in your hands and use your thumbs to push it back in place - it should fold back to the original size. Is it a Corvette style MC?

it is a corvette style...the rubber seal might be able to be pushed back up but it still seems bigger than the other side...o well.

i have the lines all bent up for the most part now. it has turned out pretty well for a first time effort . i had some challenges drilling and feeding the lines through the frame in a couple spots, but i seem to be in the clear.

one question...do i need any sealant on the fittings? I just need to figure out what fittings i need to connect the lines to the master cylinder and i'll be in bussiness.

im taking a long weekend off work this weekend and hope to set the engine/trans and body back on the frame and get it looking like a car a little bit again

Originally Posted by 35fordcoupe

it is a corvette style...the rubber seal might be able to be pushed back up but it still seems bigger than the other side...o well.

i have the lines all bent up for the most part now. it has turned out pretty well for a first time effort . i had some challenges drilling and feeding the lines through the frame in a couple spots, but i seem to be in the clear.

one question...do i need any sealant on the fittings? I just need to figure out what fittings i need to connect the lines to the master cylinder and i'll be in bussiness.

im taking a long weekend off work this weekend and hope to set the engine/trans and body back on the frame and get it looking like a car a little bit again

You should be able to push it back in place with your thumbs - if not, get a new seal

Sealant on fittings - generally no, but pipe threads occasionally need some - and I use it on any of my project cars there. AN fittings, never. Fittings into the MC - never - they should have copper seals. If you are using calipers with a banjo type fitting, never. They, too have copper seals.

Give these folks a call (http://www.inlinetube.com/) for MC fittings - they are unique fittings. Also, they may be able to supply a new MC seal as well

most late master cyls have built in resudial valves so it does mater a drum drum mc has difrent valving than disc drum so find out what you have thats my 2 cents ted