Master cylinder

[pflaming]

Would it be beneficial to put an oil pressure gauge of some type on the outlet of the MC to test how good it is? The local parts stores and mechanics say mine is good to go. A test would be nice.

[NiftyFifty]

Did you do something too it? Rebuild? Or hasn't been used in a long time? If its the first two and store says ok I would waste your time... Not to mention getting brake fluid in your oil tester

[TodFitch]

Just guessing, I think there is about a ten to one mechanical advantage the way my brake pedal is connected to the master cylinder. And I can easily put my full body weight worth of force on my might foot while pressing on the brake. Call it 200 pounds for nice round numbers. So we have about 2,000 pounds of force on the master cylinder piston. I think that my master cylinder has a 1 1/8 inch bore so the cross sectional area is very close to 0.99 square inches which make calculating the PSI real easy (force/one).

So you better have a "oil pressure gauge" that goes to around 2,000 PSI.

[Don Coatney]

Just guessing, I think there is about a ten to one mechanical advantage the way my brake pedal is connected to the master cylinder. And I can easily put my full body weight worth of force on my might foot while pressing on the brake. Call it 200 pounds for nice round numbers. So we have about 2,000 pounds of force on the master cylinder piston. I think that my master cylinder has a 1 1/8 inch bore so the cross sectional area is very close to 0.99 square inches which make calculating the PSI real easy (force/one).

So you better have a "oil pressure gauge" that goes to around 2,000 PSI.

Tod;

I disagree as with my fat mass, and bulky frame sized additional mustle pressure (i think) I far exceded your mass and frame size. 2,000 PSI is not enough:eek: With my new master cylinder install I slammed my brake peddle with all the power I could muster up mister and I fully believe I exceeded the two grand figure. Plus I have a mechanical advantage with my linkage setup as pictured.

[pflaming]

So the answer is a qualified 'yes' but it would take a good gauge. So I take it one could set it all up, mount the gauge on the dash and if the presure is dropping have a 'warning' that some maintenance: leaky cylinder or line or MC, is in order.

OR maybe use an electronic sensor??????

[JBNeal]

I don't see much benefit to putting a brake pressure gauge to the system; the extra fittings introduces another avenue for possible fluid leaks. I've had the brakes done on the '48 since '99, and as of this afternoon, that pedal is still firm. One of the tests I did when I first got the brakes put back together, replumbed with DOT5, and adjusted, was to put a masonry block on the pedal, measure it from the floor, and go back to work for a week. When I checked it again, the pedal had not moved, nor were there any spots on the cardboard I had under the truck, so I figgered I was good to go. Occasional inspection of the lines shows that they are not weeping, and the fluid level is constant. Unless there is component deterioration or damage to the system, hydraulics will act the same for many cycles before any kind of performance malfunction. Adding a fluid sensor can be done, I've seen them available at JC Whitney...maybe just putting an unlabeled red lamp on the dash could work, but I don't know how a system check would work to verify the light works on startup...that's a challenge for another day

[Rusty O'Toole]

Master cylinder pressure is not the problem. It is not going to vary as long as the cylinder is working and has fluid in it.

Mastery cylinders wear out, get rusty, and leak. In rare cases they can hold too much pressure and cause the brakes to drag. In either case you will find out about it without any pressure test.

It won't hurt to check fluid level at oil change time, and inspect the cylinder for leaks while you are under the car. Other than that they are maintenance free.

[pflaming]

An automechanic's teacher friend suggested I mount a good flashlight on the truck. Then every time I have driven a decent distance, look under the truck for tell-tale signs when I stop. It's a practice he uses even on today's cars.

Not a bad idea.

Thanks all for the tips.

[48Dodger]

in racing we use a Hydraulic Brake Pressure Test Kit. Not cheap.

48D

This is a gauge you coud use too.

http://www.jegs.com/i/Auto-Meter/105/4626/10002/-1?parentProductId=756715

Edited May 1, 2012 by 48dodger

[Dave72dt]

That's a gauge I'd never look at in a moving vehicle. It'd only be an accurate indication of the system pressure when you're locking up the brakes and your eyes should probably be focused on something else at that point.

[48Dodger]

That's a gauge I'd never look at in a moving vehicle. It'd only be an accurate indication of the system pressure when you're locking up the brakes and your eyes should probably be focused on something else at that point.

It is a gauge for racing...lol.

48D

"It is amazing how may drivers, even at the Formula One Level, think that the brakes are for slowing the car down." – Mario Andretti

Edited May 2, 2012 by 48dodger

[pflaming]

Even with an AT I always use the tranny and engine for slowing down. Brakes are for stopping not slowing down! IMHO. Dad taught me that when he taught me how to haul a load of wheat, 250 bu @ 60#/bu in a 2 ton IH truck. He always said, its not the bump in front of you that you watch it's the one down the road! Andretti was correct.

[Don Coatney]

I have said for many years that everytime you tromp the brake pedal you waste gas. My logic is that you have already spent the money buying gas to accelerate to speed. If you do not let the car coast to a stop you have wasted the gas you used to get up to speed and added un-needed wear to the brake system. I am amazied at how many drivers only know how to drive using full throttle, or full brakes. And they think they are making good time.

[TodFitch]

I have said for many years that everytime you tromp the brake pedal you waste gas. My logic is that you have already spent the money buying gas to accelerate to speed. If you do not let the car coast to a stop you have wasted the gas you used to get up to speed and added un-needed wear to the brake system. I am amazied at how many drivers only know how to drive using full throttle, or full brakes. And they think they are making good time.

I've always liked to "time signals" to see if I can keep the car rolling. Just a bit of a harmless game: Let off on the gas when you see a red light ahead and coast down to the light trying to time it so it will turn green when you are just far enough away that you won't have to use your brakes to stop. You get to where you are going just as fast as those who drive full speed up to the intersection then slam on the brakes, you'll use less gas and you'll wear out your brakes a lot slower.

[Merle Coggins]

Wasn't it Enzo Ferrari that said, "Who needs brakes? They'll just slow you down." (or something like that)

[ggdad1951]

I've always liked to "time signals" to see if I can keep the car rolling. Just a bit of a harmless game: Let off on the gas when you see a red light ahead and coast down to the light trying to time it so it will turn green when you are just far enough away that you won't have to use your brakes to stop. You get to where you are going just as fast as those who drive full speed up to the intersection then slam on the brakes, you'll use less gas and you'll wear out your brakes a lot slower.

that's called "hypermiling". There are people out there that are FANATICAL about it.

[Don Coatney]

I've always liked to "time signals" to see if I can keep the car rolling. Just a bit of a harmless game: Let off on the gas when you see a red light ahead and coast down to the light trying to time it so it will turn green when you are just far enough away that you won't have to use your brakes to stop. You get to where you are going just as fast as those who drive full speed up to the intersection then slam on the brakes, you'll use less gas and you'll wear out your brakes a lot slower.

I do the same but it becomes not so harmless when the driver behind you drives right up to your rear bumper and toots his or her horn and or swings out to pass only so they can cut back in front of you and slam on the brakes at the red light. If I have a timed destination I always allow myself ample time to arrive as I know that speeding and tailgating does no good.

[48Dodger]

Wasn't it Enzo Ferrari that said, "Who needs brakes? They'll just slow you down." (or something like that)

lol....

In stock car racing (short track) the front brakes come in way before the rears...so you can use braking into a corner with hard acceleration to help pull (slide) your back tires around the corner. The extreme version of this is "drifting".

48D

[Robert Horne]

I've always liked to "time signals" to see if I can keep the car rolling. Just a bit of a harmless game: Let off on the gas when you see a red light ahead and coast down to the light trying to time it so it will turn green when you are just far enough away that you won't have to use your brakes to stop. You get to where you are going just as fast as those who drive full speed up to the intersection then slam on the brakes, you'll use less gas and you'll wear out your brakes a lot slower.

Some of the streets in China have signal lights that count down the seconds before they change color.

[Rusty O'Toole]

I would like a fluid level gauge a lot better than a fluid pressure gauge. With the MC under the floor it would save a lot of work (when you check it) and worry (when you don't).

Late model cars all have them. Wonder if you could adapt one.