PINTO CAR CLUB of AMERICA
Welcome to FordPinto.com, The home of the PCCA => General Help- Ask the Experts... => Topic started by: Reeves1 on December 03, 2017, 07:40:44 AM
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Been thinking a bigger master cyl would work better ?
Especially folks that use a 9" diff & bigger fronts.
Anyone try this & which one used ?
If my info is right, the Pinto is 15/16 bore .
Mustang equal is 1" bore. Better ?
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The smaller the bore is the more pressure you have. You can use a 84 Ranger non power brakes master cylinder to clean up under your hood but it too is 15/16. It will not rust and look like it was made back in the 20's like the stock master cylinder will do. Ranger mc will require work on the length of the rod. I made mine adjustable.
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As Dick states you will get more pressure with a smaller M/C..., but it comes at the cost of pedal travel. It seems that the smaller the M/C the better but if you hit the floor before the brakes lock..., not so. So, if you go with unboosted brakes and want a stronger feel go prudently in your downsizing. There are likely sizing tutorials somewhere on the internet but the "math" does not translate into "feel" and my assumption is it is kind of a trial and error process of the average man.
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wouldn't the pressure be regulated by the size of the orifice at the exit from the master? The increased volume of fluid needed (especially in larger calipers &/or brake cylinders will also lower the pressure.
If you are pushing into a larger volume with the stock master the end result is that, as others have suggested, you will run out of travel & hence the pressure in the calipers/cylinders will be lower.
I think !
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An orifice may delay the amount of pressure but it will ultimately not restrict the full amount of pressure. As far as M/C to Caliper/Wheel Cylinder size goes there are formulas for that. The builders do all the math to get that right..., but there is some leeway. Emphasis on the word "some." Thus one can go to a slightly smaller M/C and get a somewhat easier pedal. But as mentioned it comes at the cost of (lengthening) pedal travel. If the driver is OK with that "feel" and the travel still leaves a reserve before bottoming out then that is a matter of preference.
As far as to why the smaller M/C makes for an easier pedal..., it is all about the resistance of volume. Consider the plunger on a floor or bottle jack. The smaller it is the easier to move, but at the cost of multiple pumps. In brakes you don't "pump" them. So you get one shot. Too much volume and the pedal gets hard. Too little and the pedal bottoms out. Just right is a small window that allows for a little size variation.
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An orifice may delay the amount of pressure but it will ultimately not restrict the full amount of pressure. As far as M/C to Caliper/Wheel Cylinder size goes there are formulas for that. The builders do all the math to get that right..., but there is some leeway. Emphasis on the word "some." Thus one can go to a slightly smaller M/C and get a somewhat easier pedal. But as mentioned it comes at the cost of (lengthening) pedal travel. If the driver is OK with that "feel" and the travel still leaves a reserve before bottoming out then that is a matter of preference.
As far as to why the smaller M/C makes for an easier pedal..., it is all about the resistance of volume. Consider the plunger on a floor or bottle jack. The smaller it is the easier to move, but at the cost of multiple pumps. In brakes you don't "pump" them. So you get one shot. Too much volume and the pedal gets hard. Too little and the pedal bottoms out. Just right is a small window that allows for a little size variation.
This sounds like relationship counseling, but then I digress :D
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I road raced my 72 Pinto for 20 years with the stock master cylinder and disc brakes up front equipped with metal master brake pads. I never had one problem with the brakes in that 20 years and I really wonder why anyone would want to mess with the factory set up. If you need better brakes forget the stock set up and go with after market brakes. Just don't mess with a good thing please.
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I'm wondering if it is a leverage issue. That being running larger wheels/taller tires exerts a greater leverage on the braking system and thus reducing the braking ability??? Frankly on the street I find the '73 Pinto brakes marginal at best. There certainly is no reassurance that I am stopping fast enough. But then I find the brakes in my 2000 Protege to be far superior to my wife's 2010 Civic. Maybe because the brakes in the Protege are SO GOOD that everything else seems substandard.
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Some of the things I've seen on cars makes little sense like wider tires making the steering easyer or a smaller steering wheel making the steering easyer. How about the rear brakes on my Pinto filling up with gear lube do to the wrong seals yet the lap times staying the same as before the oil got in the drums. Then we have the story of the headers being beat to death with a hammer with NO loss of hp on the dyno as posted by me in the FAQ (tech tips) forum. Then there's my 93 Suburban that had a rad leak so I removed the guts from the rad cap to releave the pressure and stop the leak. That was 8 years and 100,000 miles ago and the cap is still on the rad which had the leak fixted. You just cannot explain some things you would have bet money on.
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Another influence to "feel" and ultimately Stopping Power ( with a given standard M/C and calipers) are the Brake hose materials. By switching to braided Stainless Hoses and Slotted rotors up front, my 84 GTI does fine with all other components stock sized. If the Proportioning valve is doing its job properly, The Bleeding process and Pad/ Shoe material are the way to improved stopping. This of course has nothing to do with ABS vehicles unless you have experience with electronics and centralized PCM vehicles.
Pintosopher, Bled by the Hotel , adding pad area to stop the room rates from climbing ;D
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I'm wondering if it is a leverage issue. That being running larger wheels/taller tires exerts a greater leverage on the braking system and thus reducing the braking ability??? Frankly on the street I find the '73 Pinto brakes marginal at best. There certainly is no reassurance that I am stopping fast enough. But then I find the brakes in my 2000 Protege to be far superior to my wife's 2010 Civic. Maybe because the brakes in the Protege are SO GOOD that everything else seems substandard.
On a 71/73 Pinto, the right pads make a world of difference in the way it stops. I used the simi metallic pads from NAPA on the street and metal master on the race car. Both worked great but the metal masters were not suited for the street due to the fact they needed to be hot before they worked good.