Ok, I need to get a new master cylinder for my truck, I have the 1 1/16th bore cylinder right now and my pedal is way too low, I tried bleeding the brakes and it didn't help, so i was looking for the biggest master cylinder i could find, and I found an 1 1/8 at the autoparts stores, and i found 1 1/4 at summit, I would like to use the 1 1/4 because it should bring my pedal up alot higher, but summit only has it listed for 93-96 E and F-series, was there a mid year change between 92 and 93, or should it fit no problem? PS, i looked up 92 and 93 master cylinders on autozone.com and it came up with the same parts, so i'm thinking it should be just fine, any help is greatly appreciated. Thanks

 

also is there a difference between automatic and manual master cylinders?

 

anybody ever run into this?

 

Where did you get the half-baked idea that cylinder bore size has anything to do with how high the pedal is?

Also, if you are buying master cylinders from autozone make sure you get the lifetime warranty because you will be changing that cheap POS out every few months.

 

Half-Baked? The more fluid the master cylinder pushes, the quicker it pushes the pistons in the calipers and wheel cylinders, hence your pedal is up higher when the brakes are activated, kinda common sense

 

Using a different master cylinder to fix a low pedal is a band-aid solution. I guess I didn't make that very clear in my post.

Why don't you find out why the pedal is low and fix that instead of the band-aid?

 

The master cylinder isn't pushing enough fluid to fill the 1-ton wheel cylinders along with the calipers because its the small 1 1/16 bore cylinder, the 1 1/4 will push a lot more fluid which means my pedal won't push to the floor before my brakes slow me down, a new master cylinder is good maintenance, not a band aid

 

Assuming everything is installed and operating correctly, there is no need to go to a larger bore master cylinder. If your pedal is too low you may need to adjust the pushrod nut. For some reason are the wheel cylinders larger than the ones Ford installed when it was new?

Replacing a master cylinder is not a maintenance item to be performed every X years or Y miles. They are not like spark plugs or tires. In a properly maintained vehicle (including a brake fluid flush done in accordance with the manufacturer's maintenance schedule) there should never be a need to a replace a master cylinder. They simply don't wear out.

Do you realize how many cars and trucks from the 60's and 70's still have the original master?

If the master is bypassing, then by all means replace it. But going to a larger bore won't solve any problems that can be solved the correct way. This is what I mean by a band-aid fix.

 

The wheel cylinders are bigger because I put a dually rear end under the truck, and no, they aren't like spark plugs but they are commonly sold for a reason, because they can wear out over time, depending on many variables of course, so considering everything else is working accordingly, and the brake pedal was perfect before installing the dually rearend, this "band-aid" you speak of, seems the only likely culprit for the sinking brake pedal, considering I have no leaks in the system, the pads and shoes are more than 1/2 life, and because in the real world, things break, just because you know of some vehicles that have the original master cylinder, doesn't mean they never go bad, or they wouldn't make replacement parts, so instead of trying to reprimand me for what you think is a band-aid, how about you either: A-give insite regarding the bigger cylinder having the same stroke as the smaller ones and the pedal leverage being the same between the 92 and 93 model year hence the cylinder will fit, or B-keep quite and learn something instead of riding your high horse acting like you know all.

 

Let me put it this way, lets say for example you need to push 4cc's of brake fluid to build enough pressure in your OEM calipers and wheel cylinders to activate the brakes, then you replace the rear axle and the wheel cylinders are bigger bore so they require, lets say 1 extra cc of fluid, so now you need 5cc's of fluid to activate the brakes, but your OEM master cylinder is still only capable of pushing 4cc's per inch, so you have to push your pedal farther to get that extra 1cc to build enough pressure to activate the brakes, and a new bigger cylinder is capable of pushing, say 6cc's per inch, so then you only have to push the cylinder 5/6ths of an inch to build the required pressure, so when you hit the brake pedal is will not travel as far before you reach the proper pressure, and because of mechanical efficiency you may push your pedal 3 inches and move the cylinder an inch, so you would have to push it say 3.5 inches with the oem cylinder, versus 2.5 with a bigger cylinder, so you have a more reactive pedal, and more available pressure at the rotor and drum meaning more friction=better stopping ability, and those are just example measurements, but you get the idea of how it works

 

You think maybe you should have mentioned this in the original post? Maybe saved us both some time and a lot of back-and-forth? How is anyone supposed to know that you changed your rear axle for a dually? The vast majority of the time when a user with only a few posts poses a question like this, it's because they didn't correctly diagnose the problem in the first place and the correct approach is to start the person over with a detailed problem description so the problem can be correctly identified and the correct solution given.

You're right - you need a bigger master cylinder. Unfortunately, I don't have the answer to your question, but I can give you some advice. Do not buy master cylinders from Autozone. They sell cheap imported junk and it will not last.

I'm sorry for my tone - I did come across harsher than I intended now that I read it again.

 

the op was simply a question of if there was a difference between the 92 and 93 model year master cylinders, not asking which one i need

I apologize too for my harshness, i should not have been a d!ck

 

The most common cause of a low brake pedal is the rear brakes have not been adjusted correctly. Adjust them so that the shoes are just rubbing on the brake drum when you spin the drum. The automatic adjusters only activate when the vehicle is moving backwards and the brakes are applied.