Technical Correct brake master pistons

i have a dual brake master on my 40 Ford pu. Running juice brakes all around. Anyway I developed a leak in the clutch side of the master and at the piston. I'm going to replace rather than rebuild but someone was asking me if the pistons were correct for the brakes? I have no idea how to verify this or even able to figure out what should be on the master. Anyone have any suggestions?

 

yes, post a picture of the master cylinder

 

Post a picture? Why?, it just sounds like the old International pickup/Travelall and Chevy/GMC master. Single fluid chamber, one cylinder for the clutch and another cylinder for the brakes.
The GM version oddly had the brake side on what would normally seem to be the clutch side, for hot rod use the RPV needs to be switched to the correct side.
If it is just worn cups and not corroded bores I would lightly hone and rebuild.

 

You say, Quote "Anyway I developed a leak in the clutch side" end of quote. I ***ume you have been driving said vehicle. My question is, are you unhappy with the brakes? If it stop's just fine who cares what Master bore size it is. Just replace it with same parts and move on. Don't create a problem that isn't there.
The Wizzard

 

Pretty strange question... Especially since you are working on the clutch..!
As was said by another...as long as the car stops properly, the brake master cylinder piston size is fine. Normally, a coupla different diameter pistons WILL work. One will work better than others, but the diameter is not limited to "one" single size.
It all depends on the brakes at the four corners (disc or drum), the pedal length, and the pedal lever length...that's how the master cyl. piston size is chosen.

Mike

 

because i thought that was what it was , but by his description and his apparent lack of familiarity with it i wanted to be certain before opening my mouth...

 

Thanks for the input guys. As mentioned, the clutch side was the bore leaking. I ***ume this would also allow air into the system right? I think I'm gonna just replace master with another one and redo my lines coming into the master as I noticed some fluid on them as well. Definitely getting air in there and know the brakes will be better by doing that.