When I replaced the original master cylinder many years ago, I ended up with one from a 1-1/2 ton truck.
Fits on the same mount, but uses a larger diameter reservoir and piston and has a bit more pressure than the stock 1/2 ton.
I disagree with this logic.
A 1.5 ton truck master cylinder is larger than a 1/2 ton. this is so the larger truck can move lots of fluid to the larger wheel cylinders.
All you gained was less pedal travel and less mechanical advantage for your 1/2 ton. You move more fluid with the same stroke, but have less line pressure for the same amount of foot effort.
To get more advantage you would use a smaller cylinder, say for the 1.5 ton truck you put the 1/2 ton master on, if you keep the brakes adjusted tight and the fluid in the reservoir you would get really strong brakes with a long pedal travel, and hopefully you will not run out of travel before they lock up. You move less fluid but with higher pressure.
What you did didn't hurt anything, just takes more pedal effort.
The other way around would be unsafe, as you may not be able to move enough fluid for the brakes to function fully, and if out of adjustment you have less room for error (lower factor of safety).
Grigg
