swapping my 10" rear brakes on my satellite to 11X2.5. Are the wheel cylinders the same for 10 & 11 inch rear brakes? Everyone shows only 1 part # for everything and I nolonger have the old ones to compare.....

Yes the same and since you are drastically increasing your rear bias w more swept area a different bore size wheel cyl MIGHT be appropriate. Are you running an adjustable rear prop valve. If you were just looking for a yes or no ans disregard the rest of my post

If the wheel cylinders are the same why would anything change? I just was asking if the same part # is used for 10 & 11 inch rear brakes. I've done this before in the past w/o changing prop valve and they worked fine.

I would think that withOUT a wheel cylinder increase, you're wasting all that increased shoe area.

all you'll be doing is spreading the current braking force out over a larger area, which COULD benefit you with cooler temps, less heating during hard braking, etc.

but to utilize the larger surface area of the bigger shoes, I would want to get a larger bore wheel cylinder.

I was not offrended at all, I'm sorry if I came across that way....What I was trying to figure out is if the factory used the same wheel cylinder for both 10 & 11 inch rear brakes because all the parts places say they are the same..I was curious if they did come with different ones and now the aftermarket is only making one because it will kinda work with the 11 too, just to save money instead of making two different ones...

unless drum brakes are different because of how the shoes grab the drum and possibly 'self energize" meaning they naturally increase braking pressures by the way the shoes rock back and forth on the backing plate...you won't get more braking force, but your shoes will last much longer because they'll wear much less.

Like I say though, this may be wrong since I know the shoes will rock back and forth on the backing plate and possibly have a natural tendancy to be pulled outwards increasing brake "pressures"

but on disc brakes, if you keep the master cylinder the same, and you increase the pad size, you don't get any harder braking efforts, all that happens is the pad wear goes way down, and heat is spread out over a larger area which will help keep them cooler, longer during hard braking...and in order to increase brake effort, you need to increase brake pressures...thus a larger bore caliper or smaller bore master. when you increase the caliper size, you COULD keep the pad the same size as well, you'll just have much higher pad wear rates.

now, another possibility as to why the rear cylinders are the same, is because of the "torque multiplication" you press on the brake pedal, you make a pressure--psi, that pushes out on the wheel cylinder, pushing out on the shoe...that translates into a certain amount of pounds of pressure. for simplification reasons, let's say you're making 100 lbs of pressure against the drum. at a 10" drum, that's a 5" radius from the pivot point, or, 500 inch pounds of torque acting to slow you down. move that out to 11" and now you have a 5.5" radius, increasing your torque to 550 inch pounds. because again, with disc brakes, the further out your braking force is (larger diameter rotors) the more effective your braking pressures will be.

now, with real numbers...most drum brakes need (I THINK!!!) around 900 psi for maximum stopping power, so that's 900 psi, multiplied by the combined surface area of the wheel cylinders--since they push out in 2 directions, a 1" bore manual has the surface area of (pi x R^squared) x 2. I have no idea what the wheel cylinder bores are...I'm assuming they're around 1" -- 3.14159 x .5^2 or, 1.57 square inches total, times the 900psi, 1413 pounds of force.

1413 lbs x 5" (radius of 10" drums) is 7068 inch pounds...or 589 ft lbs of torque stopping the car...at one wheel.

move that force out by 1/2" by switching to 11" drums, and your 1413 lbs becomes 7771 inch pounds, or 647 ft lbs of torque...without changing anything else.