I'm in the process of overhauling my rear axle. I'm putting in new wheel cylinders and am considering going to '79 F-350 wheel cylinders in the rear drums. They have a 1" bore instead of the 15/16ths of the stock one. I want to shift my brake balance forward (so the front brakes are activated more powerfully than they are now) to avoid having to install a proportioning valve. I'm thinking that going with the larger cylinder will cause the rear brakes to activate more gradually than they are now, causing more braking in the front. Does this make sense, or will the larger bore increase the power of the rear brakes compared to the fronts, causing them to lock up sooner?

Well I'm not sure you're going to get the result you're after, I can't believe a 1/16th of an inch will make that much of a difference. A simple or in my case poor man's way to have the rears engage with less power is to just back them off a bit on their adjustment. I think the only way you'll acheive what you are after is the correct proportioning valve or an adjustable one.

The larger bore will transfer more force into the rear shoes.

Sorry, I could have been way more clear about the goal of doing this. My rear brakes lock up before the fronts and I'd like to make them either neutral or have the fronts lock first. I know the larger bore will make the rears more powerful, but wasn't sure if they would delay lockup by having a shorter stroke for the same amount of pedal travel. My guess is that the larger bore will make them more likely to lock due to the increased power.

I don't know what the larger wheel cylinders will do to the rears.

T-bird front calipers pulled my brake bias forward. When I was having troubles, I called & talked to someone from BC Broncos (he obviously worked on the trucks, not just a salesman), he said they do the T-bird caliper swap specifically to pull the bias forward, with lots of success. Or install a proportioning valve.

Chad

If memory serves me I think they are almost a drop in replacement for the originals.

I know what your thinking: you have a bigger bore that requires more volume to get the same amount of movement effectively slowing the movement of the rear shoes in relation to the front pads. I think you would get the desired results but the more pressure applied on the pedal the more force will be applied to the rears. The difference in movement between the two is the larger bore would be about 6.6% slower but has 6.25% more force. I think it would be easier to just add an adjustable proportioning valve.

Well now ya have to go and post up a physics question. I just finished that section in class and think its funny that I learned to calculate the power that piston (cylinder) would apply when activated. Force = Power X Volume.

you can always loosen up your rear shoes just a tad and see how it responds. Usually you end upp with a bit of a delay in rear brake response when you do this. Your ration front/rear should be 60/40.

snowball justin snowball , replace wheel cylinders then prop. valve and new lines then disc brakes , then hydroboost then 4 wheel discs then new master cylinder welcome to my world.