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Hmmm...

Drum brakes shouldn't work like that.

What a lot of people miss is the ratio of the brake lever.

Almost all jap rear drum brakes need a pedal ratio of 7:1. that's to say the bit you stomp with your foot need to be 7 times longer than the bit that pulls on the brake rod.

This isn't very practical with forwards, so a lot of those have ratios in the 2:1 - 4:1 range.

This gives you a brake with very little "feel" and a tendency to just grab all of a sudden, if it locks the wheel at all.

What we do is build controls with something like a 3.5:1 ratio in the pedal, and have that operate an idler arm with a 2:1 ratio, giving 7:1 over all. That's not written in stone, you could have 2.333:1 on the pedal and 3:1 on the idler, whatever suits as long as the all th numbers on the left mulitplied together give you 7, and all the numbers on the right, give you 1.

For instance, 2.333:1 is 7:3, the idler is 3:1 multiply the numbers on the left and the numbers on the right together and you get 21:3. Divide both sides by 3, you get 7:1. If you were odd you could use a 14:1 pedal and a 1:2 idler and get the same result.

Two things to watch though, be wary of very short levers (under around 1" say) and you want the rod a 90 degrees to the lever it's attached to when its doing the most work. Short levers go over center, and are generally a pain in the ass in use, having less than 90 degrees between the rod and the lever costs you effort (worse with short levers) some sort of adjustment helps.

This helps with getting a straight shot for the brake rod too. We also use a cable from the pedal to the idler, as it's under half the load it would be if you just ran it straight to the brake, and being shorter also means it's going to stretch less.

You'll get exactly the same problem with a disc too. Most modern jap disc rear stuff uses a 4:1 pedal ratio. Older stuff may use a weird ratio as it often shares a brake pedal with an earlier drum brake version.

So, bottom line is that if your pedal ratio is wrong, your brakes are going to be crap no matter who made them.

Same deal applies to master cylinders too. A hydraulic system is a kind of lever, get the ratio between the master cylinder bore and the caliper pistons wrong, you're screwed. That's way more complicated though....