Bone stock 96 civic non ABS drum brakes - right rear locks up under light braking, both rears lock up under moderate braking, fronts lock up last. Something seems wrong that the rears would lock up before the fronts in the first place. Perhaps the friction coefficient of the front pads are less than the rear?

I've bleed the whole system, replaced the rear cylinders, and swapped rear drums from left to right - no change at all.

The right rear drum has previously been replaced which indicated to me that this problem has lasted a while.


Proportioning valves don't control left to right bias or even go bad do they?

 

Hmm this is weird.
Since you swapped the cylinders already I would think the last thing is the prop valve. Swap it give it a shot or remove yours and clean it/inspect it.

 

First things first. Are the shoes and pads new on everything? Emergency stop cable adjusted? It could just be that you also have bad tires. start small. ALways start small. Tires, shoes, drums, rotors, and rear cylinders. then work you way up the list.

 

It is my understanding that the proportioning valve is setup with two channels. One for the front left and back right and the other vice versa.

 

Someone has replaced the right brake drum, but not the left, that makes me think this has been a problem for a while. I did swap sides with the drums and no change. The pads appear fairly new and identical from side to side.

Start small huh? I suppose the next logical thing to do would be to rotate the tires, then news pads, then rotors, ugh... One step at a time

 

 

Tonight I went deeper in this. I was going to rotate tires but realized since the car squats in that corner while braking it wasn't a traction issue. The next thing was to replace the rear shoes, but the ones on it appeared to have just been changed so I aborted.

After removing the shoes and inspecting everything and reinstalling I found nothing unusual, the car behaved the same.

Finally I said screw it - I was pissed and tired anyway - and yanked the hand brake up for a couple of miles until they faded away. After this the car would actually stop since the fronts were doing most of the work. Hope the rears don't start working again...

 

Time for a rear disk brake conversion...