American Motors: bad wheel cylinder? Proportioning valve?, combination meter, wheel cylinder

Question
I have a 1972 AMX and I replaced the driver's rear wheel cylinder. When bleeding the brakes fluid comes out at slightly above a trickle and stops flowing before the brake pedal hits the floor. With the brakes installed and doing "panic stops" the shoes pop out and then return to the inner position with the brakes engaged. The pedal also goes pretty much to the floor. The brake fluid was dark brown and has been changed (at all 4 wheels and master cylinder) so that its nearly clear. New front calipers and new wheel cylinders all around. Could I have a bad wheel cylinder or do I need to check the proportioning valve and how?

Answer
Remy,
Sorry for the late response, I just returned from out of town.
Let me take a quote from the AMC Repair Manual:
"Before bleeding disc brake system, the metering valve section of the combination meter must be rendered inoperative. Use Metering Valve Release Tool J-23774 which holds the valve stem out at the correct travel with 22-35 lb. pull."
What could be happening is the metering valve portion of the combination valve is restricting the fluid flow to your left rear wheel cylinder.
Use a pair of vise grips to pull out and hold the metering valve stem on the end of the Combination meter while beelding the brakes.
You could crack loose each line at the valve, one at a time, while someone depresses the brake pedal, in case you have air in the valve.
If your master cylinder is OK and you are still unable to bleed that wheel cylinder, you might end up replacing the combination valve assembly.

Kevin