this may help..these anti-lock systems can be hatefull sometimes...also make sure you have the rear shoes ajusted all the way out against the hubs
Bench bleed the master cylinder before installation on the vehicle. Bench bleeding removes air from the master cylinder. Bench bleeding reduces the time required in order to bleed the brake hydraulic system after installation.
TWO PERSON PROCEDURE
If a pipe is disconnected at one wheel, then only bleed that wheel.If the master cylinder has been removed, bleed the master cylinder before installing it on the vehicle. This will reduce the time required to bleed the system.NOTICE: Brake fluid will damage electrical connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always re-seal and wipe off brake fluid containers to prevent spills.MANUAL BLEEDING
NOTICE: Refer to Fastener Notice in Service Precautions.
Use a diaphragm-type pressure bleeder. The pressure bleeder must have a rubber diaphragm between the air supply and the brake fluid. This prevents air, moisture, oil and other contaminants from entering the brake hydraulic system.
NOTICE: Refer to Fastener Notice in Service Precautions. Check the brake pedal for sponginess. Repeat the bleeding procedure if the brake pedal is spongy.
A manual adjustment of the rear drum brakes is required after replacing the rear linings.
REMOVAL PROCEDURE GM replacement brake lining material is recommended for all vehicles to maintain the balance between front and rear brake performance. GM replacement brake parts have been carefully selected to provide the proper brake balance for the purposes of stopping distance and control over the full range of operating conditions. Installation of front or rear lining material with performance different from that of recommended GM replacement parts can change the intended brake balance of this vehicle.
NOTICE: Do not over-stretch the upper return spring. Damage can occur if it is stretched to more than 204.2 mm (8.04 inches) .
NOTICE: Do not over-stretch the lower return spring. Damage can occur if it is stretched to more than 107.3 mm (4.22 inches) .
anything is posable...will the brakes get tight if you pump tit 3 or 4 times and hold them?
if it will pump up and hold,,you still have air in the system..if not,,the master cylinder may be bad
the fluid will bleed through the modulator when you bleed the calipers/cylinders