To remove and install the wheel cylinder on 1990 vehicles with anti-lock brakes, first depressurize the hydraulic accumulator, then raise and safely support the vehicle. Remove the wheel and tire assembly along with the brake drum, and clean the area around the wheel cylinder inlet, pilot, and bleeder valve. Next, remove the brake shoes and the bleeder valve, disconnect the brake line from the wheel cylinder while plugging the opening to prevent fluid loss, and take out the wheel cylinder mounting bolts and the wheel cylinder itself. Clean the old sealant from the backing plate and the wheel cylinder if it is to be reinstalled. For installation, apply Loctite Master Gasket or an equivalent to the wheel cylinder shoulder face that contacts the backing plate, position the wheel cylinder, and install the mounting bolts, tightening them to 106 inch lbs. (12 Nm). Connect the brake line to the wheel cylinder and tighten the fitting to 11 ft. lbs. (15 Nm), then install the bleeder valve and tighten it to 88 inch lbs. (10 Nm). Install the brake shoes, adjust them, and put the brake drum back on. Bleed the brake system, install the wheel and tire assembly, lower the vehicle, and check the parking brake adjustment. For overhaul, while wheel cylinder overhaul kits may be available, it is often more sensible to substitute a new or reconditioned part. If opting for an overhaul, ensure no contaminants enter the system by using clean, new, high-quality brake fluid. If dirty fluid has been used, drain and flush the system, replace all rubber components, refill, and bleed the system. Remove the wheel cylinder from the vehicle and place it on a clean workbench, then discard the old rubber boots and withdraw the pistons, which are equipped with seals and a spring assembly. Remove the remaining inner components, seals, and spring assembly, using compressed air if available, and discard all components for which replacements are supplied in the rebuild kit. Wash the cylinder and metal parts in denatured alcohol or clean brake fluid, allow them to air dry or use compressed air, and avoid using rags. Inspect the piston and replace it if scratched, lubricate the cylinder bore and seals with clean brake fluid, position the spring assembly, install the inner seals and pistons, insert the new boots into the counter bores by hand without lubrication, and finally install the wheel cylinder.
Posted by GMPartsGiant Specialist