Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 333 (DISC BRAKES)OVERHAULMASTER CYLINDERREASSEMBLY
1999 GMC Forward Control 5.7 R, Automatic
Master Cylinder: Reassembly
1999 GMC Forward Control 5.7 R, AutomaticSECTION Reassembly
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
- Clean the interior and exterior of the master cylinder, the secondary piston, and the return spring in denatured alcohol, or equivalent.
- Dry the master cylinder and the individual components with non-lubricated, filtered air.
- Lubricate the master cylinder bore, the secondary piston, the return spring, and all of the individual overhaul components with Delco Supreme 11, GM P/N (12377967), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
- Assemble the lubricated, NEW primary seal and retainer, and NEW secondary seal onto the secondary piston.
- Install the lubricated return spring and secondary piston assembly into the cylinder bore.
- Install the lubricated, NEW primary piston assembly into the cylinder bore.
- Using a smooth, round-ended tool, depress the primary piston and install the NEW piston retainer.
- Install the master cylinder reservoir to the master cylinder. See MASTER CYLINDER RESERVOIR under REMOVAL & INSTALLATION.
- Install the reservoir cap and diaphragm to the reservoir.
- Install the master cylinder to the vehicle. See MASTER CYLINDER under REMOVAL & INSTALLATION.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.