2005 Pontiac Sunfire Brake Service (ONLINE REPAIR MANUALS)

Two basic types of power assist mechanisms are used: vacuum assist diaphragm assemblies, which use engine vacuum or, in some cases vacuum pressure developed by an external vacuum pump. The second type is a hydraulic pressure assist mechanism, which use pressure developed by an external pump (usually the power steering pump). Both systems act to increase the force exerted on the master cylinder piston by the operator. This in turn increases the hydraulic pressure delivered to the wheel cylinders while decreasing driver effort required to obtain acceptable stopping performance.

Vac...

If brake fluid is old, rusty or contaminated or whenever new components are installed in hydraulic system, the system must be flushed. Bleed brakes...

When working on or around brake assemblies, care must be taken to prevent breathing asbestos dust, as many manufacturers incorporate asbestos fibers in the production of brake linings. During routine service operations the amount of asbestos dust from brake lining wear is at a low level because of a chemical breakdown during use and a few precautions will minimize exposure.

• Do not sand or grind brake linings unless suitable local exhaust ventilation equipment is used to prevent excessive asbestos exposure.
• Wear suitable respirator approved for asbestos dust use during repair procedure...

These brakes have self-adjusting shoe mechanisms that ensure proper lining-to-drum clearances at all times. The automatic adjusters operate only when the brakes are applied as the vehicle is moving rearward.

An initial adjustment is required after the brake shoes have been relined or replaced, or when the length of the adjusting screw has been changed during service operations.

Frequent usage of an automatic transmission forward range to halt reverse vehicle motion may prevent the automatic adjusters from functioning, thereby inducing low pedal heights. Should low pedal heights be enc...

Removal

• Raise and support rear of vehicle, then remove tire and wheel assembly.
• Mark drum and axle hub, then remove brake drum. If brake lining is dragging on brake drum, back off brake adjustment by rotating adjustment screw. If brake drum is rusted or corroded to axle flange and cannot be removed, lightly tap axle flange to drum mounting surface with suitable hammer.
• Unhook primary and secondary return springs using brake spring removal and installation tool Nos. J-8049 or J-29840, or equivalents, Fig. . Observe location of brake components being removed to aid during installation.
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