1998 Chevrolet Astro Brake Service (ONLINE REPAIR MANUALS)

General System

• Inspect components for damage or unusual wear. Replace as required.
• Inspect backing plate mounting bolts and ensure they are tight.
• Inspect wheel cylinders. Excessive fluid indicates cup leakage and need for wheel cylinder replacement. Slight amount of fluid is always present and is considered normal, acting as lubricant for cylinder pistons.
• Check adjuster screw operation. If satisfactory, lightly lubricate adjusting screw and washer with suitable brake lube. If operation is unsatisfactory, replace.
• C clean rust and dirt from shoe contact surfaces on backing plate using fi...

Brake Lines & Linings

Remove one of the front wheels and inspect the brake disc, caliper and linings.

Do not allow any oil or grease on the linings. It is recommended that linings be replaced in sets when worn or damaged.

If the caliper is cracked or fluid leakage through the casting is evident, it must be replaced as a unit.

Brake Roughness

The most common cause of brake chatter on disc brakes is a variation in thickness of the disc. If roughness or vibration is encountered during highway operation or if pedal pumping is experienced at low speeds, the disc may have excessive thickness v...

Battery Ground Cable

Prior to service disconnect battery ground cable and isolate as required.

Radio Security System

Theftlock

If the Theftlock system is active when battery power is interrupted, the customers security code must be entered to restore proper function of the radio. To unlock a secured radio after power loss, proceed as follows:

• "LOC" appears with ignition in On position.
• Press "NM" and "000" will appear on display.
• Press "NM" again to make last two digits agree with security code.
• Press "HR" to make first 1 or 2 digits agree with security code.
• Press "AM-FM" to select code entered. "SEC" wi...

Removal

Front

• Siphon brake fluid out of master cylinder until fluid level is approximately ^1/3 full, this will prevent fluid overflow when caliper piston is pushed back into its bore.
• Raise and support vehicle, then remove wheels.
• Push piston back into its bore using suitable C-clamp, Fig. .
• Remove two caliper mounting bolts and lift caliper off of rotor.

Rear

Blazer, Bravada & Jimmy

• Raise and support vehicle.
• Mark position of wheel to hub for installation reference.
• Remove wheel assembly.
• Remove mounting bolt and disconnect brake hose fitting from caliper. Discard gaskets and plug brake h...

Refer to "Hydraulic Brake... "

This system is used on all models except Montana, Silhouette, Tracker, Trans Sport and Venture. On 2000 S & T Series , four door utility vehicles can be equipped with either a 310 or 325 ABS system. Pickups and two-door utility vehicles are equipped with 310 ABS systems. While both systems are functionally the same, the 310 differs in size and appearance from the 325. It is designed to reduce the occurrence of wheel lock-up during severe braking conditions. To accomplish this function, the system regulates hydraulic brake line pressure by using an Electro-Hydraulic Control Unit (EHC...