Disc & Drum: Diagnosis Eagle Vision I

MASTER CYLINDER & POWER BRAKE UNIT ASSEMBLY TEST

1. Start engine. Ensure there are no power brake unit vacuum hose leaks. Stop engine. Shift transmission to Neutral. Pump brake pedal until all vacuum reserve in power brake unit is depleted. Lightly press and hold brake pedal.
2. If pedal does not hold firm (falls away), replace master cylinder. If pedal holds firm, start engine. If pedal falls away slightly under light foot pressure, then holds firm, go to next step. If no change in pedal occurs, replace check valve, and retest. If no change in pedal occurs, replace power brake unit.
3. Release brake pedal. Start engine and operate at 1500 RPM. Release accelerator, and immediately turn off engine. This rebuilds power brake unit vacuum reserve.
4. Wait at least 90 seconds. Press brake pedal. If power brake unit does not assist pedal application at least twice, test power brake unit and check valve. Refer to the «POWER BRAKE UNIT TEST»(ref-27173-S34853215082001011500000) and the «CHECK VALVE TEST»(ref-27173-S04088979162001011500000) .

POWER BRAKE UNIT TEST

1. Connect vacuum "T" fitting in vacuum hose between power brake unit and intake manifold vacuum supply. Connect vacuum gauge to "T" fitting. Operate engine at idle for one minute.
2. Clamp hose between power brake unit and intake manifold vacuum supply. Stop engine and observe vacuum gauge. If vacuum drops more than one in. Hg within one minute, test check valve. See CHECK VALVE TEST. If check valve is okay, replace power brake unit.

CHECK VALVE TEST

Disconnect vacuum hose from check valve. Remove check valve and seal from power brake unit. Apply 15-20 In. Hg to large end of check valve. If vacuum does not hold, replace check valve.

PROPORTIONING VALVE TEST

1. Remove bleed screws from right front caliper and left rear caliper (or wheel cylinder). Install 2 Pressure Gauges (7212), one in each bleeder screw hole. Bleed air through gauge bleed valves. Start engine.
2. Press brake pedal and observe gauge pressure readings. If gauge pressure readings do not match pressures specified in appropriate PROPORTIONING VALVE PRESSURE TEST table, replace proportioning valve.
3. Remove pressure gauges, and install bleed screws. Bleed right front caliper and then left rear caliper (or wheel cylinder). This completes right front/left rear portion of test.
4. Repeat procedure for left front/right rear caliper (or wheel cylinder). (Scheme 2)

PROPORTIONING VALVE PRESSURE TEST (REAR DISC)

PROPORTIONING VALVE PRESSURE TEST (REAR DRUM)

Scheme 2

Inspection

If pad thickness is worn down to wear indicator, replace pads.

If pad thickness is worn down to wear indicator, replace pads.

1. Measure disc parallelism (thickness variation) at 8 equally spaced locations, 2" (51 mm) inward of outer circumference of disc. If parallelism exceeds .0005" (.013 mm), machine disc. DO NOT machine disc beyond minimum thickness marked on disc.
2. Install disc with wheel lug nuts and washers. Measure disc lateral runout approximately 1" (25.4 mm) inward of outer edge of disc. If disc lateral runout exceeds .002" (.05 mm), chalk a line across disc and hub stud (in line with highest point of lateral runout).
3. Remove disc. Clean outer edge of hub at hub-to-disc surface, outside diameter of hub studs. Measure hub lateral runout at cleaned surface. If hub lateral runout exceeds .002" (.05 mm), replace hub. If hub runout is within specifications, perform steps 4) and 5) to reduce combined runout of disc and hub.
4. Remove disc. Rotate disc by one stud in relation to hub, and install disc with 2 wheel lug nuts ( DO NOT install lug nuts next to each other). Measure and record disc lateral runout for each position of disc in relation to hub.
5. If lateral runout is within specifications, install disc on hub at point least runout was recorded. If lateral runout is not within specifications after installing disc at point of least lateral runout, machine or replace disc. DO NOT machine disc beyond minimum thickness marked on disc.

Replace brake shoes if lining thickness is less than .13" (3.3 mm). DO NOT machine brake drum beyond maximum diameter listed on drum.