Great Wall Florid. Manual — part 24

GWFLORID Maintenance Manual

94

Brake System

Brake System Components Arrangement Schematics. ...95
Brake System Maintenance. . . . . . . . . . . . 96
Brake Pedal . . . . . . . . . . . . . . . . . . 98
Parking Brake Control Mechanism Assembly. . . . ...102
Vacuum Booster with Brake Cylinder Assembly . . . ...103
Anti-lock Brake System . . . . . . . . . . . . . 107
ABS General Problem Maintenance and
Areas of Importance . . . . . . . . . . . . . . .109
Steering Knuckle and Hub Brake Assembly . . . . . . 112
Front Brake Caliper . . . . . . . . . . . . . . .. 118
Rear Brake . . . . . . . . . . . . . . . . . ...124
Rear Support Axle . . . . . . . . . . . . . . . 131

95

Brake System

Brake System Components Arrangement Schematics

Brake pedal assembly

Vacuum booster with brake

cylinder assembly

Left steering knuckle and hub brake assembly

Left parking brake cable assembly

Rear brake

assembly RH

Rear brake

drum

Rear wheel speed

sensor assembly RH

Right parking brake

cable assembly

ABS controller assembly

Right steering knuckle and hub brake assembly

Brake line assembly

Rear wheel speed

sensor assembly LH

Front wheel speed sensor assembly RH

Front wheel speed

sensor assembly LH

Rear brake assembly LH

Parking brake control mechanism assembly

GWFLORID Maintenance Manual

96

Brake System Maintenance

Brake fluid inspection and replacement

Brake fluid directly influences the brake performance and the operating conditions and use life of the brake

system components. Brake fluid has very strong hygroscopic properties, and thus absorbs water easily,

which will then deteriorate the metal and rubber pieces. Polluted and deteriorated brake fluid or its mixture

would cause the brake fluid to boil and gasify, hence reduces braking efficiency. Therefore, pay attention to

the items below when filling or changing the brake fluid:

1. Containers used to hold brake fluid must be tightly closed and sealed

2. Brake fluid is poisonous and damaging to the paint. Hence if it gets on the vehicle surface, rub it

off at once

3. If water or other contaminates found in the brake fluid, and the brake master cylinder's piston seal

has been broken, then the brake fluid and all the rubber pieces inside the brake system including

the brake hose must be replaced

4. The correct brake fluid level in the reservoir must be between MAX and MIN. After the vehicle has

been driven for over 1000 km, check the brake fluid level in the reservoir. If the brake fluid level is

not up to regulation, more brake fluid should be added to the reservoir until it reaches MAX.

Hydraulic component inspection and system flushing

1. If the oil-based solvent gets into the hydraulic system, flush the whole system and change all of

the rubber pieces

2. Clean your hands before installing new rubber pieces or other components

3. Do not use regular solvents (kerosene, gas, etc.) when inspecting or cleaning hydraulic

components, instead use absorbing alcohol or brake fluid

4. After inspecting the components, drain the brake fluid from the system. Use new brake fluid to

flush the system. Afterwards, add new brake fluid to perform hydraulic system exhaust

5. Flushing completion sign: When the brake fluid flowing out of the dump valve is clear from any

contaminate.

Hydraulic pressure system drainage

If the brake fluid inside the whole hydraulic pressure system needs to be emptied, open all the bleed screws

with each connected to a hose, as to allow the brake fluid to flow into a container. Step on the pedal slowly

until only air flows out. During the whole procedure, make sure all the valves are open.

Hydraulic pressure system air bleeding

The hydraulic brake system must work under a vacuum environment. The air will cause spongy brake or

overall brake failure when it flows into the hydraulic system. It is extremely necessary to bleed system air

when performing any operation on the brake system or if any air inside the brake system is suspected.

1. Air bleeding sequence

If air inside the brake master cylinder is suspected, first perform air bleeding.

(a) If numerous valves are equipped, air bleed each valve

(b) Another sequence principle is: Air bleed from the wheel brake furthest away from the master cylinder.

The air bleeding sequence for the LHD modules is: rear right wheel - left rear wheel - front right wheel

- front left wheel, Right rudder vehicles: rear right wheel - left rear wheel - front left wheel - front right

wheel.

2. Air bleeding method

(1) Manual air bleeding

Use the brake pedal or pump as the air bleeding power source. When the air bleed screws are open, vent the

brake fluid containing the bubbles from the system. Usually this is simultaneously done by two people. One

steps on the brake pedal and the other operates the air bleed screws. Important points to take note of when

performing the operation:

(a) Place the ignition switch to the off position and step on the pedal repeatedly to remove the

vacuum pressure or hydraulic pressure.

(b) Before and after air bleeding, add clean brake fluid into the master cylinder until it reaches

the correct (stated) level.

(c) Check the fluid level frequently to make sure that more than half of the reservoir's capacity is

available.

(d) Bleed screws should only be opened when the pedal is pressed down, and closed before the

pedal is loosened. Meanwhile, check if the vented brake fluid has bubbles inside.

97

Brake System

(e) Make sure not to let the system valves block the air bleeding.

(f) When the brake fluid that flows out of the hose or connector has no bubbles, it means that the air

in the system has been exhausted. There is still air inside the system if the hose inserted into the

brake fluid is still bubbling when pressing down the pedal.

(g) Keep the free end of the hose immerged in the brake fluid to avoid air from flowing into the

system while opening the screw.

(h) While air bleeding, hammer the casting part of the vibrating brake device with a rubber hammer.

This is helpful for removing bubbles deep in the brake fluid.

(i) If air in the master cylinder is suspected, then perform air bleeding on the master cylinder first,

then the wheel cylinder or brake caliper.

(j) When releasing air from the tires, generally make sure to release air out of all the tires.

(k) To avoid the possibility of air reversely entering into the system, a bleeder hose that has a check

valve could be used.

(2) Pressure blow-off

Under the proper conditions, a pressure blow-off device can be used to release the air inside the brake system.

3. Air releasing sequence

(1) Master cylinder air bleeding

If the master cylinder does not have air bleed screws, perform the following steps:

(a) Check the brake fluid level inside the master cylinder’s reservoir and add to it if necessary.

(b) Slowly take off the front brake pipe connector until the brake fluid flows out from the end.

(c) Reconnect the brake pipe, but do not tighten it.

(d) Slowly step down and press on the brake pedal, check if the brake fluid flowing out of the connector

contains bubbles.

(e) Tighten the pipe fitting.

(f) Have the assistant loosen the pedal, wait for 15 s.

(g) Repeat the above steps until all the air is released.

(h) Take off the rear brake pipe connector, repeat the above steps.

(2) Wheel brake air releasing

(a) Check the brake fluid level inside the master cylinder’s reservoir and add to it if necessary. During the

entire air releasing period, check repeatedly and add promptly.

(b) Connect one end of the bleeder hose with the bleed screw and the other end immerged in the brake fluid.

(c) Have the assistant step on the pedal several times, raise the pedal gradually until it cannot be stepped on

any more, then forcibly press on the pedal once more.

(d) Loosen the bleed screw, check if there are any bubbles in the brake fluid flowing out. Meanwhile, slowly

lower the pedal.

(e) When the brake pedal is close to the stroke end or the out flowing brake fluid does not have any bubbles,

tighten the bleed screw.

(f) Have the assistant release the pedal and wait for 15 s.

(g) Repeat the above steps until there are no bubbles in the flowing brake fluid when the screw is loosened.

(h) Release the air for all the wheels in turn using the same method.

(i) After releasing the air from the entire system, switch the ignition to the on position.

(j) Inspect the stroke of the brake pedal and its reaction.

(k) Inspect the lighting condition of the brake warning lamp, and repeatedly perform maintenance or air

bleeding if necessary.

(l) Add brake fluid to the reservoir until the specified fluid level, air bleeding is complete.