ALTRACO ELECTRONIC DISC BRAKE CALIPER Manual de Serviço descarregar pdf (Página 4)

Compare the new pads with the old ones to ensure

they are correct. Be sure to note whether the mounting

surfaces (metal shoe) portion is correct, and the linings are

not too thick to prevent the caliper from fitting over the

rotor. After ensuring the pads are correct, install any clips

and anti-squeal insulators on the new pads. If the vehicle

has a separate pad wear sensor, install it in the proper

position, Figure 13-13. If desired, place anti-squeal

compound on the pad shoes where they contact the

caliper. See Figure 13-14.

Place high temperature lubricant on the parts of the

caliper that move in relation to the spindle assembly.

Typical lubrication points would be the sliding surfaces of

the caliper and spindle, guide pins, sleeves and bushings,

and any related moving parts. Do not use motor oil, wheel

bearing grease, or chassis lubricant. The high temperatures

of the brake system will cause it to burn off almost imme-

diately, leaving a sticky residue which will interfere with

brake operation.

Caliper Reinstallation

Caliper reinstallation is relatively simple, but must be

done correctly if the brakes are to operate properly. Install

the rotor if it was removed. Before reinstalling the caliper,

check the spindle assembly, splash shield, and other

related parts for damage. Place high temperature lube on

any sliding surfaces of the spindle or adapter bracket.

Place the caliper over the rotor, Figure 13-15. If the

caliper does not slide easily over the rotor, do not force it

into place. Remove it and check to see if the piston is fully

retracted and the pads are correct. Some vehicles require

that one end of the caliper be installed first. On other vehi-

cles, the caliper must enter straight into the mounting

bracket. After the caliper is in position, install the attaching

hardware and the brake hose if necessary.

After the fasteners are tight, ensure the rotor can turn

freely with the caliper installed. While turning the rotor, lis-

ten for scraping noises that indicate the caliper or another

stationary part is contacting the rotor. Bleed the brakes if

necessary, then reinstall the tire and rim.

Staking the Brake Pads

Some brake caliper designs require the technician to

pinch a portion of the outer pad shoe against the caliper.

This is referred to as clinching or staking the brake pads.

Staking must be performed to prevent the outer pad from

moving. This procedure is done using a large pair of

adjustable pliers (channel lock) or a hammer. Have an

assistant pump the brake pedal to bring the pads against

the rotor. Then, while the assistant presses the brake pedal,

stake the outer pads to the caliper, Figure 13-16.

Chapter 13 Disc Brake Service 215

Figure 13-13.

Installing one type of outboard brake shoe and

lining. Note the retaining clip and audible wear sensor position.

(DaimlerChrysler)

Audible wear sensor Outboard

brake pad

assembly

Retaining

clip

Brake

caliper

Figure 13-14.

Two different styles of brake pad shoes showing

the correct placement of anti-squeal compound. Do not allow

this compound to touch the friction material. (Bendix)

Pads

Anti-squeal

compound

Note: Some technicians prefer to slightly

bevel (grind) the edges of the pads to

reduce the likelihood of brake squealing.

Some newer pads come with beveled edges from the

manufacturer.

Caution: Do not allow non-graphite anti-

squeal compounds or lubricants to touch

the pad friction surfaces or rotor.

Note: If the calipers were removed from the

vehicle, be careful not to switch calipers

between the left and right sides of the

vehicle. On many vehicles, reversing the calipers will

place the bleeder screws in a position that makes it

impossible to completely remove all air from the

caliper.

Caution: Start all fasteners by hand before

using a hand or air tool to tighten.

Rear Caliper and Pad Removal

Rear disc brakes with the parking brake assembly

built in require slightly different procedures, Figure 13-17.

In some cases, special tools are needed to retract the

piston into the bore. When servicing pads and rotors on

a rear disc brake assembly, the first step is to disconnect

the parking brake cable from the caliper. Once the park-

ing brake cable is disconnected, loosen the caliper bolts

and carefully remove the caliper. You may need to

remove other components before caliper removal can be

performed.

Three common parking brakes are used with rear

wheel disc brakes. They are the screw, ball and ramp, and

cam. Special procedures for each type is discussed in the

following paragraphs. See Chapter 6 for additional infor-

mation on caliper service.

Screw-Type Caliper Service

On disc brake calipers with screw type parking brake

mechanisms, the cable actuating lever is connected to an

actuating or high lead screw. The screw passes through a

splined nut cast in the piston. When the cable moves the

lever, the screw rotates and moves the piston outward,

tightening the pads against the disc.

When servicing this type of caliper, there are two

ways to compress the piston in the caliper. The first is to

turn the piston back into the caliper using a spanner

wrench or special tool once the caliper is removed,

Figure 13-18. The second method allows you to push the

piston back in, similar to front calipers. The first step is to

remove the parking brake actuator lever from the caliper

after the cable has been removed. Do not turn the caliper

high lead screw. Once this lever has been removed, com-

pressing the piston in is much easier, Figure 13-19. Once

the pads are removed, carefully push the piston back into

the caliper. The piston can usually be pushed into the

caliper without damage.

When installing the pads, make sure the “D” shaped

locator lines up with the “D” shaped projection on the

back of the inner brake pad, Figure 13-20. The two-way

check valve should also be replaced whenever the caliper

is serviced. If the actuating lever was removed, replace the

lever seal and make sure the high lead screw is all the way

out after caliper installation.

216 Auto Brakes

Figure 13-15.

A—Placing the caliper over the rotor. B—Caliper

is being installed over pads and rotor after one side (end) has

been attached to the caliper support. (Chevrolet, Honda)

Caliper

bolt

Caliper

support

New pads

Piston

Rotor

Caliper

Rotor

New

pads

Figure 13-16.

Some brake pads require that metal tabs on the

pad shoe be staked to the caliper. Use a pair of adjustable

pliers to stake the pads. (Chevrolet)

Caliper

Adjustable

pliers

Note: Some technicians stake pads by

wedging a small chisel between the bottom

edge of the outer pad and the hub, then

staking the pad using a second chisel and hammer.

This practice is not recommended.

Note: Always service one rear caliper at a

time.

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