REMOVAL & INSTALLATION
See Figures 1 through 6
Fig. Fig. 1: The front disc brake assemblies are the same for all 1986-96 models of Aerostar
Fig. Fig. 2: Exploded view of the front rotor, hub and disc brake assembly-rear wheel drive models
Fig. Fig. 3: Use an eight inch (20cm) C-clamp (positioned as shown) to depress the caliper piston until the torque buttons are clear of the caliper body
Fig. Fig. 4: Initially set the guide pin removal tool at a 45° angle to gently tap the caliper pin out of the front disc brake caliper ...
Fig. Fig. 5: ... but as the retention tabs are compressed, move the tool to gain a straight approach to the pin
Fig. Fig. 6: For correct installation, the guide pins should be positioned as shown
Always replace all disc pad assemblies on an axle. Never service one wheel only.
- To avoid fluid overflow when the caliper piston is pressured into the caliper cylinder bores, siphon or remove part of the brake fluid out of the larger master cylinder reservoir (connected to the front disc brakes). Discard the removed fluid.
- Raise and safely support the front end on jackstands.
- Remove the front wheel(s).
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Use an 8 in. (20cm) C-clamp to move the wheel cylinder piston back into its bore as follows:
- Place the head of the C-clamp against the front disc brake caliper, and the screw end of the clamp against the outer shoe below the spring clip.
- Tighten the clamp until the torque buttons just clear the caliper (about 1 / 8 in. or 3mm).
- Remove the C-clamp from the caliper.
Do not use a screwdriver or similar tool to pry the piston away from the rotor.
- Clean excess dirt from the area around the pin tabs.
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Using the Caliper Pin Remover D89T-2196-A or equivalent and a light hammer, drive the caliper pin from the front disc brake caliper as follows:
- Position the notched end of the tool against the caliper pin (retention tab half), at a 45° angle from the pin retention tabs.
- Tap the tool with the hammer to compress the retention tabs.
- As the retention tabs are compressed, move the tool to gain a straight approach to the pin. Continue tapping to drive the pin through the caliper/spindle groove.
Never reuse caliper pins. Always install new pins whenever a caliper is removed.
- Repeat the same caliper pin removal procedure for the lower pin.
- Remove the caliper from the rotor. If the caliper is to be completely removed for service, remove the brake hose from the caliper, otherwise wire the caliper so that it hangs from the vehicle body. Make sure that there is no stress placed on the brake fluid line while it is hanging.
Do not let the caliper hang from the brake hose.
- At this point the brake pads may be removed from the caliper.
- The brake caliper piston must be "bottomed out" when installing new pads. Be sure that enough fluid has been removed from the brake master cylinder to prevent fluid overflow. Bottom out the wheel cylinder piston with an 8 in. (20cm) C-clamp using a worn-out inner shoe or a block of wood to push against the brake caliper piston.
- Install new brake pads, if necessary.
- Install the caliper on the rotor, making sure the mounting surfaces are free of dirt. Lubricate the caliper sliding grooves with disc brake caliper grease, or the equivalent.
- From the caliper outboard side, position the pin between the caliper and spindle grooves. The pin must be positioned so the tabs will be installed against the spindle outer face (inward).
Never reuse caliper pins. Always install new pins whenever a caliper is removed.
- Tap the pin on the outboard end with a hammer. Continue tapping the pin inward until the retention tabs on the sides of the pin contact the spindle face. Repeat this procedure for the lower pin.
During the installation procedure do not allow the tabs of the caliper pin to be tapped too far into the spindle groove. If this happens it will be necessary to tap the other end of the caliper pin until the tabs snap into place. The tabs on each end of the caliper pin must be free to catch on the spindle face.
- If removed, install the brake hose to the caliper.
- Bleed the brakes as described earlier in this section.
- Install the wheel and tire assemblies. Tighten the lug nuts to 85-115 ft. lbs. (116-156 Nm).
- Remove the jackstands and lower the vehicle. Check the brake fluid level and fill as necessary. Check the brakes for proper operation.
CALIPER OVERHAUL
See Figures 7 through 11
Fig. Fig. 7: Use air pressure to push the piston from the caliper-use a piece of wood to prevent damage
Fig. Fig. 8: Remove the brake caliper piston from the piston, then ...
Fig. Fig. 9: ... remove the piston boot and ...
Fig. Fig. 10: ... inner seal from the caliper-make sure not to scratch the caliper piston bore
Fig. Fig. 11: Exploded view of the front disc brake caliper assembly
- Remove the front disc brake caliper as described earlier in this section.
- Disconnect the brake hose.
- Clean the exterior of the caliper with denatured alcohol.
- Remove the plug from the caliper inlet port and drain the fluid.
- Air pressure is necessary to remove the piston. Apply air to the inlet port slowly and carefully until the piston pops out of its bore.
- If the piston jams, release the air pressure and tap sharply on the piston end with a soft hammer. Reapply air pressure.
- When the piston is out, Remove the boot from the piston and the seal from the bore.
- Clean the housing and piston with denatured alcohol. Dry with compressed air.
- Lubricate the new piston seal, boot and piston with clean brake fluid, and assemble them in the caliper.
- The dust boot can be worked in with the fingers and the piston should be pressed straight in until it bottoms. Be careful to avoid cocking the piston in the bore.
- A C-clamp may be necessary to bottom the piston.
- Install the caliper as described above.
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