Drum Brake System: Service and Repair

REMOVAL

WARNING: CLEAN BRAKES WITH A VACUUM DUST COLLECTOR TO MINIMIZE THE HAZARD OF AIRBORNE MATERIALS.

CAUTION: Make sure parking brake lever is released completely.





1. Release parking brake lever fully, then remove drum. If drum is hard to remove, the following procedures should be carried out.





a. Remove adjuster plug. Shorten adjuster as shown to make clearance between brake shoe and drum.





b. Install two bolts as shown. Tighten the two bolts gradually.
2. Push in shoe hold-down pins from behind the back plate. While pushing in the retainer, turn it and remove the shoe hold-down pins.





3. Pull out brake shoes in the direction of the arrows as illustrated.





4. Using pliers, remove the lower return spring from shoe.





5. Separate shoes, one at a time, from wheel cylinder, and remove them from back plate with the adjuster assembly still on as shown.

CAUTION: Be careful not to scratch or damage wheel cylinder boot.





6. Disconnect parking brake cable from toggle lever.

CAUTION: Be careful not to damage parking brake cable when separating it.

7. Remove adjuster return spring and shoe return spring.





8. Remove retainer ring with a suitable tool. Then separate toggle lever and brake shoe.

INSPECTION

Wheel Cylinder





- Check wheel cylinder for leakage.
- Check for wear, damage and loose conditions. Replace if any such condition exists.

Wheel Cylinder Overhaul





- Check all internal parts for wear, rust and damage. Replace if necessary.





- Pay attention so as not to scratch cylinder when installing pistons.

Drum
- Contact surface should be fine finished with No. 120 to 150 emery paper.
- Using a drum lathe, lathe brake drum if it shows score, partial wear or stepped wear.
- After brake drum has been completely reconditioned or replaced, check drum and shoes for proper contact pattern.





Maximum inner diameter: 230 mm (9.06 inch)
Maximum out-of-round: 0.03 mm (0.0012 inch)

Lining
- Check lining thickness.
Standard lining thickness: 4.1 mm (0.161 inch)

Measuring Brake Lining:

Lining wear limit (A): 1.5 mm (0.059 inch)

INSTALLATION

NOTE: Always perform shoe clearance adjustment.





1. Fit toggle lever to brake shoe with retainer ring.





2. Apply brake grease to the contact areas shown.
3. Shorten adjuster by rotating it.
- Lefthand wheel adjuster: Lefthand thread
Depression: Yes
- Righthand wheel adjuster: Righthand thread
Depression: No





NOTE: Pay attention to direction of adjuster.

4. Apply brake grease to adjuster as shown.

Adjuster And Return Spring Components:

5. Install adjuster and adjuster lever; then install upper return spring and adjuster spring.





6. Connect parking brake cable to toggle lever.

NOTE: Be careful not to damage brake cable.





7. Install shoes on wheel cylinder one at a time.

CAUTION:
^ Do not allow the piston to spring away when assembling.
^ Be careful not to damage wheel cylinder piston boots.

8. Install lower return spring.
9. Secure shoe installation with shoe hold-down pins and retainers.
10. Check all parts are installed properly.





NOTE: Pay attention to direction of adjuster assembly.

11. Install brake drum.
12. When installing new wheel cylinder or overhauling wheel cylinder, bleed air.
- Refer to Bleeding Hydraulic System procedure under Hydraulic System / Service and Repair.
13. Adjust parking brake.
- Refer to Parking Brake System / Parking Brake Lever / Adjustments.