DEFINITION: This diagnostic table is designed to diagnose ONLY the components of the DRUM brake system in order to determine if the DRUM brake system is operating properly. You will be directed by the appropriate Symptom table to go to other brake system diagnostic tables as appropriate.

Were you sent here from a Brake Symptom table?

Go to Step 2

Go to Diagnostic Starting Point - Hydraulic Brakes

1. Remove the brake drums. Refer to Brake Drum Replacement in Drum Brakes.
2. Inspect the drum brake shoes for the following conditions:

•	Lining thickness below specifications

•	Uneven and/or abnormal wear - edge-to-edge and/or side-to-side

•	Contamination from an external substance

•	Looseness, damage, glazing, or incorrect lining material

Did you find any conditions to indicate a concern with any of the drum brake shoes?

Go to Step 3

Go to Step 7

Are any of the brake shoes contaminated?

Go to Step 4

Go to Step 5

1. Inspect the wheel cylinders for evidence of an external brake fluid leak.
2. Replace any wheel cylinder that is found to be leaking brake fluid. Refer to Wheel Cylinder Replacement in Drum Brakes.

Did you complete the inspection and replacement?

Go to Step 6

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1. Inspect the drum brake hardware for any components which are worn, damaged, discolored due to stress, broken or missing. Refer to Drum Brake Hardware Inspection in Drum Brakes.
2. Replace components as required. Refer to Drum Brake Hardware Replacement in Drum Brakes.
3. Replace the drum brake shoes. Refer to Brake Shoe Replacement in Drum Brakes.

Did you complete the inspection and replacement?

Go to Step 8

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1. Clean the remaining drum brake system components to remove any traces of the contaminant.
2. Inspect the drum brake hardware for any components which are worn, damaged, discolored due to stress, broken or missing. Refer to Drum Brake Hardware Inspection in Drum Brakes.
3. Replace the drum brake hardware components as required. Refer to Drum Brake Hardware Replacement in Drum Brakes.
4. Replace the contaminated brake shoes. Refer to Brake Shoe Replacement in Drum Brakes.

Did you complete the cleaning, inspection and replacement?

Go to Step 8

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1. Inspect the drum brake hardware for any components which are worn, damaged, discolored due to stress, broken or missing. Refer to Drum Brake Hardware Inspection in Drum Brakes.
2. Replace components as required. Refer to Drum Brake Hardware Replacement in Drum Brakes.

Did you complete the inspection and, if necessary, the replacement?

Go to Step 8

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1. Check the diameter of each of the brake drums.

Important: Make the following determination AND ANSWER the question INDIVIDUALLY for EACH drum.

2. Make a determination for each brake drum if the drum can be REFINISHED and REMAIN ABOVE the minimum requirements.

Refer to Brake Drum Diameter Measurement in Drum Brakes.

Does the brake drum meet the minimum requirements for REFINISHING?

Go to Step 9

Go to Step 11

1. Inspect each of the brake drums for the following surface and wear conditions:

Refer to Brake Drum Surface and Wear Inspection in Drum Brakes.

•	Braking Surface Conditions

-	Heavy rust and/or pitting

-	Cracks and/or heat spots

-	Excessive blueing discoloration

-	Missing balance weights

•	Braking Surface Wear Conditions

-	Deep or excessive scoring beyond maximum acceptable level

-	Radial runout beyond maximum acceptable level

Important: Make the following determination AND ANSWER the question INDIVIDUALLY for EACH drum.

2. Make a determination for each brake drum if the drum requires refinishing based upon the results of the inspection.

If the brake drum exhibits any of the following conditions, it requires refinishing.

•	Drum exhibits one or more of the Braking Surface Conditions listed previously

•	Drum is beyond the acceptable level in one or more of the Braking Surface Wear Conditions listed previously

Does the brake drum require REFINISHING?

Go to Step 10

Go to Step 14

1. Refinish the brake drum. Refer to Brake Drum Refinishing in Drum Brakes.
2. Inspect the brake drum diameter. Refer to Brake Drum Diameter Measurement in Drum Brakes.

Were you able to REFINISH the brake drum within the minimum requirements?

Go to Step 14

Go to Step 13

Is the brake drum at or below the DISCARD requirements?

Go to Step 13

Go to Step 12

1. Inspect each of the brake drums for the following surface and wear conditions:

Refer to Brake Drum Surface and Wear Inspection in Drum Brakes.

•	Braking Surface Conditions

-	Heavy rust and/or pitting

-	Cracks and/or heat spots

-	Excessive blueing discoloration

-	Missing balance weights

•	Braking Surface Wear Conditions

-	Deep or excessive scoring beyond maximum acceptable level

-	Radial runout beyond maximum acceptable level

Important: Make the following determination AND ANSWER the question INDIVIDUALLY for EACH drum.

2. Make a determination for each brake drum if the drum requires replacement based upon the results of the inspection.

If a brake drum exhibits any of the following conditions, it requires replacement.

•	Drum exhibits one or more of the Braking Surface Conditions listed previously

•	Drum is beyond the acceptable level in one or more of the Braking Surface Wear Conditions listed previously

Does the brake drum require REPLACEMENT?

Go to Step 13

Go to Step 14

Replace the brake drum. Refer to Brake Drum Replacement in Drum Brakes.

Did you complete the replacement?

Go to Step 14

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Inspect the brake shoes for proper adjustment. Refer to Drum Brake Adjustment in Drum Brakes.

Are the brake shoes adjusted properly?

Go to Step 18

Go to Step 15

Inspect the components of the brake drum adjustment hardware system for free movement and correct operation. Refer to Drum Brake Adjusting Hardware Inspection in Drum Brakes.

Do the drum brake adjusting hardware components operate freely and correctly?

Go to Step 17

Go to Step 16

Replace the drum brake adjusting hardware components as necessary. Refer to Drum Brake Adjusting Hardware Replacement in Drum Brakes.

Is the replacement complete?

Go to Step 17

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Adjust the drum brake shoes. Refer to Drum Brake Adjustment in Drum Brakes.

Were you able to complete the adjustment?

Go to Step 20

Return to Symptom Table

18

Inspect the drum brake backing plate for the following:

Does the drum brake backing plate exhibit any of these conditions?

Go to Step 19

Go to Step 20

Repair or replace the drum brake backing plate as necessary. Refer to Rear Brake Backing Plate Replacement in Drum Brakes.

Did you complete the repair or replacement?

Go to Step 20

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Install or connect components that were removed or disconnected during diagnosis.

Did you complete the operation?

Drum Brake System OK

Return to Symptom Table

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