HOW - TO SERVICING DRUM BRAKES
Contents
1. Parts 4 PLUS a HOW TO SERVICING DRUM BRAKES Tool And Material Checklist O Brake Cleaner O Vacuum Cleaner with O Clean Rags HEPA Filter Attachment O Wheel Chocks O Wheel Cylinder Clamp LJ Jack and Jack Stands O Brake Spring Tool O Wire Brush LJ Pliers O Lubricant O Brake Shoes O Brake Adjusting Tool O Assorted Screwdrivers L Asbestos proof Face O Safety Glasses or Goggles Mask or Particle Mask This How To Guide is designed as a general overview of a vehicle repair procedure You should always refer to a service manual designed for your vehicle for detailed instructions Parts Plus assumes no liability for an incorrect procedure Most backyard mechanics are leery of doing any brake system maintenance because of the importance of brakes to driving safety Such maintenance however is well within the range of the do it yourselfer If you study a service manual and work carefully you can easily and safely do a complete brake job at home using ordinary tools and equipment THE IMPORTANCE OF SERVICING BRAKES It is not a very safe or economical idea to wait until your car s brakes are making loud squealing sounds to finally think about servicing them For instance letting the linings wear too thin causes costly damage to the brake drums which could be avoided by timely replacement of the linings The only way to be sure of the condition of drum brakes is to regularly pull the drums and check the l2. e tightens up all the way Then back off the adjustment until the wheel turns freely Be sure to back off both brakes the same amount to equalize them Equalizer Adjusting Nut Front Brake Cable Rear Brake Cables Adjusting the parking brake
3. er Check for broken teeth or any other signs of damage then lubricate at both ends 5 Install the adjuster connecting spring on the primary and secondary shoes 6 Install the star wheel adjuster in its previous position Refer to the sketch if necessary 7 Expand both shoes to form a circle Position the assembly on the backing plate so that the anchor will hold the shoes in place when they are released 8 Install the hold down spring pins through the backing plate and shoes 9 Install the spring assemblies over the pins using pliers or a brake spring tool 10 Install the emergency brake lever on the larger shoe Anchor Pin Backing plate lubrication areas 11 Before reconnecting the parking brake cable make sure that it is free by applying and releasing it the cable should return to its normal position 12 If not disconnect the opposite end of the cable from the front parking brake cable Clean and lubricate the front of the rear cable then pull the lever and cable out of the braking plate and clean and lubricate the rear portion 13 Pull the cable forward and connect the front cable then attach the parking brake lever to the replacement secondary shoe 14 Reinstall the cable tension spring and self adjusting lever of the self adjusting brake mechanism if the car is so equipped 15 Use a brake hold down spring tool to reinstall the two brake shoe return springs 16 Grasping the shoe nearest the sta
4. hoe hold down springs Press against the head of the hold down pin at the rear of the backing plate with your finger then compress the hold down spring with a pliers or brake hold down spring tool Turn the cup to remove it from the pin 6 Remove the parking brake cable Slip it up and out of the lever bracket that is attached to the larger brake shoe 7 Sketch the star wheel adjusting mechanism noting the location of the star wheel in reference to the brake shoes The star will be closer to one shoe than the other 8 Remove the entire brake shoe assembly from the backing plate The primary and secondary shoes star adjuster and connecting spring should come out as a unit 9 Disconnect the spring and star wheel adjuster from the brake shoes INSTALLING BRAKE LININGS Non asbestos brake linings are available for use on most vehicles made today When replacement linings are needed it is wise to install good quality brake shoes as well While relined shoes are a little less expensive the brakes are only as good as their linings 1 Clean the backing plate with a wire brush and wipe off any grease on the backing plate bosses and surrounding areas 2 Inspect the backing plate for damage If the bosses are deeply grooved replace the backing plate Make sure that the anchor bolt 1s tight 3 Apply a light coat of brake lubricant to the bosses and all areas that will have metal to metal contact 4 Clean the star wheel adjust
5. ining thickness It should be more than 1 8 above the rivets on riveted linings and 1 8 above the metal on bonded linings If the linings are soaked with brake fluid the shoes should be replaced at the same time the leak is repaired It is usually recommended that brakes be inspected at least every 10 000 miles However rear drum brakes normally last about twice as long as front disc brakes If you know when the rear brakes were last checked you can get by with inspecting them every other time you inspect the front brakes But do not hesitate to pull the rear drums at the first sign of any brake problem NOTE Whenever the brakes are serviced be sure to make a thorough check for leaks in the system Anchor Pin Retracting Spring Helper Spring Primary Shoe Connecting Shoe Spring Adjusting Star Adjuster Lever Typical drum brake components PREPARATION Because of the work involved be prepared to do a complete brake job if necessary when you pull the rear drums l Make sure that your local shop has the necessary parts before beginning 2 Arrange some means of transportation to pick up the parts 3 Locate a machine shop that offers while you wait service in case the brake drums must be machined Many auto repair shops and parts stores have the special lathes and equipment needed for doing brake machine work 4 Gather all necessary tools as well as the following items safety glas
6. r adjuster move the shoes back and forth to make sure that they are free to assume a normal position during operation 17 Check the operation of the automatic star adjuster the shoes should expand when the adjuster cable is pulled or released Repeat on the other wheel 18 Once the brake drums have been replaced adjust the parking brake by releasing it and turning the cable adjusting nut clockwise until the rear wheels turn freely 19 Have someone operate the pedal while you spin both drums by hand to be sure the brakes work Installing hold down spring pins 20 Put the tires back on then take the vehicle for a test drive If there are no unusual noises and the braking action is good the job is finished NOTE Always take it easy on new linings for the first couple hundred miles to give them a chance to wear in Without Self Adjuster With Cable Type Self Adjuster With Lever Type Self Adjuster With Link Type Selt Adjuster Types of self adjusters ADJUSTING BRAKES New brakes need to be adjusted several times as they wear in While the self adjusters normally handle this when the car is driven in reverse and when the brakes are applied it 1s a good idea to perform the initial adjustment manually this is considered standard procedure by most professional mechanics To do this use a brake adjusting tool or screwdriver as explained earlier With the parking brake off turn the adjusting wheel until the brak
7. ses or goggles clean rags denatured alcohol a clean surface on which to lay out parts paper and pencil to make sketches of the brake assembly as a supplement to the diagrams in the service manual Polaroid camera optional to make a foolproof record of how the assembled brake should look REMOVING THE BRAKE DRUM 1 Block the front wheels and set the parking brake to keep the vehicle from rolling 2 Use a large screwdriver to remove the rear wheel covers 3 Use the wrench end of the jack handle as a socket wrench to loosen the lug nuts on both rear wheels approximately one turn 4 Carefully jack up the car s rear end just enough to get the wheels off the ground 5 Position the jack stands securely under the car s frame 6 Place a block of wood under the brake pedal to prevent accidentally depressing the pedal which could cause problems when the brakes are disassembled 7 Remove both rear wheels and release the parking brake 8 Try to pull the drum free while rotating it slightly forward NOTE Sometimes the brake adjustment must be backed off before the drums can be pulled free To do this follow steps 9 through 12 9 Remove the rubber plugs that cover the adjustment access slots which are located on the backing plate behind the brake assembly Some cars have a filled access slot that must be punched out to gain access to the adjuster 10 Insert a brake adjusting tool or scre
8. steners are securely in place and undamaged Repair or replace as needed New Retracting Spring um gt Shoe End Anchor End OC CANARIA D Stretched and Distorted Retracting Spring inspecting springs 6 Check for any signs of leakage from the wheel cylinder If any leakage is apparent have the brakes inspected by a professional 7 Clean the brake drums with a soap and water solution 8 Inspect the inside surfaces of the drums for heat discoloration cracks or scratches large enough to catch a fingernail If the drums are worn they should be taken to a machine shop and turned 9 Check the flexible brake hoses for crimping or other damage Replace as needed REMOVING BRAKE LININGS It is a good idea to work on one brake at a time This way you can use the properly assembled brake as reference 1 Use a wheel cylinder clamp to hold the wheel cylinder pistons in place while removing the brake shoe return springs 2 Make a sketch showing how the brake shoe springs are secured to aid in reassembly Note the different coil diameter of the springs Cylinder Clamp Clamping the wheel cylinder pistons 3 Remove the two brake shoe return springs using a brake spring tool 4 Use pliers to remove the cable tension spring and self adjusting lever bf the self adjusting brake mechanism if the car is so equipped f Using a brake spring tool to remove shoe re turn springs 5 Remove the brake s
9. wdriver in the slot 11 While holding the automatic adjuster lever away from the star wheel with a small screwdriver turn the adjuster up until the drum turns freely 12 Give the adjuster four or five good turns to make sure the brakes are completely backed off 13 1f the drum still will not pull free try backing off on the parking brake cable Keep in mind that the drum might be rusted to the wheel hub if this is the case seek the help of a professional mechanic A S Y Is nn y CI Move Handle Upward to Retract Brake Shoe Loosening the automatic adjuster Rubber Plug Gan Removed INSPECTION Once the drum is removed the brakes are inspected in the following manner 1 Use a vacuum cleaner with a HEPA filter attachment to remove the asbestos dust from the brake assembly and interior of the brake drum NOTE Wear a special particle mask or asbestos proof facemask to do this because asbestos is a health hazard when inhaled Never use compressed air to remove asbestos dust Lining Lining Bond Shoe Riveted vs bonded linings 2 Inspect the linings for looseness cracks or imbedded foreign matter Watch for brake fluid oil or grease on the linings 3 Measure the linings to see if they have worn thinner than 1 8 If necessary replace the linings 4 Check the brake shoes for cracks distortion or broken parts Defective shoes must be replaced 5 Make sure all springs and fa
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