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TSB 05-04-97

Accelerated brake lining wear, front versus rear.

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Date: Nov 15, 1996

This supersedes TSB 05-02-96A which superseded 05-02-96

Models: 1994-1997 BR 2500HD and 3500 series Ram Trucks

Symptoms: Front brake pads wear prematurely compared to the wear experienced on the  rear shoes Normally, it is expected that the front brake linings will require replacement approximately twice before the rear lining assemblies need replacement.  The accelerated wear condition can be identified by requiring the front brakes to be replaced 4 to 6 times before the rear lining assemblies are replaced.

Diagnosis:

  1. Review service history to determine if front brake wear appears to be accelerated.
  2. If a 2500 series, 8800 GVW is operated continuously near the GVWR, have the vehicle weighed to determine if the loaded condition is at 75% or more of GVWR.
  3. Visually inspect the front and rear brake assemblies for any signs of abnormal wear. Refer to the appropriate service manual for abnormal conditions.
  4. If the front brake pads are evenly worn, and the rear brake linings indicate light wear, perform the repair procedure.

Parts:

    1      05003163AA      80 mm Front  brake lining set
                                        2500 series 7500 GVW (all) and 8800 GVW 4X2
    1      04886279AA      86 mm Front brake lining set - 2500HD, 4X4, and all 3500
    1      04886328AA      Rear brake lining set - all 3500
    1      04761560            Hold down spring package - all 3500
    1      04761603            Wheel cylinder (27mm) - 2500HD (sales code Z2B and Z7B)

Repair:

Replace front brake linings on 2500 and 3500 series vehicles, the rear linings on 3500 series vehicles.

For 2500HD 8800 GVW (sales code Z2B and Z7B only) that are operated near 75% GVWR, replace the rear brake cylinders with 27mm 1 ton cylinders.

Also, because rear brake adjustment is critical to the total operation of the braking system, it is recommended that the customer be made aware of the proper procedures to operate the rear automatic self adjusting brake system. The procedures are outlined in the Owners Manual. The procedure states "To maintain correct adjustment, you need only drive your vehicle in reverse and apply the brakes until the vehicle comes to a complete stop. NOTE: sometimes it takes several FIRM stops to get the adjusters to tighten. - Dave

2500HD rear wheel cylinder replacement  THIS PORTION SHOULD ONLY BE USED FOR 2500 SERIES, 8800 GVW (SALES CODE Z2B OR Z7B) WHICH IS CONTINUOUSLY OPERATED AT 75% GVWR OR GREATER.

  1. Be sure parking brake is released
  2. Raise the vehicle on a lift.
  3. Remove rear wheel and tire assemblies.
  4. Remove the brake drum. - this step is not listed in the TSB, but it is necessary!
  5. Using tube nut wrenches, disconnect brake line from wheel cylinder.
  6. Lift adjusting lever away from adjuster screw then, turn adjuster screw star wheel until screw is fully retracted.
  7. Remove Brake shoe return springs, adjuster spring, and adjuster screw. Move upper ends of shoes apart to provide removal clearance for wheel cylinder links.
  8. Remove wheel cylinder attaching screws and remove wheel cylinder from support plate. Discard the cylinder.
  9. Apply thin coat of Mopar Silicone Sealer (P/N 4318025) to wheel cylinder mounting surface of support plate. Sealer prevents road splash from entering drum past cylinder.
  10. Start brake line in cylinder by hand.  Do not tighten fitting at this time.
  11. Mount wheel cylinder on support plate and install cylinder attaching screws. Tighten screws to 15 ft-lbs (20 Nm).
  12. Tighten Brake line fitting to 15 in lbs (13 Nm).
  13. Install brake shoe components.
  14. Adjust brake shoe to drum clearance. Refer to 1997 Service Manual pages 5-40 and 5-41 for adjustment procedure.
  15. Install  brake drum.
  16. Repeat for opposite side of vehicle.
  17. Fill and pressure bleed brake system with Mopar DOT 3 Brake fluid.
  18. Install wheel and tire assemblies. Refer to 1997 Service Manual pages 22-8 through 22-10 for proper lug nut torque sequence.
  19. Lower the vehicle if it is a 2500 8800GVW 4X2.  For a 2500HD 4X4, or 3500 proceed to the next repair.
Front brake lining replacement
  1. With raise  the vehicle on a lift
  2. Remove the front wheel assemblies.
  3. Press caliper piston back into the bore.
  4. Remove caliper mounting bolts with 3/8 hex wrench or socket
  5. Rotate the caliper rearward off rotor and out of steering knuckle support ledges.
  6. Remove and discard inboard brake lining by tilting the shoe at the top to unseat the retaining spring clip (fig 1).
  7. Remove and discard outboard brake lining by unseating the retaining spring on one end and rotating the lining out of the caliper (fig 2).
  8. Secure caliper to chassis or suspension component with wire.
  9. Clean caliper and steering knuckle slide surfaces with a wire brush.
  10. Lubricate the caliper mounting pin and interior of the bushing with silicone grease (fig 3).
  11. Install new inboard brake lining in caliper. Be sure the end of the retaining spring clip does not get jammed between the piston and the edge of the shoe plate (fig 4).
  12. Install new outboard brake lining in caliper. Be sure retaining spring ends are seated in dimples in caliper (fig 5).
  13. Install caliper over rotor and into steering knuckle mounting arms (fig 6). Be sure caliper is seated flush on mounting arm surfaces as shown.
  14. Start caliper bolts by hand to avoid cross threading then, tighten the mounting bolts to 38 ft lbs (51 Nm).
  15. Install wheel and tire assemblies.
  16. Pump brake pedal to reset caliper pistons and brake linings.
  17. Check brake fluid level and add DOT 3 fluid if necessary.
  18. If the vehicle is a 2500 and the rear brakes were not adjusted, do so now.
3500 Series Vehicles Only - Rear Brake shoe replacement
  1. Release parking brake.
  2. Raise the vehicle on a lift.
  3. Remove rear wheel and tire assemblies.
  4. Remove the brake drum.
  5. Remove primary (front) brake shoe return spring from anchor pin with brake pliers (fig 7).
  6. Remove primary brake shoe hold-down spring, pin, and retainers using a hold down spring tool.
  7. Disconnect shoe spring and remove primary brake shoe and parking brake lever strut.
  8. Remove adjuster screw assembly.
  9. Remove secondary brake shoe hold down spring, pin, and retainer assembly then, remove adjuster lever, spring, and spring retainer assembly.  It is not necessary to disassemble the adjuster lever components unless they are worn or damaged.
  10. Disconnect parking brake cable from lever attached to secondary brake shoe, then remove brake shoe.
  11. Remove and discard E-clip attaching parking brake lever to secondary brake shoe and remove lever.
  12. Clean support plate with Mopar Brake Parts Cleaner. Then smooth brake shoe contact pads with a wire brush or emery cloth.
  13. Lubricate adjuster lever, anchor pins, and brake shoe contact pads with Mopar Brake Lubricant (p/n 04796269).
  14. Clean and check operation of adjuster screw assembly. Replace assembly if threads are heavily rusted, corroded, or damaged. Make sure each screw assembly rotates freely then, lubricate the adjuster screw threads with Mopar Spray White Lube (p/n 04318066)
  15. Attach parking brake lever to new secondary brake shoe. Use new E-clip to secure lever to shoe. If lever is secured with a U-clip, pinch new clip together with channel lock pliers to secure it.
  16. Attach parking brake cable to parking brake lever.
  17. Install secondary brake shoe and adjuster lever as follows:
    1. Insert secondary brake shoe hold down pin through support plate.
    2. Position secondary brake shoe on support plate and insert new pin through shoe.
    3. Position adjuster lever on brake shoe and insert new hold-down spring inner retainer into lever and shoe. Inner retainer has a shoulder which seats in in lever and shoe.
    4. Install new hold down spring over pin and seat it in retainer. Then install and seat hold-down spring outer retainer on pin with hold-down spring tool.
  18. Install adjuster lever spring between brake shoe and lever. Be sure spring is seated on lever tang.
  19. Attach shoe spring to secondary brake shoe. Long end of spring goes into secondary shoe.
  20. Install oval shaped spring onto parking brake strut and engage end of strut into secondary brake shoe.
  21. Install primary brake shoe onto support plate. Use new hold-down spring, pin, and retainers to secure shoe. Be sure parking brake strut is seated in both brake shoes.
  22. Install adjuster screw assembly.  Be sure star wheel is positioned adjacent to adjuster lever and that notches in adjuster screw are properly seated on brake shoes.
  23. Attach shoe spring to primary brake shoe. Use brake spring pliers and long screwdriver to seat spring in shoe.
  24. Install shoe guide plate onto anchor pin.
  25. Attach adjuster spring to spring retainer at the top of the adjuster lever, then seat spring on anchor pin with brake spring pliers.
  26. Install secondary brake shoe return spring. Attach short end of spring to brake shoe, then hook opposite end on adjuster spring. Use brake spring pliers or long shank screwdriver to engage return spring in adjuster spring.
  27. Install primary brake shoe return spring.
  28. Check component installation. Be sure adjuster screw, wheel cylinder links, and park brake struts are all seated in brake shoes.
  29. Adjust brake shoe to drum clearance. Refer to 1997 Service Manual pages 5-40 and 5-41 for adjustment procedure.
  30. Install brake drums.
  31. Install wheel and tire assemblies. Refer to 1997 Service Manual pages 22-8 through 22-10 for proper lug nut torque sequence.
  32. Repeat for opposite side.
  33. Lower vehicle and install wheel covers.

note:

It is quite normal to use two sets of front pads to the one set of shoes in the rear. If you have this same problem in a 1500, then review your braking/driving habits and investigate the lack of automatic adjustment in the rear brakes.  You must back up and come to a complete stop to cause the automatic adjustment to work.


Thanks to Bob Bergevin and Barry Drodge for supplying this TSB information

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This page was edited on: May 3, 2004