NOTE: The burr on the slave piston bore will not affect the performance of the brake. It only affects the ability to reset the lash.

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1 SERIES 60 SERVICE MANUAL 12. Inspect slave piston bore for burrs at the depth where the slave piston contacts the adjusting screw. [a] If no burrs are found, proceed with inspection. [b] If burrs are found, repair as follows: The burr on the slave piston bore will not affect the performance of the brake. It only affects the ability to reset the lash. [c] Use a triangle-shaped machinist s scraper, coating the tool with a generous amount of grease. See Figure 1-458a. Gently remove the raised burr until the surface is flush with the remainder of the bore. Figure 1-458a Removal of Slave Piston Bore Burr [d] Remove any remaining grease and debris using a soft cloth or paper towel. Most of the debris will be picked up by the grease. 6SE Copyright 2001 DETROIT DIESEL CORPORATION From Bulletin a

2 1.29 JAKE BRAKE Assembly of Model 790/795 Jake Brake Assemble Model 790/795 Jake Brake as follows: 1. Insert slave piston into bore. See Figure Solenoid Valve 13. Control Valve Cover 2. Solenoid Upper Seal Ring 14. Retaining Ring 3. Solenoid Center Seal Ring 15. Adjusting Screw* 4. Solenoid Lower Seal Ring 16. Locknut 5. Master Piston 17. Slave Piston 6. Master Piston Pushrod 18. Slave Piston Bridge 7. Master Piston Spring 19. Outer Slave Piston Spring 8. Master Piston Retainer 20. Inner Slave Piston Spring 9. Master Piston Retaining Ring 21. Spacer Tube 10. Control Valve 22. Shoulder Bolt 11. Outer Control Valve Spring 23. Drive Screw 12. Inner Control Valve Spring 24. Wire Harness Clip *Note that Model 790 Jake Brake uses a J-Lash assembly. Model 795 Jake Brake uses a solid screw. Figure Typical Model 790/795 Jake Brake Assembly 1-582b From Bulletin SE Copyright 2001 DETROIT DIESEL CORPORATION

3 SERIES 60 SERVICE MANUAL 2. Install slave piston bridge. See Figure To avoid injury from flying parts when working with components under spring tension, wear adequate eye protection (face shield or safety goggles). 3. Install new springs and shoulder bolt. Torque bolts to 23 N m (16 lb ft). See Figure Repeat step 1 through step 3 for installing the remaining slave pistons. 4a. To ensure proper installation of the slave piston, use the following procedure as a check. [a] [b] [c] [d] [e] [f] Loosen the adjusting screws nuts and back off the adjusting screws sufficiently to allow the slave pistons to retract fully into the bores. Verify that all slave pistons have fully retracted to where the slave piston bridge, meets the housing. If any remain in the initially set position, identify the slave piston or pistons affected. Disassemble the shoulder bolt, bridge, and springs; remove the affected slave piston or pistons, and clean the slave piston bore of any remaining oil. Replace the pistons with the new slave piston replacement group. If only one piston of the same cylinder is affected, replace both pistons within that cylinder. After coating the new slave pistons with clean engine oil, inspect and verify that the new slave pistons drops to the bottom of the bore under its own weight or light pressure. In most cases, simply installing the new pistons will allow this to happen. If it does, proceed to step 5. If it does not, proceed to step 4[f]. Remove the piston and look for a burr on the slave piston bore at the depth where the slave piston contacts the adjusting screw. 6SE Copyright 2001 DETROIT DIESEL CORPORATION From Bulletin b1

4 1.29 JAKE BRAKE [g] Use a triangle-shaped machinist s scraper, coating the tool with a generous amount of grease. See Figure 1-459a. Gently remove the raised burr until the surface is flush with the remainder of the bore. Figure 1-459a Removal of Slave Piston Bore Burr [h] [i] Remove any remaining grease and debris using a soft cloth or paper towel. Most of the debris will be picked up by the grease. Verify that slave piston now drops to the bottom of the bore under its own weight or light pressure. If not, repeat step 4[a] through step 4[h]. [j] Reassemble the slave piston of the brake with step 1 through step 3. [k] Adjust slave piston lash, refer to section b2 From Bulletin SE Copyright 2001 DETROIT DIESEL CORPORATION

5 SERIES 60 SERVICE MANUAL 5. Install the master piston and pushrod into the bore. See Figure Install new spring. See Figure Install new master piston retainer over spring. See Figure While depressing master piston retainer, insert the new master piston retaining ring with snap ring pliers. See Figure Rotate the retaining rings 90 degrees to ensure that the ring is seated in the groove. 9. Repeat step 5 through step 8 for installing the remaining master pistons. 10. Flip housing over. 11. Install the adjusting screw and locknut. See Figure For Model 790 Jake Brakes install the J-Lash assembly screw. For Model 795 Jake Brakes install the solid screw. Do not tighten the locknut at this time. 12. Repeat step 11 for installing the remaining adjusting screws and locknuts. 13. Slip the new control valve into the bore. See Figure Install new control valve springs. See Figure Place new control valve cover over springs followed by the retaining ring. See Figure Press down on the valve control cover with an appropriate diameter rod and set the retaining ring into the groove with snap ring pliers. See Figure Rotate the retaining ring 90 degrees to ensure that the retaining ring is seated in the groove. 6SE Copyright 2001 DETROIT DIESEL CORPORATION From Bulletin b3

Model 797/797A/797B Tune-Up Kit

Model 797/797A/797B Tune-Up Kit Jacobs P/N 032146 This Tune-Up Kit requires Master Piston Assembly Tool, P/N J-45976. The tool is available through Kent-Moore. Information in this manual was current at