1993/05/24 Caterpillar


Summary Of Changes To Timing Advance Drive Groups{1272}

Usage:


3406B/C (8TC, 4MG, 3ZJ, 5KJ, 2EK, 4CK, 5YG) Truck Engines

The changes to the timing advance drive groups are divided into lists for the mechanical engines and the electronic engines. The changes are listed in chronological engine serial number order.

Mechanical

4MG3600

Released new style timing advance with a cone shaped cover. When compared with the former advance, this advance provides increased advance capacity (up to 12.5 degrees). The new drive group part numbers are 4W8334, 4W8333, 9Y1838, 7E1041, 7C0841, 9Y1545, and 7E1043.

4MG18385

The change provides a new 9Y7450 Retainer (flyweight pin) with a different material and heat treatment. The new retainer will service the previous retainer to first production of the new style timing advance (4MG3600).

4MG25122

This change provides a 8L5832 Lock Nut (full width) in place of the former half nut. The new lock nut will service the former lock nut to first production of the new style timing advance (4MG3600).

4MG57674

This change provides two new 7E2460 Bearing Races (top hat shaped) to replace the one former bearing race. This change also provides a new high strength 093101 Ring. These changes significantly improve flyweight and race life. These new components will service the former bearing race and ring to first production of the new style timing advance (4MG3600).

4MG97295

This change provides a new 7E8097 Carrier Assembly that eliminates body-carrier slip. The preferred service method is to replace the former 7W5242 Carrier, 7C5902 Body Assembly, 8F1145 Ring, and 4W2754 Seal with the new 7E8097 Carrier Assembly back to first production of the new style timing advance (4MG3600).

5KJ465

This change provides eight mounting bolts instead of the former four for increased clamping and reduced slippage. The carrier assembly is changed to accommodate a larger 52 tooth spline. Both of these changes are needed for the 1991 emissions fuel system configuration. These changes are not adaptable to earlier engines. The components involved with change include the 4P2921 Ring, 4P2644 Carrier Assembly, 9X7715 Seal, 4P2920 Retainer, 4P2922 Plate, 4P2924 Ring, and 0T0065 Bolt.

5KJ2681

This change provides a new wider flyweight toe and race for improved resistance to wear and increased overall durability. The components involved in this change include the 4P7693 Carrier, four 4P1634 Weights, 4P1638 Screw, two 4P1635 Races, 4P1637 Spool, and 4P3337 Race. Those component are required to service back to first production of the new style timing advance (4MG3600). This change was actually released with the 4P1636 Carrier which was canceled and replaced by the 4P7693 Carrier.

3ZJ1

This change provides a new 4P7693 Carrier to replace the former 4P1636 Carrier to solve a manufacturing problem. This change will service back to first production of the new style timing advance (4MG3600). The part number of the new drive groups released are the 4P1923, 9Y5395, 4P1925, 4P1401, 4P1403, 4P1408, 4P1409, and 4P1922.

3ZJ911

This change provides a new thicker leg flyweight, race, carrier assembly, and spool. This change will help reduce the chance of fly weights binding or breaking. The carrier no longer has the acceleration noise control orifice. The components involved with this change are the 4P7693 Carrier, 4P7692 Weight, 4P7690 Race, 4P7691 Spool, and 4P2641 Carrier Assembly. Those components are required to service back to first production of 3ZJ1.

3ZJ-(See Chart)

This change provides new "heat set" springs that do not change load characteristics over time when exposed to engine heat. These new springs will help better maintain factory timing advance settings. A list of Drive Groups and their corresponding new springs follow:

Electronic

8TC1

This change provides the 2W4544 Drive Group for the 8TC engine introduction.

8TC----(Unknown)

This change provides the new 7W0993 Drive Gear with improved material quality. This change will service the former drive gear back to 8TC1.

8TC----(Unknown)

This change provides the new 7W3218 Ring (Quadseal) with improved material quality. This change will service the former ring back to 8TC1.

8TC----(Unknown)

This change provides the new 3P3547 Clip (used to retain the brushless torque motor sleeve assembly on the spool). This change will service the former clip back to 8TC1. (Also the see 4CK15345 improvement.)

8TC8730

This change provides the new stronger 7E5564 Spool. This change will service the former spool back to 8TC1. (Also see the 8TC13234 and 5YG1 improvements.)

8TC12973

This change provides a the new 7E9060 Carrier Assembly which eliminates body-carrier slip. The preferred service method is to service the 2W7986 Body Assembly, 8F1145 Ring, 1W4329 Carrier, and 4W2754 Seal with the new 7E9060 Carrier Assembly.

8TC13234 And 5YG1

This change provides the new 4P2648 Drive Group for use on the 5YG engine. This release also provides the new 4P3500 Sleeve Assembly and 4P3384 Spool with improved material properties for the 2W4544 (8TC1) and 4P2648 (5YG1) Drive Groups. The new sleeve assembly and spool will service back to 8TC1. The 4P2648 Drive Group is like the previously built 2W4544 Drive Group except for the new 4P3500 Sleeve Assembly and 4P3384 Spool.

8TC13823

This change to the 2W4544 Drive Group provides eight mounting bolts instead of the former four for increased clamping and reduced slippage. The carrier assembly is changed to accommodate a larger 52 tooth spline. These changes are not adaptable to earlier 8TC engines or any 5YG engines. This change occurred at the end of the 5YG serial number prefix. The components involved with change include the 4P2921 Ring, 4P2642 Carrier Assembly, 9X7715 Seal, 4P2922 Plate, 4P2923 Ring, and eight 0T0065 Bolts.

2EK1823 And 4CK993

This change provides the new longer 6J2819 Bolt for improved torque retention. The new bolt will service back to 8TC1.

4CK4699

This change provides the new 1011944 Carrier Assembly. This new carrier assembly has a threaded plug to reduce the chance of the plug coming out. The new carrier assembly will service back to 8TC13823.

4CK15345

This change provides the new split clamp design to replace the previous 3P3547 Clip. These parts are used to retain the brushless torque motor sleeve assembly on the spool. The new 1084511 Split Clamp Assembly will service back to 8TC1. Also included in these change are two 1072961 Washers for better wear and durability with the sleeve assembly. These washers also service back to 8TC1.

Caterpillar Information System:

1993/05/17 New Fuel Injection Lines, Clamps, And Brackets Used In Fuel Injection Lines Groups {1252}
1993/05/17 Baffles Available To Help Reduce Turbocharger Noise {1052,1058}
1993/05/10 New Low Crevice Volume (LCV) Piston Body Assembly Used{1214}
1993/05/10 0R3735 Remanufactured Camshaft Available{1210}
1993/05/10 Service Tips For Effective Repair Of Failed Turbochargers{1052,1063,1059}
1993/05/03 Governor Control Adjustment {1264}
1993/04/12 New Bearing Assemblies Used On Main Shaft{3322}
1993/04/12 New Damper Guard Group Used{7150}
1993/04/12 New Expansion Tank Assembly Used In Expansion Tank Groups{1354}
1993/04/12 Adjustment Of 60670 Idle Air Lines Group (Idle Bleed Circuit){1266}
1993/04/12 New Seal Group Used In Water Pump Groups{1361}
1993/04/12 Fan Drive Pulley Group Components{1359}
1993/05/31 New Fuel Injector Group Help Reduce Plunger And Barrel Seizures{1290}
1993/06/07 New Jacket Water Heater Mounting Groups Include Improved Hoses{1383}
1993/06/07 New Electronic Speed Switch Assembly Used In Junction Box Groups Increases Service Life{1900}
1993/06/14 Low Idle Adjustment, Additional "Buffer" Adjustment Screw Used On Marine Governors {1264}
1993/06/14 Lock Removed From Front Timing Gear Group To Help Prevent Loss Of Tightening Torque {1206}
1993/06/14 New Fuel Pump Drive Idler Gear Assembly And Shaft Used In Front Timing Gear Groups {1206}
1993/06/14 New Bonnet Used In Fuel Injection Pump Group {1251}
1993/06/14 3E3761 Coolant Level Sensor Assembly {7422}
1993/06/21 Windshield Washer Jet Nozzle Assembly Available For Parts Service{7306}
1993/06/21 Measuring "Dynamic Rack" Of Unit Injectors{0780}
1993/06/21 New G3500 Gas Engine Performance Manual Available{0376}
1993/06/21 New Cylinder Head Assembly Provides Improved Valve Seat Retention{1100,1103}
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