Flywheel

This procedure covers removal and replacement of the flywheel on manual transmission or flexplate on automatic transmission 5.9L Cummins diesel engines, requiring transmission removal.

Warnings

Tools required

Parts

• Flywheel (manual) or Flexplate (automatic) × 1 — Use OEM specification
• Flywheel bolts or Flexplate bolts × 1 — Often TTY (torque-to-yield), use new bolts
• Clutch disc and pressure plate (manual, recommended) × 1 — Use OEM specification
• Pilot bearing (manual) × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Transmission pan gasket or RTV sealant × 1 — Use OEM specification
• Transmission drain plug washer × 1 — Use new crush washer
• Transfer case gasket or RTV sealant × 1 — Use OEM specification

Fluids

• Mopar ATF+4 — 14 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Raise vehicle and support securely on jack stands at frame rails
4. Remove skid plates if equipped
5. Place drain pan under transmission and drain transmission fluid via drain plug
6. Mark driveshaft orientation to pinion flange with paint pen for proper alignment on reassembly
7. Support engine from above using engine support bar or hoist to prevent movement when transmission is removed

Procedure

1. 1

   Remove transfer case from transmission
   Remove transfer case shift linkage and electrical connections. Remove transfer case mounting bolts (typically 6-8 bolts around perimeter). Carefully slide transfer case rearward off transmission output shaft. May require gentle prying. Support transfer case weight during removal.
2. 2

   Disconnect driveshafts
   Remove rear driveshaft by removing four bolts at rear differential flange and four bolts at transfer case flange. Remove front driveshaft by removing bolts at front differential and transfer case. Support driveshafts and remove from vehicle. Plug transfer case outputs with rags to prevent fluid loss.
3. 3

   Disconnect shift linkage and electrical connections
   For manual transmission: Disconnect hydraulic clutch line at transmission or slave cylinder. For automatic transmission: Disconnect shift cable at transmission lever and remove cable bracket. Disconnect all electrical connectors including speed sensors, reverse light switch (manual), or neutral safety switch and solenoid connectors (automatic). Label connections for reassembly.
4. 4

   Remove exhaust crossover pipe
   Remove exhaust crossover pipe or downpipe section that interferes with transmission removal. Typically requires removal of clamps and bolts connecting exhaust sections. May need to remove exhaust hangers for clearance.
5. 5

   Support and remove transmission
   Position transmission jack under transmission pan and secure with safety chains. Remove transmission crossmember mounting bolts and remove crossmember. Remove bellhousing-to-engine bolts (typically 6-8 bolts). For automatic: ensure torque converter is secured to transmission with safety wire or bracket before separating. Carefully slide transmission rearward ensuring it clears input shaft/torque converter. Lower transmission from vehicle.
   ⚠️Verify transmission jack is properly positioned and secured before removing crossmember. Transmission can shift unexpectedly.
6. 6

   Remove clutch assembly (manual transmission)
   If equipped with manual transmission: Mark pressure plate orientation to flywheel. Gradually loosen pressure plate bolts in star pattern, loosening each bolt 2-3 turns at a time to prevent warping. Remove pressure plate and clutch disc. Inspect clutch components for wear and replace as needed.
7. 7

   Lock flywheel and remove flywheel bolts
   Install flywheel holding tool to prevent crankshaft rotation, or use starter ring gear lock. For automatic transmission, ensure torque converter is pulled away from flexplate. Remove flywheel or flexplate bolts. Note: On the 5.9L Cummins these bolts are high-strength fixed-torque bolts (not torque-to-yield); inspect them and reuse or replace per condition, applying fresh thread locker on reinstall. Remove bolts in star pattern to prevent warping.
8. 8

   Remove flywheel or flexplate
   Remove flywheel (manual) or flexplate (automatic) from crankshaft flange. Note orientation and any alignment dowel pins. Inspect flywheel friction surface for scoring, heat checking, or cracks. Manual transmission: Flywheel may be resurfaced only if within manufacturer specification. Verify step dimension and maximum material removal against Mopar service data before machining, as the Cummins flywheel is often a stepped design. Automatic: Flexplate should be replaced if cracked or bent. Measure flexplate runout if reusing.
9. 9

   Inspect and replace rear main seal
   With flywheel removed, inspect rear main seal for leaks. This is optimal time to replace rear main seal. Remove old seal using seal puller or carefully pry out with screwdriver (avoid scratching crankshaft). Clean sealing surface thoroughly. Install new rear main seal using seal driver or large socket, ensuring even installation. Seal should be flush with housing.
10. 10

    Replace pilot bearing (manual transmission)
    For manual transmission only: Remove old pilot bearing from center of crankshaft using pilot bearing puller or slide hammer. Clean pilot bearing bore in crankshaft. Install new pilot bearing using appropriately sized driver, ensuring bearing is fully seated and square in bore.
11. 11

    Clean and prepare crankshaft flange
    Clean crankshaft flange thoroughly with brake cleaner, removing all oil, debris, and old thread locking compound. Inspect crankshaft flange threads and surfaces for damage. Clean flywheel or flexplate mounting surface and bolt holes. Ensure alignment dowels are present and undamaged.
12. 12

    Install new flywheel or flexplate
    Position new or resurfaced flywheel (manual) or new flexplate (automatic) onto crankshaft flange, aligning dowel pins. Apply medium-strength thread locking compound to NEW flywheel or flexplate bolt threads. Install bolts finger tight. Use flywheel holding tool to lock rotation. On the 5.9L Cummins the flywheel/flexplate bolts are fixed-torque high-strength bolts (not torque-to-yield). Inspect bolts and replace if damaged; apply fresh thread locker. Torque bolts in star pattern in three stages: 1/3, 2/3, then final torque of approximately 101 ft-lbs (verify against Mopar service data for your specific year). For manual transmission use flywheel bolt specification; for automatic use flexplate bolt specification. Verify torque specification for your specific year.
    ⚠Flywheel and flexplate bolts are often TTY (torque-to-yield). Always use NEW bolts. Verify torque specification for your specific year as procedures may vary.
    Torque spec

    Flywheel Bolts95 Nm (70 lb-ft)

    Flexplate Bolts85 Nm (63 lb-ft)
13. 13

    Install clutch assembly (manual transmission)
    For manual transmission: Install new clutch disc with pressure plate. Use clutch alignment tool inserted through clutch disc into pilot bearing to center disc. Position pressure plate over clutch disc, aligning marks made during disassembly or aligning per manufacturer instructions. Install pressure plate bolts and tighten gradually in star pattern. Torque per clutch manufacturer specification. Remove alignment tool.
14. 14

    Reinstall transmission
    For manual transmission: Apply small amount of high-temp grease to input shaft splines. For automatic: Verify torque converter is fully seated in transmission (should have 2-3 distinct clicks when installing). Position transmission on transmission jack and raise into position. Align transmission with engine, ensuring input shaft enters clutch/pilot bearing (manual) or torque converter aligns with flexplate (automatic). Install bellhousing bolts and torque in star pattern. Install transmission crossmember and torque mounting bolts.
    ⚠For automatic transmission: DO NOT use bellhousing bolts to draw transmission to engine. Transmission must slide into position freely or torque converter may be damaged.
15. 15

    Reconnect all components
    Reconnect shift linkage and all electrical connections. For automatic: Connect transmission cooler lines. Reconnect hydraulic clutch line (manual). Install front and rear driveshafts, aligning marks made during disassembly. Torque driveshaft bolts to specification. Reinstall transfer case with new gasket or RTV sealant, torque mounting bolts. Reconnect transfer case linkage and electrical connections. Install exhaust components. Install skid plates if equipped.
16. 16

    Refill fluids
    Remove engine support. Refill transmission with the transmission-specific fluid through fill tube (automatic) or fill plug (manual). Note: NV4500 manual transmissions require Mopar/Castrol synchromesh (75W-85 GL-4-type) fluid, not standard gear oil. For automatic transmission, refill with approximately 14 quarts of the specified fluid (ATF+4 for later models; earlier 1994-1998 models originally specified ATF+3/Mopar 7176, with ATF+4 as the backward-compatible replacement). Install transmission drain plug with new washer and torque to specification. Refill transfer case if fluid was lost. Check all fluid levels.
    Torque spec

    Drain Plug34 Nm (25 lb-ft)

Reassembly

1. Lower vehicle from jack stands
2. Reconnect negative battery cable
3. For automatic transmission: Start engine and cycle through all gear positions with foot on brake, then recheck fluid level with engine at operating temperature and add fluid as needed to reach proper level on dipstick
4. For manual transmission: Bleed hydraulic clutch system if clutch line was disconnected, check clutch pedal feel and engagement point

Verification

• Start engine and verify no abnormal noises from flywheel/flexplate area
• Check for fluid leaks around transmission, transfer case, and rear main seal
• For manual transmission: Verify smooth clutch engagement and disengagement, test in all gears
• For automatic transmission: Test drive vehicle through all gear ranges, verify smooth shifting with no slipping or harsh engagement
• Verify proper operation of 4WD system if equipped
• Recheck all fluid levels after test drive and top off as necessary

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