Shift Fork

Replace worn shift fork(s) in the NV4500 or NV5600 manual transmission, requiring complete transmission removal and disassembly to access internal shift mechanism components.

Warnings

Tools required

Parts

• Shift fork (specify which gear) × 1 — Use OEM Dodge/Mopar or quality aftermarket
• Transmission gasket and seal kit × 1 — Use OEM specification
• Transmission oil × 1 — Mopar ATF+4 or 75W-90 synthetic gear oil per model
• Clutch alignment tool × 1 — Use OEM specification for pilot bearing
• Pilot bearing (inspect and replace if worn) × 1 — Use OEM specification
• Throwout bearing (inspect and replace if worn) × 1 — Use OEM specification
• Transmission drain plug washer × 1 — Use new crush washer
• Shift rail detent balls and springs (if damaged) × 1 — Use OEM specification

Fluids

• 75W-90 synthetic gear oil or Mopar ATF+4 (depends on transmission model) — 4 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Remove shift boot and shift lever assembly from inside cab
4. Raise vehicle and support securely on jack stands at frame rails
5. Remove skid plates and crossmembers as needed for transmission access
6. Place drain pan under transmission and drain fluid via drain plug
7. Mark driveshafts and companion flanges for reinstallation alignment
8. Support engine with jack or support fixture from above
9. Position transmission jack under transmission pan with securing chain or strap

Procedure

1. 1

   Remove transmission from vehicle
   Disconnect vehicle speed sensor, reverse light switch, and any other electrical connectors from transmission. Disconnect clutch hydraulic line at slave cylinder (both NV5600 and NV4500 use hydraulic clutch actuation). Remove starter motor mounting bolts and position aside. Remove exhaust crossover pipe if interfering with removal. Unbolt rear transmission mount and crossmember. Remove front and rear driveshafts after marking positions. Support transmission securely on transmission jack. Remove bellhousing to engine mounting bolts and carefully slide transmission rearward off clutch splines. Lower transmission from vehicle.
2. 2

   Clean and prepare transmission for disassembly
   Clean exterior of transmission thoroughly with degreaser. Position transmission on sturdy workbench with front facing up. Remove all external components including shifter housing, speed sensor, and backup light switch. Drain any remaining fluid. Inspect case for cracks or damage before proceeding with internal disassembly.
3. 3

   Remove shifter cover and shift rail assembly
   Remove shifter cover bolts from top of transmission case. Carefully lift shifter cover assembly, noting position of shift rail interlock system. Remove shift rail detent springs and balls, keeping them organized by position. On NV5600, note the location of the reverse inhibitor mechanism. Inspect shift rail ends for wear or damage where they engage shift forks.
4. 4

   Split transmission case halves
   Remove all case bolts securing rear extension housing and front bearing retainer. Note bolt length and positions as they vary. Carefully tap case with rubber mallet to break gasket seal. Separate case halves, keeping shims and bearings with their respective components. On NV5600, be prepared to support countershaft and mainshaft assemblies as case separates. Place case halves on clean work surface with internal components accessible.
   Torque spec

   Transmission Pan Bolts12 Nm (9 lb-ft)
5. 5

   Remove mainshaft and countershaft assemblies
   Remove mainshaft and countershaft as assemblies, noting exact position of all gears, synchronizers, and spacers. Take detailed photos or notes of gear stack arrangement. Place assemblies on clean bench. On NV4500, remove 5th gear assembly from rear of mainshaft first if accessing 5th gear shift fork. On NV5600, note that 6th gear components are at rear of case.
6. 6

   Remove and inspect damaged shift fork
   Locate the specific shift fork requiring replacement. Remove shift fork roll pin using punch and hammer, supporting fork to prevent damage. Slide shift fork off shift rail. Inspect fork pads for wear grooves exceeding 0.020 inches depth. Inspect fork pivot bore for elongation or cracking. Inspect corresponding slider and synchronizer hub engagement teeth for wear, chipping, or rounded edges. Measure synchronizer ring gap with feeler gauges; replace if gap is less than 0.020 inches.
7. 7

   Install new shift fork and rail
   Clean shift rail thoroughly and inspect for straightness, scoring, or worn detent grooves. Install new shift fork onto rail in correct orientation (fork pads face slider engagement grooves). Position fork at proper location on rail for corresponding gear position. Install new roll pin using brass punch, ensuring pin is fully seated and flush. Check that fork moves smoothly on rail without binding. Apply light coat of assembly lube to fork pads and pivot points.
8. 8

   Reassemble mainshaft and countershaft
   Reassemble gear stacks onto mainshaft and countershaft in exact original order using photos and notes. Install all snap rings, thrust washers, and bearings in proper positions. Ensure all synchronizer assemblies are oriented correctly with alignment marks matched. Check that all gears rotate freely and synchronizers slide smoothly. Install shift fork onto corresponding slider assembly, verifying proper engagement depth.
9. 9

   Reinstall shafts into case and join case halves
   Apply thin bead of Mopar gasket maker or equivalent to case mating surface, avoiding bolt holes. Position mainshaft and countershaft assemblies into rear case half with all bearings properly seated in bores. Install shift rail assembly with detent balls and springs, ensuring proper alignment with shift fork. Carefully position front case half over shafts, guiding bearing bores over bearings. Install case bolts finger-tight, then torque in criss-cross pattern to specification. Rotate input shaft to verify all gears engage properly and no binding occurs.
   Torque spec

   Transmission Pan Bolts12 Nm (9 lb-ft)
10. 10

    Install shifter cover and external components
    Install new gasket on shifter cover mating surface. Position shifter cover onto case, ensuring shift rail ends properly engage shift mechanism. Install cover bolts and torque to specification in criss-cross pattern. Install speed sensor with new o-ring and torque sensor bolt. Install reverse light switch with thread sealant. Rotate input shaft and cycle through all gears using shift rail mechanism to verify proper fork engagement and shift quality.
11. 11

    Prepare transmission for installation
    Install new transmission drain plug with new crush washer and torque to specification. Install fill plug temporarily. Apply high-temp grease to input shaft splines. Install new pilot bearing in crankshaft if removed or worn. Install new throwout bearing and clutch fork assembly. Inspect clutch disc and pressure plate; replace if questionable. Use clutch alignment tool to center clutch disc in pressure plate before installing transmission.
    Torque spec

    Drain Plug34 Nm (25 lb-ft)
12. 12

    Install transmission into vehicle
    With transmission secured to transmission jack, carefully align input shaft with clutch disc splines using alignment tool as guide. Slide transmission forward onto engine, ensuring input shaft engages pilot bearing and bellhousing aligns flush with engine block. If resistance is felt, do not force; verify clutch disc alignment. Install bellhousing mounting bolts and torque to specification in star pattern. Install transmission mount and crossmember, torquing mount bolts to specification. Remove transmission jack once securely mounted.
13. 13

    Reconnect drivelines and components
    Install front and rear driveshafts, aligning marks made during disassembly. Torque driveshaft yoke bolts to specification. Reconnect clutch hydraulic line or mechanical linkage. Install starter motor and torque mounting bolts to specification. Reconnect all electrical connectors including speed sensor and reverse light switch. Install exhaust components if removed. Install shift lever assembly inside cab and adjust linkage if applicable.
14. 14

    Fill transmission with fluid and test
    Remove fill plug from side of transmission case. Fill transmission with appropriate fluid (Mopar/Pennzoil Synchromesh or 75W-85 GL-4 for NV4500, or Mopar synthetic manual transmission fluid for NV5600) until fluid begins to seep from fill hole. Install fill plug with new washer and torque to specification. Reconnect battery negative cable. Start engine and test clutch operation. With engine running and clutch depressed, shift through all gears verifying smooth engagement without grinding or resistance. Check for fluid leaks around case, drain plug, and shifter cover.
    Torque spec

    Fill Plug34 Nm (25 lb-ft)

Reassembly

1. Ensure all snap rings are fully seated in their grooves and not twisted
2. Verify shift rail detent balls and springs are properly installed to prevent rail from walking out of position
3. Apply Loctite to all case bolts except those requiring gasket maker on threads
4. Use new gaskets and seals throughout; do not reuse old gaskets even if they appear undamaged
5. Check that all gears have proper end play per factory specifications (typically 0.003-0.010 inches)
6. Ensure synchronizer assemblies are not installed backwards; index marks must align

Verification

• Test drive vehicle through all gears under light load, verifying smooth shifts with no grinding or gear clash
• Verify no fluid leaks from transmission case, drain plug, shifter cover, or output shaft seal after test drive
• Confirm shift effort is normal and all gears engage positively without jumping out of gear under load
• Check for abnormal noise from transmission in neutral and in each gear position
• Recheck transmission fluid level after test drive when transmission is at operating temperature
• Verify clutch pedal free play and engagement point are correct; adjust if necessary

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