Synchros - All

Complete transmission disassembly and synchronizer replacement for all gears in the Tremec T56 6-speed manual transmission. This procedure requires full transmission removal from vehicle, internal disassembly, replacement of all synchronizer assemblies, and reassembly with fresh transmission fluid.

Warnings

Tools required

Parts

• 1-2 synchronizer assembly × 1 — Use OEM Tremec specification
• 3-4 synchronizer assembly × 1 — Use OEM Tremec specification
• 5-6 synchronizer assembly × 1 — Use OEM Tremec specification
• Reverse synchronizer assembly × 1 — Use OEM Tremec specification
• Input shaft bearing × 1 — Use OEM Tremec specification
• Counter shaft bearing (front) × 1 — Use OEM Tremec specification
• Counter shaft bearing (rear) × 1 — Use OEM Tremec specification
• Mainshaft bearing (rear) × 1 — Use OEM Tremec specification
• Transmission case gasket × 1 — Use OEM specification
• Tail housing gasket × 1 — Use OEM specification
• Shift cover gasket × 1 — Use OEM specification
• Front bearing retainer seal × 1 — Use OEM specification
• Rear output shaft seal × 1 — Use OEM specification
• Shift fork pads (set) × 1 — Use OEM specification
• Transmission assembly lubricant × 1 — Use Tremec specification assembly lube
• Thread locker (medium strength) × 1 — Loctite 242 or equivalent
• RTV silicone gasket maker × 1 — High-temp transmission rated

Fluids

• 75W-90 synthetic GL-4 — 4 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Raise vehicle on lift or jack stands to provide adequate working clearance underneath
4. Remove shifter assembly from interior by removing shift boot and unbolting shifter mechanism from transmission
5. Drain transmission fluid into appropriate container by removing drain plug
6. Remove complete exhaust system from manifolds back to provide transmission clearance
7. Remove driveshaft by marking yoke-to-differential flange orientation, then removing driveshaft mounting bolts
8. Support engine from above using engine support bar or hoist to prevent engine from dropping when transmission is removed
9. Prepare clean workbench area with shop towels for transmission disassembly
10. Have all replacement parts, tools, and fluids ready before beginning disassembly

Procedure

1. 1

   Remove Transmission from Vehicle
   Disconnect clutch hydraulic line from slave cylinder at transmission. Support transmission with transmission jack. Remove transmission crossmember mounting bolts and remove crossmember. Disconnect reverse light switch connector and vehicle speed sensor connector. Remove the bellhousing-to-engine mounting bolts. Carefully slide transmission rearward off input shaft, supporting weight on transmission jack. Lower transmission and move to clean workbench.
2. 2

   Remove External Components
   With transmission on bench, remove clutch slave cylinder from bellhousing. Remove vehicle speed sensor from tail housing. Remove reverse light switch from case. Remove shift cover bolts and carefully lift shift cover off, noting position of shift rail detents and springs. Remove bellhousing bolts and separate bellhousing from main case. Remove front bearing retainer bolts and remove retainer with input shaft seal.
3. 3

   Remove Tail Housing and Output Components
   Remove tail housing mounting bolts from rear of transmission case. Carefully slide tail housing off output shaft, tapping gently with plastic hammer if needed. Remove output shaft rear bearing snap ring from inside tail housing. Remove the vehicle speed sensor pickup/reluctor components from the output shaft area as applicable. Note position and thickness of any shims behind rear bearing for reassembly reference.
4. 4

   Split Transmission Case
   Remove the case half bolts that join the transmission case halves together. Install T56 case spreader tool at front and rear of case to gently separate case halves. Carefully lift rear case half away, keeping all internal components with front case half. If components stick to rear case, carefully note their position and remove them to keep with corresponding shafts.
5. 5

   Remove Shift Forks and Rails
   Remove shift fork interlock pins from case. Carefully withdraw shift rails one at a time, noting the position and orientation of each fork and detent. Remove the 1-2 shift fork, 3-4 shift fork, 5-6 shift fork, and reverse shift fork from their respective synchronizer sleeves. Inspect shift fork pads for wear and note condition for replacement. Keep shift components organized and labeled by gear position.
6. 6

   Remove Counter Shaft Assembly
   Remove counter shaft rear bearing snap ring from case. Use bearing puller or hydraulic press to carefully press counter shaft rearward, removing rear bearing from case. Lift counter shaft assembly with all gears and front bearing from case. Place on clean work surface. Note position of all gears, thrust washers, and spacers on counter shaft for reassembly reference.
7. 7

   Remove Mainshaft Assembly
   Remove mainshaft rear bearing snap ring. Press or pull mainshaft rearward to remove rear bearing from case. Carefully lift mainshaft assembly with input shaft, all gears, and synchronizers from front case half. Support input shaft to prevent it from separating. Place complete mainshaft assembly on clean work surface for disassembly.
8. 8

   Disassemble Mainshaft - Remove 5-6 Synchronizer
   With mainshaft on bench, remove 5-6 synchronizer snap ring from front of mainshaft. Slide 5-6 synchronizer assembly, 5th gear, and 6th gear from mainshaft, noting orientation of each component. Remove the blocking rings and inspect wear patterns. Remove thrust washers and note their position. Mark the 5-6 synchronizer hub orientation to sleeve before disassembly if planning to reuse hub.
9. 9

   Disassemble Mainshaft - Remove 3-4 Synchronizer
   Remove 3-4 synchronizer snap ring from mainshaft. Slide off 3-4 synchronizer assembly, 3rd gear, and 4th gear, keeping blocking rings with their respective gears. Note the position of any thrust washers or spacers. Mark synchronizer hub-to-sleeve orientation before separating. Remove and inspect blocking rings for wear, scoring, or broken teeth.
10. 10

    Disassemble Mainshaft - Remove 1-2 Synchronizer and Input Shaft
    Remove 1-2 synchronizer snap ring. Slide 1-2 synchronizer assembly, 1st gear, and 2nd gear from mainshaft. Remove blocking rings and note wear condition. Press or tap input shaft from front of mainshaft, separating the two shafts. Remove input shaft bearing using bearing puller if replacement is needed. Remove reverse gear and reverse synchronizer assembly from rear of mainshaft, noting snap ring position.
11. 11

    Inspect and Measure All Components
    Thoroughly clean all gears, shafts, bearings, and case components with solvent. Inspect all gear teeth for chips, wear, or pitting. Measure mainshaft and counter shaft endplay specifications using dial indicator. Check all bearing surfaces for scoring or discoloration. Inspect case bores for wear or damage. Verify all new synchronizer assemblies are correct part numbers for each gear position. Measure gear-to-shaft clearances and compare to factory specifications.
12. 12

    Install New Bearings and Prepare Shafts
    Press new input shaft bearing onto input shaft using hydraulic press and appropriate driver. Install new front counter shaft bearing onto counter shaft, pressing until fully seated. Install new rear counter shaft bearing and new mainshaft rear bearing onto their respective shafts. Apply thin coat of assembly lubricant to all bearing surfaces. Install new front bearing retainer seal into retainer housing.
13. 13

    Assemble Mainshaft - Install Reverse and 1-2 Synchronizer
    Slide reverse gear onto rear of mainshaft with gear teeth facing correct direction. Install new reverse synchronizer assembly with blocking ring, ensuring proper orientation. Secure with snap ring. Install 1st gear with new blocking ring onto mainshaft. Install 2nd gear with new blocking ring. Slide new 1-2 synchronizer assembly onto mainshaft, aligning marks if reusing hub, and engaging shift fork groove. Install 1-2 snap ring, ensuring it fully seats in groove.
14. 14

    Assemble Mainshaft - Install 3-4 and 5-6 Synchronizers
    Install 3rd gear with new blocking ring onto mainshaft. Install 4th gear with new blocking ring. Slide new 3-4 synchronizer assembly onto shaft, ensuring proper orientation and fork groove position. Install 3-4 snap ring. Install any thrust washers or spacers in original positions. Install 5th gear and 6th gear with new blocking rings. Slide new 5-6 synchronizer assembly onto front of mainshaft. Install 5-6 snap ring, verifying full engagement in groove.
15. 15

    Install Input Shaft to Mainshaft
    Apply assembly lubricant to input shaft pilot bearing surface. Carefully align input shaft with front of mainshaft and press or tap together until fully seated. Verify smooth rotation and proper engagement. Check that input shaft bearing rotates freely without binding.
16. 16

    Install Counter Shaft Assembly in Case
    Apply assembly lubricant to counter shaft bearings and case bores. Carefully lower counter shaft assembly with all gears into front case half, aligning front bearing with case bore. Press front bearing into case until seated. Align rear bearing with rear case bore. Install rear bearing snap ring once bearing is fully seated in case.
17. 17

    Install Mainshaft Assembly in Case
    Apply assembly lubricant to mainshaft bearings. Carefully lower complete mainshaft assembly into front case half, ensuring input shaft bearing aligns with front case bore. Guide mainshaft rear bearing into rear case bore. Press or tap bearings into position until fully seated. Install mainshaft rear bearing snap ring.
18. 18

    Install Shift Forks and Rails
    Apply light oil to shift rails. Install reverse shift fork onto reverse synchronizer sleeve. Install 1-2 shift fork onto 1-2 synchronizer sleeve with new shift fork pads. Install 3-4 shift fork onto 3-4 synchronizer sleeve with new pads. Install 5-6 shift fork onto 5-6 synchronizer sleeve with new pads. Carefully insert each shift rail through its corresponding fork and into case bores, ensuring detent notches align correctly. Install shift rail interlock pins with medium-strength thread locker.
19. 19

    Join Case Halves
    Apply thin bead of RTV silicone to mating surface of front case half, following case gasket channel. Alternatively, position new case gasket if using pre-cut gasket instead of RTV. Verify all shift forks are properly engaged and positioned. Carefully align rear case half over front case, guiding all shafts and shift rails into rear case bores. Remove case spreader tool. Install case half bolts with medium-strength thread locker, tightening in criss-cross pattern to ensure even case loading.
20. 20

    Verify Shift Operation and Endplay
    Before installing external components, manually shift transmission through all gears using shift rail ends to verify smooth engagement without binding. Check mainshaft endplay using dial indicator - should be within factory specification range. Check counter shaft endplay. Verify all synchronizers engage properly and gears rotate freely in each position. If endplay is out of specification, disassemble and adjust shim thickness as needed.
21. 21

    Install External Components
    Install front bearing retainer with new seal, applying RTV to mating surface if specified. Install tail housing with new gasket or RTV, ensuring proper alignment with output shaft. Install the vehicle speed sensor pickup/reluctor components as applicable. Apply thread locker to all external bolts. Install vehicle speed sensor and reverse light switch with new O-rings. Install shift cover with new gasket, ensuring shift rail detents and springs are properly positioned.
22. 22

    Install Bellhousing and Slave Cylinder
    Install bellhousing to front of transmission case, ensuring proper alignment of input shaft bearing with bellhousing bore. Install clutch slave cylinder to bellhousing. Verify input shaft splines are clean and lightly lubricated for clutch disc engagement.
23. 23

    Reinstall Transmission in Vehicle
    With transmission on transmission jack, carefully guide input shaft into clutch disc while aligning bellhousing with engine block. Use clutch alignment tool if needed to ensure clutch disc is properly centered. Push transmission forward until bellhousing contacts engine block. Install bellhousing-to-engine mounting bolts, tightening in star pattern. Remove transmission jack. Install transmission crossmember and tighten mounting bolts. Reconnect clutch hydraulic line, vehicle speed sensor, and reverse light switch.
24. 24

    Final Assembly and Fill Transmission
    Install driveshaft, aligning marks made during disassembly. Install complete exhaust system. Install shifter assembly inside vehicle, ensuring proper engagement with shift rails. Fill transmission with the OEM-specified fluid (verify Mopar service spec for 2005 Viper T56 — typically an ATF-type transmission fluid, approximately 3.0 quarts) through fill plug until fluid reaches bottom of fill hole. Install and torque transmission drain plug with new crush washer if equipped. Reconnect negative battery cable.
    Torque spec

    Transmission Drain Plug30 Nm (22 lb-ft)

Reassembly

1. Installation follows reverse order of removal with attention to proper torque specifications
2. All snap rings must be fully seated in their grooves - verify by attempting to rotate them
3. Shift fork pads must be replaced and properly oriented to prevent fork breakage
4. All bearings must be pressed squarely and fully seated - cocked bearings will fail immediately
5. Synchronizer assemblies have specific orientation - blocking ring teeth must align with synchronizer teeth slots
6. Case halves must be joined with even pressure - use case spreader tool and criss-cross bolt tightening pattern
7. Verify smooth shift operation before final assembly - binding indicates misalignment or incorrect assembly
8. Use only GL-4 rated fluid in T56 transmission - GL-5 additives will damage brass synchronizers

Verification

• Start engine and verify no unusual noises from transmission
• With engine running and clutch depressed, shift through all gears verifying smooth engagement without grinding or resistance
• Test drive vehicle through all gears under light load, verifying smooth shifts in both upshift and downshift directions
• Check for fluid leaks around case seams, tail housing, shift cover, and front bearing retainer after test drive
• Verify no gear clash when engaging reverse from neutral
• Confirm clutch pedal feel is normal and clutch disengages fully
• After 50-100 miles, recheck transmission fluid level and top off if needed
• Listen for any abnormal whining, grinding, or rattling noises during operation in any gear

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