Flexplate

Replace the flexplate on a 2008 Dodge Viper 8.4L V10, requiring transmission removal to access the flexplate bolted to the crankshaft.

Warnings

Tools required

Parts

• Flexplate × 1 — Use OEM specification
• Flexplate bolts × 1 — Use OEM specification (typically supplied with flexplate)
• Transmission pan gasket × 1 — Use OEM specification
• Rear main seal (inspect and replace if leaking) × 1 — Use OEM specification

Fluids

• Pennzoil Synchromesh 75W-90 — 4.2 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 all four corners at manufacturer-recommended lift points
4. Remove belly pan or undertray if equipped to access transmission and exhaust
5. Allow exhaust system to cool completely if vehicle was recently driven

Procedure

1. 1

   Drain transmission fluid
   Position fluid catch pan under transmission drain plug. Remove drain plug from bottom of transmission case and allow fluid to drain completely. Reinstall drain plug finger-tight for now (will be torqued during reassembly).
2. 2

   Remove exhaust system components
   Disconnect exhaust at the header collectors or mid-pipe connection points. The Viper side-exit exhaust system requires removal of hangers and supports from the chassis. Remove exhaust system from headers back to the point where it clears the bellhousing and transmission removal path. Support exhaust components safely to prevent damage.
3. 3

   Disconnect driveshaft
   Mark driveshaft-to-differential flange orientation with paint or punch marks for reinstallation alignment. Remove the driveshaft flange bolts at the rear differential (verify exact bolt count against OEM documentation). Lower driveshaft and slide forward to separate from transmission output shaft. Support driveshaft and remove completely from vehicle.
4. 4

   Disconnect shift linkage and electrical connections
   Disconnect shift linkage from transmission shift tower. This typically involves removing a retaining clip and sliding the linkage rod off the shift lever ball stud. Disconnect all electrical connectors from transmission including reverse light switch, speed sensor, and any other sensors present. Label connectors if necessary for reinstallation.
5. 5

   Disconnect clutch hydraulic line
   Locate the clutch slave cylinder hydraulic line connection at the transmission bellhousing. Disconnect the hydraulic quick-connect fitting or banjo bolt (depending on model year specifics). If the hydraulic circuit must be opened, have a fluid catch pan ready as some fluid may be released; note that a quick-connect coupler typically allows disconnection with minimal or no fluid loss. Cap or plug the line to prevent further fluid loss and contamination.
6. 6

   Support transmission with transmission jack
   Position transmission jack under the transmission case, centering the jack saddle to balance the weight. Raise jack until it just contacts the transmission and takes slight load, but do not lift the transmission yet. Secure transmission to jack with a safety strap or chain.
7. 7

   Remove transmission crossmember
   Locate and remove the transmission crossmember mounting bolts. There are bolts securing the transmission mount to the crossmember and additional bolts securing the crossmember to the chassis frame rails (verify exact counts against OEM documentation). Remove all fasteners and lower the crossmember away from the vehicle. The transmission will now be supported only by the transmission jack.
8. 8

   Remove bellhousing-to-engine bolts
   Remove all bellhousing bolts securing the transmission to the engine block. The Viper V10 bellhousing is secured by several bolts of varying lengths around the perimeter (verify exact count against OEM documentation). Note the location of different length bolts for proper reinstallation. Check for any additional ground straps or brackets that must be removed.
9. 9

   Remove transmission from vehicle
   With an assistant guiding, carefully slide the transmission straight back away from the engine, keeping it level. The input shaft must slide out of the clutch disc and pilot bearing without binding. Once the input shaft clears the bellhousing, carefully lower the transmission jack and roll the transmission out from under the vehicle. Be aware of the weight distribution shift as the transmission moves rearward.
10. 10

    Lock crankshaft rotation
    Install a flywheel holding tool or locking device to prevent crankshaft rotation. This can be a purpose-built tool that engages the ring gear teeth and braces against the block, or a large screwdriver/pry bar wedged between the flexplate and bellhousing. Ensure the locking method is secure before attempting to remove flexplate bolts.
11. 11

    Remove flexplate mounting bolts
    Using a socket and breaker bar, remove all flexplate mounting bolts securing the flexplate to the crankshaft flange (verify exact bolt count against OEM documentation). These bolts are typically installed with thread locker and may require significant force to break loose. Work in a star pattern to evenly release tension. Keep bolts organized as they may be reused if not damaged, though new bolts are recommended.
12. 12

    Remove flexplate and inspect
    Carefully remove the flexplate from the crankshaft flange. Inspect the old flexplate for cracks, particularly around bolt holes and where the ring gear is welded. Check ring gear teeth for damage, wear, or missing teeth. Inspect the crankshaft flange mating surface for damage, burrs, or debris. Clean the crankshaft flange thoroughly with a razor scraper and solvent. Inspect the rear main seal for oil leakage; now is the ideal time to replace it if any seepage is present.
13. 13

    Install new flexplate
    Verify the new flexplate matches the old unit in all dimensions and ring gear position. Position the new flexplate onto the crankshaft flange, ensuring proper orientation (many flexplates are asymmetric and can only be installed one way, but verify any offset or indexing features). If specified by OEM, apply the correct thread locker to the new flexplate bolt threads (many OEM bolts are pre-coated; verify requirement before applying). Install all flexplate bolts hand-tight initially (verify exact bolt count against OEM documentation).
14. 14

    Torque flexplate bolts
    With the crankshaft still locked, torque the flexplate bolts in a star pattern to the OEM-specified torque (verify exact value and staging against factory service manual before final tightening). Work progressively across the bolt pattern to ensure even seating. Remove the flywheel locking tool after torquing is complete.
15. 15

    Reinstall transmission
    Apply a small amount of high-temperature grease to the transmission input shaft splines. Position the transmission on the transmission jack and roll it into position under the vehicle. Raise the transmission and carefully align the input shaft with the clutch disc splines and pilot bearing. The transmission should slide forward smoothly without force once properly aligned. If resistance is encountered, do not force it—lower slightly, rotate the output shaft to align splines, and try again. Once the bellhousing is flush against the engine block, install all bellhousing bolts hand-tight, then torque to OEM specification in a cross pattern (verify exact value against factory service manual).

Reassembly

1. Reinstall transmission crossmember and torque all mounting fasteners to specification
2. Reconnect clutch hydraulic line and bleed clutch system if air was introduced
3. Reconnect all electrical connectors and shift linkage to transmission
4. Reinstall driveshaft, aligning marks made during removal, and torque flange bolts to specification
5. Reinstall exhaust system components and secure all hangers and clamps
6. Refill transmission with Pennzoil Synchromesh 75W-90 to proper level (4.2 quarts total capacity)
7. Torque transmission drain plug to specification
8. Reinstall belly pan or undertray if equipped
9. Lower vehicle and reconnect negative battery cable

Verification

• Start engine and verify no abnormal noises from flexplate or transmission area
• Check for transmission fluid leaks around drain plug and case seams
• Test clutch operation through full pedal travel for smooth engagement and disengagement
• Test drive vehicle through all gears, listening for any unusual sounds from flexplate or transmission
• Verify smooth starts and no vibration that would indicate flexplate imbalance or improper installation
• Recheck transmission fluid level after test drive and top off if necessary

More procedures for this vehicle