Flexplate

This procedure covers removal and replacement of the flexplate on a 2007-2013 Mercedes-Benz S65 AMG with the 6.0L V12 BiTurbo M275 engine, requiring transmission removal.

Warnings

Tools required

Parts

• Flexplate × 1 — Use OEM Mercedes-Benz specification
• Flexplate bolts (if not included with flexplate) × 1 — Use new bolts - single-use fasteners
• Torque converter seal × 1 — Use OEM specification
• Transmission pan gasket (if resealing required) × 1 — Use OEM specification
• Driveshaft center support bearing (inspect and replace if worn) × 1 — Use OEM specification
• Transmission filter (recommended during service) × 1 — Use OEM specification

Fluids

• Mercedes-Benz ATF 134 — 10 qt

Preparation

1. Connect SDS diagnostic system and place ABC suspension in service/lift mode per manufacturer procedure
2. Disconnect negative battery terminal and wait 15 minutes for system capacitor discharge
3. Raise vehicle on lift to comfortable working height and support securely
4. Remove engine undertray and transmission heat shields
5. Drain transmission fluid completely into appropriate container and note condition
6. Remove exhaust system from catalytic converters rearward to provide clearance
7. Mark driveshaft-to-differential flange orientation with paint or punch marks for proper reinstallation alignment
8. Remove complete driveshaft assembly including center support bearing
9. Disconnect all electrical connectors from transmission (conductor plate, speed sensors, solenoids, temperature sensor) and label each
10. Disconnect transmission cooling lines at transmission and plug openings to prevent contamination
11. Remove transmission crossmember mounting bolts and carefully lower crossmember
12. Install engine support fixture to safely support engine weight during transmission removal

Procedure

1. 1

   Remove torque converter access cover and mark converter position
   Remove the inspection cover from the lower bell housing. Rotate the crankshaft using a 27mm socket on the crankshaft pulley bolt to access each torque converter bolt through the inspection opening. Mark the torque converter orientation relative to the flexplate using a paint marker before removing any bolts. This ensures balanced reassembly in the original position.
   Torque spec

   Cover Bolts22 Nm (16 lb-ft)
2. 2

   Remove torque converter-to-flexplate bolts
   While rotating the crankshaft to access each bolt position, remove all torque converter-to-flexplate bolts. Support the torque converter with a strap or wire to prevent it from sliding out of the transmission pump during transmission removal. Count the bolts as you remove them (typically 6 bolts) to ensure none are missed.
   ⚠The torque converter can slide forward out of the transmission and damage the pump seal or cause injury. Secure it with wire or a retention strap before proceeding.
   Torque spec

   Torque Converter Bolts50 Nm (37 lb-ft)
3. 3

   Support and remove transmission
   Position transmission jack under transmission oil pan with appropriate adapter to distribute load. Remove all transmission-to-engine bell housing bolts while carefully supporting transmission weight. Note that bolts may be different lengths - document their positions. Carefully slide transmission straight back from engine, ensuring torque converter remains fully seated in transmission. Lower transmission on jack and remove from under vehicle. Verify torque converter hub did not damage pump seal during removal.
   ⚠️The 7-speed automatic transmission weighs approximately 250-300 lbs. Ensure transmission jack is rated for this weight and properly positioned to prevent tipping.
   Torque spec

   Transmission-to-Engine Bolts55 Nm (41 lb-ft)
4. 4

   Inspect flywheel/flexplate condition
   With transmission removed, thoroughly inspect the flexplate for cracks, heat discoloration, missing or damaged ring gear teeth, and elongated bolt holes. Pay special attention to the area around the bolt holes and the outer ring gear. Check crankshaft flange surface for damage, burrs, or debris. Clean the crankshaft flange thoroughly with brake cleaner and inspect for any cracks or damage. This is the primary diagnostic opportunity to identify the cause of flexplate failure.
   ℹ️Common failure patterns include cracks radiating from bolt holes (overtorque or improper sequence) or heat cracks near the ring gear (excessive starter engagement or converter issues).
5. 5

   Install flywheel holding tool and remove flexplate bolts
   Install the flywheel holding tool (Mercedes 601 589 00 40 00 or equivalent) to prevent crankshaft rotation. The tool typically engages the ring gear and braces against the engine block. Remove all flexplate mounting bolts in a crossing pattern (star pattern) to relieve stress evenly. Keep bolts organized if different lengths are used. Discard all bolts as they are torque-to-yield single-use fasteners.
   Torque spec

   Flexplate Bolts85 Nm (63 lb-ft)
6. 6

   Remove flexplate and inspect crankshaft flange
   Carefully remove the flexplate from the crankshaft. The flexplate should come off easily - if it binds, do not force it as this indicates misalignment or damage. Clean the crankshaft flange mounting surface thoroughly with brake cleaner and a lint-free cloth. Inspect the flange for any scoring, cracks, or warping. Use a dial indicator to check flange runout if previous flexplate showed unusual wear patterns (maximum runout specification is typically 0.2mm or 0.008 inch). Check the pilot bearing or bushing in the center of the crankshaft if equipped.
   ⚠Any damage to the crankshaft flange surface requires additional repair or machining before installing a new flexplate. Installing a flexplate on a damaged flange will cause premature failure.
7. 7

   Prepare and install new flexplate
   Verify the new flexplate is the correct part number for the S65 AMG application. Clean the flexplate mounting surface with brake cleaner. Position the new flexplate on the crankshaft flange, ensuring proper orientation - the flexplate is typically offset and will only fit correctly one way, with the torque converter mounting pads facing the transmission. Ensure all alignment dowel pins are properly seated. Install new flexplate bolts finger-tight in a star pattern to ensure even seating before torquing.
   ⚠Flexplate orientation is critical. The offset design ensures proper balance - installing it backwards will cause severe vibration and potential failure.
8. 8

   Torque flexplate bolts in proper sequence
   With the flywheel holding tool still installed, torque the flexplate bolts using the specified sequence from the Mercedes-Benz service manual. Typically, this involves a multi-stage torque pattern working in a star/crossing pattern. Torque all bolts to the specified value in at least three progressive stages: first to 30 Nm, then 60 Nm, then final torque. If torque-angle is specified in service documentation, apply the angle specification after reaching final torque. Verify each bolt is properly torqued and none were missed.
   ⚠️Improper torque sequence or values will cause flexplate cracking and catastrophic failure. Always follow the manufacturer's specified pattern.
   Torque spec

   Flexplate Bolts85 Nm (63 lb-ft)
9. 9

   Inspect torque converter and transmission front seal
   Before reinstalling transmission, inspect the torque converter hub for wear, scoring, or damage. Check that the torque converter is fully seated in the transmission pump - there should be a specific measurement from the bell housing face to the converter mounting pads (typically around 10-15mm depending on converter design). Inspect and replace the transmission front pump seal if any seepage was noted. Measure the depth to verify full seating using a straightedge across the bell housing and ruler to the converter mounting pad.
   ⚠A torque converter that is not fully seated will pull the transmission pump out during installation, causing catastrophic transmission failure on startup.
10. 10

    Reinstall transmission to engine
    Apply a small amount of high-temperature grease to the torque converter hub and pilot. Carefully raise the transmission on the jack and align it with the engine. The transmission should slide smoothly into position without excessive force - if it binds, the torque converter is not properly aligned with the flexplate or crankshaft pilot. Once the transmission is fully seated against the engine (bell housing flush with engine block), install all transmission-to-engine bolts in their correct positions and torque in a crossing pattern to specification.
    ⚠️Never use transmission-to-engine bolts to pull the transmission into position. This indicates improper alignment and will damage the transmission pump.
    Torque spec

    Transmission-to-Engine Bolts55 Nm (41 lb-ft)
11. 11

    Install torque converter bolts
    Align the torque converter to the flexplate using the alignment marks made during disassembly to maintain original balance. Rotate the crankshaft to access each bolt hole through the inspection opening. Install all torque converter-to-flexplate bolts and torque to specification in the sequence specified in the service manual. Typically this is done in a star pattern, torquing opposite bolts sequentially. Verify all bolts are installed and properly torqued.
    ℹ️Reinstalling the torque converter in its original orientation maintains the factory balance and reduces vibration potential.
    Torque spec

    Torque Converter Bolts50 Nm (37 lb-ft)
12. 12

    Reinstall inspection cover and complete assembly
    Install the torque converter inspection cover with new bolts or fasteners as specified. Reinstall the transmission crossmember and torque mounting bolts to specification. Remove the engine support fixture. Reconnect all transmission electrical connectors per your documentation. Reconnect transmission cooling lines with new sealing washers. Reinstall the driveshaft assembly, carefully aligning the marks made during removal to maintain driveline balance. Torque all driveshaft fasteners to specification.
    Torque spec

    Cover Bolts22 Nm (16 lb-ft)

    Mounting Bolts64 Nm (47 lb-ft)
13. 13

    Refill transmission and perform system checks
    Fill transmission with the correct quantity of Mercedes-Benz ATF 134 fluid (approximately 10 quarts, but verify exact level per service procedure as it requires specific temperature and procedure). Reinstall exhaust system and all heat shields. Reinstall engine undertray. Lower vehicle and reconnect battery. Using the SDS system, clear any stored fault codes and take the ABC suspension out of service mode. Start the engine and verify no unusual noises or vibrations. Check for fluid leaks around all disturbed connections.
    ⚠Mercedes-Benz automatic transmissions require specific fill procedures including temperature monitoring. Improper fluid level will cause transmission damage.

Reassembly

1. Reverse disassembly process, ensuring all electrical connectors are properly seated and locked
2. Torque all fasteners to specifications in the proper sequence
3. Use new single-use fasteners (flexplate bolts, transmission pan bolts if disturbed) as required
4. Verify driveshaft alignment marks are matched to prevent vibration
5. Refill transmission using proper procedure including temperature verification
6. Reset ABC suspension from service mode using diagnostic system

Verification

• Start engine and verify smooth idle with no unusual vibration or noise from bell housing area
• With engine at operating temperature, verify transmission fluid level using proper procedure with SDS system
• Test drive vehicle through all gear ranges, verifying smooth shifts and no vibration at all speeds
• Perform a second inspection for fluid leaks after test drive with vehicle on lift
• Use SDS system to verify no transmission fault codes are present
• Verify torque converter lockup function operates properly using diagnostic system in all applicable gears
• Listen specifically for any starter ring gear noise during cranking that might indicate flexplate misalignment

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