Shift Fork

Complete transmission removal and disassembly to access and replace shift fork components in the ZF 6-speed automatic transmission. Requires drivetrain removal and transmission rebuild skills.

Warnings

Tools required

Parts

• Shift fork assembly (affected gear position) × 1 — Use OEM ZF specification
• Transmission gasket kit × 1 — Use OEM specification
• Transmission output shaft seal × 1 — Use OEM specification
• Transmission input shaft seal × 1 — Use OEM specification
• Transmission pan gasket or RTV sealant × 1 — Use OEM specification
• Transmission drain plug crush washer × 1 — Use OEM specification
• Propshaft center bearing (if disturbed) × 1 — Use OEM specification
• Transmission mount bolts (as required) × 6 — Use OEM specification

Fluids

• Touchtronic 6-speed ZF ATF — 9.5 qt

Preparation

1. Park vehicle on level lift and engage parking brake
2. Disconnect negative battery terminal and wait 10 minutes for system discharge
3. Remove engine undertray panels (multiple Torx fasteners around perimeter)
4. Place transmission drain pan under transmission oil pan
5. Remove transmission fluid temperature sensor connector from pan
6. Allow transmission to drain completely (minimum 30 minutes)
7. Document or photograph all electrical connector routing before removal

Procedure

1. 1

   Remove Exhaust System Components
   Remove exhaust system components as required to access the rear-mounted transaxle. Disconnect oxygen sensor connectors and secure wiring clear of work area. Remove exhaust hangers from rubber mounts and support the exhaust system. Note that on this vehicle the transaxle is mounted at the rear of the car, integrated with the final drive — plan access accordingly. Note: Remove catalytic converter-to-manifold fasteners (verify fastener type against OEM documentation before selecting tools).
2. 2

   Remove Propeller Shaft
   Mark propeller/torque-tube shaft flanges for reinstallation alignment. The DB9 uses a torque tube linking the front engine to the rear transaxle with the driveshaft running inside it. Follow OEM procedure for torque tube and driveshaft handling; verify exact fastener counts against the Aston Martin workshop manual before removal. Carefully withdraw propeller shaft assembly from vehicle, supporting center bearing. Cap transmission output to prevent fluid loss and contamination. Note: Mark the torque tube driveshaft coupling to the engine flywheel/flexplate and to the rear transaxle input for reinstallation alignment. The DB9 uses a torque tube connecting the front engine to the rear transaxle rather than a conventional propeller shaft with center bearing. Support and remove the torque tube assembly per OEM procedure, noting the transaxle is integrated with the final drive at the rear of the vehicle.
3. 3

   Disconnect Transmission External Components
   Disconnect the rear transaxle wiring harness connectors. Disconnect the shift/gear-selector linkage at the transaxle and remove bracket fasteners. Disconnect any transaxle cooler/oil lines using a line wrench to prevent fitting damage. Note the transaxle is located at the rear of the vehicle. Cap all open fittings immediately. If equipped, remove the fluid level/fill plug access as required. Note the ZF 6HP26 is typically a sealed unit without a dipstick tube — verify against the Aston Martin workshop manual.
4. 4

   Support Engine and Remove Transmission Mount
   Install engine support fixture across engine bay or attach overhead hoist to engine lifting eyes. Apply slight upward pressure to engine/transmission assembly. Remove transmission crossmember-to-chassis fasteners (verify exact count and locations against the Aston Martin workshop manual). Remove transmission mount-to-transaxle case fasteners (verify exact count against the Aston Martin workshop manual). Lower and remove transmission crossmember from vehicle.
5. 5

   Remove Starter Motor
   If starter removal is required for access, disconnect starter motor wiring (main power cable and trigger wire) and remove the starter mounting fasteners from the engine/flywheel housing at the front of the vehicle. Verify exact fastener count and locations against the Aston Martin workshop manual. Note: Remove starter motor mounting fasteners from bellhousing (verify count and type against OEM documentation). Note: Disconnect starter motor wiring connections (main power cable and trigger wire). The starter is mounted at the engine flywheel housing at the front of the vehicle, not at the rear transaxle. Remove starter mounting fasteners and withdraw starter as required; note this is unrelated to rear transaxle removal.
6. 6

   Remove Bellhousing-to-Engine Fasteners
   Position transmission jack under transmission oil pan with wide adapter plate distributing load. Secure transmission to jack with safety chains. Separate the transaxle from the torque tube per OEM procedure. On this rear-transaxle vehicle there is no bellhousing-to-engine-block fastener set at the transmission; the transaxle attaches to the torque tube. Verify all fastener locations and counts against the Aston Martin workshop manual. Note: Remove the torque tube-to-engine and torque tube-to-transaxle coupling fasteners per OEM procedure, noting exact fastener count and lengths from the service manual. There is no bellhousing-to-engine joint; the transaxle is rear-mounted.
7. 7

   Separate Transmission from Engine
   Verify all fasteners, electrical connections, cooler lines, and linkages are disconnected. With assistant support or overhead hoist backup, carefully slide transmission rearward on jack, keeping transmission aligned with engine centerline. Before separating, follow the Aston Martin workshop manual for decoupling the torque tube driveshaft from the rear transaxle torque converter. Verify the torque converter stays seated on the transaxle pump hub during withdrawal and does not slide forward; support all components on the jack per OEM procedure. Once input shaft clears bellhousing, lower transmission on jack and roll clear of vehicle. Note: Verify torque converter handling per OEM procedure. On this rear-transaxle vehicle, follow the Aston Martin workshop manual for separating the transaxle and torque converter from the torque tube, supporting all components on the jack before withdrawal. Note: The clutch/flywheel remains with the engine. Lower the rear transaxle on the jack and roll clear of the vehicle once the input is disengaged from the torque tube shaft.
8. 8

   Clean and Prepare Transmission for Disassembly
   Mount transmission on sturdy workbench using wood blocks or transmission stand. Clean exterior of transmission case thoroughly with degreaser and compressed air. Drain the manual transaxle gear oil if not already drained. Remove the transaxle end cover/housing fasteners per OEM procedure to begin accessing the internal gear train and shift mechanism. Note fastener counts and lengths from the service manual.
9. 9

   Remove Transmission Case Components
   Remove the transaxle shaft bearing retainers and any gear cluster retaining snap rings per OEM procedure. Keep gear and shaft assemblies together and documented for reassembly. Note this is a manual transaxle with no hydraulic pump or clutch packs. This is an automatic transaxle with hydraulically actuated multi-plate clutch packs and planetary gearsets (no shift forks or synchronizers). Photograph or diagram spring, plate, and disc orientation for each clutch pack during disassembly.
10. 10

    Split Transmission Case
    Remove all case half fasteners working in systematic pattern (approximately 18-24 fasteners around case perimeter and through center sections). Note fastener lengths and locations. Insert plastic pry tools at case split line (never metal tools). Gently pry case halves apart. Separate case halves, keeping all internal components with their original case half. Gear train, shift forks, and shift rails will typically remain in one case half.
11. 11

    Access and Remove Shift Fork Assembly
    NOTE: The ZF 6HP26 automatic transaxle does not contain shift forks, shift rails, synchronizer hubs, sleeves, or blocker rings. If a shift-related concern exists, diagnose the valve body, solenoids, and clutch packs instead. Confirm the actual failed component against the Aston Martin workshop manual before proceeding.ynchronizer hub, sleeve, and blocker ring for damage that may have caused fork failure. If hub shows wear grooves or sleeve has radial cracks, these components must also be replaced. Note: NOTE: The ZF 6HP26 automatic transmission in this vehicle does not contain shift forks, shift rails, detent balls, or synchronizer assemblies. Shift actuation is hydraulic via the mechatronic/valve body controlling multi-plate clutch packs. Verify the diagnosed fault and consult the ZF service manual for the correct internal component (e.g., clutch pack, piston, or mechatronic unit) before proceeding.
12. 12

    Install New Shift Fork
    NOTE: This automatic transmission has no shift fork, shift rail, or detent assembly to install. Refer to the ZF 6HP26 service documentation for the correct reassembly procedure and clearances for the actual component being serviced.ift rail through case bore and through shift fork bore. Align shift rail detent notches and install detent ball and spring. Install shift rail retaining clips or pins. Verify shift fork moves smoothly through full travel range. Any clearance or end-float checks must follow the Aston Martin / ZF service specification for the 6HP26 automatic transaxle; no shift-fork clearance specification exists for this automatic transaxle; disregard the 0.1-0.3mm figure entirely and service the actual hydraulic/clutch-pack component per the ZF 6HP26 service manual. Note: Check shift fork-to-synchronizer sleeve/gear clearance with a feeler gauge or dial indicator to the value specified in the Aston Martin / Graziano service manual (do not use a generic assumed figure).
13. 13

    Reassemble Transmission Case
    Clean all case mating surfaces with appropriate solvent. Inspect case for cracks, damaged bearing bores, or damaged fastener threads. Apply new gasket or RTV sealant to case mating surface per OEM specification. Carefully align case halves, ensuring all shift rails, shafts, and bearings properly seat in both case bores. Install case fasteners finger-tight in star pattern, then torque in three progressive stages to final specification. Verify all shafts rotate freely after case assembly.
14. 14

    Reinstall Internal Components
    Install clutch pack assemblies in reverse order of removal, ensuring correct orientation of springs, plates, and discs per documentation. Install snap rings securing clutch packs, verifying complete seating in grooves. Install transmission pump assembly with new gasket, aligning marks made during removal. Torque pump fasteners in star pattern to specification. Install valve body assembly with new gasket. Reconnect internal wiring harness to solenoids. Torque valve body fasteners to specification in sequence. Install transmission pan with new gasket. Torque pan fasteners in star pattern to specification.
15. 15

    Reinstall Transmission in Vehicle
    Mount transmission on transmission jack with safety chains. Roll transmission under vehicle and raise to approximate installation height. Apply small amount of high-temp grease to torque converter pilot bore. Install torque converter to transmission input shaft, ensuring converter is fully seated (will have distinct engagement clicks as converter splines engage pump, then turbine, then stator). Measure converter seating/recess depth and compare to the ZF 6HP26 specification to confirm full engagement before installation; do not rely on any assumed value — obtain the exact figure from Aston Martin/ZF documentation. Align transmission with engine, carefully sliding forward on jack. Guide transmission input shaft into engine crankshaft pilot bearing. Continue until bellhousing contacts engine block evenly. Reinstall the rear transaxle to the torque tube per OEM procedure, verifying the input shaft properly engages the torque tube driveshaft/torque converter. There is no bellhousing-to-engine joint on this platform; torque all torque-tube coupling fasteners to the Aston Martin specification. Note: Install torque converter per OEM procedure, ensuring it is fully seated with the correct number of engagement drops. Measure converter seating/recess depth and compare against the Aston Martin / ZF 6HP26 specification before installation — do not rely on an assumed value. Note: Reinstall the rear transaxle to the torque tube per OEM procedure, verifying the input shaft properly engages the clutch/torque tube shaft splines. There is no torque converter in a manual transaxle; follow the Aston Martin service manual for engagement verification.
16. 16

    Reinstall Transmission Mount and External Components
    Raise transmission crossmember into position. Install transmission mount to transmission case and torque fasteners to specification. Install crossmember-to-chassis fasteners and torque to specification. Remove engine support fixture. Reconnect transmission cooler lines, torquing fittings to specification. The ZF 6HP26 is a sealed unit with no dipstick tube — do not attempt to reinstall a dipstick. Reconnect the shift selector linkage and adjust per OEM procedure. Reconnect transmission wiring harness main connector.
17. 17

    Reinstall Propeller Shaft and Exhaust
    Install propeller shaft assembly, aligning marks made during removal at transmission and differential flanges. Install front flange fasteners and torque to specification. Install center bearing support bracket and torque fasteners to specification. Install rear flange fasteners and torque to specification. Raise exhaust system into position, connecting catalytic converters to manifolds. Install all exhaust fasteners and torque to specification. Connect exhaust hangers to rubber mounts. Reconnect oxygen sensor connectors.
18. 18

    Fill Transmission and Perform Initial Checks
    Install new transmission drain plug crush washer. Install drain plug and torque to specification. Fill the transmission through the fill/level plug using the ZF-specified fluid (ZF Lifeguard 6 / equivalent ZF-approved ATF per Aston Martin specification). Perform the fill-level check at the OEM-specified fluid temperature using the overflow method. Verify exact fluid capacity against the Aston Martin workshop manual; the ZF 6HP26 is typically a sealed unit without a dipstick. Reconnect battery negative terminal. Start engine and allow to idle. With foot on brake, cycle transmission through all gear positions, pausing 3 seconds in each position. Return to Park. Check and set fluid level using the fill/level plug overflow method with fluid temperature in the ZF-specified window (approx. 30-40°C) and engine idling; allow excess to drain from the fill port until a thin stream reduces to drips, then install the fill plug. Check for leaks at pan, drain plug, cooler lines, and case mating surfaces. Note: With foot on brake, cycle transmission through all gear positions, pausing briefly in each. Return to Park. Perform the fluid level check via the fill/overflow plug at the ZF-specified fluid temperature window using the OEM overflow method; do not use a dipstick. Add fluid as required to achieve the correct overflow condition. Note: Fill the transmission through the fill/level plug on the pan (not a dipstick) with ZF Lifeguard 6 ATF (Shell M-1375.4 specification). Refill to the level plug with the fluid at the ZF-specified temperature (approx. 30-40°C), following the ZF 6HP26 level-check procedure. Verify the exact fluid capacity against the Aston Martin workshop manual (do not rely on an assumed quantity); set final level per the temperature-dependent overflow method. Note: This is an automatic transaxle (ZF 6HP26) — perform the fluid level check at the fill/overflow plug with the engine idling and fluid temperature in the ZF-specified window (approx. 30-40°C) per OEM procedure. Disregard any manual-transaxle gear-oil level instructions. Note: Fill the manual transaxle with the gear oil type and quantity specified in the Aston Martin service manual through the fill/level plug (not a dipstick tube). Verify fluid type and capacity against OEM documentation.
    Torque spec

    Transmission Drain Plug38 Nm (28 lb-ft)

Reassembly

1. Reinstall engine undertray panels with all Torx fasteners
2. Torque all fasteners to specification - critical for transmission case and bellhousing fasteners
3. Verify all electrical connections are fully seated with locking tabs engaged
4. Check transmission fluid level when at full operating temperature in Park position
5. Perform shift quality relearn procedure using OEM diagnostic tool if transmission control module requires adaptation

Verification

• Start engine and verify no fluid leaks at all connection points and case mating surfaces
• Road test vehicle through all gear ranges, verifying smooth shifts without slipping, flaring, or binding
• Verify shift fork repair has resolved original concern (hard shifts, gear engagement issues, or internal noise)
• Scan transmission control module for fault codes using OEM diagnostic tool
• Verify transmission fluid temperature remains within normal range (80-110°C) during operation
• After 50-100 miles of operation, recheck transmission fluid level and inspect for leaks

Related trouble codes on this vehicle

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