E90/E91/E92/E93; N55; GS6-45BZ gearbox — BMW

🧭 Before you start

Support the engine on a hoist, remove heat shields and exhaust brackets, and disconnect the exhaust at the manifold and rear mounts. Release the propeller shaft middle support, unbolt the shaft from the gearbox and lower it out. Disconnect the gear-shift rod, wiring loom brackets and reversing light switch, support the gearbox with safety straps, remove the cross member and the engine-to-gearbox bolts, then lower the gearbox away. Refit in reverse with clean, greased input splines and new aluminium bolts, tightening in the stages given for steel and aluminium bolts.

Fits: platform codes 335I, XI

• Timing position: the crankshaft or camshaft is set and locked during this job
• Special tools named: locking pin

Don't miss

• Use aluminium bolts on the magnesium crankcase and renew them every time they are removed.
• Clean and grease the gearbox input shaft splines before installation.
• Safety straps must be used on the gearbox support during removal.
• Do not damage the propeller shaft rubber boot when lowering the shaft.
• Observe the separate tightening values for hexagonal and Torx bolts, steel and aluminium.

Written for this job from the workshop steps below · TorqFix editorial.

🔧 Engine codes this applies to

📐 46 workshop diagrams for N55B30A

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. Installation is in the reverse order of removal
2. Aluminium screws/bolts must be used for a magnesium crankcase
3. Aluminium screws/bolts must be renewed each time they are removed
4. Aluminium screws/bolts, with or without colour coding (blue), may be used
5. Fit a lifting jack

6. Clean the gearbox input shaft splines
7. Apply grease to the gearbox input shaft splines
8. Disconnect the exhaust pipes from the manifold
9. Disconnect the rear exhaust mounts
10. Propeller shaft/differential
11. Remove the heat shield(s)
12. Propeller shaft middle support
13. Disconnect the coolant hoses from the front of the engine
14. Disconnect the wiring loom bracket
15. Use a hoist to support the engine
16. Remove the exhaust pipe bracket(s)
17. Remove the engine/gearbox lower attaching bolts
18. Disconnect the electrical wiring from the gearbox
19. Unclip the wiring from the gearbox
20. Disconnect the wiring loom bracket at the gearbox
21. Disconnect the reversing light switch from the gearbox
22. Exhaust pipe/gearbox support:
23. Steel
24. Aluminium
25. Remove the exhaust pipe bracket(s)
26. Support the gearbox
27. Use a special tool:
28. Caution! Safety straps MUST be used
29. Remove the cross member
30. Disconnect the propeller shaft from the gearbox
31. Remove the propeller shaft middle support
32. Disconnect the propeller bearing
33. Lower the propeller shaft
34. Do not damage the rubber boot
35. Remove the propeller shaft
36. Remove the locking pin
37. Disconnect the gear-shift rod from the gearbox
38. Disconnect the gear-shift rod from the gearbox
39. Remove the gear-shift control at the gearbox
40. Use a hoist to support the engine
41. Remove the engine/gearbox attaching bolts
42. Lower the gearbox slightly
43. Remove the gearbox

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