Reconditioned BMW Gearbox

BMW Gearboxes: 6-speed manuals on the diesel side, petrol units from 1.5 to 3.0 litres, naturally aspirated and turbocharged

Across the BMW models covered here — 1 Series, 3 Series, 5 Series, 4 Series, X1, X3, X4 and 2 Series Gran Tourer from 2003 to 2022 — every gearbox in this selection is a 6-speed manual. There is no dual-clutch and no torque-converter automatic in this range: if your BMW is fitted with a Steptronic or a ZF 8-speed, this page does not apply to you. If, however, you have a manual transmission — diesel or petrol — the coverage is broad: 1.5d and 1.6d units (B37, N47D16A) on the smaller-capacity models, 2.0d in N47 or B47 on the 318d, 320d and X1/X3 diesel, 3.0d in M57 (306D2, 306D3) or M57N2 on the six-cylinders, and on the petrol side 2.0i in N43, N46 or N20, 2.5 in M54, and 3.0i covering N52, N53, N54, N55 and B58 through to the 440i and 435i.

Identification pitfalls: the engine code takes priority over engine capacity

A 3 Series 320d may carry an N47D20 or a B47D20 depending on whether it was built before or after approximately 2012 — these two units do not share the same gearbox. Equally, an X1 2.0 petrol may have an N20B20 (E84) or a B48B20 (F48) depending on the body generation, and the gearbox references differ accordingly. BMW gearbox codes (in the format GS6-…) often incorporate the torque family and axle architecture: GS6-17 denotes a casing suited to moderate torque outputs (1.6d, smaller 2.0 units), while GS6-37 and GS6-45 cover higher-torque applications, in particular the six-cylinder M54, M57 and their successors N52/N53/N54/M57N2. Mixing up these families when placing an order is the most common mistake: always check the engine code stamped on the block first — do not rely solely on the rated power output or engine capacity.

Two purchasing options available depending on the condition of your original gearbox

Reconditioned BMW gearboxes are available either on an exchange basis or as a rebuild of your own unit. The second option is aimed at cases where the exact reference is hard to source, or where the original gearbox has localised damage (synchros, selector forks) without casing failure. The 3 Series accounts for the largest number of available references, followed by the 1 Series; coverage for the X4 and 4 Series is more limited — worth bearing in mind if lead time is a concern.