Reconditioned BMW 5 Series Gearbox

Which gearbox for my BMW Série 5 diesel or petrol between 2003 and 2010?

The answer depends above all on the engine code stamped on your block, not simply on the engine capacity. Every engine variant in this selection is paired with a 6-speed manual gearbox, but the internal references differ according to the powertrain — and confusing a 3.0d unit with a 2.0d one can lead to a fitment incompatibility.

Three engine variants, distinct engine codes

The 3.0d is the most widely represented engine in this collection, with codes 306D2, 306D3, 306D5 et M57D30. These 6-cylinder in-line blocks cover the various evolutions of the 3.0 diesel across the 2003–2010 period; the same vehicle may carry different codes depending on its exact model year, which is why it is essential to check on the engine itself. The 2.0d encompasses three successive generations — M47D20, N47D20A et B47D20 — which do not share the same mechanical interfaces; the N47 is notably known for its timing chain issues, something to check before carrying out any work on the gearbox. On the petrol side, the 2.5 comes in M54B25, N52B25 et N53B25: the M54 belongs to an earlier generation than the N52 and N53, and their gearbox-to-engine coupling characteristics differ.

What determines compatibility

On the Série 5 of this generation, the exact gearbox reference — visible on the label affixed to the casing, for example in the form GS6-45DZ or GS6-17BG — encodes the axle ratio, the type of torque capacity and sometimes the market. Two vehicles that appear identical may therefore take gearboxes with different ratios. Before selecting a part, note down the engine code, the original gearbox reference and the year of first registration at the same time: it is the combination of all three that guarantees a like-for-like replacement with no adaptation required.