Volvo M56 / M58 / M59

Volvo's five-speed manual transaxle — in the 850, S40, V40, C30, C70, S60, S80 and V70.

It is the gearbox the M66 replaced, and telling them apart is most of why this page exists: nothing outside the car distinguishes a five-speed Volvo transaxle from a six-speed one, the model years overlap for a decade, and a parts listing that says only manual covers both.

The M58 and M59 are the same gearbox with different final drives, fitted to the higher-output and turbocharged cars. They are not stronger in any structural sense, so a diagnosis does not change between them — but a ratio, a speedometer calibration or a differential part does.

Its characteristic failure is the input shaft bearing, and it announces itself in a way that is close to diagnostic: a whine or growl present in neutral with the clutch pedal out, which goes quiet the moment the pedal is pressed. Pressing the pedal unloads that exact bearing; a noise that behaves the other way round is a different fault.

Second-gear synchro wear is the other recurring item, crunching on a fast change when cold and nowhere else — and it is worth distinguishing from a clutch that is not fully releasing, which produces the same crunch in every gear rather than only in second.

A vague or notchy change is usually the linkage. Cables and bushes are a fraction of the cost of anything inside the gearbox, and they are what wears first.