Ford iB5 / B5

Ford's small five-speed manual transaxle — in the Fiesta, Focus, C-Max, Puma and Transit Connect, over twenty-five years.

It is a light-duty gearbox and the cars it is in are driven hard in traffic, which sets the pattern of what goes wrong: this is a gearbox whose faults are about wear and linkage, not design.

The complaint people report is a change that has gone vague, long or notchy, and on this gearbox it is very often the gear-change cables and their end bushings — a cheap repair repeatedly mistaken for a worn gearbox, because the symptom is identical.

When something inside does wear it is the differential. The iB5's diff bearings and, on higher-mileage cars, the differential pin, produce a whine that rises with road speed and is present in every gear including neutral while moving — which distinguishes it from gear noise, which changes when the gear does.

Second-gear synchro wear accounts for most of the rest, crunching on a fast cold change. A crunch in every gear is the clutch not releasing, which is hydraulic and outside the gearbox.

It is not the MTX-75, the larger transaxle behind the bigger engines in some of the same cars; the two share no parts.