Getrag 6DCT450 (MPS6)

The wet-clutch six-speed dual-clutch gearbox Getrag built for larger transverse cars, rated to 450 Nm and fitted by Ford and Volvo from 2008. Volvo developed it with Getrag and calls it MPS6; both marques sold it to customers as PowerShift, and that shared name is the source of more confusion than any other gearbox on this site.

If you have arrived here because a Fiesta or a small Focus is juddering, this is not your gearbox. Ford applied the PowerShift badge to two entirely different machines: the dry-clutch 6DCT250 (DPS6) in the Fiesta, small Focus and EcoSport, and this wet-clutch unit in the Mondeo, S-Max, Galaxy and Kuga and across the Volvo range. The clutches here run submerged in about seven litres of fluid; the dry one has under two litres of gear oil and friction faces with nowhere to put their heat. They fail differently, they are serviced differently, and advice written for one is close to useless for the other. The Focus is the model where both were actually sold, which is exactly where the confusion does the most damage.

The layout is the conventional one for a dual-clutch: one clutch carries the odd gears and reverse, the other the even gears, and the next ratio is already engaged before the change happens — so there is no interruption in drive. Because the clutches are cooled by the fluid they sit in, this unit tolerates the traffic, hill starts and towing that destroy a dry one. That is the whole reason it exists at the torque ratings it does.

Its defining weakness is a small plastic part, and it is a design fault rather than neglect. The clutch damper springs are located by plastic guides that carry the engine's full torque on its way to the clutch baskets. They sag, crack and eventually disintegrate, and the debris goes into the same fluid that feeds everything else. A gearbox that has begun to shift roughly and noisily, without any history of abuse, is very often describing this.

The wet design's own trade-off is the second theme. Fluid that cools the clutches also carries away what the clutches shed, and it carries it straight into the valve body:

• Clutch pack wear, which is a wear item here rather than a scandal — the trade expects to be into them somewhere beyond 100,000 km.
• Clogged mechatronic solenoids and valve body passages, the direct consequence of the above, and what turns smooth shifting into jerking.
• Cracked plastic tips on the shift forks, which break under abrupt take-offs and produce a refusal to engage that is not a clutch fault at all.
• Input shaft bearing wear and seal leaks, which arrive late and announce themselves as vibration.
• Input shaft speed sensor failure, which makes a sound gearbox behave like a broken one — read the codes before agreeing to anything.
• Soldering failures inside the control unit on units built up to late 2016, which are electronic rather than mechanical and present abruptly.

The honest summary, and it is a different verdict from the dry unit's. This gearbox has a poor reputation and a good deal of it is inherited from the machine it shares a badge with. Its own faults are real — the damper guides especially — but they are repairable wear in a serviceable design, and it responds to fluid changes in a way the dry unit never could. The fluid is a genuine service item at roughly 45,000 km and not a lifetime fill, and it is the single thing that decides how the rest of the list above arrives.