Clutch Clinic: Nissan Micra K12

Concentric slave cylinders make sense from a design viewpoint, but cylinder failure means a gearbox-out operation. Kim Henson explains how the job can be tackled at home.

As with many modern cars, recent versions of the Nissan Micra are fitted with a concentric clutch hydraulic slave cylinder. Instead of being attached to the outside of the engine/transmission bellhousing, where they are fairly accessible, they are mounted within the bellhousing and around the gearbox first motion shaft. In this position, they can exert pressure directly and evenly onto the release bearing, so there is no requirement for a release fork/arm to move the bearing in response to clutch pedal pressure. On the other hand, when the slave cylinder seal gives up the ghost, hydraulic fluid will escape and the clutch will no longer operate. An early sign of impending failure of the clutch system is a trail of hydraulic fluid coming from the bellhousing.

Unfortunately, the only way to access and renew the concentric slave cylinder is to take out the transmission assembly. As this is a lengthy process, especially if you’re working at home, it makes sense to renew the clutch driven plate, pressure plate and release bearing at the same time, regardless of how worn the clutch components look. Conversely, if you need to renew the clutch driven plate, pressure plate and release bearing, we recommend you fit a new slave cylinder at the same time.

Always fit all three of the main clutch components – the driven plate, pressure plate assembly and release bearing – at the same time. Kits are available to tackle the entire job.

It is a good idea to make notes and draw diagrams as required, to ensure correct refitting of components. It also pays to temporarily place all parts and fasteners removed from the car in clearly-labelled containers.