Clutch master cylinder, slave cylinder and bleeding

Which part has failed?

• Pedal goes to the floor and fluid is dripping at the master cylinder (the owner found it by tracing where the fluid went): the master cylinder has failed.
• Pedal feels floppy or the car is hard to get into gear, perhaps after hard track use: suspect air in the system. One owner's symptoms returned after a few track laps, and he bled the clutch to fix them.
• Clutch slip can come from air that expands as it warms up, so bleed it before blaming the clutch. Check the pedal return spring too.
• Fluid leaking from the gearbox top can be the bleed turret, not the slave cylinder. See the F23 guide.

Master cylinder

The Vauxhall part (9197407) was reported as unavailable new, with no rebuild kit, in 2018. Options discussed:

• Buy a new one from Vauxhall or an aftermarket supplier. One owner expected it to cost no more than about £100 as the part is shared with many other cars. He advises not to rebuild it, because the tolerances on hydraulic parts are too tight for home rebuilds to be reliable.
• Astra 2.2 master cylinder: one owner says it is just an Astra 2.2 part, and recommends a decent make such as LUK (part number 510003810, for NA or supercharged cars, as he gave it).
• Other Vauxhalls of the same era (Vectra B, Astra G, Zafira A) are thought to be similar. Looking closely, the owner replacing his found the Vectra B outlet has the wrong angle, and the Zafira one has the right angle but embedded studs that might be hard to fit.
• Lotus Elise (2006 to 2012) or Europa part: it looks like it fits. The owner reasoned that the bore is the same as the one used with the M32 gearbox, so it should suit an F23, and another owner uses the VX220 F23 master cylinder with an M32 gearbox without problems. This is reasoning from the thread, not a tested fit.

The Europa shares many parts with the VX220. A Lotus part number that starts with a letter followed directly by "116" identifies them (for example B116C0004F).

Slave cylinder

• It is mounted on the gearbox, so the gearbox has to come out to replace it. This can be done from underneath, without removing the engine. See Clutch replacement: dropping the gearbox.
• One owner suggested the whole engine and gearbox can be tilted by loosening the offside engine mount, without removing the exhaust. Another said you need to take off the downpipe. The threads don't settle this.
• Cost: about £75 from a parts chain (2017), or £119.95 with a Courtenay clutch (2013).
• An owner couldn't say whether an Astra G slave cylinder could be used, and the thread didn't answer him.
• Always fit a new one when you change the clutch. Quality varies: one owner found the "quality" OEM part poor, and two non-OEM ones fine.
• An owner who fitted an M32 gearbox says he had to adjust the slave cylinder spacer on it, which meant dropping the gearbox again. The thread has no detail.

Bleeding the clutch

• The brake and clutch share one reservoir, in the front clam. Top it up as you go.
• Where the bleed valve is (Turbo): in the engine bay, to the left of the main block. Take the engine cover off. One owner undid the 9 mm nut on the right of the slave cylinder. The brake fluid guide lists a 6 mm spanner for the clutch valve, so try both sizes on your car. The NA bleed valve isn't described.
• Two-person method: one person sits in the car and pumps the pedal while the other loosens the bleed valve. Repeat until the air comes out, then tighten the valve and the reservoir cap. The pedal should feel solid.
• Pressure bleeding: one owner says the service manual claims pressure bleeders don't work as well when air is trapped. The F23 guide reports that a pressure bleeder worked well for them. See F23 gearbox removal and clutch replacement for that method.
• If you only have a pedal that returns, it is hard to tell whether air is still in the system, so bleed it again before you assume the clutch is worn. One owner's clutch slip improved after a second bleed, but didn't go away.
• Why air gets in: an owner who bled his said many Lotus owners have changed the clutch hose because it has a tendency to let air in, especially under track stress. That is his reading from the Lotus website, not confirmed here.