Clutch action gone - Master of slave cylinder?

[lewis s]

The clutch went on the MGF last night, it still just about works, but the majority of the travel is just slack as though there is loads of air in the system and its not disengaging fully. The clutch fluid level is still fine and whilst getting my dad to work the clutch pedal i cannot see any fluid leaking from either the master or slave cylinder. What is likely to be the cause as we have to get this sorted this week as we have a track day booked up for next weekend

[Steve_D]

First thing I would be looking for is to see if the clutch slave cylinder is travelling what I would guess to be normal travel.
If it is not then the master cylinder is at fault.
If it is then you have a failure somewhere inside the release mechanism or even the clutch pressure plate itself..Does the clutch slip?

For the slave cylinder to be at fault there would be fluid loss.
A master cylinder would normally fail without fluid loss.

Steve

[lewis s]

Thanks Steve

How will i find out what normal slave cylinder travel is? At the moment its roughly just over 10mm?

I'm suspecting the master cylinder now then. I will pop down the scrappy's tomorrow and try to pick one up.

[Steve_D]

lewis s said:

....How will i find out what normal slave cylinder travel is? At the moment its roughly just over 10mm?........

Just look at the outside of the cylinder and guess from its length how far you think a piston inside could move. Way more than 10mm I would think.

If you can, get someone to pump the pedal repeatedly/quickly and see if you can get more travel. If you do then get them to hold the pedal down after the pumps and see if your new found travel goes back. A sure sign of the seals failed in the master cylinder.

Steve

[lewis s]

Got a new master cylinder from the breakers today for £20, fitted and bled up and now all is working well! Thanks for your help

[Steve_D]

lewis s said:

Got a new master cylinder from the breakers today for £20, fitted and bled up and now all is working well! Thanks for your help

No problem.

Steve

PS I shall have stern words with anyone who thinks about replacing a brake master cylinder with second hand....life is not worth the extra £££ for a new one.