M8 Greyhound clutch problem

[Malcolm Towrie]

Originally Posted by Lynn Eades

Does the master cylinder have a residual line pressure valve in the end of it?
Is there a rubber seal for it to seat on?
Is the R.L.V. functioning correctly?
Has someone added a non std. return spring to the clutch fork?
Is there lost motion at the push rod? (m/cyl.)
Are the M/cyl and slave cyl. the correct bore sizes?
It sounds like you have done a good job of getting the air out, so I doubt it is the air?

Lynn,
Yes, the m/c has a residual pressure valve. The rubber seal looks in good condition, as does the rest of the valve. I haven't checked it actually traps pressure in the line, because, to be honest, I'm not sure how a bad valve would explain what is happening.

I installed a new slave cylinder. There is a heavy return spring on the new slave cylinder that's looks the same as the one on the original slave cylinder (which was replaced because it leaked). I don't know if the clutch fork itself has an internal return spring. Why would this be a factor?

I have minimized the lost motion on the m/c in a rather desperate attempt to get a bit more m/c piston movement to get the clutch to work but it made no difference. Same for the lost motion at the slave cylinder end.

Re bore sizes, I don't know if they are stock. The new slave cylinder certainly made no difference so I assume original and new were the same bore. The m/c bore size is 1", the slave cylinder bore size is 1.25". See my post above for volumes pumped. I suspect the smaller volume pumped by the m/c is to prevent the slave cylinder bottoming out the release bearing and overloading it.

Malcolm