do i have to remove gearbox of 1.8 mondeo to change clutch slave?

Yes, they are fitted with a concentric slave cylinder which has the thrust bearing built into it, as the whole gearbox has to come out, which is a complete pain, you'd be as well putting a new clutch in as well. It's not a DIY job unless you REALLY know your stuff. Make sure no one squeezes the CSC before fitting as this usually dislodges the internal seal and it leaks as soon as it's bled.

PRFP
February 2008