[cbreez]

Alignment theoretically could be a problem...but I have done many clutch repairs and have never seen that problem with a quality aftermarket transmission or bellhousing such as you have...the manufacturing quality is too good, so it's not likely.

The reason heat is affecting things is that when cold, the master and slave will hold better pressure. When you begin to introduce some heat, the rubber/neoprene softens and your hydraulic pressure will weaken and it will still work BUT not give the same movement to disengage your clutch.

If everything works cold, there is no problem with the transmission, pilot bearing, bell housing alignment, brackets, etc. It is internal hydraulics, period. Don't go down the wrong bunny trail.

For what it's worth, my car had a no good, leaky, stock Mazda slave cylinder fail at 600 miles. I replaced it with the same stock Mazda slave, and I use DOT 5 silicone fluid, and 2 years later it's still working properly. Plus I live in Fl. where there is overall higher ambient heat to boot! Works for me! Good Luck to you.