MY95, on hard boost in 5th for a good length of time, when i come to the end of the fun and go to change down to 4th i notice the clutch pedal a bit lower than it usually is, a quick flip of foot under the pedal springs it back to its normal position.

Only happens with 5th gear pulls not if i give it beans in other gears

clutch is good, flywheel is good etc

could it be the slave or master cylinder ?

cheers

 

Check if the small spring that attached to the clutch fork arm is still there.
If still intact, might have to bend the bracket to increase the spring tension.

 

could it be heat related?

Even a small amount of air in the clutch line will mean the pedal doesn't behave correctly. What I'm thinking here is that if you have a small amount of air, but put a lot of heat into the clutch fluid from the engine, turbo etc heating up the engine bay, the air will expand and thus take larger room, which would make the clutch feel like it had more air in it than when the engine was cold.

The clutch is a bit of a pig to bleed, btw... I've only ever had success when I've disconnected the slave cylinder from the box and angled it so that the bleed nipple is at the very top (if you leave it on the engine block, this is not the case). Remember to block the piston with a g clamp or similar if you do disconnect, as otherwise you'll probably push it out.


Personally, I'd start off with fresh clutch fluid and bleeding, especially if the clutch goes back to feeling normal after cooling down.