I have a quirky problem that I hope someone out there can help with.

My 98 S70 T5 clutch has been acting up. It actually sat on the floor once and then came back up a couple of minutes later.

My mechanic bled the lines, replaced the fluid and checked the clutch master cylinder and slave for leaks. He found nothing so concluded that the likely cause was the clutch master cylinder. We changed this for close to $800 Canadian as changing the slave would have been even more expensive. The service manager wanted to change both.

This didnt really fix the problem which seems to be wierd. With the engine off, the clutch is fine. At low rpm's the clutch is fine. But at highway speeds or if I wind it out shifting up, I lose about 1/3 of the play at the top of the clutch. It gradually comes back.

My mechanic has a theory and I dont know if it makes sense. He thinks that the weights on the clutch plate that spin out as the rpm increase must somehow be creating some play before the release bearing makes contact.

Does this make sense?