Sudden Extra Clutch Pedal Play ?

[Robert Crandall]

My clutch pedal suddenly went from 1 to 2 inches of play to near half its travel distance of play.

My truck is a 1978 C20, 292, granny gear 4-spd. I bought it new. This has happened twice before. Reviewing my records shows it happened at 163k miles and again at 233k miles. In both cases I replaced the clutch to fix it. The speedometer broke at 365k miles, so I estimate that I now have around 380k miles, and the same thing just happened again. It takes me 2 evenings after work to get the clutch out and 2 more to get it back in. I don't want to do it again.

Does anyone know what happens to cause this? In all three occurrences, the clutch works fine, but I have to stretch and get the pedal to the floor to use it. I adjusted the linkage a little, but the play is not free, open play.

Thanks.