911 Transmission hard to shift after driving 1 hour

[911Tfan]

Hi, I have a 1970 911T that I drive often. I have had the clutch disc replaced as well as most of the hardware associated with it. A problem that I had before was caused by the clutch fork pivot bolt slowly unscrewing itself and letting the clutch adjustment to change making shifting difficult. this was because after the pivot backed out, the clutch was not disengaging completely and the gears were still spinning even when clutch was fully depressed.
i don't believe this is happening again but after driving around for about an hour in 80-85 degree weather I feel the shifter becoming tighter and tighter until it is very hard to select a gear. It seems that some part is expanding due to heat buildup because after cooling down the problem goes away. At times i have had to limp home in third so I don't have to shift and at lights the car wants to stall as the clutch is partly engaged. If it was clutch wear or the pivot bolt backing out I think the problem would not dissappear after cooling down. Any ideas?

[Norm01]

Cable? Is it possible you have a very old clutch cable that's stretching.

[911Tfan]

UPDATE
I tried to drive yesterday and the clutch won't release at all . I can pop it out of gear into neutral but when a gear is selected and I try to start engine the car rolls even with the clutch pedal all the way in.
I am starting to think the fork pivot bolt is working its way out again but I hope not.

[911Tfan]

Could it be the clutch disk I bought?

[NICE 69 S]

+1 on clutch cable. It could be broken and unraveling, adding to it's length. Pull it out and check it's length compared to a new one. If you do have to pull the engine, put some LocTite on that pivot bolt.
Bob B

[911Tfan]

I thought about locktite on the pivot bolt. If it does come out I am gonna check how that bolt is first thing. If that is it I'm gonna be pissed.

[911Tfan]

I was looking at the car today and the clutch pedal does seem to have dropped an inch.

[pete3799]

Check the roll pin that goes through the clutch pedal down at the pedal cluster.

[911Tfan]

I checked the roll pin and without removing it it looks ok but I noticed that with my hand I can move the pedal all over, like 3/4 inch to the left, 3/4 inch to the right, just sort of loose compared to the brake pedal for instance. Also I notice the big coil spring on the brake pedal returns it all the way back to the stop when pressure is not being applied to it.

[69911e]

Watch the cable/pedal attachment as you push the pedal in to check pin integrity; they shear and you can't see it.

If good, have some one press pedal while you look at the arm movement.

Verify cable length is adjusted properly.

If all good, pull trans.

[notmytarga]

That is one loose pedal! Left and right movement is not in the spec books I didn't consult!

A the least your pedal cluster needs to be pulled and rehabilitated - which requires removal of the roll pin that is likely sheared.