[TR] Weird Brake issue

[Irv Korey]

My car, a 74 TR6, is experiencing a very long brake pedal after I have been
on the road for a while. The pedal goes almost to the floor, just like the
dreaded brake pad knockback. When I drive around town, this doesn't occur,
only on a road trip (I am on my way to VTR). This doesn't happen after a
hard corner, just some highway cruising. My current setup is

new brake rotors
freshly rebuilt Toyota calipers with new pads
Uncle Jack front stub axle, wheel bearing kit, front hubs
new ss brake lines
new aluminum drums
new 7/8" Morgan rear wheel cylinders
new rear shoes
new master cylinder
rebuilt servo
fresh DOT5 fluid, bled twice, no air visible

Using the grab the wheels and shake test, the wheel bearings are tight. I am
not losing any brake fluid. I was, and discovered that the o-rings in the
PDWA were bad, and was losing fluid and I imagine brake system pressure from
under the switch. I just discovered the source of that leak just before
leaving for VTR, and didn't have time to replace the o-rings so I removed
the switch and put a plug in its place. Other than this issue, the car stops
great.

Any thoughts/ideas/suggestions gratefully accepted.

Thanks,

Irv Korey
74 TR6CF22767U
Highland Park, IL (now in Council Bluffs, IA)