Front Brakes Locking On After Car Idles.

I had a similar problem. My front brakes would lock up after driving around for about 20 minutes. I also thought it was heat soak. I even bought a laser temp gauge to check the brake line temperature. The line temps would go up to 180 under the hood but as it turned out it was the push rod in the Master Cylinder. As long as you have some space (above the fluid level) in your MC any line pressure should be able to bleed back up into that space. When you step on the brake pedal fluid is forced out and when you release the brake some fluid flows back up to the MC. If that didn't happen your brakes would be locked up all the time. That's why MCs have a flexible rubber boot under the cap (or a small vent hole), so that pressure isn't static.
Get the front wheels off the ground, remove the MC (but leave it attached and floating), start your engine and spin the tires/wheels (by hand) every 10/15 minutes to see if it makes a difference....it won't cost a dime (except for the gasoline!!). That's how I figured it out on my car!!!:steering::thumbsup:

Treblig