Hey,

My car has a subaru motor, and an A caliper set up up front with a stock 914 rear and no prop valve.

What I'm finding is that when the car is at rest, the brake pedal has a bit of slop in it. When the car warms up a bit - say I drive it 10 miles or so; the pedal firms right up and seems to be sitting right on the stop (it's usually about a quarter inch or so of slop).

The only think I can think of is that there's some water somewhere in teh system (maybe near or in a caliper) that is expanding when things get hot; and causing the system to pressurize a bit.

The car does stop okay but:
1) Could it overpressure and burst something (my guess is no, because hitting the brakes hard will product much much more pressure)

2) is it unsafe?

I'm working on my new 914 right now, so I'm trying to avoid putting too much any effort into the old one until I start actually putting the new one together.

Anyone else run into something similar? It's always something eh?

If the lines overheat the fluid will boil and you'll lose brake pressure completely.

Could it just be that you have a bubble in the lines? Can you 'pump up' pressure while it's cold by hitting the pedal a few times?

Check your venting on the rear calipers....might be it.