Having some brake problems...please help!!!

[malibu9in]

78 Malibu g body. I did a lsx swap and in the process i did some brake up grades as well. The car has Baer track system with pbr calipers. I had the Front calipers and parts powercoated. I also changed from a brake booster to a factory style grand national hydraboost. I changed all the brake lines from the prop valve forward to braided stainless. The diameters of the lines from the master cylinder down to the prop valve are the same ( stainlees braided from areoquipe). From the prop valve back to the rear is the same...bear discs as well on the rear. I had zero problems before. This is what the car is doing. Car has a awesome pedal when cool. As i drive the car for about 30 min or so with NORMAL stop and go driving the pedal starts to get harder and the car starts to stop on its own. You can smell the brakes. I left the car on a slight incline with it in nuetral, the car didnt move...as it cooled down it started to roll. All the rotors are reading about 340 degrees. I do believe the front calipers are free of trash and have no powder in spots where it does not belong. After 30 min of driving you can tap the brake pedal and the car will stop on a dime. Then its hell getting it to move again. I don't have a clue on whats going on. It's almost like the hydroboost is building to much pressure??? All new lines, new master, a new ( rebuilt ) hydroboost, correct size lines for hydroboost, power streering is great, Thanks for taking the time to read. Im about this close to swaping back to a booster...Any ideas are fantastic.

[MonzaRacer]

Are saying that you used stainless steel flexible brake line from front to back? if so you need to run some hard lines from prop valves to wheels.
Also are those lines anywhere near exhaust, actually sounds like you may have heat building up in the lines.
Also are they the teflon lined hose? if not its way wrong for brakes.
Actually only flex lines should be from frame to wheels.
also make sure pedal is returning all the way.

[malibu9in]

All the lines are braided from the prop valve forward. They are teflon lined. I dont see heat as being a factor, but i will take another look. Thanks for your time on the reply.

[HILROD]

Look into the hydroboost. How are the return lines run? I've seen that when the returns are t'd into each other, this can happen. Good luck.

[malibu9in]

They are t'eed right at the return. I just drove the car and it's great...25min later back to square one. Yall think it's the hydraboost? i think that might be the problem too.

[Apogee]

It sounds like you may not have enough freeplay between the MC and the pushrod coming out of the hydro-boost. If that isn't allowing the piston to fully retract, you will have the issue that you're describing. I personally am not a big fan of the GN style electro-hydro units...ugly, horribly expensive units IMO.

Tobin
KORE3

[malibu9in]

its not electric. it runs off of the power steering unit. I will look into the rod as well. thanks again guys.