OK so I have racked my brain trying to figure out my issue. First off I have a '93 CX hatch with a LS swap and my problem is after 10 minutes of driving my car, the brakes build up so much pressure it gets near impossible to drive the car. The brake pedal is so stiff it barely moves. All the wheels are locking up but the fronts are especially worse. It drives just fine until after you drive the car a few miles but after that the brakes start to freeze up. Here's alittle history of what I have done with the car.

I did a rear disc conversion with 94+ Integra brakes. Trailing arms and all.
I have replaced both front and rear rubber brake lines that go to the caliper
I have replaced all calipers besides the front driver side.
I have replaced the brake booster
I have replaced the master cylinder
Ive bled the brakes so many times and there is definitely no air in the lines I can confirm that.

The only thing I haven't replaced is the prop valve, which is the stock 30/30. Could that be causing my issue?? The car drove just fine before besides the brake pedal seemed too soft over normal. It just randomly started building up pressure one day and I cant think of anything else it could be!

Could anyone let me know what could be causing this so I can fix it and get this thing back on the road I greatly appreciate it!

 

do u have the vacum line on that connects the brake booster up to the intake mani. i know when my car is off if u pump the breaks they get really hard till u start it and it pulls a vacum. if it is connected id pull it off and make sure its not cloged

 

Yep I already checked that. That's not the issue either. I pulled it off and blew into it and its perfect. I even took a different one and put it on but didnt change anything so I know for a fact that's not the issue.

 

So I replaced the prop valce with a 4040 and it still didnt fix my issue. The brakes bled fine and I drove the car down the road and it did perfect until about 3 miles of driving then I noticed the brake pedal getting stiffer. I drove about another mile and bu the time I got home the front brakes were smoking hot and the pedal would barely move. 45 minutes later, after I let it cool down, I started it up and everything was back the way it used to be. The brakes arent locked up anymore and the pedal basically went to the floor.

Does anybody else have a clue? Every brake component has been replaced and Im still not gotten anywhere. Maybe the new booster is bad??? Please help!

 

Which master cylinder and which booster are you using?

Have you checked the master cylinder pushrod depth at the back of the MC and compared the pushrod length sticking out of the booster?

Have you tried driving the car without the booster assist to see if the problem persists?

After the brakes have locked up have you tried loosening the master cylinder mounting bolts and see if the brakes release?

 

my bet would be on a mis-adjusted pedal rod.