I've searched for the answer prior to the post, did the suggested fixes, yet the problem still persists. Integra GSR brake swap on a Civic, has been on the car for over 15 years, but the car sits a lot. Trying to get in back road worthy and have had continuous brake issues. After driving for abut 10 minutes, the pedal pumps up and the front brakes lock up. Here's what I've done so far. Replaced brake booster with new booster. Replaced master cylinder with one from a junk yard. Removed both front calipers, disassembled and cleaned, greased, reinstalled. Flushed the fluid through 2 times. Adjusted the booster rod to brake pedal. Check valve is working properly in vacuum line. At this point it seems like the only other possible part to replace is the proportioning valve since everything else has been replaced. Any thoughts or suggestions aside from everything I've already done would be greatly appreciated.

 

Forgot to mention one thing. We I removed the vacuum line, it didn't release any pressure. It seems like the booster is building pressure and won't release it. Thoughts?

 

Pushrod adjustment
Search Honda brake booster push rod adjustment.

https://www.google.com/search?client...d+adjustment.+

 

If the front brakes are dragging then it is probably the booster rod is inneed of adjustment.
Try adjusting it on the slightly loose side of expected.
Recheck the MC as well if you are mixmatching parts the depth of the hole for the rod can change depending on mode, and the rod length may not have enough adjustment.
Also check your rear brakes.
Verify the caliper cables are not sticking/dragging, and they are fully releasing. Manually actuate the parking brake lever on the rear calipers and make sure they are fully releasing as well. If they do not fully release and returns the levers to the stop bolt position, the rear calipers may not fully auto adjust.