Front brakes not releasing

[Boats90GT]

1990 GT, Front brakes (both) not fully releasing . Car had the issue when I bought it so threw money at it with new hoses, calipers and pads, inspected and repacked bearings. Still not releasing fully. Car came with Wilwood proportioning valve so the factory one is long gone. Would like to remove that and put back OEM one but anyway. Anyone know what else I can check? Also just realized when I start the car they release but when I hit the brakes with car still running they don't fully release, Kind of doesn't make any sense. Thanks

 

[nickyb]

When you bleed the calipers how was the flow? Could be kinked/clogged line.

 

[Boats90GT]

When you bleed the calipers how was the flow? Could be kinked/clogged line.

flow was good no issues.

 

[rednotch]

What master and booster? The push rod probably needs adjustment if nothing else is causing it to hold pressure.

 

[FastDriver]

Bad booster or caliper? Both sides binding? Doesn't have a line lock, does it?

 

[nickyb]

Also check that the calipers slide on the pins freely,they maybe hanging up

 

[Qtrhrse23]

Calipers.

 

[rednotch]

Both sides means sometimes holding the pressure, only thing he didn't swap was the master and booster... Doubt its the prop valve since everyone mounts those for the rear bias... Either booster rod too far out or MC psiton seals messed up one of them isn't allowing it to fully release.

 

[FastDriver]

Yep. Why I asked about the booster first. When the booster is compromised, it can build a vacuum that brakes the front. With engine shut off, that goes away. This was a year-long painful issue to work through with a brand new LMR 93 Cobra booster.

 

[AeroCoupe]

Went back and read the fist post and the OP said the factory proportioning valve is gone. With that I am gonna have to ask the OP an important question...what do you mean by the facoty proportioning valve is gone? Did the previous owner remove it from the factory combination valve and and leave the rest of it intact such that you have factory plumbing or did they remove the combination valve completely and all you have is a manual proportioning valve for the rear brakes and some custom plumbing?

For reference this is the factory combination valve with instructions on what to remove to delete the proportioning valve side of it.