47-55.1 Electric hydraulic power brakes problem

[leegreen]

So that is a master cylinder with built-in hydraulic power servo? I have no experience but my thoughts are that it is either a pedal adjustment issue, where the pedal is putting some pressure on master at all times or there is something wrong with the power boost servo and it is always applying braking force.

It sounds like it has gotten worse which would seem to indicate the servo failing. If you disconnected everything but the 2 lines to the pump and ran the pump I wonder if you'd find fluid coming out the two brake line ports. It would be a difficult and messy test, see what the supplier has to say first.

Since your build is all new stuff I'm assuming you don't have water in the brake fluid boiling to steam and locking brakes up, or sticking caliper slides, or overly tight drum brake adjustments, or collapsed flexible brake lines, those could all cause locking up brakes.