OK, are you saying that the brakes lock up while applying and let loose as soon as you let of the pedal or that they are staying locked after releasing. Alot of these answers are refering to the brakes staying on after you get off the brake but you kinda made it sound as if you meant the back lock before the front but release as soon as you are off the brake pedal. Just wanted to make sure which so you can get the right answers.