I recently purchased a 55 Buick Century with power brakes and I replaced the rear brake shoes , it has new front brake hoses and a new brake light switch, the problem I have is the brakes drag and cause the rear brake light to come on, adjusted the brakes as the manual says as to the power brake booster . I have hafe a brake petal when start up but as I drive the petal keep coming up until it is a full petal and then the brake light stays on. I have adjusted the brakes at the wheels, is the problem the power brake booster or something else. If I adjust the rod on the power brake booster to where the brake light does not come on I have little or no brake petal at all. I hope any of you can help me with this . If it is the booster where can I get it rebuilt? Thanks--SID
Sounds that you are bulding up pressure in the system for some reason. I would start by checking brake booster and main cylinder.
I would also make sure the wheel cylinders are free. Make sure they release. When the brakes start dragging, crack rear wheel cylinder bleeder and see if they release. Is this still a single reservoir or has it been converted?
There is a big ol' spring on my 54, i'm guessing its the same on the 55. It is on the rod at the master under the seat. Is it stretched out? Worth a look...
Why did you adjust the brake booster if you replaced the rear shoes? Do you get the same issue if you disconnect the vacuum hose from the brake booster?
Or along the same lines, what happens if the OP loosens/ separates the master from the booster? Does the issue go away or remain?
The brake light switch is activated by hydraulic pressure. I agree, it's worth a look at the return spring..