I've been trying to get my '61 Austin Mini out this year and on the first drive my front left brake locked up. I was in need of new calipers so I replaced the ones on the front wheels. After replacing the caliper I bled the system and adjust the brakes. All wheels are stopping good, but the left front still will not release pressure after pushing brake pedal.
My car still has the drum style brake on all 4 wheels.

Anyone have any idea why this is happening and how to fix it. I would love to put some miles on the car this summer. Thanks

 

First thought would be to replace the spring in the drum as its function is to pull the shoes back when the pedal is released.

But, this spring is really not very strong and if the brakes are holding strong pressure then I suspect the shoes must be binding so I'd be looking for anyplace the shoe could be catching. Some thoughts are

the back plate is rusted and there's something there catching the shoe - take everything off, wire brush then paint with a heat resis' paint.

or

the drum is SO worn that the shoe is dropping into a groove and somehow is actually getting hung up.....solution is new drums and shoes

or - and this is really where you should start - is everything assembled correctly????? If not, there may be restricted movement just for that reason. First time I pulled my rear drums apart I found one side all screwed up assembly wise and it sure explained why I seemed to have no rear brakes (to the point the e-brake could not hold the car AT ALL)

digging deeper into brain cells suggests a blocked brake line that's allowing fluid to go thru under pressure but not return....a one way valve caused by blockage - but you saw nothing wierd when bleeding huh?

just random thoughts .... I'd take apart - de-rust and re-coat.

 

You say you replace "calipers", yet you say you have drum brakes on a 4 wheels? Calipers are disc brakes. Wheel cylinders are drum brakes.

I'll assume the latter is true and you replaced "wheel cylinders" which were leaking or seized in the out position causing the lockup.

Nothing mechanical will cause the pressure to stay in the cylinder. BJ is on to something with the flexible rubber lines. Sometimes these lines deteriorate/break inside and can become blocked. That may cause pressure to be held once applied. Check them. If they are several years old, they should be replaced anyway....

 

I stand corrected I replaced the wheel cylinders. Thanks Minimad & Capt_bj for the info. I will try you ideas. Thanks

 

drum brake guys called 'em "master cylinders" didn't they?

whoops - time post cross -

 

my money is on a bad flexible brake line. if you removed and reinstalled wheel cylinders on it, you may have it twisted as well. You don't want it to look spiraled at all when the wheel cylinder is installed- it should make a nice gradual J going from subframe to brake slave.
--Spank

 

Also, use DOT4 rather than DOT3-- DOT3 will cause the rubber to deteriorate in the lines/cylinders.

I Like Castrol LMA (White with red/green)or Valvoline synthetic (silver can)

 

This is a good possibility. It also is quite possible the line has collapsed internally. When they do they will let the brake fluid move the wheel cyl, but will not let the fluid release once you let off the brake. If you crack the breeder open & can turn the wheel that pretty much tells you. With the age of your Mini I would replace all of the rubber flex lines.

 

I had a similar incident about a month ago, although I've got front disc brakes with braided SS lines. An automotive guru of mine suggested replacing all of the brake fluid because it could have gotten moisture in the line, which will boil and vaporize at a lower temp than the brake fluid, resulting in a locked up brake until the fluid cools down. Not sure if that's what's going on for my Mini, but I thought I'd throw it out there.

I haven't done anything yet, as I'm replacing my entire front brake system.

Jeff

 

Thanks for the added information. I have ordered new brake lines and will try DOT 4 fluid. Thanks again