I drove my '68 the other day after it had sat in the garage for some period of time (many, many months of work). I was in my neighborhood on a "shake-down" run and came to a stop. When I pulled away the left front caliper wouldn't release. I drove the tenth of a mile back to my house. By then, smoke was billowing from the left front. No major problem, the caliper had seized and would need a rebuild... right? Wrong. After everything cooled down I removed the caliper (4-piston) and the pistons move freely (not seized). But, when I disconnected the brake line NO BRAKE FLUID came out. There was fluid in the line (I can see it wanting to drip... but it doesn't) and caliper (when I push the pistons, fluid shoots out). What gives? Any ideas what might cause the caliper to clamp down and not release until it cools off? And what about the fluid not running out all over the garage floor? Is this a master cylinder issue? By the way, I removed the right caliper and line and got a nice "pool" of brake fluid. I've never experienced anything like this!

My first guess would be a bad caliper hose. Is it old? They deteiorate from the inside out and can cause problems similar to what you describe. I'd check that out first. ;)

[ 09-11-2003, 12:45 PM: Message edited by: bretcopsey ]

The same thing happened to me on my 64 Nova last year. It has single piston calipers. They were on the car for a couple of years with no problems. Then the seizing problem on the way to work one day. I pulled the wheel after it cooled off, couldn't find a problem, and have never had a problem since. I suspect it had dirt/rust in the caliper, but I really don't know. I don't know the history of the calipers, and didn't rebuild them. In my case, it couldn't be the hoses or M/C as they were all new. My car is also driven daily. I know this may not be of any help, I'm just relaying my experience.

Tim

I've had the exact problem you describe on my last '69. Drove me NUTS!!

Turned out to be a bad proportioning valve. Bought a new combo valve from MP Brakes, and everything was fine.

Probably a swollen hose.

-Mark.

I had a similar problem with my rear brakes and the flex hose. When they get old they will let the fluid push through under pressure, but will not let it back as the fluid return is more of just a pressure release. The fluid will seep back very slow so a short time later everything seems fine again. What you can do is pump it up until it locks up again and then work from the caliper backwards. First, crack the bleed screw at the caliper and see if pressure releases. If it does not it's a problem with the caliper. If it does it's a fluid return problem further upstream. If that is the case. repeat the process by pumping up to lock again and then crack the line on the master cylinder side of the flex line. Once you get on the other side of the clog breaking the line will not release the pressure and you have found your problem. Basically what you are doing is working backward from the problem. Could be any number of things, but typically its the rubber line. They wear from the inside, so even if it looks good it might still be bad. Good luck.

I dunno.... no fluid immediately pouring out of the hose? Even after sitting it should at least drip.
I'd leave the hose off, drop the end on a catch can and then have someone apply the brakes lightly and slowely. Even light and slow it should flow real good through the hose. That'll tell you if it's the prop valve or a line\hose.

On the other hand, the left caliper is the first to get any pressure so maybe it got TOO much.

Thanks for the suggestions! The rubber lines look pretty bad (dry-rot). I'll start there since they're cheap and need replacing anyway. Then, I'll start moving my way up the brake system.

one other thought, how close is the line to your exhaust/headers?
my fathers 66 GTO kept hanging the drivers front up, turned out a small section of the brake line was just too close to his headers, moved the line, problem gone.
the old rubber hoses are more likey though. just a suggestion, good luck....

Good idea. I'll check it. I do have headers instead of manifolds.

Change the hose, better yet, change all three of them. If the front one locked a caliper, the center rear one will lock both rear drums. Try to use the best brake fluid you can find, IMO the cheap one causes premature hose clogging. I always use dot 4 or better, not 5.

All the rear brake stuff is new. I replaced it when I swapped rear ends last year. New caliper lines and hoses are on the way. I'll post the results.

Hey ET, what's the story with your brakes? Any progress?