Brake Help Needed - RF locking up - pistons not stuck - what is it?

[hzl6cm]

Last time I drove my '70 the right front brake locked upwhile I was on the highway after brake at a stop sign. I was driving about a 40mile loop, it locked up briefly (maybe for 50 yards) and then released. Ithought , what the heck? and kept driving. When I was almost home and brakingfor a stop sign coming in to the small town near where I lived it locked up bigtime at didn't really want to release. I was able to get going, with the brakepads on the right front smoking big time. It did release somewhat and I wasable to drive through town without using the brakes again (helped by the4-speed manual tranny. Unfortunately the door tom my workshop was closed andwhen I rolled to a stop in the grass outside of the workshop again I wasn'table to get going again since the ground was a little wet and the brake wasstill partially locked - I just dug holes with my back tires. Unfortunately abig thunderstorm was coming in so I was trying to get it in the garage in ahurry since the top wasn't too water tight. The only way I could release thebrake was to unscrew the brake pipes at the distribution block. It had beenabout six months since I had last driven the car before this had happened. Thecar has power brakes and I hadn't done anything to the brakes in the 10 yearsor so that I had the car. Today I finally put the car up on the lift anddecided to finally look at the brakes (a year and a half or more since ithappened). I started with the right front brake, thinking I had a stuck pistonor swollen hose. I pulled the brake caliper off and all of the pistons movedfreely and the bleed valve came right out and I was able pull air and fluidthrough the system with my hand held vacuum bleeder. I pulled the hose off anywayand it seemed fine inside, I was able to pull air through it easily. I loosenedthe bleed valves on the other three calipers, pulled air and fluid through themand I pulled all of the brake pads and pried all of the pistons back and theyseemed to move easily. I also pulled the other front brake hose off and itseemed fine inside. I don't know the history of what had been done with thebrakes in the past and this is the first time I've had the wheels off in the 12years or so that I've had the car, but as far as I can tell the calipers andmaster cylinder are all originals, they all look a little cruddy but nothingleaks. Originally I had planned to get one of those all inclusive brake kitsfor about $400 (the one with a new MC and 4 rebuilt ss sleeved calipers, newbrakes hoses and pads), but now with all of the pistons moving freely and thebleed valves all working fine I am thinking of just replacing the front hoses,installing new front and rear pads and thoroughly flushing the system withfresh brake fluid and seeing how it all works, total cost about $50. Anythingelse I should look for? The fluid that was left was all pretty cruddy so maybea bit of sludge was caught somewhere and made it so the RF brake wouldn'treturn, I can't think of anything else that would just stick brake on onewheel. Thanks.

 

[GTR1999]

I believe it was the hoses, BF,and long time period. I would at least take the calipers apart and reseal them, flush the system, and replace the rubber hoses. Try to bleed the system when you take it out of storage next time, the Motive bleeder works the best for this. Good Luck

 

[berry1133@bellsouth.net]

Sounds like your brake hose is collapsing under pressure and not allowing the fluid to release from the calipers.

 

[hzl6cm]

I kind of figured the hose as well, especially once I found out the caliper pistons moved freely. The hose tested fine but the car sat for at least a year and a half since I had the problem, plus I used a torch to heat up the fitting on the brake pipe that screws on to the hose so that I didn't destroy it trying to brake it loose. When I got the nut good and hot it blew the brake hose out of the swadged fitting, so that might have opened up the inside of the hose.

I knew that I should have gone through the brakes earlier, but everything always worked fine on the car so I never got to it, plus the car is somewhat of a rat so I figured the brake bleeders would be rusted solid - a concern that turned out to be misplaced.

I've had brake hoses swell internally at least three different cars that I can think of so it isn't all that uncommon for them to look good on the outside but be bad on the inside. I had the front hoses swell on a very clean 42,000 mile '82 Camaro that I picked up as a CP autocrosser about 6 years ago. I also just recently picked up an '87 Fiero for the kids to autocross that had sat for 10 years and both rear brake hoses were so swollen than I couldn't pull any fluid through them.