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I just picked up this big
block 68 convertible a couple months ago and have been trying to drive it as I'm working on it and it seems every drive nets a repair. I can't wait till these growing pains are over and i won't have to fix it all the time.
The brakes worked great, for manual brakes, until a few days ago. The pedal got very stiff and it seems the front brakes are not working. I had a panic stop situation and the rear brakes locked up, not offering much stopping power at all. Fortunately, there wasn't an accident.
So, real stiff pedal, no front brakes, where do I start?
Taking the cap off the master cylinder and checking the condition of the brake fluid is where I would start.
Was the car just sitting around for a long time before you bought it ?
Is the brake light coming on in the dash board? Does it work with pulling the handbrake lever on and off ?
The fluid levels are good and it appears pretty clear.
I think it had been sitting for a year or so.
The warning light does come on intermittently depending on the pressure applied.
The handbrake is on my to do list, it needs a cable.
Look for leaking calipers, Look at the rubber lines to the calipers. Its possible they have swollen and not allowing enough fluid to pass. The MC could be shot. The clear fluid could be they just removed the old crappy fluid and put in new so it does not look so bad. If you have the wheels off have someone push the pedal and see if you see any movement in the front calipers.
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Do the easy stuff first. Try bleeding the front brakes to see if you get good solid stream out of the bleeders. If not then the hoses are probably swollen, clogged or crushed. They are an easy and cheap replacement and should be replaced if they are old anyway. If they are clear then it could be the master but I never had one fail like that, but that doesnt mean its not possible
collapsed rubber hose,
pinched steel line on front,
master cylinder seal leaking back thru the piston rod in the front circuit.
if air in line you would not have firm pedal.
all possible...
take the car out, drive it around, apply brakes several times, get it home and test heat at all 4 rotors to confirm that the fronts are not hot at all. ideally all 4 should be the same temperature.
I won't be able to get the wheels off until this weekend to check for caliper movement. I should probably go ahead and replace the hoses but if one of them were bad, wouldn't the other front brake still work? I'm thinking there is something wonky with the master cylinder or possibly the line that goes from the MC to the three-way. Maybe a clog in there somewhere?
I'll be taking a good look this weekend, am I missing anything?
Most likely, you have developed a fluid leak somewhere in the front portion of the system. When that happens, the fluid pressure differential (front vs. rear) causes the shuttle valve in the brake distribution block to trip and move to shut of the leaking portion of the system. The pedal will stay solid, as the leaking component is disconnected from the yet working part of the brake system. Check the inside of your front wheels and around the master cylinder for fluid leakage.
The rubber jumper hoses at each wheel are a "risk" item as well. They could develop a leak...or they could disintegrate internally to actually block the release of applied pressure, which causes a partial apply to occur. If they are old (originals?), change them.
05-29-2019, 05:14 PM
68 Stiff Pedal, No Front Brakes
