WagonCrazy
12-03-2015, 07:09 PM
The Setup:
57 wagon with front discs/rear drums
CPP power front disc conversion kit (2 inch drop spindles,10 inch rotors with single piston calipers)
8 inch vacuum booster
CPP dual mastercylinder (front disc, rear drum)
CPP "auto" proportioning valve properly plumbed in.
New rubber brake lines installed. Still holding tight...no leaks.
New steel brake lines installed all the way around 8 years ago.
This brake system has been installed and working just fine for about 8 years now. Haven't had to mess with it.
The Symptom:
Brakes working fine for the first 15 minutes or so.
Then about 2 weeks ago while running around town, hit the brakes and the fronts BOTH "skip". they lock up, release, lock up, release, etc. Very fast, as if I had antilock brakes. Let off the pedal, and brake again...same thing. Then they don't do it for 10 or more minutes afterwards. Intermittant!
No pull to one side or the other....both wheels seem to lock up and release quickly while "firmly on the pedal". Don't really feel it in the pedal at all (like you can with antilock brakes). Brake pedal is firm.
But after one of these events, I smell hot brake pad and the brakes feel like they "faded"...can feel it in the pedal.
First Diagnosis/Fix:
Removed and Disassembled the 2 front calipers, then cleaned up the pistons and inner surfaces. Nothing was scratched/marred/worn BUT there was a sort of hard shellac on portions of the piston surface, and what looked like a little rust shellac'd on them.
Reassembled, added brake fluid, bled the system (via wife inside on the pedal).
Brakes worked fine for about 10 to 20 minutes of city driving, then did the same thing.
Ive never drained the brake fluid since installing 8 years ago.
Ive never run the system out of fluid...always kept it topped off.
Dot 3 used.
Next up:
Thinking the Master Cylinder is sticking...caused by 8 years of crud, or some moisture, rust, lack of driving...sitting in the driveway, etc.
Gonna pull it, clean it, inspect it for leaking seals, etc. It's a cast iron corvette style MC that CPP sells with the clip on lid.
Would the proportioning valve malfunction to the point of causing intermittant fronts to lockup/release/lockup/release quickly?
57 wagon with front discs/rear drums
CPP power front disc conversion kit (2 inch drop spindles,10 inch rotors with single piston calipers)
8 inch vacuum booster
CPP dual mastercylinder (front disc, rear drum)
CPP "auto" proportioning valve properly plumbed in.
New rubber brake lines installed. Still holding tight...no leaks.
New steel brake lines installed all the way around 8 years ago.
This brake system has been installed and working just fine for about 8 years now. Haven't had to mess with it.
The Symptom:
Brakes working fine for the first 15 minutes or so.
Then about 2 weeks ago while running around town, hit the brakes and the fronts BOTH "skip". they lock up, release, lock up, release, etc. Very fast, as if I had antilock brakes. Let off the pedal, and brake again...same thing. Then they don't do it for 10 or more minutes afterwards. Intermittant!
No pull to one side or the other....both wheels seem to lock up and release quickly while "firmly on the pedal". Don't really feel it in the pedal at all (like you can with antilock brakes). Brake pedal is firm.
But after one of these events, I smell hot brake pad and the brakes feel like they "faded"...can feel it in the pedal.
First Diagnosis/Fix:
Removed and Disassembled the 2 front calipers, then cleaned up the pistons and inner surfaces. Nothing was scratched/marred/worn BUT there was a sort of hard shellac on portions of the piston surface, and what looked like a little rust shellac'd on them.
Reassembled, added brake fluid, bled the system (via wife inside on the pedal).
Brakes worked fine for about 10 to 20 minutes of city driving, then did the same thing.
Ive never drained the brake fluid since installing 8 years ago.
Ive never run the system out of fluid...always kept it topped off.
Dot 3 used.
Next up:
Thinking the Master Cylinder is sticking...caused by 8 years of crud, or some moisture, rust, lack of driving...sitting in the driveway, etc.
Gonna pull it, clean it, inspect it for leaking seals, etc. It's a cast iron corvette style MC that CPP sells with the clip on lid.
Would the proportioning valve malfunction to the point of causing intermittant fronts to lockup/release/lockup/release quickly?