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Sticking brakes on the Coronet

patrick66

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I recently replaced the front disc brake calipers with new ones about four months ago, because the previous units were sticking badly. The car was converted to '73 - '76 A-body front discs and the master cylinder and proportioning valve from the donor car ('73 Dart Sport) in 2003. The last time, prior to this Spring, that the car had any miles put on it was 2011, so the brake calipers ended up sticking.

Replaced the calipers, bled the brakes and went off to drive the car. It ran and stopped great...for awhile. I went to drive it a couple of weekends ago, and the pedal felt weak and spongy. On a downhill driveway onto a public road, I damn near couldn't stop the car! The reservoir was full. The brakes felt like they had air in them, and the fronts once again feel sticky. I can find no leaks anywhere.

Any ideas???
 
Could be the 'slide' surfaces on the calipers bound up, or rusted.

Might be worth the time to break down both fronts, to figure out what's going on. Mainly those slide surfaces need to be clean. Lubriplate also makes a heavy white brake grease that can be used there, if so desired.
 
I'll look at that this afternoon. To be honest, I can not remember if I used brake grease or not. I'll know soon enough.
 
Good deal, patrick66.

That's the drawback of disc brakes. Dang things gotta have it so-so, or they only kinda work. Be sure to look at your bolt/pins, too.
 
Sticky meaning once they apply, they are not releasing right away?
 
Sticky meaning once they apply, they are not releasing right away?

Must be something like that, Cranky.

Sideline thought is if the piston is hanging up. Or even the right brake fluid. Heck, could be all. Naw...
 
any time i ever had this issue it has been the brake hoses......... they get phucked up on the inside
 
The brakes are very weak. I replaced the calipers a couple of months ago after finding both were sticking badly. The new ones are r/b calipers with Chrysler part numbers on them, so these units are not China imports. They worked well for about 200 miles. Then they began to feel weak. I had a mild panic when I was heading down a concrete driveway towards the street, after a car show. The Coronet did not want to stop, and I stood on the brake pedal as hard as I could to stop! Fortunately, the drive home was all freeway and required me to stop only three more times before getting home. Those stops were only mildly better. So, it's in my shop right now, awaiting my attention. I was working on the Imperial and my DD ahead of the '66.

Brake fluid is DOT3 synthetic. The master cylinder and brake lines were all replaced with new in 2003. The car has had only about a thousand miles put on it since '03.
 
Maybe get rid of the synthetic. Plus, maybe defective calipers.
 
I'm going to flush the brake fluid this weekend and replace with new. Never had problems with synthetic brake fluid before, but who knows? The master cylinder might well be the culprit, but I want to eliminate the cheaper solutions first. I'll let you know!
 
Manual brakes? Is the master original? Seems been seeing alot of stuff on rebuilt masters being bad.

Anyway, for the heck of it, it's real simple to overhaul a bad master. Mostly just a couple seals (cups), if not corroded. Good luck on getting it fixed up!

I've got synthetic in mine too. One of these days I'll get to find out how it works. Gotta get it going down the road, before I need to stop!!
 
The synth is superior. Why would anyone get rid of it is beyond me.
Look into your power booster. See if it holds vacuum.
 
Well, it's doing it again. I took it to the detailer a few weeks ago. On the drive home, my braking became quite degraded. This, after replacing the dual master cylinder that I installed back in 2015, about two months ago after the brakes went away completely. I can feel the rear brakes just fine. The fronts are grabbing, and not releasing until a couple of seconds after letting off the pedal. Another bad master, perhaps?

After work, I'm going to see if maybe my booster is wonky. Pinch off the vacuum line to the booster, drive down the driveway and see what happens from there. The booster on the Coronet is original to the car. If I have better brakes, then the fun of booster removal begins. Yay.
 
it sounds to me like your wheel cylinders are sticking,,,if they have begun to leak then the shoes can and will stick to the drum,causing the brakes to pull left or right.
My dart did the same,as I had not driven it in some time.
 
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