Early Disc Brake ?

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warwagons

November
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Picked up a 66 Valiant SW this weekend and put it on stands to check the front brakes. Surprise, it's got disc! Anyway, my question is about the brake drag on he rotors. It seems to be excessive on both sides. What would be "normal" resistance when rotating a wheel? Should it be the same as drum brakes are? What could cause both wheels to drag so much? Without the wheels on, it takes some force to spin the rotors by hand. Any advise would be appreciated.
 
Could be a drum brake master cylinder with a residual psi valve in it holding slight psi causing brake drag on the disc.
 
I assume they are 4 piston KH discs? If so, they are notorious for the pistons seizing in their bores.
 
more than likely it is a combination of things, dirty corroded calipers that haven't been cleaned and rebuilt in many years, and gook in the brake lines and master cylinder that haven't been flushed in many a year
 
chryslerfat said:
Could be a drum brake master cylinder with a residual psi valve in it holding slight psi causing brake drag on the disc.
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It has got a single Master cylinder on it which looks odd. Looks like a regular drum M/C but about a 1/2" taller. How do you differenciate the two?
 
warwagons said:
It has got a single Master cylinder on it which looks odd. Looks like a regular drum M/C but about a 1/2" taller. How do you differenciate the two?
Click to expand...

The taller m/c is the correct one for the KH discs. It's actually a bolt-on extension so the m/c has more fluid capacity for the calipers. My car had one too. It's also a KH disc car. I recommend replacing it with a dual m/c, though for safety.
 
warwagons said:
Yes, 4 pist. KH.
Both sides freezing normal?
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Yep. Par for the course. Rebuilt mine once when I first got the car 20 + years ago. I painstakingly unstuck all of the pistons, cleaned up everything only to have them seize up again a few years later. I had more money at that point, so I sent them off to have stainless sleeves & pistons installed.
 
lilcuda said:
Yep. Par for the course. Rebuilt mine once when I first got the car 20 + years ago. I painstakingly unstuck all of the pistons, cleaned up everything only to have them seize up again a few years later. I had more money at that point, so I sent them off to have stainless sleeves & pistons installed.
Click to expand...
Well, it looks like I'll have to get my hands dirty(er).
Thanks to all for the help and info!
 
Are you sure it`s not the wheel bearing adjustment? If not, as mentioned earlier, these brakes have a tendency to have sticky caliper pistons when not used daily. I had one that would stick within a week if I didn`t drive the car.
 
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