Rear brakes lock up, front disc not stopping well

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cudajim

cudajim

cudajim
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My '67 Notchback has never stopped the way it should. I'm running Kelsey-Hayes discs up front and 10" rear drums. I'm using all the factory setup from a '68 Valiant including power disc master cylinder, combination valve and all the proper brakes lines. Yesterday I took apart the front brakes, cleaned all the bores, pistons, rubber etc. Nothing looked really bad, pistons were not hung up and went back in easily. I have also changed all rubber lines with new ones and even went with smaller slave cylinders at the rear. They still lock up in the rear and the car does not stop well. Where do I go from here to solve this problem?
 
sometimes you have to " bed " new pads.
Haul it down hard from 60 mph to 30 mph hard 3 times on a safe traffic free highway and then from 30 to a stop 2 or 3 times after they cool a bit.
Mine were dreadful when new.After doing that they grabbed nicely.
 
Proportioning valve? I use an adjustable proportioning valve on my disc/drum set up. Allowed me to really dial in the front/rear bias.

Be well,
Pat
 
I had the same set up on my 72 Demon and it wouldn’t stop. I was sick of it so I did some research and ended up converting it to manual brakes.

After that, it would stop like it should. Now I have a 73 Demon (Dart Sport but it’s really a Demon) and I swapped it to manual brakes. Much better stopping.
 
You can switch to 7/8" diameter rear wheel cylinders to reduce their effectiveness.

But on my 68 cuda and 64 Val, I ditched ALL factory proporting stuff.
Ran the front brake line into a simple T. (Or plug the rear line port on the stock valve) Then one line out to the LF and another to the RF.
Installed a Wilwood (or Summit) adjustable proportioning valve in the rear line. A good place to put it is on the frame rails near the firewall.
You lose the brake warning light feature but who cares? If you develop a leak you'll know it without having a light telling you your foot is too close to the floor.
 
KosmicKuda said:
You can switch to 7/8" diameter rear wheel cylinders to reduce their effectiveness.

But on my 68 cuda and 64 Val, I ditched ALL factory proporting stuff.
Ran the front brake line into a simple T. (Or plug the rear line port on the stock valve) Then one line out to the LF and another to the RF.
Installed a Wilwood (or Summit) adjustable proportioning valve in the rear line. A good place to put it is on the frame rails near the firewall.
You lose the brake warning light feature but who cares? If you develop a leak you'll know it without having a light telling you your foot is too close to the floor.
Click to expand...

I did that already, switched to 7/8" rear slave cylinders, it didn't make much of a difference.
 
Ya, I went with an inexpensive Wilwood adjustable proportioning valve. Easy installation and effective. Sounds like you touched/checked most components, may want to give it a try?

Be well,
Pat
 
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