Trouble bleeding, no pedal - new disc conversion

[Asshat]

Just did the disc brake conversion and installed the new calipers and a proportioning valve (PV71).

No air bubbles anywhere, just cannot get pedal. If I pump a couple times I can feel it.

Checked for leaks all around and nothing.

Any ideas?

Master cyinder is pretty new - probably a cuple hundred miles on it, if that.
Anything special about that proportioning valve? It has an electrical connection, but that's ot required for braking, is it?

[Asshat]

I think my next step would be to bypass the proportioning valve; not sure what else I can do.

[Asshat]

Here’s the caliper.

[Asshat]

Could it be the size of the brake lines? I’m using 3/16; maybe I need 1/4?

The bore size on my master cylinder is 1".

Should I go with a master cylinder that has a 1-1/8" or 1-1/4" bore?

[caseyjones]

I’ve had a similar problem when I didn’t properly bench bleed the master cylinder. I’ve also had the misfortune of tripping the proportioning valve safety feature because I did t lock the piston in place before attempting to bleed the system. That electrical connection on the valve is a switch that engages when the valve closes due to a leak or lack of fluid in one half of the system. When first filling and bleeding the system you need to lock the valve in place with a little tool like this:
https://www.amazon.com/WISPAUSU-Comp...70711188&psc=1

[Asshat]

Originally Posted by caseyjones

I’ve had a similar problem when I didn’t properly bench bleed the master cylinder. I’ve also had the misfortune of tripping the proportioning valve safety feature because I did t lock the piston in place before attempting to bleed the system. That electrical connection on the valve is a switch that engages when the valve closes due to a leak or lack of fluid in one half of the system. When first filling and bleeding the system you need to lock the valve in place with a little tool like this:
https://www.amazon.com/WISPAUSU-Comp...70711188&psc=1

If the brake lines are removed and the fluid drains from the rear brake lines, do I need to bench bleed the master again?

Also, I would think the proportioning valve is not tripped since I get fluid from all calipers.

[caseyjones]

Seems like bleeding the master cylinder again is the place to start.

[kwmech]

When you installed the rear calipers did you adjust the pads first? And yes you also may need a larger bore on the MC

[Asshat]

I replaced the master cylinder with a larger bore; 1.25”.
That did it; I know have brake pedal pressure.
I also used the locking pin for the proportioning valve.
Thanks for the help everyone!

[youngrodder]

I ran into the same problem with similar calipers. See how the bleeder screw is pointed up at say 1 o'clock. Air can get trapped. I unbolted the caliper and rotated it so the bleeder was straight up 12 o'clock position. I held it in place (unbolted) while I bleed to allow the trapped air to escape while bleeding.

I was way frustrated until a mechanic friend mentioned to try that. It worked.

I hope this make sense. Good luck brakes can be frustrating.

Marc

[Bob@ProAuto]

The parking brakes need to be activated. The piston ratchets out and creates a "cavity" for the fluid. As long as you've got the correct master cylinder, you should them be able to bleed the brakes.

[Asshat]

Originally Posted by Bob@ProAuto

The parking brakes need to be activated. The piston ratchets out and creates a "cavity" for the fluid. As long as you've got the correct master cylinder, you should them be able to bleed the brakes.

I took those calipers off and installed the standard ones. They work great now.

The parking brake style calipers are available in the CLASSIFIEDS if anyone is interested.
Great deal for someone.

[Joyridin]

The rear calipers have a ratchet mechanism in them. You need to move the e-brake arm back and forth to ratchet the piston out. This is where you get your brake pedal feel from.