Trouble bleeding, no pedal - new disc conversion
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? |
Re: Trouble bleeding, no pedal - new disc conversion
I think my next step would be to bypass the proportioning valve; not sure what else I can do.
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Re: Trouble bleeding, no pedal - new disc conversion
1 Attachment(s)
Here’s the caliper.
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Re: Trouble bleeding, no pedal - new disc conversion
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? |
Re: Trouble bleeding, no pedal - new disc conversion
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 |
Re: Trouble bleeding, no pedal - new disc conversion
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Also, I would think the proportioning valve is not tripped since I get fluid from all calipers. |
Re: Trouble bleeding, no pedal - new disc conversion
Seems like bleeding the master cylinder again is the place to start.
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Re: Trouble bleeding, no pedal - new disc conversion
When you installed the rear calipers did you adjust the pads first? And yes you also may need a larger bore on the MC
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Re: Trouble bleeding, no pedal - new disc conversion
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! |
Re: Trouble bleeding, no pedal - new disc conversion
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 |
Re: Trouble bleeding, no pedal - new disc conversion
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.
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Re: Trouble bleeding, no pedal - new disc conversion
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The parking brake style calipers are available in the CLASSIFIEDS if anyone is interested. Great deal for someone. |
Re: Trouble bleeding, no pedal - new disc conversion
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.
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