Greetings running into some issues with my brakes. I had a whole lot worse issues last year on the HRPT when I lost brakes. Long story short was having issues when I would hit the brakes and the pedal would intermittently would hit the floor(not fun) went through 2 master cylinders, all lines have been replaced steel and rubber.the PO had the master cylinder put back under the seat where it belongs. but the person who did it moved the exhaust down either side of the power booster and the master cylinder. not good it was boiling the fluid causing brake failure. I had the exhaust replaced and down the passenger side as far away as possible..it still kept losing brakes so I brought over 2 friends that were both certified mechanics we put it back together and i backed up and down my driveway and had good tight brakes. my buddies left and i put the truck in the yard and the petal hit the floor and I hit a tree branch that slowed me down and scratched my hood up. this time I sent it to a shop that specializes in hot rods. They were baffled as well, they would think they had it and it would hit the floor. i told a buddy of mine who builds and races drag cars. I told him the issue and he immediately said its the caliper. you start a dive ride for 10 minutes and lose brakes 10 minutes later you have brakes. Made perfect sense. I called them and told them and he was right, the caliper was hanging be cause the plunger was out too far causing the caliper to stay engaged. A quick 1/4 adjustment and it was fixed (for the most part) other issues we found along the way Wilwood proportioning valve was on the rear drums and needed to be on the front disks, from research I found I needed 2 residual valves added on. one valve was 10PSI while the other was 2psi. I forgot where each went but they were placed where they should have went. I noticed even after I got it back that it would still drop the pedal, while frequently the pedal wouldn't return as it should. The return spring is a good heavy duty spring and there should be no reason as to why it shouldn't return. I have gotten in the habit of lifting it back up with my left foot.having the proportioning valves main purpose is to keep brake fluid in the line. I'm still baffled even though Ive nailed it down as to when the brakes fail. When you are pulling or backing into a spoy and it takes a couple rounds of adjusting you lose brake pressure luckily you are going slow enough that when it hits the floor there is enough to stop it. anybody have a guess?
The proportioning valve should be to the rear axle, not the front. The residuals keep fluid in the lines-2 lb to the discs, 10 lb to the drums. There should be 1/32"/1/16" clearance between the booster push rod and master cylinder primary piston. This is checked with full vacuum in the booster.
As to your pedal not returning: Check the pedal's stroke to make sure the plunger rod into the booster is not angled, hanging up, bent, rusty at the clevis with the pedal, or hampered in any other fashion. I recommend a spring that will pull the pedal itself back up til it contacts either the underside of the toeboard or some other stop/bumper at the top of the stroke. Those springs that go between the pedal and master that seem to push the pedal always make me think they could hamper the plunger. Get it out of there and make it pull on the pedal itself. Usually pulling on the same pivot bolt that connects the pedal to the plunger rod is a good spot. Then, confirm your operation of all components at the wheels. If you had calipers hanging up that sounds like a major concern and should be either replacing or at least rebuilding them. Or was it cheapo caliper mounts causing the hangup? Many of the 1-800 parts suppliers sell stuff made in China by a 10 year old with a welder in his mom's kitchen. No quality control on the materials, methods, or fit. As for the residual pressure valves, I like the brass ones from ECI, not the aluminum ones from many other suppliers. I've heard bad things about the aluminum ones, and I bought the quality parts to save me future headaches. Like said above, 10 lbs for the drum and 2 lbs for the disk. Make sure to put them in facing the right way as they do have an in and an out.
The Jalopy Journal
