Hello everyone, I'm helping a friend with what was a complete frame off restoration on a '70 GS Stage 1. We are having some problems getting the brakes squared away. Everything is NOS or rebuilt original parts. Front disks - When trying to bleed the system we can not get any fluid to the rear. We originally thought it was that little pass through valve that is located on top of the frame near the rear. (by the way, does anyone know what that's supposed to do?) But we bypassed it with no luck. Then we thought the proportioning valve so we swapped that out. Then we though it was the master, so we swapped that out with the rebuilt original with the same results. When we try and bleed the pedal does not really ever pump up, you can get a solid pedal but it seems to slowly go down. There are no leaks so it's not that. We were able to bleed the fronts with the first master but not the second one. The only issue with the rebuilt master is that it has sat on the shelf for a couple years - You know how that goes - Anyhow, We bench bled the master, everything you can think of we probably tried twice, but we'd appreciate any ideas you might have. Thanks, Frank
Im going to assume this is disc brakes? . In order to bleed the brakes prroperly, you have to depress the stem of the hold off valve that is mounted by the master. See attached pic of service manual-
Hello, Yes Discs, sorry forgot to mention that, I will edit the post. We did depress the valve and it looks like the same page from the manual we have, thanks for posting though. This is a head scratcher, should be a no brainer old school system but it has us stumped. Thanks again, Frank
Forgive me if I ask you a dumb question- You did bench bleed the master right? It is a possibility that you have a bad master. It could be leaking internally. A couple years back I went through 4 so called "rebuilt" masters. Couldnt get a pedal. I thought I was losing it. I started second guessing myself. I went out and got a brand new Bendix master and got a pedal right away. So in my case, 5 times was the charm. [Edit- I see you bench bled the masters]
I had something similar when I put on disc fronts. I had to have it power bled. I tried everything else. Lots of pumping, new master, vacuum drawing from the rear (pulled 20" of vacuum) nothing. -nate
Thanks for the replies, Yes, we did try bench bleeding several times. I think we'll have to try another master like you guys said. Thanks, I'll let you know what happens, Frank
