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| Brake Bleeding https://www.slantsix.org/forum/viewtopic.php?t=42244 |
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| Author: | jar84203 [ Tue Oct 12, 2010 6:22 pm ] |
| Post subject: | Brake Bleeding |
I have a 71 Duster that has been converted to 73 front disc brakes. The master and prop valve have been converted as well. My problem is that I can't get fluid out of the rear wheel cylinders when I hook up my pressure bleeder. I can get fluid out of the lines up until the prop valve, but on the outlet line to the rear brakes, no fluid comes out. Any ideas? Thanks. |
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| Author: | 66aCUDA [ Wed Oct 13, 2010 7:12 am ] |
| Post subject: | |
Plugged, connected wrong, Adjustable, Just ideas. Frank |
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| Author: | KBB_of_TMC [ Wed Oct 13, 2010 9:31 am ] |
| Post subject: | |
Check for an internally collapsed flex hose to the axle. I recently had a brand new Wagner made-in-Italy hose fail internally. The last batch of Wagner brake hoses I bought a year ago were a mixture of made-in-USA, China, Mexico and Italy. The made-in-China hose was made a little wrong, but I made it fit, and whilethe made-in-Italy fit OK, it apparently collapsed inside trapping pressure to one wheel. The replacement hose was also made-in-Italy, but seems to be working OK. |
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| Author: | jar84203 [ Thu Oct 14, 2010 4:42 pm ] |
| Post subject: | |
So I pulled everything apart and the lines and hoses are all clear. The prop valve I just replaced with a new unit from Inline Tube. The original one was just a distribution block with a brake warning light, while the new one is correct for disc/drum applications (built in prop valve). Since everything else is clear, it leads me to believe there is a problem with the valve... |
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| Author: | KBB_of_TMC [ Thu Oct 14, 2010 5:41 pm ] |
| Post subject: | |
I'd disconnect the line starting at the wheel, have a helper push down the pedal, and start working forward. I've never seen a proportioning valve go bad, but I guess it could happen. Good luck and please let us know what it turns out to be. |
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| Author: | olafla [ Thu Oct 14, 2010 6:08 pm ] |
| Post subject: | |
Hi jar84203. This problem mystifies me a bit. If you have installed the necessary master cylinder/valve assy and the correct combination valve (the one distributing the lines front/rear) for use with disc brakes, there should be a hold-off valve in the combination valve, whose function is, to quote the manual, better match front disk brakes with the rear drum brakes, resulting in a improved braking and steering control on icy surfaces. Problem is, when pressure-bleeding a disk/drum brake system, there should be no problem bleeding the rear brakes, but to bleed the disks, you have to prevent the engagement of the hold-off valve. The hold-off valve is designed to delay the action of the disk brakes a little, to give the drums time to engage at a same time as the disks, and it blocks off when the pressure is between approximately 3 and 135 psi. The bleeding methods that is not influenced by the hold-off valve is pedal bleeding, gravity bleeding or vacuum bleeding. The valve is that little metal nob sticking out of a rubber grommet at the front of the combination valve that distributes the brake lines. There is a small tool available (easy made by yourself) that can be used to hold the valve in a pulled out position when pressure bleeding. I have no access to a scanner where I am right now so I cannot give you a picture, but if someone that reads this know what I talk about, has a manual and a scanner, please feel free to use them! So, back to the mystifying bit: Is it possible that you can have switched the front/rear brake line outlets? That would invoke the situation you describe, which is opposite of what is described above, and switching the lines again would solve your problem! Olaf. |
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| Author: | jar84203 [ Wed Oct 20, 2010 8:17 pm ] |
| Post subject: | |
New master for disc/drums and new prop valve from Inline Tube. When I disassembled the new prop valve, I noticed it didn't match the picture in the FSM. Has anyone had problems with this? |
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