Problems bleeding brakes

Just finishing up undercar restoration that included new rubber lines front and back, new calipers on front and wheel cylinders on the rear. also replace the lines on the rear axle. I started with RR drum brake, and got some air through and a little fluid, but could not get it to run all fluid. Went to RF, and was able to bleed completely and get the air out of the caliper, but brake is not releasing completely. Went to LF, and was able to bleed, but it is not releasing much at all. Then went back to LR, and was unable to get any fluid or air out. Pedal is very firm with little travel. I have searched other posts and seen the info on the button on the proportion valve. Problem is I have headers, and cannot get anywhere near this without pulling the drivers side header. If you think this is the issue, I will make the effort and do it, but would like to avoid all that work if possible. Any other way to get fluid back to the rear? I did not touch the master cylinder at all and it did not run dry. Thanks

 

If you are sure the Master Cylinder is properly bench bleed I would start by cracking open every connection one at a time and go from the front to the rear . Let it gravity bleed at every connection then tighten and move further back to the next connection. Do this with the Master Cylinder cap loose and keep a eye on the fluid level . Don't touch the brake pedal.

 

I just went thru this man, drove me nuts for a week. when I opened the right rear bleeder it would never stop getting air, then the left would be all air and no fluid. what was happening was the right rear bleeder was creating a vacuum and pulling the oil from the left side, I hope I am explaining this is a way that makes sense. you need to get fluid to the right side, then close the bleeder, then have someone slowly push the pedal down with the left bleeder opened, now you have forced oil thru both rear axle brake lines, once you do this you can bleed successfully.

 

http://www.v8buick.com/index.php?threads/stupid-brake-question-help-me.331705/

see this thread..... I did not have a firm pedal tho so maybe my issue was different, reminded me of my problem so I hope this will help? Let me know....

 

Thanks, I opened the bleeders on both rear brakes tonight. I will not be able to do anything with the car tomorrow, but will get back on it on Sunday. If I have no signs of gravity moving fluid to the rear, I guess I will pull the driver side header and try the button on the prop. valve. Keeping my fingers crossed.

 

I have had a similar problem this week also I believe that my rod from pedal to booster is slightly long partially engaging the master cyl i losened the master nuts slightly as there was about 1/8 " of tension when I did that and tried it the fluid went to the rear .

 

Thanks for the reply. Did you tighten the master cylinder nuts when you were done, or add some spacers then tighten. Going out in the garage is a little while. Hope to get this resolved today.

 

Are you using OE brake lines or stainless? The stainless look nicer but can be much harder dealing with leaks when you install. Will install new axle lines and rear hose this week before installing replacement Quanta gas tank. Mine are OE steel from Inline Tube. Even their tech said you can have fluid leaks at the cylinders with stainless!

 

Yes using Stainless lines does require care when installing. The connections require a bit more torque to seal completely . But it is easily accomplished with a little extra tightening . I have installed Stainless lines and Silicone Fluid in my GSX and gravity bleed the complete system with NO problems . That was 20 years ago . In the past 5 years I have installed Stainless lines in my 2000 Chevy 2500 and my 2003 Suburban and gravity bleed both systems with Dot 4 Fluid . Again with NO problems . I like knowing that I wont have a line rust out ever again .

 

I used stainless also and I did have a leak at the left cylinder, but as was mentioned above I just tightened it a bit and it sealed up.

 

My thought on pulling the Header to get to the Prop valve : If the prop valve is that close to the header I would be more worried about the Brake fluid Boiling

 

Thanks for all the suggestions. Yes, I did end up pulling the header to get to the combination/proportioning valve. Mine is missing the rubber cover on the end, but there is a very flat brass nut with a small stem sticking out of the middle of it. The stem barely moves, but I pushed it in and held it with a large C clamp. With that in place, I was able to bleed the brakes as I would normally expect and got clear fluid at all the brakes. The fronts are still stiff, but once I put a tire on, the drag did not seem too bad. I think it will be fine once driven a little bit. I do have concerns about the proximity of the brake lines and the headers. I have Dougs 1-7/8" primaries, and they are tight everywhere. Had to dimple a few tubes to get them in and around everything. Time will tell if it is a problem, but will take it on short shake down runs before planning any distant trips. The replacement hard lines I used were the mild steel from Inline Tube. They fit great, but if the headers end up being a problem, I will probably have to custom bend some tubes and relocate the prop valve. Hopefully not. Thanks again

 

Originally I tightened the master and it engaged the front calipers so I took master off leaving the lines in place and put 3 18 gauge machine washers 1 1/2" made by hillman 2 to a pack from tractor supply i put grease on them to hold together and a small peice of card board under them to center them in the hole on the front of the booster and a washer on each stud on the booster. The new booster rod that pushes the master cyl was about 1/8 further than the original (a tire tread depth gauge worked well for me to measure it) i found a chevelle site when googling master cylinder shims apparently it is an issue with Chinese made boosters and master cylinders mine came from auto zone

 

I'm not immediately concerned with the reliability of the setup I think it is safe and functional and dosent look bad .I still haven't pushed the button on the proportioning valve to rebleed the front calipers. I dont have much help closeby to assist with bleeding .While trying to bleed the rear cylinders I attempted to loosen the rear line on the proportioning valve and the line and fitting seem stuck to each other so I am trying to test functionality of changes without changing too much at once and don't want to wring off the line either.I am still not a hundred percent sold on the booster master setup that I put on I considered grinding the rod but didn't want to not be able to return the setup if it dosent work out. ☺

 

I agree it's not ideal ☺