Bleeding Brakes

Mac

Mac

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Yes, a thread on something so elementary I am embarrassed to even start it.

I made all new lines, new turning brake master cylinder, rebuilt the main master cylinder (roughly 3 years ago but the car has sat 2 years), took the calipers apart and cleaned/inspected them. I knew this would be a pain since I have to push new fluid and get it flowing. It went fairly well and got fluid flowing and bubbles out. Now the issue is it's not holding pressure. Nothing is leaking and if you pump it up, it's a nice pressure for the pedal and turning brake. Then you switch to a different caliper and no pressure.

I've bled all 4 ports on each caliper. No change. When I have good pressure, I see the calipers/brake pads moving as they should, but again, as soon as you move to another caliper, no movement, no pressure.

SO...I'm thinking fuck it, just get a new master cylinder. It's the only common part in all this. I'm not going to rebuild it as it's an old CNC unit that is no longer around and you can't get rebuild kits, regardless of what anyone tells you, they just don't fit right. I can get a Jamar or Empi replacement that bolts up to the pedal unit.

Am I missing something? Could there be a big fucking bubble stuck that just isn't budging? I've put 2 quarts of fluid through this thing. It's small 2 seater. Not a lot of length or complexity to this system. No proportioning valves or anything like that.

I really don't want to troubleshoot by remove and replace at this point. Definitely not looking forward to all new calipers as I don't want to refab spindles and mounts.
 
I had to pressure bleed using what felt like a gallon of brake fluid for them to work correctly and I did a residual valve which helped a ton.
 
I couldn’t get my brakes bled until I bought a positive pressure type bleeder. Once I got that it took less than 15 mins
 
Johnny said:
You Can't go wrong with this harbor freight bleeder, My car for some reason had a issue with air getting trapped in the cutting brake, I broke down and got this from harbor freight , It will suck every air bubble out of your lines, It is a little expensive but it works great.
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I tried two different vacuum style bleeders like that one and couldn’t get the air out. I went with a positive pressure style and it worked much better. Only issue with these is you maybe to make a custom cap to fit your master to attach the air feed hose. I went with this one and it worked great:

 
When you say you have good pressure on one caliper is it actually clamping or just moving the pistons? Brake pedal is firm when this happens? Is the master higher than the calipers when bleeding?
 
It's clamping and it's firm. Then you move to the next caliper and nothing. So then you bleed and build the second caliper up...back to the first and nothing.
 
Did you put bigger calipers (more pistons) on your car? Just searching for a reason although air in the system does strange things. High points in the system that would trap air?
 
Sandkist said:
Did you put bigger calipers (more pistons) on your car? Just searching for a reason although air in the system does strange things. High points in the system that would trap air?
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I made and installed all new lines
 
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