Lonestar Posted April 7, 2014 Report Share Posted April 7, 2014 Ok, this is getting weird, I have finished my 280zx swap on my 1980 210. Everything with the brakes is bolted up like it should and ready to go. The problem: Last night after bleeding brakes I had no brake pedal. Get home to day, I have some pedal and both front wheels are locked up. What I did: I used a Mighty Vac-pump to do a one man brake bleed on my system. I got fluid to come out both calipers but could never seem to get the air to stop. I even checked the master to make sure as well. Never ran the master out fluid during this time. There are NO leaks anywhere in the system and everything has been installed like it should. Anyone have a clue as to what is going on and what I need to do fix it? Thanks guys. Quote Link to comment
Cahoon520 Posted April 7, 2014 Report Share Posted April 7, 2014 Did you get the front and rear circuit mixed up on the master cylinder? Quote Link to comment
datzenmike Posted April 8, 2014 Report Share Posted April 8, 2014 Back is front and front is back. There is an F and an R cast into the master. Did you say the front calipers are locked up??? This is an improperly adjusted brake pedal to master push rod. The pedal should have several mm or 1/16" of free play looseness before the pushrod comes to bear against the piston in the master. If no play the piston won't return to it's rest position and the fluid under pressure can't bleed back into the reservoir. Quote Link to comment
Lonestar Posted April 8, 2014 Author Report Share Posted April 8, 2014 Did you get the front and rear circuit mixed up on the master cylinder? Nope, never messed with the lines going to the Master, left them alone. Back is front and front is back. There is an F and an R cast into the master. Did you say the front calipers are locked up??? This is an improperly adjusted brake pedal to master push rod. The pedal should have several mm or 1/16" of free play looseness before the pushrod comes to bear against the piston in the master. If no play the piston won't return to it's rest position and the fluid under pressure can't bleed back into the reservoir. Well, this is odd because yesterday I had zero, zippo, nadda for brake pedal, it just went right to the floor like there nothing in the system at all. Came back home from work to today and BAM, there is brake pedal (not super stiff or hard) and front calipers are gripped onto the rotors hard. Is this a come thing when swapping from 210 to 280zx brakes and I should be able to adjust the brake pedal right? Quote Link to comment
ggzilla Posted April 8, 2014 Report Share Posted April 8, 2014 Sounds like air in the lines, and the pushrod is too tight. You can't bleed it correctly if the pushrod is too tight. Stop talking and get put and check it. Use your pinky to test it. If the pedal doesn't move any under very light pressure that is the first problem. Quote Link to comment
datzenmike Posted April 8, 2014 Report Share Posted April 8, 2014 I have some pedal and both front wheels are locked up. and front calipers are gripped onto the rotors hard. You're not clear. Are the fronts working or are they stuck on??? Quote Link to comment
Lonestar Posted April 8, 2014 Author Report Share Posted April 8, 2014 Sounds like air in the lines, and the pushrod is too tight. You can't bleed it correctly if the pushrod is too tight. Stop talking and get put and check it. Use your pinky to test it. If the pedal doesn't move any under very light pressure that is the first problem. The pedal will move under light pressure. You're not clear. Are the fronts working or are they stuck on??? Forgive me, let me start over, the front brake calipers are remans. The pistons are not stuck. The front brakes are engaged like the pedal is being held down (but it's not.) Left front is grabbing so hard I have to really force it to turn. Right Front is a little easier to turn but still the brakes are grabbing and not letting go. I can pry the calipers back to release but when the brake pedal is pressed, they will engage the same way and not let go. Quote Link to comment
ggzilla Posted April 8, 2014 Report Share Posted April 8, 2014 > The pedal will move under light pressure. But will it move under very light pressure? Like using your pinky finger to move an egg? There should be like 1/64" play. Quote Link to comment
datzenmike Posted April 9, 2014 Report Share Posted April 9, 2014 Yes. This sounds like the pedal push rod is too tight. If so the piston inside the master can't return back to it's rest position and release the trapped fluid under pressure. If you look up behind the pedal, the push rod is threaded with a lock nut and attached to the pedal with a clevis pin. Loosen lock nut, remove pin and turn the adjustment in. Put the pin back in and lightly push down on the pedal. You want a couple of mm or a sixteenth of an inch of pedal movement before the push rod meets the piston on the master. You can feel it when it touches. Don't forget to put the retaining clip through the clevis pin to keep it there!!!! Quote Link to comment
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