Danochumongs Posted October 30, 2012 Share Posted October 30, 2012 I am having withdrawls from my beloved 1970 240z. My brake lights have been out and ive been trying to figure that out(not main problem) and realized my front calipers havent been working. i will add my proportioning valve is leaking slightly from right side, but the front calipers havent worked since i bought it. so i rebuilt and honed the cylinders and they work slightly. every time you press the pedal one side goes in and once that side hits the rotor, the other one gets some pressure, and so on. I had put a new 72 or 73 master cylinder and rebled the whole system after rebuilding one wheel cylinder which wasnt working well either. i'm stumped beside it being the leaky proportioning valve. the brake light went on for the leak after bleeding system first time. also now the pedal gained a little pressure again if you press it too hard you feel the pressure give and it slams to the floor. i decided to become part of the the community here to seek help and possible contribute with the small problems i have found and fixed that was not on any forum. If anyone would like to hear the ordeal of my brake , and help me, pm me.Thank you for your time. Link to comment Share on other sites More sharing options...
NewZed Posted October 30, 2012 Share Posted October 30, 2012 The pedal slams to the floor because, probably, your master cylinder seals are blown. Was the "new" MC old? Corrosion happens and will destroy the seals. The brake light goes on if there's a pressure differential between front and back. There might still be a big air bubble in your lines. Check that the bleed valve for the calipers is on top, not on the bottom. The calipers are reversible. Link to comment Share on other sites More sharing options...
Danochumongs Posted October 31, 2012 Author Share Posted October 31, 2012 the master cylinder was a rebuilt one from orielly's but my proportion valve is leaking from the right brake line at the base i believe. also i just checked and the bleed valve is on the bottom. thank you for pointing out that flaw. ill let you know if that cures the problem. do you think i need a new pressure differential switch though? or what do you suggest. thank you for the help, i greatly appreciate it. Link to comment Share on other sites More sharing options...
Danochumongs Posted October 31, 2012 Author Share Posted October 31, 2012 finally got around to switching them around and bled them and they work now. now my dilema is if you slam on it it gives to the floor. could it be my leaky perprotion valve that tore all my paint off on the frame inside engine bay. also if anyone could help me on my tail lights being out even with headlights on and my flashers work. thats the last problem for me. my fuses are good and brake switch is too and regrounded the green wire. im seeing hope now because of how helpful you've been. its very discouraging seeing it on jacks everyday when you come home. Link to comment Share on other sites More sharing options...
NewZed Posted October 31, 2012 Share Posted October 31, 2012 (edited) One down. OReilly Auto is not known for the high quality of the parts they sell. Take the MC back and get a refund or get another and try again. The pedal can't go to the floor unless the seals stop sealing, therefore... Throw a few capital letters and some punctuation in to your posts also, it will improve your thought processes and make these types of problems much easier to solve. It's like exercise for the brain. (edited for mellowness). Edited October 31, 2012 by NewZed Link to comment Share on other sites More sharing options...
Lazeum Posted October 31, 2012 Share Posted October 31, 2012 Check also how the brake fluid behaves in your MC tanks. It could also related to issue with rear brakes. You should not see the level moving too much when pressing the brake pedal. it can already gives some directions about where to look to fix the issue. If you can slam the pedal to the floor, you've got a leak somewhere if you bled them well before. Can you see some drops on the floor? It could help you also localize the leak. Link to comment Share on other sites More sharing options...
johnc Posted October 31, 2012 Share Posted October 31, 2012 Your brake system should not have any leaks at all. Period. Please fix all the leaks before posting another question here. Link to comment Share on other sites More sharing options...
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