Nismo280zEd Posted August 10, 2003 Share Posted August 10, 2003 OK, i posted this before with out much luck. My Left caliper sometimes works and sometimes doesn't, the caliper bleeds just fine, the MC has clean fluid, the lines arn't kinked... yet the driver caliper works normal and the passenger side sucks most of the time! Any ideas? New MC time? BTW.. both calipers are brand new.. and the passenger has been replaced twice now.. thinking it was a faulty caliper. Quote Link to comment Share on other sites More sharing options...
j260z Posted August 10, 2003 Share Posted August 10, 2003 have you checked out the proportioning valve? working sometimes and not others sounds wierd with calipers. i'm thinking you may have something in the line at the valve that would prevent it from working properly because the front brakes are run off the same seal in the master cylinder so if the seal failed then both front brakes would act up not just one. does this make any sense? i think it would be a good place to start. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 10, 2003 Share Posted August 10, 2003 Time for a rebuild. Probably junk between the piston and the bores. Quote Link to comment Share on other sites More sharing options...
Guest rick458 Posted August 10, 2003 Share Posted August 10, 2003 I had a problem with the drivers side on my 260, it wound up being some trash at my porportioning valve, I had replaced the MC and rebuilt the calipers, and was getting NO fluid to the caliper I had to romp and stomp the brake pedal to blow the trash through the valve open a bleeder several turns so the fluid has some where to go to and just get on it see if you cant feel an obstruction blowing clear Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted August 10, 2003 Share Posted August 10, 2003 Make sure you clean up all the hardware and apply a synthethic grease to the sliding parts. But yeah, sounds like a defective caliper. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 10, 2003 Author Share Posted August 10, 2003 OK... now last time i posted this i was told that my car was not equiped w/ a proportioning valve. It's a 1978 280z 2+2 About a month or 2 months ago... I replaced the front brakes.. Brand new rotors and Calipers and pads. After about a week... the car starting pulling rather strongly to the passenger side. after a closer look.. the rotor and pads had broken in on the passenger side.. and the driver side looked like it hadn't even been used... So i sent the caliper back.. got a new caliper from a local autoparts store. worked a little better... but there are barely any score marks where as the passenger side is well seated.. and it still pulls to the right under braking. Quote Link to comment Share on other sites More sharing options...
j260z Posted August 10, 2003 Share Posted August 10, 2003 you don't have an adjustable proportioning valve but there is one there. there should be one on the firewall just to the left and under your brake booster (also called a pressure regulating valve in the haynes manual)(this is where an adjustable proportioning valve would go) and another one on the drivers fenderwall just under the master cylinder (called a dual circuit pressure differential switch in the haynes manual) . either one of those could have crud in them. the one on the fenderwall has the takeoff for the drivers side brake on it and the one on the firewall has the takeoff for the passenger side and rear brakes on it. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 14, 2003 Author Share Posted August 14, 2003 sweet i'll check it out tomorrow... can't quite picture what your talking about at the moment.. but i'm sure after i look tomorrow i'll understand. by relief you mean like a bleeder valve.. or am i looking for something else? -Ed Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 15, 2003 Author Share Posted August 15, 2003 ok... so i just looked under the hood... there are two silver objects one is about 1" by 1" on the fender driver side... other is about 3"x4" on firewall... however the one on the fender i saw no "relief" valve.. or is this a take off and clean? firewall seems to be capable of being disasembled. -ed Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 15, 2003 Share Posted August 15, 2003 I don't believe that either of them are 'serviceable' I would take them both off and 'clean' them out. Tim Quote Link to comment Share on other sites More sharing options...
denny411 Posted August 15, 2003 Share Posted August 15, 2003 Another thing you may want to check is your brake hoses. I say this since you stated that your problems started soon after a brake job. Brake hoses can develope cracks internally, which after being disturbed(i.e.Brake job) can break loose and act as a check valve of sorts, only allowing fluid to pass in one direction. This can also be caused by not supporting the caliper properly and allowing it to hang from the hose. Not only can these "check valves" cause a caliper to not work, They can also cause them to lock. Bottom line when servicing your brakes... 1)Always support the caliper(I like wire or heavy rubber straps) 2) Never stretch or pull the hose 3) Only move the hose as much as necessary 4) If the hose is cracked on the outside, chances are it`s cracked inside too Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 16, 2003 Author Share Posted August 16, 2003 they are stainless steel lines i don't suspect they are the problem, i'm gonna clean out the other parts tomorrow under the hood and see what happens from there. -Ed Quote Link to comment Share on other sites More sharing options...
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