Sideways Posted September 5, 2007 Share Posted September 5, 2007 Title says it all, ALL the brakes drag front and rear together. Anyone ever have this issue or any ideas what could be causing it? Ive checked the rod it seems to return properly, im assuming it could be the master cylinder but dont want to rush out and buy something i dont need. Any help or thoughts would be much appreciated Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 5, 2007 Share Posted September 5, 2007 Flush the system and bleed it really good. Sounds like you've either got moisture or air in the lines really bad. What car is this on and are there any mods? Quote Link to comment Share on other sites More sharing options...
mark Posted September 5, 2007 Share Posted September 5, 2007 Air in the system will not cause the brakes to drag, moisture possibly if the pistons or bores in the calipers are rusted and pitted. Need more info. Can you hear it or will the wheels not turn when the car is jacked off the ground. Has anywork been done to the car lately? Can you smell pad burning when you drive? Will the e brake grab and release? Quote Link to comment Share on other sites More sharing options...
rags Posted September 5, 2007 Share Posted September 5, 2007 Drag? How bad? With the wheels off the ground can you turn them by hand? Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 5, 2007 Share Posted September 5, 2007 Air in the system will not cause the brakes to drag, moisture possibly if the pistons or bores in the calipers are rusted and pitted. Need more info. Can you hear it or will the wheels not turn when the car is jacked off the ground. Has anywork been done to the car lately? Can you smell pad burning when you drive? Will the e brake grab and release? Pardon me? Air in the system won't make the wheels drag? What have you been smoking and why aren't you sharing? If you get enough air in the system you could end up with a bubble in the proportioning valve or the master cylinder that could cause the pressure to not return properly giving you that drag. Moisture can do the same thing even if there's nothing wrong with pistons or piston bores. I've seen it enough times to know. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted September 5, 2007 Share Posted September 5, 2007 Pardon me? Air in the system won't make the wheels drag? What have you been smoking and why aren't you sharing?If you get enough air in the system you could end up with a bubble in the proportioning valve or the master cylinder that could cause the pressure to not return properly giving you that drag. Moisture can do the same thing even if there's nothing wrong with pistons or piston bores. I've seen it enough times to know. He must be smoking the same stuff I am because my experience has always be exactly the opposite. How is air in the line going to hold pressure? Like Rags says, how bad? How hard is it to turn the wheels by hand? And what happened that you all of the sudden starting noticing this? Did you do brake work or all of the sudden started having problems coasting down hill? Quote Link to comment Share on other sites More sharing options...
mark Posted September 5, 2007 Share Posted September 5, 2007 Pardon me? Air in the system won't make the wheels drag? What have you been smoking and why aren't you sharing?If you get enough air in the system you could end up with a bubble in the proportioning valve or the master cylinder that could cause the pressure to not return properly giving you that drag. Moisture can do the same thing even if there's nothing wrong with pistons or piston bores. I've seen it enough times to know. This was not meant to sound like I was attacking you. Just disagreeing. If I'm wrong, please explain, I would like to learn something today. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 5, 2007 Share Posted September 5, 2007 Easy if you get a large enough air bubble in the proportioning valve when the master cylinder draws back it won't release the pressure post the valve completely. It'll pull back enough to release the brakes but leave them contacting the rotors giving the drag he's experiencing. When the fluid heats up the air will expand causing more drag. Air expands at a fast rate than hydrolic fluid which would only serve to increase the drag. Quote Link to comment Share on other sites More sharing options...
mark Posted September 5, 2007 Share Posted September 5, 2007 Easy if you get a large enough air bubble in the proportioning valve when the master cylinder draws back it won't release the pressure post the valve completely. It'll pull back enough to release the brakes but leave them contacting the rotors giving the drag he's experiencing. When the fluid heats up the air will expand causing more drag. Air expands at a fast rate than hydrolic fluid which would only serve to increase the drag. I still disagree. I think we will just have to wait on more info from Sideways. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 5, 2007 Share Posted September 5, 2007 I still disagree. I think we will just have to wait on more info from Sideways. And again this might not be his problem, it's just one possibility. Flushing the brakes and bleeding everything out really good would solve both problems and reduce the possibility of it being a line problem. Quote Link to comment Share on other sites More sharing options...
lbhsbZ Posted September 6, 2007 Share Posted September 6, 2007 Easy if you get a large enough air bubble in the proportioning valve when the master cylinder draws back it won't release the pressure post the valve completely. It'll pull back enough to release the brakes but leave them contacting the rotors giving the drag he's experiencing. When the fluid heats up the air will expand causing more drag. Air expands at a fast rate than hydrolic fluid which would only serve to increase the drag. Unpossible. when the master cylinder pistons are fully returned to their "unapplied" position, there is a clear path from the hydraulic system to the reservior for any residual pressure to go. Thats why you can squeeze your pistons back into the calipers relatively easily without opening the bleeder valves. Air cannot cause brakes to drag. Now, back to the original problem. Do the brakes drag when they are hot or cold or both? Here's how you diagnose it. First, duplicate the problem...make the brakes drag, jack up one end of the car so you can spin the wheels by hand....but make sure you can't spin them by hand to confirm that they're dragging. Then, unbolt the master cylinder from the booster....and pull it away about 1/2". Now try to spin a wheel again....if it spins, the booster pushrod is holding the master cylinder pistons slightly depressed into the bore of the cylinder, not allowing the lip seals to uncover the ports leading back to the reservior. Either adjust the pushrod or figure out what caused it to get longer in the first place (brake light switch adjustment, sticking pedal linkage, etc....) If a wheel does not release when you unbolt the master cylinder from the booster, loosen the lines at the master. If the brakes release, get a new master....if not, read on. Pick a front corner and go down to where the hardline connects to the soft brake hose (not at the caliper, the other end). Loosen this connection. If the wheel releases, then you know that the restriction lies somewhere between the master and the connection that you just loosened....which would be the prop valve(s). Replace the prop valve. If it doesn't release when you loosened the line connection, read on. Now go down to the bleeder on that caliper....loosen it. If the wheel releases, you have bad brake hoses. You can take them off and try to blow through them to confirm that they are a restriction. Over time, and if subjected to fluid contamination, rubber expands, which pinches the hole shut in the hose, causing it to hold a certain amount of pressure in the caliper/wheel cylinders. If the wheel does not release when you open the bleeder, there is a mechanical problem with the caliper/wheel cylinder/shoe assembly, which should be easy enough to figure out once you've pinpointed the problem using the above procedure. Good luck Quote Link to comment Share on other sites More sharing options...
Sideways Posted September 6, 2007 Author Share Posted September 6, 2007 Thats actually a good read, thanks. I couldve sworn i posted with an update last night, mightve had internet troubles or something- My apologies. The car was recently bought, and no previous brake work had been done to the car- Its actually been sitting for some time. Got onto the freeway and coudl feel the brakes starting to drag, an absense of acceleration and massive decel, plus that lovely smell. By the time the next exit was reached on the freeway (2-3 miles) the car was pulled into the first turn in ( a gas station). The rotors were the BRIGHTEST red ive ever seen a rotor be before, and the brake pads were on fire. Lovely. Water was used to quickly put the fire out, didnt need anything else getting torched. Yes i know this did in the rotors, but im sure theyd been done already (Steering wheel now plays la-bamba!). The brake lines were loosened off the master cylinder and the car was gimped home with the same problem happening one or 2 more times (Cant recall, it was about 2 am at that point). Im located in vegas and the cars currently hiding at a friends house in california, so its rather difficult to run out and check anything, so my apologies on that. Was hoping to find someone with a similar problem- Thanks for all the thoughtful and prompt inputs, its one of the things i love about the Z community (comming from an ae86 community, trust me when i say its much appreciated). Ill give all these a try and report with what ive found, ill also update with my solution for anyone else who may run into the same problem. On the bright side, i was planning on overhauling the entire brake system anyways Quote Link to comment Share on other sites More sharing options...
mark Posted September 6, 2007 Share Posted September 6, 2007 Check the free play on the brake pedal. The pedal should travel a slight bit before it starts to push in the rod that actuates the master cyclinder. could also be pistons stuck in the caliper bores. good luck. Quote Link to comment Share on other sites More sharing options...
Sideways Posted September 6, 2007 Author Share Posted September 6, 2007 Pedal had too much throw for my tastes honestly- I can hope its the pistons. But whatre the odds of both front pistons and the rear drums being angry like that at the same time? Plus would bleeding the pressure from the lines release the pistons from the bores (considering the natural wobble of the rotor didnt) Quote Link to comment Share on other sites More sharing options...
mark Posted September 6, 2007 Share Posted September 6, 2007 I doubt it is the calipers, sounds master related, make sure the push rod for the master is returning after being depressed. Sounds like something is keeping pressure from the master cylinder from releasing and it aint an air bubble. Check the linkage from the pedal to the pushrod and then thru the booster and to the master cylinder. Something is binding in there I bet. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 6, 2007 Share Posted September 6, 2007 The master cylinder piston is not retracting completely. Check the mechanical brake pedal components including the pushrod inside the boster. Quote Link to comment Share on other sites More sharing options...
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