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Old 04-02-2011, 11:40 PM   #1
coonmanx
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Default Brake Failure

I was driving along when I had to step on the brakes hard and something gave out and the pedal went to the floor. Last week my brakes had gone metal to metal in the rear but only on the driver's side. The other side was only half way worn. So I figured that something was up. I bought a new rotor for that side (other side was almost brand new still) and went about putting on new pads for both sides. When I reset the piston in the caliper on that side it was somewhat difficult to push the piston in and then the seal started to leak on the inner side of the caliper. Now that caliper was new and still under warranty (about 15 months old). So i got a replacement caliper from O'Reillys for free. Had my mechanic put it on and also replaced the flex lines in the rear on both sides. Had the entire system flushed with new Super Blue Racing Fluid. Everything was fine until tonight when it appears that another seal blew out. Brake fluid all over the wheel on the same side. Are those calipers just total crap or is there something else going on? I will pull the caliper in the morning and call O'Reillys to see if I can get another warranty replacement. But it makes me wonder why the same side has failed twice. I almost feel like going to the junkyard and finding a used replacement caliper. Any ideas about what is going on? I'm pissed at the moment.

I guess that two questions come to mind. First why was it harder to reset the caliper on the driver's side? And secondly could I have some sort of imbalance with pressure that is causing more pressure to go to that side? Seems unlikely but I am getting frustrated because all of a sudden I'm having issues. And remember that the pads were completely gone on only that side.
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Old 04-03-2011, 01:20 AM   #2
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Sorry but I have to bump this because I'm going to bed soon and tomorrow morning I will be calling O'Reillys about the caliper. I have never had a caliper blow out like that. Quite scary. Good thing the E-brake works.

Is it at all possible that somehow the proportioning valve is no longer working properly and I am somehow getting too much pressure to that caliper?

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Old 04-03-2011, 03:18 AM   #3
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Why the parking brake?

I have busted a hard metal line in the past on my 245 and still had most of the braking (80%).

Drove 500 miles home with a screw plugging the line on the front.

Is the other circuit working? There should be only a few ways to fail both circuits at the same time.
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Old 04-03-2011, 11:04 AM   #4
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I haven't tried plugging that line because I just got the car home last night and diagnosed it. At first I thought maybe the master cylinder had gone out when the pedal went down to the floor. I have never experienced a sudden fail like that. What would you do if you had to hit the brakes hard and when you did there was nothing there? You would grab the Oh $hit handle (the E-brake). And that is what I did. BTW I was on the brakes hard because I had just passed a moron in an STI and was pulling into a turn lane. I pretty much laid on those brakes full force.

I am not really sure what is going on. When I saw the brake pads worn down like that last week I figured that I had a sticking caliper. But I also saw the leaking seal on the inner piston and that was a brand new replacement caliper. So I had the caliper warrantied and replaced those flex lines (a failed flex line can prevent the piston from returning properly). And now I also have all new Super Blue fluid in the system. All that I can think is that the replacement caliper that I got was once again crap and when I put the pressure on the brakes hard it just had an epic fail. Blew it out completely. But I am also trying to eliminate the possibility that there is something else going on, that there is another reason that the brakes system is experiencing a problem on that corner of the car.

I am picking up the phone now to call O'Reillys.
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Old 04-03-2011, 11:10 AM   #5
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Something else other than lousy rebuilt calipers is going on.
Your dual diagonal system on an 84 should still have 3 braked wheels in the event of the loss of one circuit.
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Old 04-03-2011, 11:27 AM   #6
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Is the proportioning valve shot? Am I getting too much pressure to the one line? That is all that I can think of at the moment. This sucks because I just spent $150 getting the Super Blue in and the system completely flushed. I have to believe that there is something else going on. I may try to block off that one line and see if I can drive it. I need to use the car tonight. I am running out of options. The thing is the brakes were pretty good before the caliper blew out.

Epic fail for sure.
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Old 04-03-2011, 11:37 AM   #7
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The proportioning valve failure shouldn't do that.

Sounds like the master cylinder O rings may be shot from pushing the pistons past their usual working range. IE into the unused,and possibly rusty part of the MC bore.

I use the motive bleeder,and stay within the normal working range of the brake pedal for that reason.
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Old 04-03-2011, 11:38 AM   #8
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Something else other than lousy rebuilt calipers is going on.
Your dual diagonal system on an 84 should still have 3 braked wheels in the event of the loss of one circuit.
That was my first though, the damn cars have a brake system and a half just to prevent this.
When you bleed the brakes, do you get good fluid flow everywhere?
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Old 04-03-2011, 11:51 AM   #9
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I took the car into my mechanic when I had the system bled out. I thought that maybe he would use a pressure bleeder but instead he was pumping the brake pedal the whole time. I could see a master cylinder fail but that would not explain the blown out and leaking caliper. Did I experience a dual failure at the same time?

I showed him the Haynes manual as well with the proper order for bleeding out the system. But I'm not sure that he followed any of that. I have the Motive bleeder as well and now I wish that I had used that instead of letting the mechanic do it. But it is much easier to do on a lift than having to jack each corner up one by one. I only have two jack stands. But I was surprised that he was doing a "one man bleed" using the pedal. They work on Porsche and all and that is evidently how they do it. They had a very large reservoir full of fluid. I should have let him use my Motive bleeder.

I am going to try and cap off that line and see if I can drive the car before I get further with the diagnosis. If I cap it off and then get full pressure back then it would seem that the MC is OK. If I cap it off and it still goes to the floor then the MC will be shot. I think that I know where I can get a MC from the junkyard. Also I may run through the bleeders one by one after I get that line capped off.

For now I called Hertz. Looks like it's back to the rental car for the day.
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Old 04-03-2011, 12:21 PM   #10
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Is the brake failure light lit on your dash.

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Old 04-03-2011, 12:30 PM   #11
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Brake failure light comes on when I push down on the pedal far enough. I can get it to go off by tapping quickly on the pedal.
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Old 04-04-2011, 12:41 PM   #12
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I went in to my mechanic this morning to pick his brain about the situation. His response was "crappy calipers". So I went to the junkyard and pulled one off of an '83. I will install that in about twenty minutes when the sun comes over to this side of the apartment building. Then I will pick up the warranty replacement caliper from O'Reillys and just keep it as a spare. I have the Motive bleeder which I will use to get the air out of the line. First time I will be using it. I watched the online video and it looks pretty straight forward and easy to use.
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Old 04-04-2011, 02:12 PM   #13
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Aren't you going to replace the caliper with the stuck piston?
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Old 04-04-2011, 02:16 PM   #14
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http://forums.turbobricks.com/showpo...42&postcount=6
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Old 04-04-2011, 04:08 PM   #15
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Yeah, I know the bleed order. It's in the Haynes manual. I didn't need to do all of them because I only lost fluid out of the back driver's side line. I actually couldn't get the Motive bleeder to work at all (no fluid out of the bleeder). Don't know what I was dong wrong. It said not to go above 20 psi in the instructions so I tried it at about 18 psi with no luck. Ended up have another person pump and hold the pedal and now all is good.

Anyway, the seal on the caliper that I removed was completely blown out and jacked up. So now I have a caliper from the junkyard on there and I have the warrantied one from O'Reillys as a spare. Now if it blows out again then something is up. But right now everything is working good.
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Old 04-04-2011, 11:13 PM   #16
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I'd be real curious why the power bleeder didn't work, no offense intended but it's idiot proof for all practical purposes, I just bled a 240 last night with 5spi and it was all new hardlines up front and rubber in rear and the calipers had been off, took 30 seconds per bleeder, two passes. Wonder if something is wonky in your master cyl?
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Old 04-05-2011, 12:23 PM   #17
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I am curious as well. At first I tried it without putting fluid into the tank. There was plenty of fluid in the master cylinder so I figured that I would just push the fluid in that particular line and then top off. Then later I dumped some fluid into the tank but got the same results. I did put the rubber piece into the "cap". Not sure if that was needed or not but I figured that it would help the cap seal better. And the rubber piece has a hole in the middle to allow fluid to flow. But as I said as soon as I bled the system using the pedal everything worked fine. I am a bit disappointed as I was really looking forward to the ease of using the power bleeder. Something definitely seems up with the brake system but I can't really figure it out. At this point it would be nice to redo all of the lines, master cylinder and proportioning valve and then I would know for sure that everything was as it should be. I don't really get what is going on but I will just have to keep an eye on the brake system and watch out for any signs that something isn't quite right.
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Old 04-05-2011, 01:02 PM   #18
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PITA ain't it? Yay old cars. If it was me I think I'd do a new master cylinder and new rubber lines just on principle. Was the fluid really cruddy when you first started messing with it? I don't know if you can get a master cyl reseal kit for them anymore, but they are pretty cheap from advance/autozone and I've had good luck with calipers and mas cyl's form them, cost and the hassle of core return on calipers got me to try them.
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Old 04-05-2011, 01:21 PM   #19
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Fluid was cruddy so that is why I had a full flush to Super Blue about a week ago. The caliper that blew out was a brand new rebuilt unit from O'Reillys. Also the weird thing is that all of the seals that have gone out were on the inside piston of that caliper. I don't know if that means anything or not. The flex lines in the rear are brand new as well. I have new flex lines for the four front lines but have not installed them yet. I am thinking that putting on a new master cylinder might not be such a bad idea.

Now I have a spare caliper for that side because yesterday I went to the junkyard and pulled one and put it on. The warranty one that I got back from O'Reillys is now a spare. Not sure I trust them but I'm also not sure why the system didn't bleed with the Motive. Just going to keep driving and hopefully not have another blowout.
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Old 04-05-2011, 01:40 PM   #20
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Measure your rotor temp, and see if you are smoking another seal.
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Old 04-05-2011, 01:54 PM   #21
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But what would cause the rotor temp to go so high? I was thinking that maybe it was a stuck caliper before. The only other thing that I have noticed on that side is that the E-brake shoes are a bit tight on that side. It is a bit difficult to get the rotor over them. But that has been that way for as long as I can remember.

And is there any reason why it is always the inner seal on that caliper that goes bad?
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Old 04-07-2011, 12:16 AM   #22
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Didn't I skim over something in the Bentley about the alignment of the pistons in the calipers? 20 degrees on that angle cut or something like that? Just a thought.

Does it seem to brake OK? Rears lock up in the rain easy, etc? There are proportioning valves on the rear. Just another thought.

The parking brake shouldn't be that tight I don't think. Did yours have the star wheel adjuster thing or the early non-adjustable one? Mine was non, e-brake works, I didn't mess with it, was no interference putting the rotor on in the rear.

There is also a spec for centering the caliper over the rotor, I don't think it's common but they can be off center from the rotor, had to shim a 911 once.
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Old 04-07-2011, 02:22 AM   #23
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Car is braking pretty well right now. That driver's side E-brake has always been tighter than the other side. Maybe it just needs a proper adjustment. I've been too busy fixing everything else to get around to looking at that. Maybe I can have the mechanic take a look next month. Adjustment is at the back of the handle I believe.
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