odd brake problem

JapaneseDeman
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odd brake problem

Postby JapaneseDeman » Tue Sep 16, 2014 5:51 am

Hey guys,

Been a long time since i posted last. BUT here's the deal....

I finally built/ordered my new suspension set up and it finally came in. So when i went to put it on, i noticed my front passenger side brake caliper was pouring fluid. So i thought "ok, it's really bad... i'll replace it." Week later, new one comes in and i replaced it. Bleed it numerous numerous times, and had no brakes. Called my best friend who owns his own licensed and very succesful garage to come over, he's a master mechanic. We went through the motions, and he says master brake cylinder. Ok.
So i replaced the brake master 3 times total, even getting a brand new AISIN model from a toyota warehouse in japan (took a couple of weeks to come in), and still no brakes. So, being that the master mechanic was too busy, i sent the 86 to my uncle who's a master mechanic as well with 40+ years of experience.
He/we have reverse bled it, new (used but good working order) proportioning valve, new brake master, a used but near new brake booster, over 2.3 gallons of fluid bled through the entire system (reverse bled twice, gravity bled, normal pump bled, etc).
My uncle finally called me yesterday saying he has no clue, he's never seen anything like this before.

* the car (what it's doing) is that , after bleeding -car turned off- once bled enough, it has a great pedal and feel. however, once you crank the car, all pedal goes completely away like there's no brakes at all, even there. i've touched it with my index finger and it went straight to the floor. (again, once cranked) i drove it just around my block, and it acts like a bad master when, you can pump it to stop (eventually) but only the e-brake is really STOPPING the car, pumping the brakes only results in it slowing down. never enough grab to stop the car.

ANY and ALL help would be appreciated. i've been through every step i can think of, everything the book (fsm) has to offer, and my uncle's years of expertise. ANY ideas at all? thanks guys.

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Hindi
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Re: odd brake problem

Postby Hindi » Tue Sep 16, 2014 7:46 am

So that booster I gave you didn't help at all?

JapaneseDeman
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Re: odd brake problem

Postby JapaneseDeman » Tue Sep 16, 2014 7:49 am

nah brother didn't do a asingle thing. all still same issues, before and after the new booster.

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Glock30
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Re: odd brake problem

Postby Glock30 » Tue Sep 16, 2014 10:40 am

Have someone there with you and hit the brakes. Watch to make sure that the caliper is moving and contacting the disk (without putting your fingers in there. :) ). Maybe the caliper isn't sliding.
1984 Toyota Corolla Sport SR5
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saiGone
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Re: odd brake problem

Postby saiGone » Tue Sep 16, 2014 1:37 pm

My integra is doing the same thing.... just not as drastically.

Check the correct sequence for bleeding. Sometimes it's different than the normal: farthest from MC to closest.
Club 4AG member since 05 (Formally SaigonsSon)

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JapaneseDeman
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Re: odd brake problem

Postby JapaneseDeman » Tue Sep 16, 2014 2:51 pm

i've done the checking myself. had a friend turn the car on with it on the lift, and hit the brakes. the rear spin, but will slow down quite a bit but not come to a complete stop. (this is in the air, with the wheels off, in neutral.... yes the rear end/rotors are turning) and hit the brakes, it doesn't come to a COMPLETE stop, but very close. once you pump them quite a bit (5-7 times) they will stop when you hit it, but it leaks out/down. it, the brake pedal, goes to the floor.
and this is all only when the car is ON, if the car is turned off, it will not leak, it is a good solid pedal feel.

also, we've tried the order by the book, farthest away to closest. i kid you not, this car has had almost 3 full gallons of brake fluid pushed/bled through it. but still to no avail.

this is a SIMPLE system. i'm not a terrible mechanic. but when 2 registered master mechanics, one with over 40 years experience, tell me they have no clue what is wrong or what it's doing. i'm stumped.
3 new master brake cylinders. new/used brake booster. newish proportioning valve. even 2 new calipers to replace the original one that was leaking.
there's no real REASON this should be leaking down like it is. and there's no leaks anywhere. we've put some sand (well the oil-dry/kitty litter stuff) under the car to test for any leaks we couldn't see on the concrete, but nothing. not a drop anywhere.

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jondee86
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Re: odd brake problem

Postby jondee86 » Tue Sep 16, 2014 6:20 pm

Sounds a bit like a booster problem to me, but I'm no expert on
brakes, so maybe time to narrow things down a bit ? As I understand
it, you can take the booster out of the equation if you disconnect the
vacuum hose where it plugs into the booster.

So how about this. Find a place where you can drive the car around a
bit at low speed without getting into any danger. Turn the engine off
and take the hose off at the booster. You should hear a "whoosh" as
air rushes in the kill the vacuum stored inside the booster. Plug the
end of the hose leading to the intake manifold. Press the brake pedal
a couple of times... it should pump up and become firm.

You now have a non-assisted brake system that should work, but which
will require a much higher pedal pressure to stop the car. So be very
careful, and make sure you have plenty of clear space in front when
it comes time to stop ;)

Start the car and do some low speed driving around applying the brakes
and taking note of how effective the brakes are, and the pedal height
before and after braking. If the mechanical parts of the brake system
are in good order, you should get a firm pedal at a decent height.
Braking performance won't be brilliant, but it should be consistent.

Give it a try and report back :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

allencr
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Re: odd brake problem

Postby allencr » Tue Sep 16, 2014 9:43 pm

Looks like the phrase 'master mechanic' needs to be re-defined.
Fix the MC or whatever is moving that shouldn't be when it's getting pumped up!

JapaneseDeman
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Re: odd brake problem

Postby JapaneseDeman » Thu Sep 18, 2014 6:31 am

i have one of the NSTor T3 MCBstopper's installed. It is supposed to keep it all from flexing. When utilizing the pedal, i have not, nor has my uncle noticed any movement. Therein too, moving or not shouldn't have the same effect as it losing pressure, it wouldn't be there to begin with if things were moving.

jondee, good to hear from you again brother. been a long time. i'm going to get in touch with my uncle and explain what you've said to him and see if we can test it like you've suggested.

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