Need Help - Rear Passenger break sticks. Ideas?

[JDMChris]

Problem: Rear passenger break keeps sticking. I went through a rotor and brand new pads in just over a week. not good.

This passed weekend, i had to be towed off the highway because my caliper stuck to the point of failure.. lol the rotor exploded into red hot schrapnel. Gotta love CAA free flatbeds!






If you think that looked bad, you would have had a good laugh watching me take it off.. the caliper was FINISHED. the piston was out all the way, the break pads were bent inward.. no pad left what so ever.. just totaled.


Anyway,
Ive changed that caliper three times now, and im still having the same issue.... so im guessing its not the caliper. lol
Ive also disconnected the hand break on that side to see if that was the issue... still sticks.
Ive checked the break line to see if its pinched or kinked anywhere.. and it looks fine from what i can tell.. i traced it from the corner to just passed the driver seat.

It dont always stick.. just randomly.

Any ideas?

[stepchyld]

I'd suggest checking the rest of the brake line, all the way to the proportioning valve on the firewall and the master cylinder. Also, check the other lines.
I don't know exactly how the proportioning valve works, but maybe there's an issue there if you're on your third caliper. Where are you getting your calipers?

Did you bleed the entire brake system when you changed the calipers, or just that one?

[mikeinaus]

4 things i know of that will cause a problem like this.

1. seized caliper, youve gone threw 3 so most likely not the case
2. seized ebrake cable. if it was that bad youd probably notice it engaging the brake when installing it- also unlikely
3. your brake pedal/booster input shaft isnt adjusted properly. if the input shaft going into the master cylinder is too far forward it will block off the vent port which would cause hydraulic pressure to be unable to release and build until the wheel locks up.
4. pitting in the master cylinder causing one of the pistons to get stuck on its return causing the same problem as above.

im not sure our cars have proportioning valves do they? there typically used in front disc/read drum to take into account the self energizing effect shoes have in the drum. as the shoe is applied the drum forces the shoe into itself acting like a wedge which results in much less input pressures needed. the proportioning valve is meant to limit brake pressure to the rear wheels to prevent lockup. its unlikely a fault in the valve would cause a permanently locked brake. locking during braking yes, but not constantly on. if it was a rear drum it could be a residual check valve issue but once again thats not apart of our brakes.

couldnt hurt to take off the master cylinder and have a look at it on the bench. if it is a problem in the master though it should affect both sides. how are the other calipers on the car. if the caliper that shares the same line is seized its possible it wouldnt be affected as much by an excess in hydraulic pressure.

was there any pulsing or odd feeling in the brake pedal leading up to this?

ps aint it a kick in the balls to have to get saved by a honda?

[JDMChris]

Lmao, every one of my friends drive Hondas. I was on my way to a meet when this s--- happened. I was the only Mazda out of a 11 honda car convoy. lol but I stand by my car, I put them in there place when they talk s---. The guy in the DA was like.. For once I'm not the one broke down on the side of the highway.. I woulda been the only mx3 there.. Was possed it didn't make it. Lol anyway...

It's just that one corner that sticks. The other side is perfect, the front are perfect.
The two rear break lines come from the front to the back (on the left) than cross over the gas tank to the right where they Split apart and go to each side.
Following the break line passed the driver seat will require me jacking up the front. It's next on my to do list.. Damn v6 cramps the engine bay like a champ.

[wytbishop]

Something is preventing pressure from releasing when you release the brake pedal...but only sometimes. A kinked line would not be intermittent so I don't see how it could be that. Some sort of debris is theoretically possible but seems extremely unlikely in a closed system. A problem at the booster or master cylinder would seem to me to have to affect the entire braking system, or at least both fronts or both rears, so I don't think it's that.

I believe it has to be the proportioning valve. When you apply the brake pressure rises as you push harder and harder. At a certain pressure a valve closes (on each of the rear brake circuits) stopping any more pressure from going to the rears and allowing pressure to continue to rise in the the fronts. I think that valve is sticking closed randomly on that side preventing pressure from being released when you release the brakes.

I've never cut one open to see inside but I'm guessing it's a ball and seat with a calibrated spring. I bet you have had water in your brake fluid and the ball on that side is rusted and sticks in the seat.

It's a crappy job I've done it, but you need to change the proportioning valve.

[JDMChris]

^^ good explanation. Thanks for going into detail. Makes sense.
Any idea where in the engine bay it might be? The v6's bay is quite a mess.
Ya ya.. Follow the lines.. Lol I know but I'm at work and my car at home.. Just trying to save some time.

Btw, when I took my caliper back to get it warrentied, I showed them those pics and they gave me free pads and rotors aswell

[wytbishop]

It's on the firewall behind the rear cylinder bank closer to the passenger side. A single bolt holds it on the firewall. It's removing the brake lines from the valve that makes it so much fun. There's no room at all to even get your hand in there let alone swing a wrench around.

It sucks.

[JDMChris]

Thanks, found it.. I can fit my hand in there.. Lol getting the lines off looks to be a bit h. They don't tell you that here: http://www.autozone.com/autozone/repair ... 5280261617

I got quoted 150+tax for the valve..
Lol add it to the list of parts needed. *facepalm

[stepchyld]

Free pads and rotors?! SCORE!!
I thought that was the proportioning valve. I've pulled one off an sohc rs and an mx6, but neither had an engine in the way, so good luck with it! Get a wrench for brake lines, those fittings are very easy to round off.
Pinched line sounded iffy to me, and I also suspect the master cylinder would effect more than one caliper on the car.

150 plus tax, ouch. Maybe one could be found elsewhere? These don't go out often, do they? I've never had one fail...yet

[wytbishop]

I had one fail the other way...no flow at all to the rear. I managed to find one in the junk yard in a car with no engine, but putting it in took 90min for 1 bolt and 5 flare nuts.

[Redline322]

I'm not sure if you've checked them, but I've had flex lines collapse on the inside but look fine on the outside, causing it to randomly lock up that caliper. It took me 2 new calipers and a set of brake pads to realize that, so it might be something to check.

[Sleeper6]

I doubt its the valve, personally I would change the hydraulic line and put a new caliper on. Also be sure to make doubly sure when your installing the pads your putting the pins into the caliper cross (+) <the part that looks like that. Ive seen seasoned techs put pads in a caliper with the piston partially turned that caused brake pads to bind up in the same way.

[JDMChris]

I have both parts.. Flex brake line and the valve. Interesting how I couldn't blow thru the old break line and I can in the new one.. If thy fixes it I don't even have to touch the valve

[SuperK]

nothing a little rotor resurfacing can't take care of

Interesting to see the structural integrity with drilled rotors. I would think that if they were solid they wouldn't have exploderate like that.

[JDMChris]

UPDATE: it seems to have been the glex line causing the problem.. No problems since.