2012 Prius - New Calipers, Pads Still Dragging (hot brake discs)

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by andreimontreal, Nov 17, 2019.

  1. Michael Wood

    Michael Wood Junior Member

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    I had a caliper that wouldn't release on my Jeep. The rotor was heating up. Everybody, including me, thought it was a frozen caliper. The problem ended up being a collapsed/defective brake hose - the hose that connects the caliper to the metal brake line. I couldn't believe it. But I bought a new Raybestos brake hose at Autozone for $35, installed it, and the caliper worked perfectly.

    I never would have believed that something as simple a brake hose, which looked perfectly normal on the outside, could fail internally. Apparently, part of the inner rubber hose can collapse and block the flow of fluid in one direction. I'm not sure if that ever happens on Toyotas, but it happened on my Jeep. So it might be worth a look if you experience a frozen caliper.
     
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  2. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Someone mighta used hose clamps on it too?
     
  3. ASRDogman

    ASRDogman Senior Member

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    The easiest way to check is the raise the wheel and spin it, if it sticks, release the bleeder screw.
    Does the wheel turn freely? If yes, then the caliper is probably okay.
    if not, close the bleeder, pump the brake pedal a few times. Then release the hose on the caliper.
    Does the wheel turn freely? If so, not the caliper.... Hose, line, or master cylinder.
     
  4. scona

    scona Active Member

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    I had a similar thing happen and it turned out to be that the wrong disks were supplied. They were a bit
    thicker so the pads dragged. Went back to the supplier and when they rechecked and provided the
    proper disks everything worked normally. That took several weeks of torment and many disassemblies
    before the truth became evident. If you still have the old parts a cross check is not difficult. Good Luck
    with getting it sorted out.
     
  5. andreimontreal

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    Was it the last piece of the hose connecting to the caliper?

    Got busy, still have to double check all the lists I got. The good thing is that I ordered the rubber hoses for the rear calipers so I might try and see if this is the case if everything else fails.
     
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  6. andreimontreal

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    SO. Update: check rear right

    Pins were stuck like crazy. Wiped the grease to eliminate a "too much grease" issue. The rubber bushing at the end of the pin was fat/expanded. Putting it inside created so much vacuum. So I took it off cursing all those China bros, greased the pins and mounted back.

    I closed the pin bolts, pressed the brakes to make sure the cylinder was as close to the pad as needed. The cylinder's groove was aligned with the pad's notch, I stuck my head in there with a strong light to make sure (in fact the cylinder was on the pad 100% of the time - no retraction). And I unscrewed the bleeder valve until I saw some fluid coming out. The brake was just as stuck as before. It's as if the cylinder has some issues - stuck in the past issues, I need a shrink for my calipers.

    At this point I don't think that checking the hose is necessary. I am pissed off at Rockauto and their Chinese cheapos that are supposed to be brand new and working great.

    VIDEO of rear right wheel - I am getting 1/2 to 1 rotation of wheel at most when pulling with all my strength (just hear that soft grunt) , first grabbing the spoke then pulling the wheel from the rubber.

    REAR Left - same thing, maybe a bit looser. So how bad is that? Looks bad to me compared with the video posted before.

    It feels like I should contact Rockauto, send their crap calipers back and to get some OEM Tokicos locally (ie lesson learned). Anything else?

    The vids were made with the bleeder closed. I did not want to crawl under the car just to open the bleeder on this weather - got tons of things to do. So now, that looks really bad doesn't it?

    (PS: I wanna shout at somebody for no reason by this point, any volunteers ... :)
    Edit: it looks like I'm stuck with the parts too as I just went over 30 days ... oh joy, this is nerve-ana ... )
     
    #26 andreimontreal, Dec 9, 2019
    Last edited: Dec 9, 2019
  7. ASRDogman

    ASRDogman Senior Member

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    Maybe I missed it, are these NEW from RockAuto? If so, the pins should NOT be sticking!
    Too much grease won't cause that.
    Maybe the hand brake cable is too tight? Did you ever adjust it? You may have to loosen it up.
    If you have that "square" tool, or equivalent, you can try pressing the puck back in. Maybe they didn't
    screw it all the way in when they rebuilt them. ????
    Are you certain the pads are the correct ones? Not too thick?
    When you loosed the bleeders, did the wheels turn freely? Or did you not do it because the rain/snow?
    I wouldn't want to craw around on that stuff either. :)
     
  8. andreimontreal

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    Yes. And - Agreed no questions asked.

    Yes I did. But in the name of science the brake cables are OFF at this point - the ball attachment has been detached.

    Hold on. I don't remember if I went all the way in at the initial install (hmm I might have) and I see this might be a reason to mess this up - the fact that they're screwed in all the way, does that create the vacuum necessary to suck them back after the foot is off the brake? That is if I didn't go in all the way initially, there's not enough vacuum created and they drag? At least today I used the square to screw in 1/4 of the turn to have an extra mm for sliding the caliper back and I did NOT make sure I screwed everything all the way. This might be it ... I hope ...

    I have no idea. Someone mentioned the same thing for the discs. I ordered pads and discs for my car model at Rockauto ... what are the chances they're not the right thickness? Not sure what to compare measurements with though. I have digital calipers to measure the thickness.

    With bleeders open I only tried to rotate the disc by grabbing the bolts. It was just as jammed/stuck as ever; I could move it an inch sometimes but it was dragging heavy. So I didn't even think of wasting time with the wheel on. It made no difference.

    %%%%%%%%%%%%%%%%%%%%
    Troubleshooting conclusions - maybes:
    0) Edit: stuck cylinder
    1) Either not rotating cylinders all the way EDIT: my dad and his buds, both the kind that work on their cars( east EU engineers) said no way this would be the case ... so stuck cylinder is more like it
    2) Collapsed rubber hose like the Jeep dude mentioned ...
     
    #28 andreimontreal, Dec 9, 2019
    Last edited: Dec 9, 2019
  9. ASRDogman

    ASRDogman Senior Member

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    I forgot about the hose! Glad you remembered. But releasing the bleeder screw would still release the pressure.
    You could drive it a few days and let them wear in a bit, then check them. Sounds like you did screw the puck
    in all the way. The's no vacuum. New rotors and pads are usually a snug fit.
    Seems you did everything else you needed to do.
    You did like up the puck so the indents on the pad fit in the recess? The pad would be crooked if you didn't.

    Mendel will pop up a picture shortly, probably. :)
    But I think it's on the instructions for the pads.
     
  10. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    I think he's saying the pin on back of pad is between the piston spokes. It needs to start there, and stay there. It would almost be better if it didn't, in fact the piston managed to rotate: that's easily remedied.

    You can do this without even jacking it up I think, shimmy under, shine a light at the back of the rotor and brake shield. There's a little gap where you can see the inside face of the rotor. (IIRC, don't shoot me if I'm wrong...) If about 50% of it is rusty, that likely means the piston has managed to rotate, rotate a spoke up on the pin.

    This pic I had the caliper off, easier to see:

    upload_2019-12-9_17-44-25.png
     
  11. ASRDogman

    ASRDogman Senior Member

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    I meant where the back of the pad touches the puck. The pin has to line up.
     
  12. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Yeah I think he knows that. It can be a case too, that you assemble everything correctly aligned, but don't ensure its seated thus, apply the parking brake, and the piston will rotate.

    The last steps of a brake job should include a short test drive, then apply/release the parking brake a few times, then raise the rear again and see how the wheels are spinning.
     
  13. andreimontreal

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    Like I said, I stuck my head in there with a strong light. The cylinder looks like it's aligned properly and sitting snug against the brake pad.

    I can only conclude that the cylinder is jamming and not retracting properly. But why? It was fairly easy to rotate the cube. I suspected cheap grease that does poorly in low temps; not sure about that theory though.

    Edit: A detail that I forgot. In addition to swollen bushings (I'll compare with new ones, got spares, but like I said they felt and looked swollen) the rubber around the cylinder would twist too much when I was turning with the cube. As if the rubber wasn't sliding on the cylinder. I'm not sure how that rubber sits inside there but I'm wondering if that wasn't already swollen when I installed it and this is the reason for the friction. That cylinder rubber behaved like that from day 1 it twisted a lot - not sure if it's normal.
     
    #33 andreimontreal, Dec 10, 2019
    Last edited: Dec 10, 2019
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  14. ASRDogman

    ASRDogman Senior Member

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    Sounds like you've pretty much checked everything for the calipers.
    I would say it's time to contact RockAuto....
     
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  15. Siward

    Siward Member

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    Well, I replaced my rear left caliper 2 months ago with the same Element3 RL caliper from RockAuto, but was installed by a professional mechanic. I drove the car home and left it in storage for 49 days. I have driven on the new calipers for about 500km now and they are fine. I will get to drive my Prius a lot more at the end of this month.

    I find it suspicious that both your rear calipers are defective. That means you are really really unlucky. In addition, the caliper retracts when you screw it with the cube which should indicate that the piston (cylinder) is not seized.

    As mentioned in the South Main Youtube video, it is possible the caliper has been left on the shelf for a long time. The pin lubricant could have dried on the shelf. You should have cleaned caliper pin hole thoroughly to remove any dried lube. What's even more stupid is the two pins for the rear are different lengths. Careful you don't mix them up.

    I was thinking you could have mixed up the RL and RR caliper, but there's no way right? The brake line lever on the caliper should face the rear of the vehicle.
     
    #35 Siward, Dec 10, 2019
    Last edited: Dec 10, 2019
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  16. ChapmanF

    ChapmanF Senior Member

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    It is important that the piston not be seized, but it's also important that it retract in normal operation when you let off the brake. Nobody is spinning it with a cube then, and the only thing that retracts it is the elasticity of the square-cut rubber seal inside the cylinder.

    [​IMG]

    I now check calipers for that retraction (it's just a small fraction of a mm) before installing them; that's after an experience with an aftermarket one that had zero retraction right out of the box.

    There seems to be a fair amount of materials science going on, involving the composition of the rubber, the surface finish of the piston material, and the coefficient of friction between them; I get the impression some of the aftermarket suppliers make substitutions there and it doesn't always work out so well.
     
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  17. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Also, some pin lubes will swell rubber. IIRC the rear pins have have the rubber "collars"? This is a long shot though, because I think the swelling happens gradually, over months.

    I'll defer from mentioning pin lube names, leave it to @ChapmanF .
     
  18. Siward

    Siward Member

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    Both rear wheels take all your strength to turn 1/2-1 rotation? Mine does have some dragging noise (from pads), but it doesn't take much strength to turn. Sounds like you are spinning them with the hand brake engaged as it controls both rears. Make sure that the foot hand brake pedal goes all the way up and check it's hose adjustment. It is the pedal that makes clicking noise when it goes down.

    I would try unhooking the handbrake brake hose from the caliper lever and then testing it which I suggested before. You can keep the hose through the guided hole, but unhook it so it exerts no tension on the lever. Ensure the lever is fully up then test. (I guess you did this on Post #19)

    Well, there's always a defective caliper, but two in a row is really unlucky. You can also put back the one working OEM rear caliper (you had one that worked) to compare. If your working caliper fails the same way then you are doing something wrong.

    You can contact RockAuto to return outside 30 days. It may vary since the part is now previously installed. It would have been better if you installed/tested one caliper at a time before committing.
     
    #38 Siward, Dec 10, 2019
    Last edited: Dec 10, 2019
  19. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Yeah that's not right:

     
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  20. andreimontreal

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    Siward, the left side heats up way less than the right and when I spin the wheel it feels like it's more loose - so not exactly the same same story with both. The pins and holes were cleaned extensively with brake fluid, rags rolled on shafts, they were lubed with AGS sil-glyde, I mentioned it above :) - except the cylinder ... I wasn't sure I wanted to open that. No way you can mix those calipers.

    Great point with the size difference - any idea what goes where? I think I might've taken that into account as I think I always paid attention to put pins in the same hole.

    I posted on Reddit on a mechanics. The only reply so far said that Priuses are bled using a computer :| ??? C'mon.

    ChapmanF thanks for those details! That is exactly what I think it's happening. I'll have someone press the brakes while I poke my head under to see if there's any piston retraction at all. There should be a mm or something.

    Mendel Lesik AGS Sil-Glyde is the silicone grease for brakes with the highest rating that I could find ever. So, I do not know what to say. I'm also thinking that the pad was pretty hot so the rubber was hot in there too - maybe that affected it as well.

    Siward, the parking brake is already disconnected, like I said before. I disconnected the ball attachment from the caliper's hook. I agree with trying an old caliper on - that was on my mind too; next step before rockauto.

    I got some spare bushings and pin, I'll try to revive one of those Tokicos.

    EDIT: Looked for bleeding a Prius with a computer and I found this clip - does anybody recognize any of those steps in that video??? It's the first time I see any mention of plugging in some device, disconnecting that line ....
     
    #40 andreimontreal, Dec 10, 2019
    Last edited: Dec 10, 2019
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