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. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Thanks! But still. I'm thinking here that a big company like RockAuto selling premium pads would not fudge that.
     
    dig4dirt likes this.
  2. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,646
    26,447
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Pad thicknesses are spec'd in the attachment to post #11. 10mm for front and 9.5 for rears IIRC, but check. Did rotors get replaced as well? Rotor thickness spec's are in the same attachment.
     
    andreimontreal and dig4dirt like this.
  3. dig4dirt

    dig4dirt MoonGlow

    Joined:
    Apr 6, 2012
    723
    380
    0
    Location:
    Lancaster Co PA
    Vehicle:
    2014 Prius c
    Model:
    Two
    LOL, toyota fudged on the Gen3 EGR system, and perhaps 2010-13 on pistons and 10-14 on rings.
     
    Grit likes this.
  4. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    3,069
    2,561
    1
    Location:
    BOY
    Vehicle:
    2012 Prius
    Model:
    Four
    (y)(y)(y)(y)(y)(y)(y)(y)
     
  5. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    I did the Invalid Mode bleed. Instructions say that if "The parking brake is released" it cancels Invalid Mode. I put on the parking brake. Was I supposed to do that or I understood it wrong?

    Take note: My parking lines were disconnected because of previous tests. I began with RR (rear right) and finished with RL(rear left) and it felt too short. Are these even connected or what the heck?

    The Outcome: I think it did the job but there's something weird so I can't dance yet. The RR wheel spins almost like in the video and did not heat at all (I did a 2x20km run RR is cold so great!!!). The grinding when spinning it is gone. However RL seems to grind and I'm not sure if it's related to the parking cable - it didn't cross my mind at the time, but I'll disconnect the parking for future tests to narrow it down. RL got hot in my test drive today (I was able to touch it type of hot), RLeft used to get warm at its worst (it was RRight that gave me the most issues).

    I put on RR the old Tokyco rubber bushings (replacing the swollen ones). Still, even with the Tokico bushings the pins are hardly moving - but the -7C might be the reason for it, grease gets pretty stiff in freezing conditions. The Tokicos were inside at 20C so I really don't know (also the Tokicos are so rusty, only one pin of the good one was lubed and working).

    For my 2x20km runs I got 6L and 5.4L/100km. How normal are these values for mostly highway at -7C?

    A big thank you - as always this forum is awesome. I'll come back with an update. The battles aren't over.

    PS: I do not know what I was thinking originally bleeding the rears without checking the manual - I was convinced it's like every other car; but that was a stupid move by far. If you see someone mention rear calipers make sure to mention the Invalid Mode; if someone did when I was chatting then it so so escaped me.
     
  6. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,646
    26,447
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Last time I tried to put it in Invalid Mode, (about a month back, doing a brake fluid change), I completely overlooked setting the parking brake. It won't go into Invalid Mode, if parking brake is off. It's in the rules, in the Invalid Mode instruction.

    So Rear/Right is good, turning semi-freely, but Rear/Left is dragging. With me it was the pad backing plate riding up on piston spoke, because the piston had managed to rotate.

    Did you apply/release parking brake before your test drive, and the test spin? The "marriage" of that pin and the spokes is loosest till you've really pumped the brakes a few times, and/or gone for a test drive, with a bit of easy braking. And I think that parking brake application will try to rotate the piston. If solidly locked that's ok, but if things are loose, it might shift up onto a spoke, and drag.

    This may or may not be the issue, just my hunch, because it happened to me.
     
  7. dig4dirt

    dig4dirt MoonGlow

    Joined:
    Apr 6, 2012
    723
    380
    0
    Location:
    Lancaster Co PA
    Vehicle:
    2014 Prius c
    Model:
    Two
    Do you have jack stands? put them in rear, use jack to hold up front
    Now may be good time to try getting all 4 wheels off the ground and start from step one.
    Invalid mode, then bleed all 4 corners and then see what happens.

    You replaced calipers, are the pins new?
     
    #67 dig4dirt, Dec 13, 2019
    Last edited: Dec 13, 2019
  8. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Yes. They're Raybestos Element 3 from Rockauto. Sliding them in and out by hand feels rather sticky though - what I said above - so I under if it's the freezing weather or something else. Playing with Tokico's at room temperature they slide maybe twice as easier.
     
  9. dig4dirt

    dig4dirt MoonGlow

    Joined:
    Apr 6, 2012
    723
    380
    0
    Location:
    Lancaster Co PA
    Vehicle:
    2014 Prius c
    Model:
    Two
    I edited my response above.
    Looks like parking brake does get applied?
    Might want to hook that up and follow Mendel's post above to check piston orientation.
     
  10. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Thought so . I had no time to test it like you ;)

    No time Mendel. When I got to my destination to the store I wish I kept the needlenose pliers in the car to unhook the cable. I'll check what you say definitely; I'll try various to try and pinpoint if it's the caliper or other parts.

    It might. Not 100% sure. Let's leave it at that and I'll come back when I've knocked out most possibilities.

    If I did the rears I'll revisit the fronts - at most - although everything works fine there.
     
  11. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,646
    26,447
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I should clarify, after reassemble of rear brakes, you want to avoid using parking brake immediately, leave it till after lots of brake pedal pushes, and if possible even do a test drive first. My theory: you can have the piston orientation correct, but if it's not solidly locked against the pin, a parking brake application may still rotate the piston, make a spike ride up on the pin.
     
    Ed Beaty, dig4dirt and andreimontreal like this.
  12. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Ok Mendel, thanks for the heads-up. Makes sense.
     
    Mendel Leisk likes this.
  13. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,646
    26,447
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Fixing a typo, too late to edit old post.

     
  14. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Tiny update. I did 2-3 km to a store and back and the Rear Left disc was hot. I unhooked the left parking brake line and did about 20km with another errand and the Rear Left disc felt just as warm as the rest, maybe a tad warmer.

    I'll have to investigate deeper but it looks like that brake line might be faulty.
     
    Mendel Leisk likes this.
  15. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,646
    26,447
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    That's a significant clue I think. Something seized in the parking brake cable? There's an equalizer bracket shown in the attached, has an odd-ball Toyota name.
     
  16. Michael Wood

    Michael Wood Junior Member

    Joined:
    Jun 19, 2016
    27
    24
    3
    Location:
    Boston, MA
    Vehicle:
    2015 Prius
    Model:
    Three
    Yes......the brake house kit provides a piece of hose that runs from the caliper to the metal brake line mounted to the vehicle frame. A typical brake hose kit includes the hose, end fittings, and clamps - everything you need comes with the kit. Each wheel on the car has it's own designated brake hose kit.
     
  17. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    I got the brake booster replaced under JZB(W35 in QC) . I still had warm/hot discs in the rear, I'll check again when I do longer drives.
     
    Mendel Leisk likes this.
  18. andreimontreal

    Joined:
    Jan 30, 2019
    188
    65
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    @ChapmanF is there a chance in the world that a faulty booster could lead to a caliper dragging?

    I still have a rear disc getting hot. And it's not the parking cable as far as testing goes. The other side got fixed simply by putting oem Toyota bushings on the pins. I got new Raybestos calipers, discs and pads on (not remanufactured); the pads, the discs have proper oem dimmensions. I'll order some bushings from Toyota; the only fix I can think of for now.
     
  19. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    8,286
    5,935
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    If the brake actuator had one of the SLA valves not fully closing off, or something like that, the result could be constant brake fluid pressure in one line. That's one of the reasons there is a school of thought to always open bleed screws when pushing caliper pistons back, rather than forcing potentially grotty fluid back up through the actuator valves. (There are also people in the other, "I've always just forced the fluid back and never had a problem" school of thought. I'm more or less Switzerland.)

    But that's about the only way there is for the actuator to be causing such a problem. It can't affect the rear disc by magic, or magnetism, or telekinesis. Only by fluid pressure.

    Which means it shouldn't be impossible to catch it in the act.

    Does fluid spurt under pressure if you open the bleeder on that line, when no one is applying the brakes?

    If you watch the Techstream live wheel-cylinder-pressure readings while no one is applying the brakes, is there a non-zero pressure in that line? (That test would be trusting the sensor built into the actuator, but that seems mostly ok to me. The actuator is a box with a bunch of valves and sensors in it, and even if, say, one valve is messed up, I wouldn't jump right to assuming the sensors are bad too.)

    There are also electronic pressure transducers you can obtain, and plumb directly into a brake line (there are such things as adapter fittings that replace the bleed screw), and connect to a datalogger, and watch what the pressure is doing, if you distrust the sensors built into the actuator.
     
    Mendel Leisk likes this.
  20. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,646
    26,447
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Take it to dealership?
     
Loading...