Replacing rear brake pads?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Josh S, Jul 21, 2012.

  1. Josh S

    Josh S Junior Member

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    One of the rear pads was not sliding correctly due to corrosion so the pad has uneven wear and I need to replace the pads/rotors. I went at it today but I was unable to press the caliper piston it at all to make room for the new pads. I was able to get it back together with the old pads for now.

    Is there a trick to depressing the pistons? Do I need to remove the pressure somehow? I did disconnect the battery before starting.

    I've replaced brakes on a ton of other cars before and have never had this issue.
     
  2. spiderman

    spiderman wretched

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    Welcome aboard Josh. I do believe replacing the brakes on the prius is a bit more involved and I think their computer program hooked up the ODBII port is necessary for a complete job. Other will know more.
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Rear pistons typically need to be screwed in, either with a special tool or makeshiftly with pliers, due to it working as a parking brake.

    Still, as mentioned above, might be best left to the pros: as soon as you push in a piston you'll likely create a low pressure situation at next startup, which will trigger warnings from the computer, and maybe other issues.
     
  4. Josh S

    Josh S Junior Member

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    Well it was operator error on my part, I wasn't turning the piston while pressing. I did that and got the new pads and rotor on with no issues. Hopefully I don't get any check engine lights or anything..... used to working on order cars..
     
  5. The Critic

    The Critic Resident Critic

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    Just screw the pistons in and it will be fine. Do make sure the slot is at a perfect 90 deg angle or else the pads will drag. I have had mine off a few times already.

    Honda has said that cleaning the caliper brackets and applying a layer of Dow-Corning Molykote M77 UNDER the pad retainers will prevent corrosion from building up in that area.


    iPhone ?
     
  6. DumbMike

    DumbMike Active Member

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    Please excuse my lack of knowledge. I've changed the brake pads on older cars where I basically only needed to use a C-claim to push in the piston and remove the brake calipers, etc. Can somebody explain this "screw the pistons in" thing? I have to admit that I haven't even looked at the rear brakes, and kinda feel intimidated by it all. But once you explain it, I think I'll get the drift. Thanks. Mike
     
  7. El Dobro

    El Dobro A Member

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    Nowadays, most rear brake calipers need a tool to screw the piston back into the caliper to start over again with new pads. When you set the parking brake, the lever on the back of the caliper screws the piston out for contact. If you use a C-clamp, you could damage the piston. The tool screws the piston back into place.
    Here's an example of the tool.
    [​IMG]
     
  8. DumbMike

    DumbMike Active Member

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    Thanks a lot. Obviously, I have to do much more reading before even attempting this one. Maybe I'll just stick with the fronts. Thanks again.

    Mike
     
  9. El Dobro

    El Dobro A Member

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    I've used needle nosed pliers to screw pistons back in, but the tool makes it a lot easier.
     
  10. Kingsway

    Kingsway Member

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    I'm struggling with my Prius C (Yaris Hybrid) I don't have the special tool, but can turn the pistons ok - BUT they just do NOT go back in!!! They ratchet out fine, when I apply the hand-brake lever - but how the heck do you make them go back in?? Should I release the bleed nipple?? I'm reluctant to do that in case I have another problem - re bleeding the system...

    I'm getting desperate - a simple job has suddenly become a major problem!!
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Again, did you apply parking brake with the caliper off the car, maybe it screwed out too far??
     
  12. El Dobro

    El Dobro A Member

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    With some caliper pistons, you have to remove the PB lever so the screw can turn as you push the piston in. You may be able to rent or borrow the tool from an auto parts store.
     
  13. Kingsway

    Kingsway Member

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    If only I hadn't started the job today!

    I've ordered a tool set, which I can only collect first thing in the morning...
    Hilka Pro-Craft Brake Rewind Tool Kit 20 Pieces | Brake Tools | Screwfix.com

    The old pads were only 25% worn but the disks are very badly rusted. In fact I'm suprised the rear brakes worked at all. There was corrosion everywhere, and I had to use a lot of pursuasion to both get the old disks off, and to free the old pads in order to remove them. (Thanks to the winter road salt)

    The car has only done 65 000 miles, but the brakes certainly were in need of some attention... I;ll cancel my first appointment in the morning, and hope the correct tool will make the job easier. The toolset, and the loss of income will have added £85 to the cost of the job... A lot more if I have to cancel all the days appointments.

    I can't quite imagine how the piston mechanism works... I have read that sometimes you have to turn the pistons anti clockwise rather than clockwise - which is why I ordered a tool set that seems to do either.
     
  14. Kingsway

    Kingsway Member

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    I did remove the end of the cable from the operating lever at he brake end. I wonder if I am just not able to push back 'hard enough as I turn the piston....

    I've only had one car in the past that had disk brakes on all four wheels - but the parking brake worked on the front brakes, not the rear, and used a sepa rate set of pads as well!

    ( a Citroen GS 1220 Club)

    Citroën GS - Wikipedia
     
  15. El Dobro

    El Dobro A Member

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    I don't know how your calipers work, but I've had calipers where the lever had to be removed so the screw could turn when you pushed the piston in. The lever would hit a stop, if you didn't remove it. You have to check how yours is done.
     
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