Rear brakes gone after 22,644 miles!

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by DetPrius, Aug 26, 2014.

  1. DetPrius

    DetPrius Active Member

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    See http://priuschat.com/threads/rear-brakes-gone-with-severe-uneven-wear-at-55-000-miles.121113/#axzz3AzaJZ73D for the start of this story.

    The uneven wear occurred again, this time only giving me 22,644 miles on the rear brakes. So, I am on my third set of rear brakes at 78,000 miles.

    This time the dealer contacted the district rep since this was a repeat occurrence. It turns out a week after my first rear brake job, Toyota issued T-SB-0248-12, for this very problem, on the 2010 - 2012 Prius and on the 2012 Prius PHV. There is a new brake pad that is supposed to address this problem. The old part number that was put on my car during the first brake job was 04466-76011 and the new part number is 04466-47080. The receipt also shows Brake Shim Grease part number 08887-80409, which is noted in the TSB.

    Toyota did the right thing in that they covered the cost of the brake job I just had done. I just opened a case asking to be reimbursed for the first brake job since this turned out to be a problem that was addressed with a new part.

    I suggest anyone with a 2010-2012 Prius or 2012 Prius PHV that needs rear brakes, make sure you insist on getting this updated pad and point out this TSB. My service adviser said they were going to replace all of their pads with the old part number with the updated pad, so other customers going forward receive this new pad, though he also said they just don't do a lot of Prius brake jobs.

    I could not locate a copy of the TSB online so I paid to get a copy of it.

    See Please
     

    Attached Files:

  2. Former Member 68813

    Former Member 68813 Senior Member

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    Thanks for posting this for everyone's benefit.

    Attn Mods. Is there a way for this info to show up in the sticky post on TSB?
     
  3. bisco

    bisco cookie crumbler

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    this is very interesting. i just hit 22,000 miles. no noticeable problems yet. are you heavy or light on the brakes? do you drive it hard and put it up wet, or are you a little ol' lady like me?:)
     
  4. bisco

    bisco cookie crumbler

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    btw, i agree, they should reimburse you for the first work, all the best!(y)
     
  5. DetPrius

    DetPrius Active Member

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    I am light on the brakes and on the car in general. My OEM Ecopia tires lasted 68,000+ miles. Toyota has moved me closer to considering a Ford for my next vehicle by refusing to pay for the first brake job.
     
  6. MarcSmith

    MarcSmith Active Member

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    rear brakes, sound like the e-brake has been dragging...

    Det,

    I would not let the cost of one brake job sway you from the toyota camp. Ford has it own problems... the Cmax is far from trouble free...
     
  7. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    I've been having some rear brake problems, some rotor scoring, and uneven contact on the inboard sides. Ended up replacing the pads (myself) at 46000 km.

    I suspect pad installation procedure may be a problem. The rear caliper pistons have an integrated parking brake mechanism.

    Every time the parking brake is applied, a lever attempts to rotate the piston. The piston has a raised cross pattern on the face in contact with the back pad, and that pad has a pin on it's back that is supposed to lock with the piston pattern, prevent the piston rotating.

    What happens then, I'm still not 100% clear. There is a screw mechanism within the piston, connected to the parking brake's lever arm. That screw is wrapped with a spring, that (cleverly) only allows the screw to rotate in the direction causing the piston to protrude more.

    I'm still not clear on how it manages to work, but what I'm suspecting:

    If the pads are not firmly gripped by the caliper at initial assembly, when the parking brake is first applied, the piston may rotate on the back pad, shifting it's cross pattern out of proper alignment with the pad's pin, creating a chronic drag condition and uneven wear.

    It seems it's paramount to pump the brake pedal multiple times at pad install, to ensure good contact, avoid this piston rotation. I took pictures of the pads when I first disassembled, never been touched since the factory, and you can see bevelling of the pin, as if there was some rotation onto a cross spoke.

    Not sure what the solution is. With the present design, careful pad install technique, coupled with ongoing vigilance? And for Toyota, maybe a design change in future?

    I've looked at pictures of the revised pads, compared to original (I believe the pads I purchased are the original design), the main difference I can see is an increase in the end bevel of the pads. Seems a somewhat stopgap measure to concentrate the braking pressure on a smaller area.
     
    #7 Mendel Leisk, Sep 18, 2014
    Last edited: Sep 18, 2014
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  8. tv4fish

    tv4fish Member

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    I would guess that perhaps your parking brake(s) were not releasing completely in order for you to wear the rear pads that quickly. What kind of gas mileage were you getting? With a "drag" like you must have had - I WOULD think your gas mileage would suffer. I have a 2010 and I just replaced all 4 rotors and all 8 pads and the only one that showed much wear (100,000 miles) was the left rear set of pads and, yes that parking brake had been "hanging up". After I replaced everything, I checked the rear wheels - both spun freely. I even lubed up the parking cables back there to help for any future problems.
     
  9. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Spinning the back wheels when raised is good periodic check. Another is to just reach in and feel the rotors on all four corners, after an extended run. Be careful, they can get hot.

    Also, crawling under with a pit lamp (no raising of the car needed), you can just see a little bit of the inside rotor on the rear. There's about 1/8" gap between the splatter brakes baking plate and caliper, not much, to be sure. With a good light you can see if there's even wear: if there's a portion of the disk just showing rust you've got a problem.

    Here's a shot of the inside face of a rear rotor (with the caliper removed) showing uneven the uneven wear I was getting:

    photo 4.JPG
     
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  10. mjosterweil@yahoo.com

    [email protected] Junior Member

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    My rear brake pads were changed in my 2010 Prius at 57,600 with pad kit: 04465-76010 so I wonder if this is also the wrong part as it was done in April 2012. Now at 105,073 they say I need new rear pads and rotors and that the rear caliper bridge is seizing up so that the left rear caliper bridge needs replacement. I don't get why this should be happening.
     
  11. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    That's a decent set of miles, from your last brake job. But troubling that they're not just worn, more like seized, damaging the rotor. The integrated parking brake mechanism is a bit complicated, improper re-assembly can lead to problems. FWIW:

    My bill for rear brake pads says:

    PAD SET, BRAKE P/N: 04466-76012

    Not sure what the difference is.

    I also got new shims:

    SHIM KIT, BRAKE P/N: 04946-47070
     
  12. DetPrius

    DetPrius Active Member

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    That part number for the pad kit is just one digit off my old part number. That is NOT very many miles on rear brakes on a Prius. I suggest you print out the TSB I attached to this thread and take it in and bring it to their attention. They may not even be aware of it.
     
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