Rear brakes gone with severe uneven wear at 55,000 miles

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by DetPrius, Jan 20, 2013.

  1. DetPrius

    DetPrius Active Member

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    While in for an oil change, the tech pointed out that my rear brakes were almost metal to metal, and that one pad on each side of the car had severe uneven wear. He noted he had never seen rear brakes go this quickly in a Prius and he had never seen the uneven wear. He said part of the mechanism that allows the pad to slide in and out as the brakes are used had frozen, creating a pivot point, and creating the uneven wear. The front brakes are fine with plenty of meat left.

    Parts were ordered, including new shims and other hardware to try to insure this does not happen again, and the brakes were replaced. I contacted Toyota Customer Care and basically got the old line that brakes are a wear and tear item but the issue would be sent onto engineers.

    I am the sole driver of the car and use the regen brakes at every opportunity, which is most stops. Since long brake life is one of the benefits of regen brakes, this is disappointing to say the least. I have had to eat crow after touting long brake life as a Prius benefit to friends and family.

    Has anyone else seen this uneven wear, or replaced the rear brakes sooner than this? I love the MPG performance of the car but this is the kind of stuff that will have me check out the competition when it comes time for the next car.
     

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  2. bisco

    bisco cookie crumbler

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    that's a shame, i wonder what caused that part to sieze up? were they making any noise?
     
  3. rrg

    rrg Active Member

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    What comes to mind.

    Was the car dropped with lower springs or the rear is out of alignment.

    How's the tire wear?

    my2cents.
     
  4. The Critic

    The Critic Resident Critic

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    Your location explains the issue - road salt and rust.

    Over time, rust will build up between the pad support clips and the caliper bracket, which essentially "jams" the pads into place. The caliper slide pins may also be a problem, but the rust build-up on the bracket is the most likely cause.

    This is a common issue that affects many makes/models. A possible fix is to apply a moly-based lubricant (I use Molykote M77) to the caliper bracket itself (after cleaning the rust off), installing new clips, then applying more moly lubricant to the areas of the clip that the pad "ears" contact. Of course, cleaning and lubricating the caliper slide pins with new silicone grease (I use 3M silicone paste or Motorcraft XG-3-A) is also a must. This condition is simply a reality of living in an area with a lot of road salt and owning a car that does not use its brakes often, let alone the rears. I would consider doing a brake system "maintenance" service (clean brackets, lube slide pins, clean hardware) annually to prevent this from happening again.
     
  5. spiderman

    spiderman wretched

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    Yes, there was someone else just recently that mentioned something similar. Will see if I can find the thread...

    Here we go, thread
     
  6. Roland1555

    Roland1555 Senior Member

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    Good advice.
    Like yourself, Critic, I am in an area where there is little use of road salt. I did have my dealer here perform the lube service on the brake system having them also replace the brake fluid as ther car reached 3 years of service. In past years I would do some caliper work on my Volvos, but I did not wish to bleed the brakes myself on the Prius while it was still under warranty, and since they would have the wheels off, figured they could clean and lube the slides at the same time.
    They did not report any issues, and the charge was very reasonable. I intend to keep the car for many years, and now have over 81kms. on it, or just over 50k miles.

    Roland
     
  7. DetPrius

    DetPrius Active Member

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    Thanks all for the replies and suggestions. There were not making any noise. There were no symptoms of a problem brewing. The car is 100% stock. Tire wear is perfect. I am nearing the end of life for these OEM tires and intend on replacing them before the Fall of 2013.

    The tech was unable to find any explanation, other than the generic road salt explanation. Obviously all cars are designed with operating conditions in mind, be it road salt, extreme temperatures, etc. I suppose that while the brake components are designed to operate in harsh environments, I am the unlucky one out of x thousand that still has the slides lock up. I still find it odd that both sides had exactly the same problem. I forgot to note that after the roads dry up after salt has been used, I always run through the car wash with the under body wash to clean off as much of the salt as I can, in the hopes of helping the car last as long as possible.

    I like the idea of having the brakes serviced annually, and will see what they charge for that. I also believe an aggressive stop from a higher speed while in neutral every month or two is not a bad idea.
     
  8. bisco

    bisco cookie crumbler

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    55,000. on the oem's? that's excellent!!!
     
  9. bisco

    bisco cookie crumbler

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    my 04 had been driven in snow and salt for 8 years and 95,000. miles with no brake problems front or rear. we had it inspected before putting up for sale and mechanic said it would need new front pads fairly soon. i would say something is/was defective on yours, or they changed materials and more prone to rust/seizing?
     
  10. ursle

    ursle Gas miser

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    You don't mention your mpg average, if your rear brakes were rubbing it would show in the mpg, I have to assume your rear brakes were adjusted incorrectly or the emergency brake cable was improperly adjusted, the friction resulting in pad wear had to have an overall effect.
     
  11. DetPrius

    DetPrius Active Member

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    Yes Bisco, I am very happy with the life I have gotten out of the original tires. I have been watching the tire threads here but not decided yet what to put on it.

    My life time MPG has just dipped below the 50 mark, which it does each winter, and it recovers in the spring. The car has delivered on the MPGs as I have basically sat right around the 50 mark for the life of the car so far. My worst tank was around 42, which included hours of winter idling for heat, and my best was 58.something which was on a summer trip on almost exclusively 55 MPH highways.

    I have wondered about a defect of some kind since it wore unevenly on both sides, but if it was a defect, I'd expect to see more stories like this on PC. It is unlikely to be a tiny piece of gravel that got stuck in the wrong place or a fluke since it happened consistently on both sides. As for the road salt being the cause, well, I am far from the first to drive a Prius in an area that uses road salt.
     
  12. jdcollins5

    jdcollins5 Senior Member

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    Toyota has a TSB out on both the front and rear brakes. I had both performed on my car before it passed 36k. The rear brake fix was exactly what The Critic recommended, new shims and lubricating the brackets so the pads could move freely.
     
  13. DetPrius

    DetPrius Active Member

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    JD, do you have that TSB number handy? It is too late for warranty work but I'd like to read it and if it seems appropriate, let the folks at Toyota Care know about the possible relationship, as well as my local service manager.
     
  14. bisco

    bisco cookie crumbler

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    nice of the dealership to ignore a tsb, seems to me they should compensate you if it's related. all the best!
     
  15. jdcollins5

    jdcollins5 Senior Member

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    DetPrius, go to the Gen III 2010+ Prius Technical Discussion forum. At the top there is a Sticky about Gen III TSB's. In the #3 post I have both the front and rear brake TSB posted.
     
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