Curious Distribution of Brake Dust - More on Rear Wheels?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by GreenMaterialism, Dec 15, 2011.

  1. GreenMaterialism

    GreenMaterialism Junior Member

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    Greetings,
    It's that time of the year again, and I put on my show tires/wheels this morning. As I just pulled off my stock wheels (2010 Prius III) I noticed something very strange. There was considerably more brake dust on the REAR wheels than on the front. This is so strange because the opposite is virtually always true. Since the front wheels handle the lion's share of braking duties, they also accumulate the most brake dust.

    Is there any reason this would be backwards on the Prius? The car only has 5,000 miles on it. I didn't have my phone on me at the time, but the front wheels had little to no brake dust, while the rears were quite dirty.

    I have noticed that the brakes are very grabby at full stop. That is to say, that the braking feels totally normal (under both friction braking and regen), until that last foot or so - the time that the car actually stops. Had to explain, but the transition from moving to stopped is abrupt, almost sudden. (With slight noise to accompany it.) It feels almost like someone new to driving (which we're far from) and it's particularly noticeable when parallel parking - when it's grabby in both directions. You've got to be incredible light ont he brake in that last few inches to avoid the grabby halt.
    Not sure if it's related to the brake dust or not - but since yinz are so amazing and I'm just learning, I figured I'd field it...
     
    #1 GreenMaterialism, Dec 15, 2011
  2. macman408

    macman408 Electron Guidance Counselor

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    I'd guess that, depending on how hard you're braking, it very well might use more friction braking in the rear. 100% of regen has to come from the front (drive wheels), so then as friction braking is added, it makes sense to add it in the back.

    And the odd feeling you're getting when stopping is probably from the transition to friction-only. Around 8 mph, regen is no longer effective.
     
    #2 macman408, Dec 16, 2011
  3. tumbleweed

    tumbleweed Senior Member

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    I noticed the same thing on my BMW which had black brake pads and the dust really showed up on the wheels. On that car the front pads wore about twice as fast as the rears but there was still a lot more dust on the rears. It was, I believe, due to the fact the the front wheels turn and when turned they catch a little more air which blows the dust off.

    BTW I think Tire Rack has ceramic replacement pads for our cars now. I have used them on other vehicles, they work fine, last longer, and the dust doesn't show due to the color. On the negative side they do wear the discs out faster but discs are easy to replace. I doubt I will ever wear out a set of Prius brake pads on a hybrid car but if I do I'll buy the ceramics.
     
    #3 tumbleweed, Dec 16, 2011
  4. GreenMaterialism

    GreenMaterialism Junior Member

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    Actually, it's not the regen-friction change. I'm just talking about the feeling when the car fully stops. As it the literal last inch or two of movement as the car becomes stationary. It's sort of a crunchy abrupt halt. I'm hoping that as the pads and rotors get more worn in this will ease up.
     
    #4 GreenMaterialism, Dec 17, 2011
  5. GreenMaterialism

    GreenMaterialism Junior Member

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    Interesting - maybe it is from the front wheels catching more air? (Although it was mostly dust trapped under the wheel covers that was noticable.) Good to know that ceramic pads are on offer, though I agree, we'll probably never need them! On a previous Subaru I ran ceramic pads with Brembo rotors - only because it was actually less expensive than the oem stuff, and worked much better!
     
    #5 GreenMaterialism, Dec 17, 2011
  6. adamace1

    adamace1 Senior Member

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    I have seen suv's and some cars have more wear on the rear disc brakes than the front.
     
    #6 adamace1, Dec 17, 2011
  7. tumbleweed

    tumbleweed Senior Member

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    I owned an old Volvo station wagon that was like that. Rear pads always wore faster than the fronts. I think on that car it was due to the front pads being larger and the extra weight a station wagon puts on the rear wheels.
     
    #7 tumbleweed, Dec 18, 2011
  8. Duckles McGee

    Duckles McGee Junior Member

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    Interesting, I felt that on the car that I test drove, but I have yet to duplicate it on the car that I purchased.

    I would describe it as a "crunch" as well, as it was audible and could be felt through the pedal.
     
    #8 Duckles McGee, Dec 19, 2011
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