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Is the Rear Brake Applied Everytime I brake?

Discussion in 'Gen 2 Prius Technical Discussion' started by GusTheCat, Nov 20, 2008.

  1. GusTheCat

    GusTheCat Junior Member

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    Here is a sort of dumb question: is the rear drum brake on Prius applied everytime I brake, or is it only applied when necessary (such as for vehicle stability)? Thanks.
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    In general the rear drum brakes are lightly used. When the driver applies the brake pedal, the skid control ECU decides how much braking force is required. That ECU sends a request to the hybrid vehicle ECU to develop a certain amount of regen braking force. The hybrid vehicle ECU responds with its calculation of the exact amount of regen braking force being produced.

    The skid control ECU then activates solenoid valves as needed so that the hydraulic brakes will produce the remaining braking force required to slow the car according to the driver's request. If you brake relatively gently, then the regen system will produce all or almost all of the braking force required, until the car slows down to a crawl, ~6 mph or so. Then the hydraulic brakes take over.

    Under low-traction conditions where the wheels are slipping, the skid control ECU will adjust hydraulic pressure provided to each wheel's brake cylinder as needed to control the slip.

    Have you managed to get your spouse and son to accept the idea of SPM as a color choice?
     
  3. rigormortis

    rigormortis Active Member

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    only thing to add is...

    rear brakes only do 30 % of the braking in a conventional car. ive seen rear brakes
    last 150,000 ++ miles in non hybrid cars

    oh, oh, oh, and the prius ships with umm 4 or 5 mm of rear brake pad.
     
  4. David Beale

    David Beale Senior Member

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    Further, be aware that whenever you press on the brake pedal the system moves the brake pads so they are just touching the disk/drum, so even if it uses regen totally there is still a tiny bit of friction braking at all four wheels. I suppose you could say just enough to clean off the braking surfaces.
     
  5. bedrock8x

    bedrock8x Senior Member

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    The forward pitch sensor will provide info to the ECU to apply rear brake pressure to keep the car from pitching forward or nose dive. Generally it requires very little force but it is alway there when braking.
     
  6. GusTheCat

    GusTheCat Junior Member

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    Thanks all, very informative.

    Thanks, Patrick, for remembering. I showed them the other day in the dealer lot the Silver Pine color Prius, and I think they are ok with it. I think this is the color they used in "electric car" movie, or many silver. Anyway, I think it looks great in quite a few colors. Will wait for a few days when the next boat come with the one I want.