Can't Figure out Rear Brake Adjustment on 2007 Prius

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by sdrocker, Jul 11, 2015.

  1. sdrocker

    sdrocker Member

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    Hi All,

    I was at the tire shop last week getting my tires rotated and I was told the rear brakes were out of adjustment. Since then I drove the car in reverse a couple of times and applied the brakes.

    I wanted to check so I put the driver side on a jackstand. I can't see the star adjuster with the rubber plug taken out. I applied the emergency brake and also disengaged it to see if something would move and the star adjuster would show. I also pressed on the brake pedal and let go and checked. I don't see it. Is something wrong? The passenger side looks the same.

    Also I spun the wheel by hand and I can hear the brake drag lightly. I wonder if the reversing and applying the brake made it adjust. Also the parking brake has felt fine from what I can tell.

    IMG_1319.JPG

    Here is a video as well.



    Thanks
     
    #1 sdrocker, Jul 11, 2015
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My suggestion is that you remove the brake drum so you can look at the brake wheel cylinder, see how it pushes out on the brake shoes, and observe how the star adjuster wheel operates. That might make it easier to access the star wheel via the oblong slot when the brake drum is back in place.

    When the parking brake is disengaged, you may be able to just pull off the drum by hand. If it is stuck, use a couple of bolts screwed into the threaded holes, to force the drum off the wheel. I think you will need two 8 mm bolts.

    While the drum is off, determine the thickness of the brake shoe lining. New is 4 mm, minimum spec is 1 mm.
     
    #2 Patrick Wong, Jul 11, 2015
    bisco likes this.
  3. sdrocker

    sdrocker Member

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    Thanks for your help. I'm a bit low on time, I need to get back to other things related to my house sale and my move. I finished the water pump and belt and filled and cycled and got the air out. I will post on the other thread when I have time.

    In the mean time does it seem like the brakes are adjusted ok based on the youtube video I posted? You can hear the drum rub on the shoes lightly when I spin by hand if you listen closely. After going to the tire shop I drove in reverse with brakes on a couple times. I'm a bit low on time to take the wheel and drum off. I need to do the PCV valve and then stop all car work.
     
    #3 sdrocker, Jul 11, 2015
  4. sdrocker

    sdrocker Member

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    Also there is a small rubber circular plug I pulled and I could see the shoe thickness. It looked like it was 2 to 2.5mm
     
    #4 sdrocker, Jul 11, 2015
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Actually I could not hear that. If the drum rubbing is just occasional as the wheel completes one revolution then I guess that is alright. If it is continuous then I would try to slightly adjust the star wheel so there is less brake drag.
    OK
     
    #5 Patrick Wong, Jul 11, 2015
  6. sdrocker

    sdrocker Member

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    Thanks the noise is occasional with each revolution not continuous. I wonder if the reversing with brake on adjusted it correctly. I imagine if it was way out of adjustment I wouldnt hear the occasional rubbing during each revolution. It could also be the tire shop didn't listen carefully.
     
    #6 sdrocker, Jul 11, 2015
  7. 69shovlhed

    69shovlhed Surly tree hugger

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    the tech wanted to make some quick money on a clean and adjust service. he probably tells everyone with drum brakes they need it. when you do get a chance, pull the drum. meanwhile, don't even worry about it.
     
    #7 69shovlhed, Jul 11, 2015
  8. ChapmanF

    ChapmanF Senior Member

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    Toyota literature talks about two different drum brake adjuster designs: the "reverse travel adjuster" and the "parking brake adjuster". As you would guess, the first kind adjusts when you travel in reverse with the brake on, but the Prius uses the second kind, which adjusts when you apply and release the parking brake.

    You can tell them apart by where the adjusting screw/star wheel component is located; for the "reverse travel adjuster" it is down low, between the bottom ends of the shoes; for the "parking brake adjuster" it is up high, just below the wheel cylinder (just as you see in your pics).

    With either kind, each time it adjusts it will only be by one tooth of the star wheel, which is worth about 0.03 mm taken out of the shoe-to-drum clearance. The nice thing about the adjuster style used in the Prius is you don't have to look like a dork making a bunch of stops in reverse to take up your clearance; instead, the car doesn't even have to be moving and you can just apply and release the parking brake several times.

    -Chap
     
    #8 ChapmanF, Jul 12, 2015
  9. sdrocker

    sdrocker Member

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    Thanks I use the parking brake every single day. I could hear the brake shoes rubbing (though not constantly) when I spin both wheels in the rear.

    So is adjusting manually not done? I looked around at various angles and could not see the star adjuster at all. I'm ok adjusting with the parking brake for now. I am moving close to a friend of mine who does work in his driveway so if its a less than 1 day type thing I should have a place to do brakes, etc. I will take the rear drums off when I have more time at some point after I move. For now I want to finish work on my hotrod before it goes into a 1 car garage with limited space.
     
    #9 sdrocker, Jul 12, 2015
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