Brake Shoe Inspection and Grabby Brakes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jonnydwolf, Mar 3, 2022.

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  1. Jonnydwolf

    Jonnydwolf Junior Member

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    Hi Fellow Maintenance Savvy Prius Owners,

    I had an issue start when backing up where I would here a noise come from the read drum brakes. This would then continue a bit where at stops from let's say 15-20mph the Prius braking would get super grabby, like abrupt feeling. I would sometimes hear a little thunk or noise from the back brakes simultaneously.

    I did some forum research and also some internet-wide research on drum brakes, and found that if I jacked the rear of the car up, and spun the rear tires, that if the tire were to spin so freely as to spin over 1.5 revolutions, that the rear shows required adjusting.

    I found looking at a parts manual for our cars, that there is a port on the back side of each drum brake where you may adjust the tension of the jack screw (star gear??) that pushes out the shoes. I learned that you want to click the star gear DOWN to make the brakes tighten against the drum. I gradually tightened the star screw until the drum felt like it was getting resistance from the shoes. I didn't tighten anymore, as backing off the tension was a bit of a mystery, so someone who knows, please let us know how to loosen the shoes against the drum from the port. I know there is a spring loaded mechanism to push down on, one that bites against the star gear, but no sure how to reach that from the port.

    I also wanted to apply grease to the 6 grease points behind the shoes, but after looking at things, this appears to be only accomplished with the shoes out. I saw where people mentioned this was in their routine maintenance, I would like to know more precisely how that is accomplished without disassembling the entire drum brake?

    This FIXED the problem! No more grabby brakes, they simply needed to be adjusted tighter about 6-8 clicks on each side.

    NEXT, my concern is after 223,000 miles the rear brake shoes need replacing. I am the 2nd owner (Owned about 4,300 miles now), and I can hardly believe these are the original shoes. I managed to get some pictures from the inspection port Toyota kindly gave us, but not sure what to look for, this is after studying pictures of new shows, OEM and not-so OEM.

    Boroscope pics (sorry for poor quality, I took a pic of the screen using my phone):

    Here is passenger drum shoe:

    Driver Side, little bit better pic, and hoenstly, things are looking quite the same:

    Same pic as above, but with arrows, is what between them the show material??:

    Any insight on how to use the inspection port, if I have some brake material left, and also how to apply grease to the 6 knubs is greatly appreciated.
     
    #1 Jonnydwolf, Mar 3, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    The shoes are held down to the backing plate by little coil springs.

    I typically just slide a small screwdriver or pry tool between the shoe and backing plate, and use it to lift the shoe away from the backing plate just enough to slide another little screwdriver with some grease over each of the little raised spots where the shoe rests on the plate, and then let the shoe back down.

    The adjuster ought normally to adjust itself, so any kind of fussing through the adjuster hole should be very rarely needed if that is working right.

    Every time you apply the parking brake pedal, if the shoe clearance is out of adjustment, the adjust lever will click past one tooth of the star wheel. When you then release the parking brake and step on the service brake, the hydraulics will expand the shoes and the adjust lever spring will rotate the star wheel by that one tooth, and that adjusts 0.03 mm out of the shoe clearance.

    So you can adjust by alternately pressing/releasing the parking brake then pressing/releasing the service brake.

    If you do this in a place that's quiet enough, you can hear the adjust lever click in the back as you are pushing the parking brake pedal down. Once the shoes reach proper adjustment, that click will stop happening.

    Sometimes the adjuster gets gummed up and won't turn freely. Sometimes if it has been gummed up in one place for a while, it will have a tooth worn down where the adjust lever has been going up and down over it. Replacement is called for then. The adjusters are just a few bucks.

    One other thing to watch for is that the left and right adjusters are mirror images. Swap them by mistake, and you get brakes that automatically adjust themselves looser.
     
    #2 ChapmanF, Mar 3, 2022
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  3. Jonnydwolf

    Jonnydwolf Junior Member

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    So I gather that this prying the backing plate is done to circumvent the need to remove the drum? If so, I will have to try that.

    I will try this method next time, the car is 18 years old with 223k miles, so I bet a tooth might be missing, but I was unable to see that with my borescope.

    As for inspecting the amount of material left on my shoes, do those pictures tell us anything?
     
    #3 Jonnydwolf, Mar 3, 2022
  4. ChapmanF

    ChapmanF Senior Member

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    No, you haven't got any way to access those lube points without taking the drum off. Taking the drum off is the basic first step for working in there.

    If there's no rust making it sticky, the drum slips right off after the wheel's removed (parking brake has to be released, of course). In case there's a bit of rust, you'll find a couple threaded holes near the center of the drum. With a couple small bolts of the right size (M8 x 1.25 if I remember right??), you can tighten them alternately, bit by bit, in those holes to get the drum to pop off. That bolt size is a common size on the car that you can "borrow" from lots of other little brackets and what not on the car, if you don't have a couple that size in your junk drawer.
     
    #4 ChapmanF, Mar 4, 2022
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    To lube rear drum brake shoe contact points, (after removing drum) I’ll remove the spring clips that hold the shoes against the backing plate, leaves everything still assembled but loose, a little easier sneaking in the grease.

    the attached should have info, on the lube points and on adjusting the rear brakes.
     

    Attached Files:

    #5 Mendel Leisk, Mar 4, 2022
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  6. Jonnydwolf

    Jonnydwolf Junior Member

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    Thank you Chapman and Mendel for the help. I was going to use the bolts from the fender under the hood, but those are the first things I look at when looking at a car I’m going to buy. I’m going to find another donor location on the car to borrow them from….

    so still wondering if anyone uses that inspection port for shoe material level check? I’m just not sure if what I’m
    Seeing is the edge of the material or what?
     
    #6 Jonnydwolf, Mar 4, 2022
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  7. ChapmanF

    ChapmanF Senior Member

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    No; the port's roughly at the midline of the backing plate, so you can access the adjuster starwheel there, which is what it's for.

    The linings are way out on the outer surfaces of the shoes.
     
    #7 ChapmanF, Mar 4, 2022
  8. Jonnydwolf

    Jonnydwolf Junior Member

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    ChapmanF,

    The inspection port I am referring to is this one:


    Is that the one you were thinking I was talking about?

    Thanks, J
     
    #8 Jonnydwolf, Mar 4, 2022
  9. ChapmanF

    ChapmanF Senior Member

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    Oh, my mistake, no. I had a Gen 1, with similar rear drums, but I don't think they had that hole. They only had the one for adjuster access.
     
    #9 ChapmanF, Mar 5, 2022
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