Parking Brakes not working after brake caliper change

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Benjibabs, Dec 10, 2024.

  1. Benjibabs

    Benjibabs Junior Member

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    Hello,

    I just replaced the the rear brakes for my 2012 Prius and now the parking brake is not holding the vehicle at all. I replaced the calipers, rotors and pads. I bled all the wheels, both rear and front. Adjusted the parking brake, even till when the adjustment nut stopped moving; still no dice from the parking brake. There is simply no difference between pressed and released parking brakes. I've crossed checked and ensured that the groves on the piston fit the tabs on the inner brake pad. I have googled and chatgpted and still stuck. I'll appreciate any info to knock this issue out. BTW, the parking brakes worked perfectly well before the brake change.

    Thanks.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Usually what I find best thing to do is have somebody sit in the car for me and push the parking brake down and up and back down slowly and up and maybe one more time while I look and see if the linkage is not routed correctly it's right there with the wheel off you're just staring at it you'll probably see what's wrong immediately
     
  3. ChapmanF

    ChapmanF Senior Member

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    Start by putting that nut back where you found it, to the best of your ability to remember how many turns you moved it. It's not part of the game unless the parking brake pedal or cable have been replaced or the cable has been stretched by Sasquatch driving the car. Cable stretch, if involved at all, would have happened over years, and would have been noticed starting before the brakes were changed.


    Did you replace the brake calipers, or only the brake pads and minor hardware? If you replaced calipers, where did you get them?

    [​IMG]

    One key is to start by applying the service brakes (properly bled first, if need be) enough to bring the pads fully toward the rotor. That movement of the piston, under fluid pressure, is what spins the sleeve nut outward along the adjusting bolt so that the pads will meet the rotor when the parking lever cam pushes on the bolt.

    If that doesn't take care of it for you, check whether you see the piston move at all when you move the parking lever on the caliper by hand. (You'll also see then if anything is weird with the parking cables' connections to both those levers.)

    If moving the lever doesn't move the piston at all, or applying the service brake doesn't advance the piston along the adjusting bolt, something is amiss inside the caliper. The storyline splits here according to whether you still have original calipers or you put replacements on that came from somewhere.
     
  4. Benjibabs

    Benjibabs Junior Member

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    Caliper is third party from EBay. I will observe the movement of the piston when I press the parking brake. I still have the OEM Calipers. I plan on rebuilding them.
    Thanks for the response.
     
  5. Benjibabs

    Benjibabs Junior Member

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    Thanks. I’ll have a friend operate the brake while I observe the movement of the piston.
     
  6. Tombukt2

    Tombukt2 Senior Member

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    That's really weird and Raleigh North Carolina a 2010 or a generation 3 should not be having bad calipers I mean it's just not in our nature for this area weather etc I mean I don't know how somebody could beat the caliper to death just driving the car. But I guess where there's a will there's a way usually I find on Toyota's calipers and things like that aren't going out until 225,000 mi or better even in Corollas and Yaris same but you just never know rebuilding the calipers yeah there's not much to that Make sure you fit the rubbers correctly and all that clean everything up well with light sandpaper what have you.
     
  7. Eddie25

    Eddie25 Active Member

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    Consider purchasing an OEM caliper from an online Toyota dealer. You can get just the caliper part minus the bracket for under $120 and use your old bracket (assuming it's in good condition). ChapmanF did some great leg work to figure out why... The aftermarket stuff doesn't retract properly. After learning about this I checked both my rear wheels (which both had aftermarket rebuilt calipers) and neither spun that great. After getting some calipers from a dealer they spin much better. Sadly it doesn't get talked about much.
     
  8. ChapmanF

    ChapmanF Senior Member

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    If there's anything about the original calipers that calls for rebuilding, the rubber kit is inexpensive. The caliper body is aluminum and probably just fine to rebuild and reuse.

    More about testing the return of the caliper piston (easy enough to check, I would do so on any caliper, dealer, rebuilt, or aftermarket, before going to the trouble of putting it on the car) can be found in this post. (That post happened to be about gen 1 calipers, which were iron and could get rusty too, unlike the later aluminum ones you've got.)
     
  9. Benjibabs

    Benjibabs Junior Member

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    Thanks for the great info. I had my suspicions of the aftermarket calipers. As soon as I replaced one of the OEM ones, the parking brake lost some of its grip. When I replaced the second one, the parking brake quit completely - zero grip! I decided to replace the calipers because I noticed one of the rear caliper piston was stuck. After replacing the brake pads, I could not get the piston to retract by rotating and pushing the piston. I noticed the boot was completely out of the piston and dry. A few days ago, I've been able to extract the stuck piston by simply pushing repeatedly on the parking brake lever where the parking brake cable hooks, mimicking pressing the parking brake. The piston and the inside of the cylinder were dirty. I was able to clean them out and they look okay. I'm leaning towards just getting the kit and reusing the OEM parts I removed. The second rear caliper works fine. I'll take another look at those OEM calipers and then decide whether to reuse them with new boots or buy new ones.
     
  10. Benjibabs

    Benjibabs Junior Member

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    You are right, both OEM calipers I removed look great after cleaning with brake cleaner. I actually purchased the rebuild kit, but I returned it when I saw the price of the aftermarket. I failed to check the operation of the parking brake after replacement before putting everything together. I'm leaning towards rebuilding as I did not see anything wrong with the calipers expect the dry boot that was out of place.
     
  11. Benjibabs

    Benjibabs Junior Member

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    I was initially replacing the brake pads when I encountered a stuck piston. Since I was already replacing the pads and rotors, I decided to go ahead and replace the caliper with the stuck piston and the one on the other side as well. After cleaning the caliper, the only issue I found was the dry and misaligned boot. The Piston was sparkling clean after using brake cleaner and 3000-grit sandpaper.
    Thanks for the info.
     
  12. Tombukt2

    Tombukt2 Senior Member

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    Yeah maybe put it back on and I don't know what you bought for replacements but advance Auto or O'Reilly's that's usually through geez I can't think of the major rebuilder but they have a lot of mistakes generally speaking so you might want to take your factory cleaned up calipers and just stick them back on it take a whopping 20 minutes I have caliper sitting here on cars with 400,000 mi on them I don't give him up unless something's broke something stuck that's just croakers cloth and little cleaner No reason to give the caliper up that came from the factory that we know works correctly when it's not stuck
     
  13. Eddie25

    Eddie25 Active Member

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    I tried a rebuild kit when I couldn't find a caliper locally (the aftermarket rebuilt one on my car was leaking from the parking brake mechanism seal). It's harder than it looks to get that piston seal on. I didn't try that hard since I finally figured out you could use the caliper body from a certain scion model that was available locally, but it was not fun. If you do it, let us know how it goes.

    That's not to say you shouldn't first diagnose the parking brake issue. Have you done a visual check yet?
     
  14. ChapmanF

    ChapmanF Senior Member

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    That raises an interesting point about the rubber kit available from Toyota—as far as I can tell, it doesn't include that seal. So if a caliper starts leaking from that one, there's no fixing it with the Toyota kit.

    Other than that, rebuilding is pretty straightforward. With the right red glycol / lithium thickened grease on the seal (a little packet of it comes in the Toyota rubber kit), inserting the piston shouldn't be too hard. Not a strength exercise, make sure the piston is straight, easy does it.

    Confession: that's from general experience; I've never rebuilt one of these rear ones, where you have the added challenge of getting the sleeve nut threads started onto the adjusting bolt, with the clutch spring in position and anchored in the piston, then rotating the piston as you press it in. Maybe easiest to hold things with the piston down. Still, I would not expect it to be too hard.

    If you rebuild the originals and the parking brake then works, it could be interesting to take the aftermarket ones apart to see why they don't. Maybe it could be as simple as the clutch spring being left out*, or not anchored in the piston as shown. Wouldn't say much for any functional testing done by the rebuilder ....

    I'd check the piston return after rebuilding, as described at the link I included in #8, before putting the calipers on the car. No surprise there—I would do that test in any case. But this just reminded me of it because I seem to recall the Toyota pistons having a kind of matte finish from the factory, which might be part of the magic giving the rubber seal a good grip to retract it. I remember an aftermarket caliper that had zero piston return, and that rebuilder used a piston with a very smooth mirror finish, which I speculated could be part of the problem. I assume all you did with the 3000-grit paper was lightly clean the piston, but not really leave it with a 3000-grit surface finish.


    * don't laugh, I bought an aftermarket door lock actuator on eBay once where one of its electrical signals didn't work, and taking it apart showed the internal copper contact for it was just plain left out, not there at all. After I told the eBay seller how to check for that with a multimeter, he checked all the rest of his stock and said they were all that way, and took down the listing.
     
  15. Tombukt2

    Tombukt2 Senior Member

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    Pictures are always good too just to see what somebody's got going on this should be well generally pretty clear