New Brake Pads = Car barely moves!!! Help please...

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Tommerdoo, Aug 27, 2015.

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  1. Tommerdoo

    Tommerdoo Member

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    Hello Forum,

    I've looked alot for this answer, hopefully someone can help me out....

    I recently changed my front pads on my prius because both the pads are getting close to finished, and also within the last month my fuel mileage and the feel of the car seem plus sounds from the brakes have been telling me that the brake pads were rubbing the rotors while driving, even while pulling out of the driveway.

    So I finally got around to changing them today. Now here comes the part where I admit how stupid I am to everyone. I didn't really think to change out the rotors for new ones. I'm sure that's the cause to my problem, but it never really crossed my mind until now. Anyways, the driver's side brake pads were nearly finished, while the passenger's side had about 25% left I'd estimate. So clearly at least one of them was rubbing.

    Now I changed out my pads, and I hop into my car and while my car felt like it was rubbing before a little, now the car won't even move forward or backward unless I push on the accelerator stronger to overcome the brakes! It's like the brakes are acting like emergency brakes or something.

    My question for you dear forum is: Is this a simple fix with new rotors or is something else going on here? I mean, I know warped rotors will obviously give you road shimmy while braking and not be good, but my brakes are really really locked like someone is braking all the time in forward or reverse.

    Thanks for any help, I really appreciate it! (And I will keep looking for answers on this forum)
     
    #1 Tommerdoo, Aug 27, 2015
  2. exstudent

    exstudent Senior Member

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    Did you even touch the brake caliper pins? Remove old lube and apply NEW disc brake lube? Sounds like this was your problem all along, give the 25% material difference you report on the old front brakes.

    Front rotors only need to be replaced if warped or close to, or below the required minimum disc rotor thickness. Correct autotive maintenance practice is to resurface the braking surface (rotor/drum), when replacing the braking material (disc brakes/brake shoes). If the rotors below or really clost to the minimum thickness, just replace with new.

    How did you depress the front caliper piston?

    Spend $15 to get the official repair manual from Techinfo.toyota.com. it has a ton of valuable info. Haynes/Chilton is junk.
     
    #2 exstudent, Aug 27, 2015
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  3. Tommerdoo

    Tommerdoo Member

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    Hey, thanks for your reply. Regarding the brake caliper slider pins, I checked them all to see how much movement they had. They seemed to slide fairly well enough back and forth so I decided not to relubricate them (I should have done it anyways, I know).

    It really feels like I have one or more seized calipers on my hands. I think that at least on one wheel because it was dragging for so long against the brake (and giving me bad fuel economy for a prius) the rotor warped and the caliper seized. That's my theory anyways....
    I guess I'll have to go through the steps to find out if that's the case now.

    I'll say this about pushing the caliper piston back in though: I have a brake piston tool, the kind that you screw in. It was the first time I've ever used it and the caliper piston wouldn't budge. It wasn't until I used the C-Clamp with ALOT of force that the caliper piston finally pushed back in again. I've never had to use that much force on any other car. So I'm not sure if that's also indicative of caliper piston seizure or normal. Thanks.
     
    #3 Tommerdoo, Aug 27, 2015
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Does sound like a caliper piston seizing. A quick check you can do right after driving is to feel the wheels. If the front's are hot it'll confirm drag.

    It is good to relube pins, but if as you say there was some caliper back/forth movement, they're fine for now.

    FWIW, I've replaced lots of pads, but never bothered to replace rotors. There's one or two instances when I maybe should have, but...

    You can check runout and thickness on the rotors if you're concerned, too. Spec's in here:
     

    Attached Files:

    #4 Mendel Leisk, Aug 27, 2015
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  5. Tommerdoo

    Tommerdoo Member

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    Thanks for that awesome link to the repair manual. Is that 2010 repair manual use the same brake system as the Generation 2 Prius? I see online that there is a possibility that the brake line is collapsed as well. It looks like to diagnose a bad brake line one has to pump the brakes strongly 20 times then go to see if the seized wheel will turn after opening up the bleeder valve and see if that let's the pressure off the brake pads. If the rotor moves freely after cracking the bleeder valve, that means it's the brake line that's faulty, but if it still won't budge, that means the caliper is seized....does this sound correct? But on a Prius, everyone says don't bleed the system unless you have a special tool of some kind. So I guess the only way I can correctly diagnose this problem is to buy that scan tool...but looking at this forum, the scan tool appears to be thousands of dollars....so if there is a problem with the brake line or the caliper, it looks like the dealership is the only recourse here or perhaps a shop that sprung for the expensive diagnostic tools a Prius requires.....shoots.

    At the moment I will not drive the vehicle because even putting it in drive or reverse the car won't budge unless I put quite a bit of gas and one or more of the brakes just won't let go. So if the caliper glide pins were moving freely prior to throwing the wheels back on, you must be right that the pins are not the cause of this extreme lock up. Thank you for your help.
     
    #5 Tommerdoo, Aug 27, 2015
    Last edited: Aug 27, 2015
  6. valde3

    valde3 Senior Member

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    Actually front brakes can be bled traditional way if you remove the two brake relays first. Relays you need to remove: Brake service relays just pull out (may need some wiggling). As long as you don’t let too much of the brake fluid out, which shouldn’t be problem when testing for seized caliber.

    I would first remove the relays then push the brake pedal down many times strongly and hold it at the button for a bit every time. You should do this when Prius is off. At some point you will start to hear brake failure alarm (this will tell you that brakes are in failure mode and front brakes can be bled manually). Then you can test if your front wheels are rotating free. If they are not open the bleeder a bit. If it still doesn’t rotate free its seized caliber.

    Regardless of the outcome of the test you now need to bleed the front caliper(s) where you opened the bleeder. With helper you can now do it traditional way. Don’t turn the Prius on or install the relays until all brakes where bleeder was opened are bled!
     
    #6 valde3, Aug 27, 2015
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Oh I'm sorry, that's third gen excerpt from Toyota Repair Manual. Maybe it's of some help anyway, I think the front brakes would be similar.
     
    #7 Mendel Leisk, Aug 27, 2015
  8. exstudent

    exstudent Senior Member

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    You should get mini VCI from Amazon/eBay, $25. Any one will do. Software version 8.0 or later is sufficient. You can always find the latest software version, to work on the latest Toyota/Lexus models, somewhere. Generic OBD2 reader's, miss a lot of Prius specific codes. The mini VCI will give you the same dealer level diagnostic capability! Also, you will be able to bleed the rear brakes with ease! There are countless diagnostic features Techstream offers.

    You will need a spare laptop, ideally running a 32bit Windows OS (XP or 7). Macintosh and Windows 64bit OS is possible, but more difficult to get working.

    Assume the hacked Techstream software has malware, thus the laptop being a spare that is only used for working on your Prius. Do not use this laptop to enter valuable information such as log-on ID/password, banking, email, etc. Despite this, many use hacked Techstream w/o any issues. Read this for useful info on install/set-up:
    TundraTalk.net - Toyota Tundra Discussion Forum - View Single Post - Offical TechStream software thread( settings and such)

    Pay the $15 for a two business day subscription to Toyota's TIS (Toyota - New Subscription), to get THE Service and Repair manual, written by Toyota. This manual has a wealth of info and trouble shooting. Chilton/Haynes is junk, compared to Toyota's Service Manual. Be warned, PDFs are no longer available, as Toyota went to a CHM format. Maybe you are more technically advance and know how to save a CHM file; the benefit of CHM are the hyperlinks w/in the file, that will take you to another section of a manual. If you can't/don't know how to save CHM, you can go old school and save as PDFs like this person (Toyota TIS download tips | PriusChat).
     
    #8 exstudent, Aug 27, 2015
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  9. jdenenberg

    jdenenberg EE Professor

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    If you PM me, I'll send you a link to a zip archive of the Gen2 repair manual.

    JeffD
     
    #9 jdenenberg, Aug 27, 2015
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  10. Lucifer

    Lucifer Senior Member

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    The new pads are bigger than the old pads, unless you properly adjust the brakes, they have no reason to not stop you dead.

    So, take it somewhere to have the rotors ground, pity, it's probably to late as the new pads are already burned in to the old rotors.
     
    #10 Lucifer, Aug 27, 2015
  11. Tommerdoo

    Tommerdoo Member

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    Valde3 -- I saw someone post about bleeding brakes the "old fashioned way" here:
    Bleeding 05 Prius brakes the old fashion way | PriusChat

    It looks like you are referring to this page. Very interesting stuff. Thanks for your detailed explanation about working with the brakes.
    Mendel thanks for your help too, it looks like the systems are pretty similar.
    exstudent - I think you're right....I should get one of those cables and a cheap dedicated windows laptop to use with it. I've got a really nice newer macbook pro, but I'm not sure how hard it would be to get those to work together.
    Jeffd - thanks for your help too.
    Lucifer - I havn't driven the car anywhere with the new pads yet, because I know if I do those brakes and rotors will scorch like an inferno so I've had to use my wife's CRV :)

    Thanks for your help everyone...this should be an interesting outcome. And here I thought I was going to do a simple brake job....sheesh!
     
    #11 Tommerdoo, Aug 27, 2015
  12. ChapmanF

    ChapmanF Senior Member

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    Hmm, you're making it sound sort of like to "properly adjust" disc brakes is some advanced technical exercise. You shove the piston back until the space is wider than the new pads, flop the caliper back down, tighten the bolts, and mash the brake pedal a few times. You have to do all those things to be able to put it all back together anyway. :)

    Mendel will chime in about the pad pin, when you're doing the rears.

    Now, what might have led to problems here was simply not testing the calipers for free action before reassembling with the new pads. Always important, that's especially important if the reason for going in was because of suspicion they were dragging.

    The whole caliper has to slide freely on its slide pins. The piston needs to move smoothly in and out, and if you stick blocks in the caliper and apply light brake pressure till the piston touches the blocks, then release, you need to confirm the piston sucked back in by about 0.3 mm leaving a tiny gap. If that action isn't happening, you'll have a dragging brake.

    Here are some shots of doing that test off the car, using air pressure. If you do it on the car using the brake pedal, be sure to use only light, light pedal pressure just to have the piston kiss the blocks, then release the pedal to measure the return. If you put more force than that on the brake pedal, the fluid pressure is so much higher than any air pressure you would test with on the bench that all you will be measuring is the elasticity of the caliper itself and your blocks, not the piston return that you want to measure.

    Ok, there is one moral here about how to "properly adjust" the brake. When you reassemble and flop the caliper down over the new pads, the piston does need to have been shoved back far enough to make this a loose fit. Mashing the brake pedal after assembly is what will move the piston out to pad position, and then let it retract by its proper 0.3 mm or so. If you have not started by shoving the piston back far enough, and closing the caliper over the new pads ends up being a squeeze, when you are done the rubber seal will be stretched in the wrong direction, and won't be supplying its retraction action. It will get sorted out as the pads wear, but that's less ideal than starting out right.

    If it drags badly enough to cook the rubber, you're out of luck until you buy the rubber kit and overhaul the caliper.

    -Chap
     
    #12 ChapmanF, Aug 27, 2015
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  13. Tommerdoo

    Tommerdoo Member

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    ChapmanF -- thank you for that description of how the brake caliper should retract .3 mm or so. That makes so much sense to me now that you said it. I never really thought about how much a brake caliper ought to retract, but that being said, they have to retract or else brakes wouldn't last very long. As for the caliper brackets + pins, they were both sliding freely on their slide pins (I took them off and inspected them) before reassembly then tried them again once I bolted them back on and they were still moving back and forth, so I'm reasonably sure that the pins are not the issue. It looks like I have enough information here to be able to keep diagnosing this issue. Thank you again!
     
    #13 Tommerdoo, Aug 27, 2015
  14. Tommerdoo

    Tommerdoo Member

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    So just to give a quick update -- I took my Prius literally one block and let the car stop itself with the rubbing rotors. I only applied the brakes to shift from park into reverse or drive. And the rotors get very very hot to the touch (on BOTH sides!). Does this mean that my brake line is the most likely culprit? I mean....there's no way that both calipers would fail at the same time, right? Or...highly unlikely?
     
    #14 Tommerdoo, Aug 27, 2015
  15. ChapmanF

    ChapmanF Senior Member

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    Go ahead and flip the calipers up and put some pressure on the pistons to shove them back in (using your piston tool or C clamp). If you've got moderate pressure on them and it's not enough to move them, crack open the bleeders and see if the pistons then move more easily, squirting some fluid out of the bleeders. (That's what some people routinely do when shoving pistons back anyway.)

    Opening the bleeders in that situation does not mean that you will then have to bleed the brakes. Bleeding is necessary when you have allowed air in. Opening the bleeders with a tool pressing the pistons is only going to let fluid out. Close them again after the experiment (and before removing the piston tool/clamp) and you'll be fine.

    A Gen 2 may notice the pressure drop and log codes though (as I understand it; I don't have a Gen 2). To avoid that, have the 12 volt power disconnected at the aux battery first. I am not sure how long to wait for the discharge of Gen 2's capacitor bank, but that should be in the book.

    I'm pretty sure Gen 2 still has an unpluggable positive cable connector back at the battery, which is an easier way of cutting the power than the usual undo-the-negative-terminal-clamp. (It was recently brought to my attention that Gen 3 no longer has that nice feature.)

    Once the power is off, using up the accumulator pressure is just a matter of pumping the brake pedal, may take 20 or more strokes, but they don't have to be especially strong ones. All you're doing is releasing a small amount of fluid from the accumulator on each stroke (it ends up back in the large reservoir). If it's anything like my Gen 1, you will have no trouble knowing when the boost pressure is used up. Somewhere between your 20th and 40th stroke or so, squish, squish, squish, squish, squish, WONK! the pedal turns so hard the shock wave rattles your kneecap. At that point you can be sure there will be no stray boost pressure to surprise you as you work on the calipers or open the bleeders.

    When you're all done experimenting, the pump will probably start and re-pressurize the accumulator for you as soon as you reconnect the 12 volt power. (On a Gen 1, it would only do that with the key turned on.)

    If the pistons are hard to shove back at first but suddenly get a lot easier with the bleeders open, you may have a hydraulic issue somewhere upstream. (Daunting ... I haven't had to diagnose one of those yet.) If they stay stubborn even with the bleeders open, that would suggest your calipers need work. If the brakes were dragging for a while and getting way hot, you may by this point have piston seals made of ex-rubber.

    -Chap
     
    #15 ChapmanF, Aug 27, 2015
  16. Tommerdoo

    Tommerdoo Member

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    ChapmanF, thanks again for adding to this growing thread. I'm in Hawaii where we have had a tropical storm pass near us and up the mountain where I live we have gotten hammered by all the moist air so I havn't had a chance to try this out and with two possible hurricanes coming our way, not sure when I'll get another chance.

    BUT!!!! SOMETHING STRANGE JUST HAPPENED TO THE PRIUS!!!

    Ok, I jump back into the Prius to again test it. Since both sides were sticking so hard an hour before so I wasn't expecting the car to go forward or backward when I took my foot off the brake.....to my surprise the brakes seemed to have loosened up somewhat and the car very slowly moved forward and also backward....then it seemed to loosen more.

    The brakes are no longer completely locked up and now the car crawls forward or backward without needing the gas pedal. No longer a heavy scraping sound, it almost felt as though the rotors were free of the brakes....but not quite.

    I took the car again out down a block and though it seems to be much freer than it was earlier (when it was really locked up), it now seemed as though it could be drivable, though it would probably be terrible for all the braking components -- so of course I won't be driving it yet....

    It seems like it now has the same resistance I noticed it having BEFORE changing out the brake pads. Enough to somewhat affect fuel economy (I'm getting 39 miles to the gallon though I do go up down the mountain and hilly terrain)

    Here's another weird thing. When I apply the brakes, it feels like the brakes are lagging 1/4 of a second to engage. I'm not getting that instantaneous amazing really responsive braking I had before all of this. That to me seems like it has something to do with the brake lines or something.....
     
    #16 Tommerdoo, Aug 28, 2015
  17. Tommerdoo

    Tommerdoo Member

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    Ok folks, it's an amazing sunny day in between tropical storms! I'm trying to tackle my brake problem today before we get wet again.

    First off, The brake hoses don't seem to be the problem, because like you said, I pumped the brakes 20 times strongly and cracked the bleeders and only oozing out brake fluid. Check.

    Again, the caliper slide pins are not having any trouble moving, but I will still lube them with the best stuff I could find locally made for brake calipers. Check.

    I put the wood block into the caliper and lightly pushed the brake pedal in slowly and let go while filming it with my phone. When I watched the video the brake caliper piston does not retract at all. I've only confirmed this on the driver's side so far. I'll post again when I find out about the passenger side.

    If what you say is true, the brake caliper should retract .3mm or something like that? And is that true with the car OFF, because right now I have it completely off, or do I need to turn it back on again so that the weird calibration thing is working? Examing the caliper shows no structural damage and the seals all look fine on it.

    UPDATE: Ok, I just did this test with the car powered up and found out that the brake actuator thingy that activates when you push on the brake simply compresses the brakes thus ending the test. I'm sure this is obvious to all of you out there helping me, but I'm kinda new at this so I figured I had to cross every T so to speak. Yeah....looks like the caliper piston doesn't retract at all.

    Thanks!
     
    #17 Tommerdoo, Aug 29, 2015
    Last edited: Aug 29, 2015
  18. valde3

    valde3 Senior Member

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    If you did do the test correctly then this already means that the brake caliper is bad no need for further testing.

    So sliding pins move freely, and pads move freely, but break is locked. And then you tried to open the bleeder and brake is still locked? If all of that is true it 100% sure that you have faulty brake caliper.

    It’s not possible to see the piston retract by looking at the video.
     
    #18 valde3, Aug 29, 2015
  19. Tommerdoo

    Tommerdoo Member

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    Valde3 -- Thank you SO much for your quick reply! Honestly, I don't know how I could get this accomplished without all your help! OK, so I crimped off the brake hose with a needle nose vice grip carefully padded to protect the brake line as best as I can (got that idea from Eric the Car Guy) and fully opened the bleeder valve to check the brake caliper piston's movement.

    Put the C-clamp onto the piston and it still is very difficult to push back in --- exactly just like before I opened the bleeder valve. And what's interesting is that when the brake fluid comes out of the bleeder as I push the piston back in again, it's coming out in spurts like a squirt gun as the piston gets stuck and frees itself like jittery starts and stops. That doesn't seem like a normal lubed up brake caliper piston, correct?

    So I think I've fully diagnosed the problem of at least ONE of my two sides. Does this sound correct to anyone?

    Thank you again!
     
    #19 Tommerdoo, Aug 29, 2015
  20. valde3

    valde3 Senior Member

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    Only bad thing in testing it that way is that it’s hard to tell what you mean by “difficult to push back in” but if it actually is too difficult to push in then it can only be bad caliper.
     
    #20 valde3, Aug 29, 2015
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