Front Brakes lightly dragging after Pad/Rotor change & tech stream bleed ???s

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by gd420mj, Feb 10, 2019.

  1. gd420mj

    gd420mj Junior Member

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    Hello,
    This past June, I change the front rotors and pads on my 06 at 253K miles. This was the first time the brakes were serviced. (although front wheel bearings had been done previously) I was reluctant because everything was working properly, and despite the miles, the pads had material remaining. But since I was doing the left front wheel bearing (2nd), I figured do the brakes now and not have to touch it for 10+ yrs.

    I did not change fluid or bleed the brakes. I gently compressed the calipers (with proper tool) and installed new pads and rotors. Pads were greased at contact points and slid freely.

    But ever since I replaced them, the front pads have been dragging. Not enough to generate heat, but enough to be noisy and make the front wheels black.

    (In the past on regular cars, the pads usually wear in after some miles and don't drag.)

    What could be causing the fronts to drag?

    This wknd, I checked FL pads for hangup and they were free to move in bracket. I did not re-compress the caliper.

    Also, I thought maybe I should bleed the brakes and before I did, read many posts here and FSM. I used the tech stream, and when I did the front brakes, only a very small amount of fluid comes out each time we open bleeder with pedal depressed. Is this correct? I'm used to more fluid coming in other cars. I did not make it to rear wheels. At this rate it would take hours to get some fresh fluid through there.
    (I had a few problems initially form car being not level and forgetting to set p-brake and low 12v, I found driving all four wheels up on some wood blocks makes accessing the bleeds screws easier than jacking and setting stands. since you don't need to remove the wheels)

    It seemed to me like the tech stream didn't even do anything other then just tell me steps, like remove relays, do FR, do FL, stop install relays, wait 2 min etc. When I was under the car while bleeding, there were no sounds other than mechanical brake action. (at pedal and wheel) So, IDK.

    I had error codes related to brake stuff in the tech stream, but I ignored assuming it was related to the work I had done, and no MIL on. I erased them. This AM, after a drive, I had C1253(hydro boost pump motor) C1256 (ACCumualtor Low Press) show up. I erased them and after a shorter drive, they did not come back.

    Also, as far as I can tell, ABS works. I tried stopping hard on pavement and loose gravel, brakes didn’t lock and VSC flashed. Currently have no dash lights, and the two different pumps noises I hear don’t seem to run more or less than I am used to hearing for 7.5 yrs.

    Despite the slight dragging, the brakes work well, pedal is high, and they grip real good if I press hard. They don't feel spongy and I don't think there is any air in the lines.

    Also, fluid appears clear, but I’m sure thats not a good indication of its condition. (i’ve bleed other cars with dirty fluid).

    My guess is maybe fluid is old and lost some if its hydraulic properties and calipers are not retracting as well as they could coupled with pad and rotor at maximum thickness and compressing the caliper all the way back to its starting position, maybe its hung up a bit.

    Thanks if anyone can shed some light on these pads dragging.

    Thanks. I should knock on wood. maybe I bought a cherry, but we've had very little problems with this car for 7.5yrs since 113k mi. 3 wheel bearings, One 12v Bat (using an oem used one), MAF, spark plugs.
     
    #1 gd420mj, Feb 10, 2019
    Last edited: Feb 10, 2019
  2. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Has the brake fluid ever been changed?

    I'd guess it's somehow related to pushing the pistons all the way back in, and maybe there's some rust debris hanging it up.

    How about caliper slide pin relube?
     
  3. sam spade 2

    sam spade 2 Senior Member

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    Major mistake. You should have changed the brake fluid.....at least 3 times in 12 years.
    And if I was doing brakes on a 12 year old car with 253K miles, I would have done calipers too.
    I would maybe NOT have done rotors depending on the wear.

    ALL disk brake pads rub a tiny little bit; the rotors are just so smooth that you don't know it.
    The dust might be from a combination of extra hard rotors and soft pads.

    "Normal" stops won't seat new parts very fast. A few hard stops might help.
    But if there is no heat there I wouldn't lose any sleep over it.
     
  4. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Rotors you want to do when they're nearing mininum thickness, or have a seriously "wow", or hopeless rust. The stock and minum thickness are in the attached, and runout spec. You need a micrometer and dial indicator with magnetic base, together that's under $100 these days.

    OTOH, 253K miles, that's a lot of miles.
     

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  5. edthefox5

    edthefox5 Senior Member

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    Local dealers will not change the brake fluid. I asked they say no. Reports of bench failures of the ABS actuator whne performing that which is already a very expensive service item older G2's suffer from.

    I know when I do my brakes I will not bleed out the entire brake fluid system.
     
  6. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Third gen there is documented procedure in the 3rd Gen Repair Manual, either with or without Techstream. And Toyota Canada recommends it, tri-yearly or 48K kms IIRC.

    I've managed to do this with no special equipment, a large mayo jar with a hole in the lid, some tubing, a large syringe with tube extension (for basting out the reservoir), and the one fancy thing: a rubber gizmo for pushing onto bleed bolt, though you can manage with just tubing and zip-tie in a pinch.

    My wife helped, pushing the brake pedal, I put the car in "Invalid Mode", and it took about an hour. Two pints of Toyota DOT3 brake fluid worked out about right. No problems, and the brake pedal good and firm after.

    That said, there is no equivalent instruction in 2nd Gen Repair Manual.
     
  7. gd420mj

    gd420mj Junior Member

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    Thanks for the replies folks. Turns out, the pad guides were rubbing on the rotors. mostly at the outer edge of the rotor. 3 of them were loose, so with some pliers, I made them fit snug in bracket and was sure they cleared the rotor. Cleaned everything and re-lubed. Everything is super quiet now.

    I can't say the pads were dragging. I just assume because of increased dust. But that may be the ol' lady's driving habits. Even got ceramic pads to reduce dust.

    btw, discs were 0.860" thick and pads were about 9.7mm.
     

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