HOW TO : Replace Front Brake Pads and Discs (Rotors) Prius Gen 2

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by prius-walla, Jul 26, 2013.

  1. prius-walla

    prius-walla Junior Member

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    after being told i had only 2000 miles of wear left on my front brake pads and the discs (rotors) being worn and rusty. i searched online to see how to replace discs and pads. as i could not find a piece that showed me how to do it but i did find some odd, misleading and sometimes just wrong information online.. as such i am posting pictures and a write up of how i did it.. hopefully this will help others to do a fairly easy job (that the dealers are charging extortionate amounts for) and dispel the myths circulating online.

    i bought replacement discs and pads online for less than half the price the Toyota dealers were charging.

    you will also need

    brake cleaner aerosol spray
    copper grease
    WD40 spray

    Tools needed.

    17mm spanner
    17mm socket and ratchet handle
    10mm spanner
    rubber mallet
    hammer
    torque wrench
    'G' Clamp

    trolley jack
    axle stand
    tyre chocks


    1: first chock the rear tyres

    1.JPG
    2: loosen the wheel nuts on the side you will be working on. dont remove them, just loosen.

    2.JPG

    3: jack up the car using the jack points and remove the tyre. i also placed an axle stand under the suspension arm in case the car dropped. you can see where in one of the later pics..

    3.JPG

    4: disconnect the battery to prevent the brake system operating while you are working on it or storing faults which may need a dealer visit to clear.

    4.JPG

    5: to be extra safe remove the 2 ABS motor relays in the fuse box under the bonnet (hood). its the blue ones i'm pointing at. Before removing, note which way round they fit and mark them or take pictures.


    5.JPG

    6: remove the cover on the brake fluid reservoir. this is to allow the fluid some space when you push the caliper piston back (which i will explain later) 6.JPG

    7: to be able to take the old pads out and remove the brake disc (rotor) you need to remove the brake caliper. this is a frame that holds the brake mechanism, im pointing at one of two brake caliper bolts that hold the caliper in place. this is the top one and there is another about 6 inches straight below this one (couldnt take a picture of it) they are 17mm in size

    7.JPG

    8: as the bolts have been in place for years and are rusted on you will need to spray WD40 penetrating fluid onto them and leave it to work for about 10 minutes or longer if you can.
    the bolts are on very tight. i had to place the ring end of a 17 mm spanner on to the bolts and then hit the spanner quite sharply with a hammer to loosen them. this is the best way as there isnt space in there for you to be able use socket and a long handle with any force. also there is another bolt that gets in the way of the socket

    8.JPG

    9: once you have loosened the caliper bolts, unscrew them till they are almost out but dont take them out completely.

    to understand why you do the next part you need to know that the caliper slides along 2 slide pins as a way of adjusting itself to allow for when the pads wear and get thinner.

    these slide pins will be a bit stiff and will be holding the pads tight against the disc making it hard to remove the caliper from the disc.

    you need to get the slide pins moving again and create space between the pads and disc to enable the caliper to come off easily.

    i used a 'G' clamp on each slide pins to squeeze it about 1 to 2 cm. this made the slide pins softer so i could move them with my hands.

    ( i took the pictures of the 'g'clamp on the slide pins when i was doing the second side as i forgot to do it on the first side.. )
    9.JPG

    10: this is the 'G' clamp on the lower slide pin

    10.JPG

    11: once the slide pins have been squeezed and they loosen up, this will make space for the pads inside the caliper and enable the caliper to be removed easily from the disc. so remove the caliper bolts completely and remove the caliper.

    once the caliper is removed from the disc, note carefully how the pads are located inside the caliper. take pictures if you can. one of the pads has a metal clips protruding from it. please note which side of the caliper this pads fits on and which way round.

    once you have made your notes, pictures etc then remove the pads and place them to one side. each pad has thin metal plates on it. these are called shims and they prevent noise. ensure you remove these also when you remove the pads. dont throw the pads or shims away just yet.

    Now you need to place the caliper carefully onto the top of the brake disc and will need your 'G'clamp to push the piston back.
    you do this to create more space inside the caliper for the new fatter pads and new thicker brake disc to fit inside the caliper.

    to explain why you're doing this.. when the old brake pads were in the caliper and as they wore and got thinner the piston pushed out further to keep the pads against the disc. now you are replacing the thin old pads with fatter new ones you need to push the piston back to make the space... get it??

    this is how i pushed the piston back using the 'G' clamp. once the piston is flush against the back of the caliper you stop pushing it any more.

    11.JPG

    12: once the slide pins are loosened and the piston is pushed back, carefully hang the caliper from the spring as shown ensuring you dont stress the brake pipe attached to the caliper

    12.JPG

    13: now to remove the old disc (rotor)

    at this stage it will be held on by nothing more then rust.. you DONT remove the big centre hub nut as some people have stated on the net. all you do is give it a few HARD SHARP blows with a rubber mallet. this will break the rust and free the disc.

    13.0.JPG 13.JPG 14.JPG

    14: clean the hub face with brake cleaner fluid and some wire wool. just to remove any rust and give the new disc a clean flat surface to mount to.

    14.JPG 15.JPG 16.JPG

    15: my new pads came with self adhesive shims which i stuck onto the backs of my pads and re-used one of the old metal shims from the old pads. (they were perfectly serviceable and just needed a clean) i then prepared the new pads by smearing the backs with copper grease then inserted them into the caliper.
    17.JPG

    i attach pictures of the old pads next to the new pads to show the difference in thickness. hopefully this will show why you need to loosen the slide pins and also push the piston back.

    there was approx 1 to 2 mm of material left on the old pads. these were the original factory fitted ones and lasted 89,000 miles.

    18.JPG


    16: before you fit the new brake discs YOU MUST CLEAN THEM WITH BRAKE CLEANER as they have a covering of oil on them for transport. if they arent cleaned with brake cleaner you could have brake failure and an accident.
    simply spray the disc generously and wipe with a clean cloth. then fit the disc. this means just pushing them onto the wheel studs. next refit the caliper by pushing it carefully onto the disc with a brake pad on each side of the disc. refit the two bolts and hand tighten. then torque the bolts to 81 lb ft.

    19.JPG


    finished job...

    20.JPG


    now refit the tyre.
    torque the wheel nuts.

    lower the car.

    check the brake fluid reservoir. as you pushed the piston back, that in turn pushed the brake fluid back into the reservoir. when i checked it was higher then the 'Max' mark on the reservoir. i sucked the extra fluid out by using a syringe dispenser that comes with childrens medicine till the fluid was at the 'Max' mark.

    i then replaced the reservoir cap.

    refit the 2 relays

    refit the battery.

    start the car to 'ready'

    if you have the ABS etc lights stay on...

    switch the car off and then switch on again.. car will run through diagnostic and should switch the warning lights off..

    Disclaimer: this is how i did MY car. it is posted as an explanation of how I did it and isnt a definitive guide.

    i hope this shows that it is quite a simple procedure done with quite basic tools by someone with basic mechanical knowledge.
     
  2. bisco

    bisco cookie crumbler

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    nicely done, thanks!(y) how many miles did you get out of the originals?
     
  3. prius-walla

    prius-walla Junior Member

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    got 89,000 miles out of them ( i think i put that on the write up)
    pretty amazing, i think when compared to some of my previous cars, Fords and BMWs.. which were needing new pads after circa 15 to 20K

    im going to be doing the rears tomorrow. discs, pads and shoes. will also do the same write up for that.

    i understand US cars only have drums at the rear so may not be so useful to you guys over the pond..
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Nice work.

    I suggest that the caliper slide pins also need lubrication (lithium soap base glycol grease recommended) and that might promote more even wear of the brake pads in the event the pins had been stuck previously. Otherwise if the pins stick, the inner pads will tend to wear faster than the outer pads.

    Instead of whacking the old discs with a rubber mallet to remove, an alternate approach might be to insert bolts into the two threaded holes in the discs (8 mm is the correct size) and then screw the bolts in to provide a force pushing the discs away from the hub. The use of bolts might be better if your intent is to reuse the discs after resurfacing.

    The NA Classic and 2G Prius have rear drums, and that is the method used to remove those drums if stuck.

    Very nice to see the photo of the shiny disc installed in your car. Looking forward to seeing your discussion about the rear disc brakes, I am interested in seeing how the parking brake works.
     
    #4 Patrick Wong, Jul 27, 2013
    Last edited: Dec 21, 2014
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  5. maverick13

    maverick13 Junior Member

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    209K miles here, original brakes, and they were just measured to be in good shape too.

    I coast a lot and brake gently which I believe does not activate the brake pads, only for more sudden occurrences.
     
  6. prius-walla

    prius-walla Junior Member

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    Patrick, i agree, if i was going to re-use the discs then a more gentler approach would have been used.

    i got the tightening torques from one of your posts on here.

    Front caliper bolts: 81 ft.-lb
    Bolts that screw into slide pins: 25 ft.-lb
    Front axle hub nut: 159 ft.-lb
    from a post on Aug 12 2011 on this thread:
    Maverick. my pads were down to approx 1 to 2mm so trying to get them to 209k miles might be asking a bit much.
    i live near the sea (approx 200m away) so have to expect that things on the car might weather a bit worse than other cars.

    Patrick, i did strip down the rear brakes this morning, but the pads and shoes still had approx half of their friction material so apart from a good clean up they were left as they were. (the discs were taken back to the shop for a refund).
    at the rate they have worn i should be changing them in approx 4 years so the write up will have to wait till then. sorry..
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You are right and I corrected my post #4 above.

    I changed the front pads on my 2004 at ~130K miles because the inner pads wore more than the outer.

    Regarding the rear disc brakes, how do the parking brakes work? Does the parking brake have a mechanism to tighten the rear disc pads; or does the rear disc have a large hub with parking brake shoes within?
     
  8. prius-walla

    prius-walla Junior Member

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    the rear brakes have a disc with pads for the abs system and the centre part of the disc, which has the wheel studs, is quite enlarged and holds a brake shoe arrangement similar to the drum brake. the rear pads are a lot smaller then the fronts and fitted at between 1 and 2 o'clock as you look at it.

    imagine a drum brake but with a brake disc attached to its edge..
     
  9. SageBrush

    SageBrush Senior Member

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    Stupendous tutorial, Thanks Prius-walla.

    When I last checked my front brakes at ~ 120k miles I had used up about 2 - 3 mm of shoe, so I will probably not check again until around 200k miles. I'm happy to know that the eventual maintenance is likely going to be a breeze.
     
  10. Britprius

    Britprius Senior Member

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    An very good write up with pictures, well done.
    An extra item to add to your post and this is important.
    The new pads should be bedded in by driving the car up to 50 mph (no more) putting the car into neutral and braking. Do this as many times as is required till the braking appears normal.
    Failure to do this can give a nasty surprise if you need to brake in an emergency and the brakes switch straight to friction brakes "no regen braking" and the pads are not bedded in, as braking can be very poor until the pads are bedded in giving almost no braking.

    On ordinary cars this is instantly noticeable, but on the Prius the brakes feel normal, but this is due to the fact that it is using regen braking down to 7 mph. This in turn means it can take the brakes a long time to bed in.

    It is also unwise to remove the fluid container cap as this lets in both moisture and dirt. Under normal use the fluid should not need topping up and is sealed from outside air with a bellows. There being sufficient fluid in the tank to accommodate any pad ware and when pads are replaced the fluid level will return to full. Any fluid loss must mean a leak somewhere that will require investigation and repair.

    John (Britprius)
     
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  11. prius-walla

    prius-walla Junior Member

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    That is incorrect Britpruis.
    you definitely need to remove the cap off the brake fluid reservoir..
    reason: to make space for the new thicker brake pads, you push the brake calipers piston back, this causes the piston to push the brake fluid back along pipes and back into the reservoir.
    if you leave the cap on, the fluid wont be able to move up into the reservoir as the air that will be trapped there (by the cap being left on) wont have anywhere to go.
    also pushing the piston will need a lot more force..
    leaving the cap off for the hour or so it takes to swap the pads wont mean the fluid getting contaminated.. that is a not an issue.
    when i did this procedure the brake fluid had been pushed to well above the max mark and some fluid had to be taken out of the reservoir.
     
  12. prius-walla

    prius-walla Junior Member

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    i will heed your advice on bedding in the pads. Britprius. been driving gently and braking gently since the procedure.
    i have noticed the brakes are alot more powerful. slightest touch now and they bite. wow... almost sports car like.

    and i think i have noticed another benefit, not sure it is real but will keep an eye on it..
    the battery seems to be charging alot better over the last 5 days.. dont know if the battery recharging is linked to the efficiency of the brake system.

    probably imagining it
     
  13. Britprius

    Britprius Senior Member

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    Prius Walla. I respect the fact that this is the way brake work has always been done in the past but things change as do braking systems particularly the Prius system.
    Although the system is sealed from outside air, air movement has to be able to take place in both directions, otherwise as the brakes ware, a vacuum would be produced in the fluid reservoir causing the brake pads to pulled back away from the discs giving a long brake pedal, or to draw in air at the caliper seals as the fluid would be below atmospheric pressure. The seals on the caliper pistons are designed to hold pressure in one direction only.
    Having tiny breather holes in the fluid container lid was the old way of getting round this. This however this let moisture into the braking systems by continuous movement of air in and out, and required regular fluid changes. Newer systems use a bellows arrangement to allow air to enter one side of the bellows, this then expands to take up the place of fluid displaced by pad ware.
    The container holds enough fluid to compensate for any pad ware, unlike containers of a few years ago that were little bigger than egg cups.
    When the pads are replaced and the caliper pistons pushed back the fluid level rises back to where it was when new pushing against the bellows collapsing it pushing out the air inside the bellows on the none fluid side.
    The reason your fluid rose above the maximum mark is because it had been topped up when not required. In this case you have no choice but to remove the cap and draw off some fluid. Another chance for the fluid to become contaminated
    I instruct my dealer not to top up the brake fluid for the reason listed here but also because garages top the systems up from a bulk container, often left open and used over a period of months.

    The only reason I take my car to the dealer is so that the service book has a full set of stamps to help keep up it's value and saleability.
    If I wish to top up the brake fluid "I have not done so on the Prius" I buy a fresh sealed can. Clean the top of the can and fluid container and top up, disposing of the rest of the unused fluid in the can.
    Wasteful perhaps but my brake system is more expensive and safety critical than a few ozs of brake fluid.
    Because the fluid is below the full line does not mean it needs to be topped up. As long as the level is between full and low that is ok.
    Every time you take off the fluid cap gives the possibility for dirt and moisture to enter the brake fluid.
    Brake fluid is hygroscopic "meaning it attracts and absorbs water".
    It only takes one tiny spec of dirt to ruin one of the seal in any brake system, and the Prius has possibly the most complicated brake system of any other car.
    Some of the brake components run into hundreds of £'s if not the low thousands. How many people including dealers clean well round the filler cap before removal with a clean microfiber cloth and paint brush? Answer none that I have seen.
    In short I stand by my statement, and method.

    John (Britprius)
     
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  14. Ian Mayo

    Ian Mayo Junior Member

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    Just for interest and for those of us in the UK should you attempt to change the rear brake pads when you push back the pistons the car throws error codes that, I am told, only the dealer can remove which will be done at a cost.

    The front pads and discs are easy peasy and well within the typical DIY skills. Be careful in the UK as a number of the online replacement part sites have the wrong part numbers referenced. Make sure the discs you order have five bolt holes, not four.
     
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  15. Britprius

    Britprius Senior Member

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    The rear pads are just as easy providing you follow the procedure of disconnecting the 12 volt battery before starting work. Fault codes can appear the Toyota workshop manual states this, but this is not always the case. They can be removed with a mini VCI and Techstream that in the UK costs about £20 and is capable of almost anything the dealer tool can do. The dealers charge around £100.
    The parts you mention are for the gen1 Prius where the discs have 4 holes and the pads are different.

    John (Britprius)
     
  16. Ian Mayo

    Ian Mayo Junior Member

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    Exactly John, But the order codes for the four hole discs appear to have been unfortunately allocated to the Gen 2 cars. If you do an online order for Gen 2 discs you receive four hole discs. It is necessary to get a human involved to make sure you get what you want.

    A couple of acquaintances have both had codes thrown when changing rear pads even with the 12V battery disconnected. These would not go using their diagnostic tools (sorry I don't know the type) and they had to rely on their dealers, at great expense, to clear the codes and the dashboard warnings.
     
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  17. Britprius

    Britprius Senior Member

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    The diagnostic tool I recommended uses the same software "TIS Techstream" as the dealer uses and at around £20 for the device and software is well worth the investment. In fact less money than buying a manual, and about 1/5 of the dealer price for clearing codes. If you work on your Prius, this equipment is just as essential as a socket set and cheaper.

    The Mini VCI is a Mongoose clone capable of reading all Toyota codes on any Toyota car and can also read HV battery block voltages and resistances, do zero point calibration on steering, calibrate the braking system, bleed/flush the brakes, and to much more to put here.

    I have done pad and or rear disc changes on four Prius and only one had codes. These did not affect the operation of the car or even put on warning lights, but did show up when scanned. Perhaps it is because I follow Toyota's instructions to remove the two light blue relays in the fuse box as well as disconnecting the 12 volt. However Toyota do state in the manual that on occasions a code may be issued.

    The discs you mention I agree I have seen misrepresented on occasions, but more so with the pads, but not by all sellers.
    The other annoying thing with Ebay adds is the discs look a good price and in the small print hidden away the pricing is for one disc.
    I was however able to buy on Ebay front discs at £30 for the pair and rear discs at £16 for the pair, this for quality known brands.

    John (Britprius)
     
  18. prius-walla

    prius-walla Junior Member

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    Britprius where can we buy the scan tool you mention?
     
  19. prius-walla

    prius-walla Junior Member

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    I bought my discs from eurocarparts. And went to the local branch to check them before purchase. They campared well price wise with eBay and internet sellers and were a lot cheaper then local motor parts shops. Plus they refunded no questions when I returned the rear discs.
    And NO I don't work for them...
     
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  20. Britprius

    Britprius Senior Member

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    Ebay has them just search "Toyota Mini VCI".

    John (Britprius)
     
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