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

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


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



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..



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.



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.




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)

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



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



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.. )


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



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.



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



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.



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.



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.


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.




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.




finished job...




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.

 

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..

 

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:

http://priuschat.com/threads/front-and-rear-brake-pad-and-disk-replacement.60713/page-3#ixzz2aGZyMMV2​

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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..

 

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..

 

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That is incorrect Britpruis.​

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you definitely need to remove the cap off the brake fluid reservoir..​

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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.​

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also pushing the piston will need a lot more force..​

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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.​

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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.​

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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

 

Britprius where can we buy the scan tool you mention?

 

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...