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

Do you restrain the shoulder of the caliper pin while torqueing the caliper bolt? The shoulder requires a slim 17 mm wrench, too thick and it won't fit.

I was thinking I'd need some sort of stamped plate wrench, but was wandering around Princess Auto, and noticed a 17 mm wrench, regular but quite thin. Picked one up and lo-and-behold it fit.

FYI, my regular 17 mm wrench is 8.4 mm thick (doesn't fit), and the slim one is 6.3 mm, fits with a bit of clearance.

 

you can buy a cheap wrench and grind it thin.

 

Bicycle tools are made thinner too, because they are often used between frames and other locking bolts.

 

I bought a cheap wrench and it WAS thin, lol. But yeah, if it's 1/4" or less, it'll fit.

 

So we now have 220K miles on our 2009. I took both front wheels off to measure the remaining pads. All 4 pads have just under 7 mm (original pads) left vs a new pad which is just under 10 mm.

So do I go for another 220K miles before doing anything? Even the brake fluid has less than 1% moisture and 0 ppm of copper on the test strips, so even the brake fluid appears to be in excellent condition.

 

All I know is that I have a 2007 USA Prius (non-touring) and the mileage is mid 90,000.

I was told today by Toyota service that my fronts are 1-2mm and need replacing and my rear were 3mm. The service guy indicated the rotors were being worn into and further use would require rotor replacement due to damage.

I thought this was odd since:
1) I thought brake systems had the "squealer" to let you know it was time, and I've heard nothing and felt nothing. Does the Prius have a "squealer" or is that reserved for when the pads are completely gone and it's the base grinding the rotors that one hears?
2) the rear brakes were less worn than the front. I thought the rear brakes were used more on the Prius than the front. Why aren't the rear worn more?
3) they had it in for an oil change and it was during this that they noticed the fronts were so worn (but nothing on the backs). How'd they get a visual measurement without taking the tire off? After I agreed to a bigger service (coolant, brake fluid, etc) did they note the measurements on the drum brakes in the rear. They can see the front pads with the wheels on while it is up on the lift?


I've done my own brakes a couple of times in the past on 2 other cars, and feel comfortable with the directions in this thread.

However, I'd like to know if I should take the time to jack up the car to check the front pads or just cast aside what the service guy said as something the service guy said to increase their service bill.

PS: It's winter here. I'd rather not be outside jacking up the car if I don't have to do that.


Also, they said my 12V battery "failed" it's test and needs replacing. They showed me a print out that the battery "health" is "low." Is this typical of the prius 12V (non-hybrid) battery life for a 2007 prius? It did get parked for 2 months up until just before Christmas and the battery was dead went I went to start it. (long story) I haven't driven it much since, but it has been starting mostly ok. There have been a couple of times I've had to fully power it off then on again to get it to start. But I have had to do that at 30k and 50k.... So, I'm unsure if this is more smoke and mirrors. For all I know they have a crappy battery in back they test and show the test results from it instead of really testing the battery actually in my car.

Another PS: I clocked a slightly over 60 mpg & 660 miles tank (forced in 11 gallons despite the pump shutoff) in it this past summer. My personal best. If someone has higher, congrats to them and I won't trying bettering them.

 

The 2G Prius has rear drum brakes and the brake lining thickness when new is 4 mm. The replacement is required at 1 mm. So you don't need to worry about the rear brakes at this time.

I think you should inspect the front pads personally, which you can do by looking through the wheel spokes. At least you can see the outside pads that way.

With almost any vehicle, the front brakes will wear faster than the rear because the weight of the vehicle shifts to the front when the car is decelerating.

It sounds like your 12V battery is near the end of its life based upon what you have described. Don't expect the battery to last more than four years if you live in an area with snow on the ground, and you don't drive the car enough to keep the battery charged. "Enough" is going to be around 12K-15K miles annually.

 

Thanks for the reply.

I'll see what I can see tomorrow on the front brakes by looking through the spokes.


As for the battery, the 2 month park was unusual for me and it previously had only been driven by me not on Sundays. (driven 6 days a week). The average mileage per year given the numbers above will be misleading. I started out driving it high miles, then low miles. Currently, my mileage per week is likely around 50 miles/week, or about 2600 miles per year. (Yes, the initial years were very, very high mileage years)

 

If you have the original 12 volt battery, then it should have died years ago. They last about 4 years. Mine died within 3 years. I've had an Optima Yellow Top for the last 4 years and just did a CCA pull on it and it still pulls more amps than rated for new so it looks like that battery will go for years.

The stock prius break pads do not have the wear indicator on them so they won't make an audible noise until it's too late. If you're really down to 1 mm, then you destroyed your rotors. If you're down to 2mm, then you're not. However, you can easily see yourself if the rotors have been scored and it won't be the entire rotor, but just the band caused by the protruding pad material fastener that poked through by getting to think.

The front brakes are of course more used in any car as the weight is transferred forward while braking. However, brake systems are designed to ideally wear evenly so the rear brakes pads and rotors will be smaller than the fronts(or in this case the rear drums).

 

I went full overkill on the annotation, and noted the pad, backing and shim.

It seems there is plenty of pad left, and certainly a lot more than 2 mm. Do you more experienced people disagree?

Also the rotors show no "rivet rut" from the pad backing. Wear seems even horizontally across the surface (no single deep ruts). Do the rotors seem "acceptable," also?

 

They're no spring chickens, but looks like you have a little time yet. Better assessment would be if you take off the wheel, and look through the opening in the shoulder of the caliper. Then you can get an idea of the inner pad thickness. There should be a groove at the center of each pad, and how much of that groove is left is a good indicator of thickness, when you're eyeballing through that window.

I wouldn't leave it too much longer, but that's me.

 

thanks for all of the replies, you are all great.

Unfortunately, I've got to drive the car starting tomorrow and will likely put 2,500-3,000 miles on it, mostly highway, shortly running all about. I likely won't have time to change the brakes even if the rivets do hit the rotors.

I'll brace myself for changing them out afterwards. Thin flat wrench, huh. My previous 2 were American cars. I guess I'll be springing for at least one thin metric wrench. (and I guess a socket + ratchet for the battery job. Luckily I carry jumper cables.)

 

That thin wrench to hold the connection in place while breaking loose the bolt can maybe be skipped. It more-n-likely won't start turning.

AFAIK, Honda's are similar construction: I never heard mention of this second wrench with them, always just broke them loose (and tightened) with a ratchet wrench on the bolt head.

 

That surprised me ... my Gen 1 stock pads certainly have the wear squealers, and they are clearly shown in this photo for the 2007 Gen 2:

From what I see in your photos, I don't think you've got anything to worry about on that score. When you get back, you might just want to check the condition a bit more closely. As Mendel hinted, the other sides of the rotors are harder to see, and there seems to be a pattern that they usually don't look as good. The easiest way to see is to at least flip the caliper up and look from behind (take out one slide pin bolt, loosen the other, pivot caliper up out of the way, pluck out the pad, look at the rotor). Really, from that point, it's only two more bolts to get the caliper bracket out of the way, then the rotor comes right off and you can look as closely as you like.

It looks a little shiny; if both sides look the same, I'd probably hand-sand with 150 grit paper to a nice dull finish and reuse it. If there is deeper scoring on the hard-to-see side, you might visit a brake shop to have it turned on a lathe. The hard-to-see side can often get a clean-band-between-two-rusty-bands look, which will also call for the lathe if it is bad enough.

If you decide on closer inspection not to replace the pads right away, you can de-glaze their surfaces with the sandpaper too before putting them back. If you get new pads they will have dull surfaces out of the box so no need to do that.

As a side effect of this checking, of course, you'll be able to clean up and regrease the slide pins and make sure everything moves easily, and you'll be set for a good while.

-Chap

 

The wear indicator is the extension of the copper "handle"? This is our 3rd gen fronts, has those handles on the inside pads. The rears are similar.

 

I agree that the pad lining thickness and the rotor looks OK. However as previously suggested, the inner pad may wear faster because that pad is directly actuated by the caliper piston. The outer pad may wear less depending upon how freely the caliper can slide when the brakes are applied (hence the suggestion that you clean and lubricate the caliper pins.)

For reference, new pads have 11 mm lining thickness.

 

Right. It only looks like a handle. It's only there to be a wear indicator.

The tip projects about 1 mm past the pad backing, so it touches the rotor when the lining gets that thin. When it touches, the whole shape and size of the "handle" is tuned to vibrate at the exact pitch that makes you say "all right! stop! I'll buy pads! I'll buy ten sets!!"

-Chap

... now, I can't help noticing yours look a little different. Your "handles" are more stout, and sit right on the backing plate locating ears. I wonder if they could be springs to try to prevent the "reverse click". I'd have to be able to see where the ends end, to be sure yours were also wear indicators.

 

Yeah I didn't look close at them, but I'm sure they're indicator too, like our prev Hondas. Maybe Canada has diff brake spec, it sometimes does.

 

comparing the remaining on the other pad to the pads in the original post, I think I'm just going to drive on them for longer.

If I don't use the thin flat wrench, I'll just return it. I'll get it just in case. The original post indicates a socket does not fit around all the bolt heads due to another bolt head in one's way.

as for the battery, I ran the diag described in another diy prius forum. It started at 12v or 12.1v in ACC mode, and then it pulled about 11.3v with the headlights on and the heater fan on high on but no rear defrost all while the gasoline motor was off. Voltage did drop precipitously from there though. It fell to 10.3v in probably 10 seconds. It wasn't until afterwards that I figured out how to toggle between the diag screen and display screen and back again to turn on the rear defrost and re-enter diag mode. So including the rear defrost as part of the test will have to be later. The other diy prius forum did not discuss how slow (or fast) the discharge from 11.3v with the headlights, heater fan on high and rear defrost (gasoline motor off) should be for the battery to be acceptable. I've left it outside for tonight and will perform the test again tomorrow. I may first be running around for a battery and metric tools tomorrow.

 

if you have the original 12v battery in there, its 8+ years old now. you should just go ahead and replace it. brake pads will go another year if you aren't one of those folks that fly up to the traffic light trying to get in front of 1 more car, and then slam on the brakes. (I'm sure you're not one of them or you wouldn't drive a prius)