2015 Prius v - Changing Front Brakes & Rotors, Need Torque Specs

Front brakes and rear brakes for gen3 Prius - better than nothing, I bet it's the same ...?

 

Gen 3 Prius Repair Manual brake info attached, again better than nothing. I know there are some variations: the rear Prius v brakes for example, have a mini-drum for parking brake, reg Prius does not.

Some general cautions:

1. Disconnect 12 volt neg cable prior to commencing, and when reassembled push the brake pedal to pressure up, remove any excess travel. Then and only then, reconnection the neg cable. Theres a couple of things that can happen: the car might try to pressurize the brake system while the caliper is off the rotor, with disastrous results. You can (maybe) avoid that if you're on your toes, but I would suggest to just play it safe. Also, if excess travel is detected post brake job, the car might throw a code.

2. If pushing in caliper pistons, use something like the old brake pad, a metal plate, piece of plywood, to ensure uniform contact. Some of the pistons are plastic (phenoloc?), prone to crack with a point load applied.

3. Don't open bleed bolts, unless you really know what you're doing, have researched official brake bleed/change technique for the Prius v. Also, attached, 3rd gen Prius brake fluid change procedure from Repair Manual, but again, this is not v, not sure how similar it is. For giggles, try putting the car in "invalid" mode, see how that goes?

It would be worthwhile to pay the $20 or whatever it is, for a short term Toyota Tech Info subscription, and get the Prius v brake info.

 

Yes, I got a can of AGS BK12 to last me and fam a long time. I heard before that copper reacts badly with aluminum and that Prius has aluminum in the caliper. So I wasn't sure what's real or not.

Speaking of the green silicone Permatex, I read on Canadian Tire 7-1/5 star reviews of guys whose rubber boots got damaged by it. The product reads "for rubber" - so I'm at a point where I'd like to ask everybody 20x times at every time of the day and night just to make sure I don't seize a brake in the near future.

 

Some notes from my Gen 3 experience (caution: not a v, just a Gen 3 liftback). I did my roughly twice-annual tire rotation and brake inspection yesterday, so it's kind of fresh:

There are a couple different automatic things the brake system can do if the power isn't cut.

• when you wake up the car (such as by opening the driver's door), the accumulator pump may run, to re-establish the fluid pressure inside the accumulator. This gets persistently mentioned as something that will pressurize your brakes, but of course the accumulator's pressurized fluid is only applied to your brakes when you are braking. If any caliper gets any pressure merely because the pump has run, probably you have a stuck actuator valve and a brake that drags all the time.
• when the car goes to sleep (say, a few minutes after you turn off the ignition and get out), it performs a brake self-test. That does open the actuator valves and pressurize all the lines. If that happens while a caliper is out of position, then yes, the piston's going to move. (This self-test may also happen if the car goes back to sleep after only being awakened by opening the driver's door. I've never listened for it then. Maybe that would explain mishaps that people are chalking up to the pump running.)

I didn't cut power or use any special mode for my inspection (roughly my sixth since getting the car) ... but I do wait until I hear the couple-minutes-after-shutoff self test, before I start any work

"Invalid mode": there might be two ways to enter that mode if you want to: one by way of a chicken dance, one by using Techstream. I tried it out one time, using Techstream, and ended up regretting it, because entering invalid mode that way sets a permanent, unclearable trouble code to force you to go through the whole Techstream bleed procedure when you're done; nothing else makes that code go away. And if the dongle you're using with Techstream is flaky at all, you might find it flaking out in the middle of brake bleed procedures, and wonder if you'll ever get all the way through.

Bleed screws: just opening a bleed screw, when the system is quiescent and no pressure is in the line, will generally not cause much to happen. Some fluid might come out just by gravity; don't let that go on too long unless you're watching the reservoir level. For actual bleeding, you'll need to be familiar with the procedures to follow.

One possible reason to open the bleed screw, other than for actual air bleeding, is just to give the fluid someplace to go as you push the piston back in. Otherwise, you push the fluid backward through the brake actuator. There are two schools of thought on that, generally the folks who never bother opening the bleeder, have always forced the fluid backward and swear there's never been a problem, and then the folks who (in cars with ABS, anyway) swear by opening the bleeder and not forcing the fluid back.

I've kind of been in both camps. I grew up in the "just mash it back" camp, but I've been a bleeder opener since I started owning cars where the brake actuator has four digits after the dollar sign.

That also gets some of the oldest fluid out of the system, so when I top the reservoir back up with fresh fluid, it could be called a partial fluid replacement too.

 

I used a stopwatch last time. In my Gen 3, the self-test comes exactly 90 seconds after powering the car off.

I didn't catch any instances of the test happening after merely awakening the system with the driver's door.