Brakes already!?!?

My apologies. I skipped one page by mistake. Did not see that @Prigirl had provided an update.
Thanks.

 

see post 59, toyota covered it. they must know they screwed up

 

no tsb, no recall, just let customers suffer

 

@Prigirl - did you initiate the conversation with Toyota on the phone or via email? Thanks!

 

Brakes, already.
This is a shaggy dog story, so get a beverage and continue reading.
A friend of mine has a 2016 Prius Touring, and at 4 years and 44k miles, we examined the brakes. The pads were worn to about 5-6mm both front & back, but what bothered me was that there was highly differential wear inside/outside on the rear rotors.
After some persuasion that "he could do it", he purchased a PowerStop kit (rotors & pads) from RockAuto, and we did the brake job over a couple of days.
Fronts were easy; the rears were a bear. The rear brake piston did NOT retract by hand; I had to use my old Lisle brake piston compressor tool to get the rear pistons to move - after some serious persuading, they rotated and moved, and then they moved easily.
So we completes the job, clean up, have an adult beverage, and I think we're done.
Oh, no.
So a day later, he calls me up, and says his gas mileage is down below average. Upon investigation, we found that in driving only a couple hundred miles, he wore a quarter of the rear brake pad (ceramic) and the rear brakes were getting HOT in only a 2 mile drive.
Took the rear brakes apart, checked the assembly; it seemed we did everything correctly. Brake pads moved freely in the brake hardware, but again it was tough to get the brake piston to start to move back. Once it moves a bit, it moves easily.
OK, so we eventually took the car to the Toyota dealership, and they said that there was too much corrosion on the brake caliper bracket to allow the brake pads to move, even with new brake hardware. At this, my BS detector went off, but it's not my car, and the owner is not particularly mech-savvy, so...
He has Toyota to do their thing: (for $600) its new rear pads, sandblast the caliper bracket, and machine the rotors.
So Toyota reassembles the brakes, and off he goes. In 5 miles, he puts his hand near the rear brakes and nearly fries his fingers.
So back to Toyota.
After a two hour wait...
Now the story is that the tech did not quite correctly reassemble the brakes so that the index pin on the inner brake pad didn't reside neatly in the groove of the brake piston, causing the pad to jam in the caliper and not release from the rotor, causing the heat.
So sorry, tech error, won't happen again, sorry you had to wait some hours for a resolution this afternoon, no additional charge.
So he drove home, and tomorrow will try again to check for proper rear brake operation.

The caliper piston boots are intact.
When we did the brake job the first time, we wire brushed the brake caliper bracket before we installed the new brake hardware (which is a very slippery nickel alloy).
We made sure the caliper guide pins are well lubricated and free to move (they were a bit stiff, but not frozen).

So, my questions are:
(1) how many folks in salt-belt states are seeing problems with premature wear of their brake pads in this generation Prius?
(2) how many folks in salt-belt states haven't looked at their Gen 4 brakes? (NY is an annual inspection state)
(note: if we hadn't been doing a brake job on the 2000 Mustang convertible that week, we wouldn't have looked at his brakes at all)
(there was no obvious operating problem, but I got real nervous looking at the wear pattern on his rear rotors)
(3) how critical is the pad-pin-in-piston-groove placement to proper operation of the rear brakes?
(4) Does anyone have opinion as to why rear disk brakes seem more vulnerable that front disk brakes?
(I have seen this effect on more than one vehicle, so I'm curious).

Now, my personal opinion is that his rear brake calipers are hanging up (intermittently) due to corrosion (NY a salty state in winter).

So maybe this belongs in a new thread, but the topic is still: Brakes, already?!!

 

You MUST orient the rear piston spoke pattern like a letter "X", get that pad backer plate in between the spokes, assemble everything this and pump the brake pedal multiple times. THEN reconnect neg cable. Do NOT use parking brake.

Take short test drive. When back: apply/release parking brake multiple times, then raise rear end and check that wheels are relatively free spinning.

 

Is this procedure documented somewhere (other than the Prius Service Manual)?
We looked, and didn't see any special notes online regarding doing a Prius rear brake job ...

Thanks for the pointer!

 

The "X" pattern requirement is stressed in the Repair Manual, though tersely. In my previous post I fleshed it out, saying not only do you need to orient the piston face pattern, but you also need:

1. To ensure it stays that way. All will be for naught if the parking brake is applied with loose brake assembly, and the piston manages to rotate.

2. Verify it's stayed that way, with a post-testdrive wheel spin.

I'll attach 4th gen Repair Manual excerpt; 3rd gen is similar.

 

When the time comes, I'm going to an independent mechanic for my brake job. Most likely Hybrid-Pit. Between forgeting to disconnect the battery, hitting the "X" factor and just paying attention, the steps involved in this are beyond my expertise.

 

I'm almost the opposite. With something so tricky, handing it over to pros can be akin to "valet parking".

I know about the "X" factor cus I screwed it up royally myself, the first time. Drove with dragging rear brakes for 6 months before I caught on. Replaced the pads.