Help please with brake mystery

@Mendel Leisk resident canadien brake expert.

 

1. what grease do you use for the pins?
2. Mendel Leisk will show you the mandatory picture how to adjust rear calipers before putting brakes together. you can search for it too.

 

How many miles on your Prius? Could it be a wheel bearing issue that might be creating the heat and taking your mileage down?

 

Sounds like all your caliper pins are lubed now? What did you use for lube, btw?

I would not lube the "channels the brake pads slide in". By that I think you mean at the two ends of the pads? There's not much point to that, and it might well get on the rotors.

There is something strange going on, if drivers side pad (outer pad, opposite the piston) is down to metal, and side at the piston is near-new. I would expect the opposite, if the caliper pins were sticking, and/or the pin was misaligned with the piston pattern.

Also very strange, that passenger side pads (both inner and outer) look near-new.

It is possible I think, to align the pin on back of inner pad with the gap between spokes on the piston face, but then have it slip. You want to do the alignment, then assemble everything, then tromp the brakes multiple times to get it well seated, then hook up the 12 volt again, then go for a short test drive, and only then apply the parking brake. Gently, lol.

It it application of the parking brake that attempts to rotate the piston, screwing things up. I think. You really want to ensure it's aligned and seated, before parking brake being applied.

I'm not sure: maybe you're ok on the passenger side? The problems are still evident on drivers side: running hot. Something to try:

Raise the whole rear end, maybe on safety stands to be safe. With parking brake released try spinning both rear wheels. See how they feel. I'd suspect passenger side is ok, and drivers side is dragging badly. A slight drag is normal I think, but you should be able to spin the wheel and it'll go at least one revolution easily.

Then, have someone pressing and releasing the brake pedal while you try spinning them some more. Does the passenger side lock up ok? And the driver's side? (I'm kind of wonderring: could the passenger side be completely non-functioning, the caliper piston seized somehow.)

Almost sounds like the passenger side is not applying properly, what with the pads looking near-new. Not sure.

One thing, if it was pad pin misalignement with the spoke pattern on piston, you would see bevelled wear on the pad. The outer edge of pad would be worn down, tapering to no wear by maybe the center of the pad, due to the piston apply force only to that pin, at the outer edge of pad.

 

If you imprint of the piston spoke pattern straddling the pin that sounds good.

By brake I meant foot brake, maybe called emergency brake in states.

Yeah maybe raising and turning wheels will reveal something.

 

Those channels beside the pads have (or should have) springy, stamped metal inserts (found at the dealer as the "fitting kit", which includes four of the little stampings, enough to do both rear calipers, and also four of the little V springs that sit above the pads to spread them out).

The fitting-kit stampings do not use extra lube (which would just be a place for road grit to stick), but they come already coated with a dry, Teflon-like surface.

When I replaced mine, I literally had to hold my pads together with one hand while putting the caliper back in place with the other, because otherwise the pads would slide right apart because of the V springs above them. So I guess that's what should be normal.

-Chap

 

I
would question those 2 items. Only special (non-mineral) grease is compatible with rubber and no force is needed to put pads in.

 

Yeah I was wondering about "orange stuff" too.

I've been using Sil-Glyde Brake Lubricant for the pins. Just recently re-applied it to the front brake caliper pins, about 30K kms since last application, and it appears to have held up fine, is performing ok.

 

Your outer pad looks like my inner pad, when I messed up on the piston orientation, first time I looked at the rears: definitely bevelled wear, down to the backing plate on the outer edge, and about 4~5 mm at the inner edge. The wear's reflected on the rotor picture, looks near untouched at the inner portion.

You say your pads are Wagner, but I see they have toyota logo on the back? Strange that they are so hard to shift when installed. I'm not quite understanding what you mean by "slide in" or "push back". I get the sense it's a tight fit, that maybe these bits are a bit too long, due to being aftermarket:



Jamming??

OEM pads are just snug, easily lifted out of or placed into the caliper bracket:

 

Can you tell where the resistance is? I'm thinking the "lobes" on the ends. They're the only thing really touching: has to be. The anti-rattle clips they directly contact look ok?

 

That sounds abnormal. I'd be curious what happens with a new fitting kit and pad set bought from a Toyota dealer.

-Chap

 

I just rotated my tires and did the thorough brake inspection this weekend. First thorough brake inspection since I bought this car 10,000 miles ago. Nothing was seized on my brakes. All the brake pads came out by hand, but were very snug. The existing grease on the pins was between clear to a slight redish color. I greased them with white lithium grease. The rubber grease boots were in good shape. The pads themselves were all evenly worn and more than 1/2 pad material left on them (just visual approximation). I applied a thin layer of silver aluminum anti-seize to the lobes on the brake pads and they seemed to slide more smoothly in the channels. I pushed the front pistons back in about 1/4" and turned the rear pistons back in one notch (1/4 turn).

I did all this with the negative battery disconnected. Then pumped the brake pedal until hard before reconnecting the negative battery cable. Operated the brakes under power a couple times, pumped the parking brake 4 times on and off. Everything seems to be great. On my 40 mile drive to work this morning, I averaged 55 mpg and my long time average has been 49 mpg. The weather took a major turn for the warmer this weekend, so that probably helped boost the gas mileage.

 

You better go back now and regrease the pins with proper grease. Mineral oil will swell the rubber and jam the calipers.

 

And what do you think is the proper grease to use?

 

I don't think, I know for sure. Answer is in the factory manual. A lot of people get away with silicone grease.