Hi all:

Rear passenger caliper piston retracts easily, but outer pad worn to metal. Destroyed the rotor. Sadly, I can see the caliper piston as the dust boot is split. It had a very slight tear in it, and as I retracted the piston manually that split it open all the way. The piston is nice and shiny what I see.

Since this is a single piston (inner side) setup, AND the piston turns either direction freely I now assume the caliper is NOT frozen / seized.
I haven't seen this before - should I guess the slide mechanism is not operating / stuck?
Would that account for brand new inside brake pad and gone to nothing outer pad? The rotor is destroyed (grooved deep cuts) on the outside and smooth and perfect on the inside.
If the slide is not operating, how to fix that?
Just clean and lube it up and make sure it slide freely? Is there more to this? Do I have to get a new slide / bracket assembly? (or can I fix it?)

Caliper / bracket and piston rebuild will be all special order and shipped to where I am. I'm too far from the big cities.

Also, I must state absolute monkeys worked on this car before I bought it.
I can start a list of all the sloppy BS mechanical 'work' they did and forgot to re-attach / couldn't be bothered...

This rear brake did not have what it appears to be the parking brake cable hooked up to it. The hydraulic brake fluid line was attached correctly.
(the front brake was missing a shock mounted brake line bolt and was hanging loose - nice, A-holes). see pics.

The "pattern of destruction" was this: The topmost / outer diameter (not width) part of rotor started getting worn down / scratched first. It was hundreds of miles - maybe 400 or so and the pattern of the groove / etch then started slowly getting into the middle and eventually the inner part of rotor. Don't know if this detail is interesting / important. But the rotor was inside diameter was 80% untouched while the outside 20% was getting ground down for quite some time.


(more fun but unrelated to posted issue
someone tin snip cut thru the exhaust manifold heat shield and put a must be non OEM O2 sensor there. I will post that later. (see pics below)
wrong lug nut wrench - not even close to correct size.
Missing:
trunk plastic water shield.
engine splash guard
passenger side front fender inner plastic splash guard.
many, many plastic pop rivet fasteners to body panels.

And this is just what I've discovered so far in two months of ownership.

 

disconnected brake line. This is the parking brake cable?



disconnected brake line. This is the parking brake cable?



hack job - illegal I assume. O2 sensor was put into a hand cut out in the exhaust manifold heat shield. I am sure Honda Motor Co. don't work like this.



dust boot tore badly turning the piston in and out. There was a small(er) tear present when I removed the caliper.





the outside - it's much worse than it looks. Very grooved and uneven. It's gonzo.



Clean inside rotor - hard to see but it's very very good!



Clean inside rotor - hard to see but it's very very good!



smooth eh? I drove this, well, about 900 miles with the caliper and rotor squawking at me the whole time. Road trip without tools. Perfect.



shot. Ya think?



Upper pad is the outside pad. Inside still has full new amount of pad left.



dust boot tore badly turning the piston in and out. There was a small tear when I removed the caliper.

 

Worn outboard pad usually comes from caliper slide-pins being stuck. Caliper piston has plenty of force to apply the brake. But when you release the brake, the outboard pad keeps dragging & wears down.

You can clean & grease those slide pins when you take the caliper off to replace the dust boot. Also check the pads slide in the caliper bracket. Sometimes I've had to file a bit around where the pad backing plate engages the caliper bracket - they shouldn't be wedged tight in place.

One of your photos asks is this the handbrake? YES the handbrake cable hooks onto that stamped thing at the funny lobe visible in the top photo.

Looks like the O2 sensor is OK. Maybe the hack job was just to enlarge the hole and get the heat-shield off without removing the sensor itself. Or maybe to get clearance for a fat sensor socket??

 

Thanks Jim.
Good to hear about the 02 sensor. I had started to think maybe the mechanical monkeys had the wrong tool to use and chopped it larger to replace it (?)
Also, I've driven this from 125K to 128K mileage.
About 400 miles ago the CEL (Check engine light came on, not flashing, on steady).
I did not read the codes. The light went out about 60-100 miles later with at least 2 ignition re-starts.
That's why I started thinking about that O2 sensor again and was getting annoyed.

So... I guess since I've had it my right / passenger parking brake has been inoperable since it was not even hooked up.
That cable is super tight. I can't so far budge it more than a tiny amount (which was squeezing the rotor / hub to stop free spinning). Not quite sure if it's supposed to be that tight - doesn't seem right, and I'll have to figure out some trick to re-hook it back up as there is not enough play to hook it back as is.

I will do a more thorough disassemble of the caliper and inspect the slides next.
Since the piston is fairly easy to spin either way it should be ok, not seized and simply replacing the boot should be ok for that for now, yes?

 

Weird.

I took apart the 'bracket' from the caliper and took out the slide pins.
I would not say they are seized or particularly sticky. I took some of the lube off the end of the pin and re-coated the slides and put them back in. They move around - maybe a little more freely now after working them by hand a bit.

The caliper piston easily turns all the way in or out. With it turned all the way in, I was able to have clearance on the 'arm' of the parking brake and able to re attach that parking brake cable.

I still have to ask why. Why did that outer pad go to sh*t? while the inside one looks new.
I always like to find causes of the problem and I don't seem to have one. I don't want to have this happen again after installing new rotor and pads either.

Anyone have any thoughts?


I am about 100% sure the detached parking brake was a coincidence and cannot cause the brake pad to stick. But it is some coincidence that brake has the problem.

 

If the caliper slide pins were OK, then maybe the pads were not free to slide on the caliper bracket? The square tabs on either end will fit into the bracket but should be able to slide. I usually have to at least file off the paint & put some caliper grease on those points. When you release the brake pedal, the piston only retracts from it's side (inboard). The outboard pad has to be free to release away from the rotor, as well as the entire caliper sliding on those pins.

The handbrake cable might have been unhooked because it was corroded & stuck in it's housing?? Working grease into the cable housing & working it with the handbrake lever to loosen it up is a lot of effort - I'd replace the cable instead.

 

That's possible about the hand brake cable. But I think it was very sloppy shade tree mechanic BS. There's too much other evidence of hack work and sloppy mistakes on the car. This was not a car (recently anyway) taken care of by real professional mechanics or even someone who really loved their car.
The little shiny inserts that the pads sit in did have some gunk build up on them. I cleaned them by hand and with a rag. They're better now, but not flawlessly perfectly smooth. Close.
The outside pad popped right out during disassembly of the caliper whereas the inside pad took much more effort to remove.
But yes, I would think that the outside pad was not completely free to slide around in the pad insert thingees.
Could I put some moly grease in that area? That's the large tube of stuff I have on hand here.

 

I've used that black moly-disulfide grease there, also have used permatex anti-seize, either works OK. A little better is brake-caliper grease which I think is silicone-based and resists higher temperatures before hardening. The brake grease will also work a little better for the dust boot & slide pins (rubber parts).

I clean up those shiny slider spring things & put a bit of grease there. Of course be careful you don't get any grease on the friction surface of the pads or rotors.

Funny thing that the inboard pad was wedged tight & outer pad came out easier. Yet it was the outer pad that wore down...?? Gonna get new rotors? The outer surface looks trashed so you don't want to go down the same road again with new pads & garbage rotors. I think they look too far gone to resurface.

 

Make sure the caliper slide pins are in the right places - they are different.

Picture shows #25 the lower one has flat sides on the long part of the pin.

The upper one #27 has a little rubber grommet on the end. Make sure that hasn't fallen off & stuck down in the bottom of the hole. THAT would hold the caliper inboard causing the outboard pad to drag.

note: #9 & #13 are shown duplicated in the picture but they are NOT in the parts list. It's confusing but those are probably for a different year/model/whatever that happens to share the same picture.

 

Thanks for the info! I will check that out today.
I have a new rotor ready to go, need to get pads locally somewhere, and it looks like wait for a shipment of the piston dust seal.
If I cannot get that for another 2-5 days I may reassemble new rotor and pistons and drive it on non rainy days until I get the piston dust boot and install it.
I know each of the slide pins went back to the same spot, but I did not notice any small item nor did I pay attention to their orientation up or down if there's a difference so I will go check it all out as it's all still off the car.