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Discussion Starter · #1 ·
So today I removed the rear left tire, to run the wires for the tire pressure module. Turned out I didn't have the rear module, only the front ones and unfortunately they are not compatible, however now the wires are there and will be a simple swap once I get the correct module.

I also noticed that my van now has a brake problem on the rear left side. The inner pad (piston side) is making barely any contact with the rotor when braking, while the outer side is doing all the braking. I noticed this by looking around the splash shield, and I saw about an inch of area from the outer edge inwards that had rust on it.
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I didn't check the fronts but I know the rear right is not doing this which I checked right away. I removed the caliper and checked the sliders move freely, which they did. Checked the pads moved freely in the bracket, re-lubricated the sides where the pads slide onto the bracket, checked the E-brake was working as intended and fully releasing.

After I re-assembled it and a short drive later, there was still almost no contact between the inner pad and the rotor. I'm currently unsure what I'm going to do about this problem.

I'm getting pretty fed up with these new brakes, this is now the 4'th time I've had to go back and fix something, first 2 were the paint on the front pads made it tight in the brackets causing slightly uneven wear, 3'rd time was a cracked rotor, and now this. Not to mention these Canadian tire pads are extremely dusty.
 

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One of the shims is jamming the pad. Remove one of the shims. It will be a bit noisy when applying the brakes, but ....

OR file/grind off some material from the bad backing plate (ends)

You can buy the caliper bracket from rockauto. Handy to have.
 
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The piston is pushing against the inboard pad, the pad is fetched up due to heat, tight fit, or both, the caliper is hauling the outside pad against the rotor (like it should). That's the way I see it. :)
Check the piston for damage too. Is the inboard wearing the same, front to rear?
 
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I was just looking at some old shims for the front of my 2016, one set had the springy thing to the side, one set didn't. I believe the ones without came with a Raybestos coated caliber and bracket combo from Bumper to Bumper. I needed the bracket.

Might be good to snip those off, only used for assembly, I think.

Something causes the pads to bind in the brackets, or something, when only about 1/3 worn on my fronts (just replaced them). The rotors get messed up for some reason, likely the ceramic pads. I can't fathom what's going on there. Things seem to be working fine.

The backs wore great for 141,000 km/5 years, with nil maintenance. Pads wore thin. Nothing to figure out there.

These brakes need 6 month to 12 month servicing, I 'm thinking, like LongVoyager does.

OE fronts lasted 3 years/83,800 km (stuck slider pin, one worn out pad, rotor faces great one side, corroded/delaminating the other side), replacements lasted 3 years/80,050 km (pads less than half worn, even wear, sliders working, rotor faces great one side, corroded/delaminating the other side. I could have gotten another 3,000 to 4,000 km or so out of them as there was no vibration yet.

So much for the heavy light duty brakes. :)
 
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Discussion Starter · #5 ·
The piston is pushing against the inboard pad, the pad is fetched up due to heat, tight fit, or both, the caliper is hauling the outside pad against the rotor (like it should). That's the way I see it. :)
Check the piston for damage too. Is the inboard wearing the same, front to rear?
I didn't fully remove the caliper, I slid the caliper almost off and tried to move the pad, I recall the inner and outer both being able to move slightly with my hand. I'm going to remove it fully and re check the pads, will likely end up removing one of the 2 caliper bracket tins. The other side is working just fin both inner and outer.

From a glance, all the rotors are shiny and normal looking on both sides, except the rear left which clearly has rust buildup on the contact surface. The plan was to service them once a year, right before the winter when I swap all season tires to winter tires.
 

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Discussion Starter · #6 ·
Took the caliper off, both pads moved freely between the bracket and the pad. Removed both sliders, they came out and went back in without any problems, plenty of grease no moisture. Removed the 2 upper caliper bracket tins on both the piston side and outside of the caliper bracket, slid the pads back on, swapped the pads and went for a drive. No improvement, rust hadn't been touched with the pad.

Everything works just as I'd expect it to, the piston moves freely, the E-brake releases perfectly, everything is installed exactly as it should be and torqued to spec minus now the 2 upper tins. The only thing I can see being wrong is the piston presses against this circular dot in the brake pad, maybe it doesn't slide into the groove of the piston and then applies uneven pressure? But at the same time looking at the piston imprint on the pad bracket, looks like it was fully seated. I have no clue, I do know it was working just 2 months ago, even if I did almost 3K kilometers since then.
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You need to align the piston so the groove lines up with the nub on the pad.
 
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Discussion Starter · #8 ·
After aligning the piston with the groove and braking/verifying with the wheel off, went for a drive and still the same issue present.

I then sanded the groove down and re-installed, and again no difference. I understand what is happening, but don't understand why it's happening.
 

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Discussion Starter · #10 ·
Maybe turn the piston out a bit to move it closer to the pad?
I'll give it a try, I did turn it 3/4 of a turn to give some space when re-installing it, and I did need to pump it once to get pressure back.

I'm still very confused by what's going on, something isn't right somewhere. Maybe I destroyed the piston while it wasn't aligned with the dot, but the dot is now sanded completely flat and the piston makes full contact with the inboard pad.
 

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Ceramic pads likely scoured off (delaminated) the face of the rotor, there's no face left on part of it, just a rusted surface that isn't going to smooth out. It's pitted, most likely. You can try an 80 grit flap sanding disk and angle grinder on it to see if it will smooth out but I don't think so. Talk with Bumper to Bumper about a rotor replacement.
 
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I had a similar issue with my 08 van. Replacing the rear calipers fixed the issue. Some areas of the rotor looked normal while others were rusted like yours.

Also, it might just be the picture but it looks like that rotor is pretty shiny. The front side of the rotor (2nd pic) seems like there are uneven wear marks.

Try replacing the caliper and see if it helps. Not much else it could be since you checked almost everything.
 

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Just thought, if this is a junk yard caliber/bracket, it could be bent. Had a distorted remanufactured caliper/bracket for a 2004 Acura TSX once (accident?). I caught the problem before installation, luckily.
 
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Discussion Starter · #14 ·
I had a similar issue with my 08 van. Replacing the rear calipers fixed the issue. Some areas of the rotor looked normal while others were rusted like yours.

Also, it might just be the picture but it looks like that rotor is pretty shiny. The front side of the rotor (2nd pic) seems like there are uneven wear marks.

Try replacing the caliper and see if it helps. Not much else it could be since you checked almost everything.
They just hit a point and then had random uneven pressure? Mine were working just fine before, the only reason I found out about this issue was I saw what seemed to be uneven marks on the rotor and a blue rotor (overheating), and after looking further i found the inner pad making no contact on half the pad.

Yeah the inner pad was applying pressure on the bottom and I assume the caliper or bracket twisted as a result of the pressure and caused a lot greater pressure on the upper portion for the outer pad. The pads are slightly melted, so I'm gonna need new pads.
Ceramic pads likely scoured off the face of the rotor, there's no face left on part of it, just a rusted surface that isn't going to smooth out. It's pitted, most likely. You can try an 80 grit flap sanding disk and angle grinder on it to see if it will smooth out but I don't think so. Talk with Bumper to Bumper about a rotor replacement.
I've already replaced that exact rotor, once due to a literal crack in the center (if you remember). The guy would give me a weird look! With the rust, definitely been a longer issue, but I do recall the caliper working as intended both before and after I replaced the rotor.

Just thought, if this is a junk yard caliber/bracket, it could be bent. Had a distorted remanufactured caliper/bracket for a 2004 Acura TSX once (acxcident?). I caught the problem before installation
I'm likely just gonna call it and replace both rear calipers, they are from pick and pull after all, unless I find something else but with brake parts there's not a whole lot that can be wrong.
 

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Michalb, I don’t remember exactly why the rotor was rusty in some spots and not the others. This occurred about two years ago, when I was not as knowledgeable.

I had replaced the rotors and pads (including new hardware and cleaning up the contact points) and after a few weeks I noticed the uneven wear (rust). I figured that calipers could be the only culprit left. Sure enough, it was the calipers.

My parking brake was also iffy (kinda worked but not strong enough for hills). Changing the calipers fixed that issue as well. I bought new calipers from eBay, two rear calipers for $90-100 USD total. The price might’ve give up now but it was worth it. The calipers still work after two years.
 

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Couple of points for thought:

This happens alot on many cars, very common with pistons pushing only on one side of the rotor - many will be invisible until looking under the car at the rotor 9and that side is covered by the dust shield..

All things have to move freely to prevent this from happening. Pads in the caliper, caliper on the pins, piston in the caliper. No matter what you do (or how good your service), you may not have control- if debris or rust gets into those components, it will happen again.

Because of the balance aspect of brakes - they are best to do in pairs, either the fronts together or the rears.
Irregular wear pattern, does not mean they don't work-- obviously the brakes work. There is no rush or emergency, unless the pads are down to limits. You have the option of waiting until you really have to service the brakes, and do them as a pair, or all 4 at that point. If the pads are still plenty, I wait until it's time.

.
 

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Rotor surfaces delaminate in these days of ceramic pads, like never before with semi-metallic pads. Ceramic is bad or bad ceramic is bad.
Ceramic brake pads can create excessive rotor wear if rotors are not the same high quality as the brake pads themselves.
I have never seen a rotor wear out, become dangerously thin. They basically rust (surface scale) and the wear surface falls apart instead. But, ceramic pads are harder on rotors.

The gap that's observed, on the OP's brake pads, could be where the wear surface has delaminated and disappeared. A rust scale is formed and then it separates. That's about 1/32" thick. Maybe the gap is larger, which would mean a twist in the pad.
 

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Bridgestone says:
Also, since both ceramic and copper can’t absorb as much heat as other types of materials, more of the heat generated by braking will pass through the brake pads and into the rest of the braking system. This can cause more wear and tear on other braking components. Lastly, ceramic brake pads aren’t considered the best choice for extreme driving conditions. If you’re facing very cold weather or an upcoming race and you’re choosing between ceramic vs. semi metallic brake pads, you’ll want to go with metallic.
Ceramic vs. Metallic Brake Pads, What's the Difference?
"Rest of the braking system" = rotors IMO.

All Rotors says:
Type of Brake Pads and Rotors. Harder (long lasting) ceramic pads cause more wear to the rotor in comparison to softer semi-metallic pads.
Interesting Raybestos Video. Check out 1:25:

Are ceramic pads a hyped up, oversold product? I think so. Just ask your rotors. :)
 
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If ceramics keep the wheels cleaner at the expense of some rotor life, that's fine with me.
 

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How are you verifying pistons movement? If it’s only by trying to compress it then it may not show the problem. Have someone press the brake pedal and watch that piston move.

Also, if any of you are in the GTA area, PM me, I have a very good supplier that supplies local mechanics, but will also sell to regular customers. He’s got really reasonable prices and I was happy with the parts I bought from him, particularly brake pads and rotors.
 
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