[drewbabich]

So I'm doing my rear disc brakes and one of the new pads does not slide freely in the caliper mounting bracket that holds the pads. The other pad slides fine in the caliper bracket. The one that does not slide does go into the right position, but once its there I can't slide it down its 'travel channel of the slide clip' or what ever you'd call it. Its just pretty much locked in place in the slide clip. I did spray the bracket with brake cleaner and scrubbed them. I can tap the brake pad down the travel channel with a hammer, but its real tight.

(I think its the inside pad, but not positivea till I go back and look at it.)

Is that normal or should both pads slide freely in the slide clip.

The slide clips look good, but reason for removal is I noticed something was up with my brakes as the outside of the rotor was showing a lot of rust and the outside pad was not making contact with the rotor.

The inside pad was worn out more at the bottom of the pad (just barely down to the metal). The top of the pad was about the thickness of a nickel or two.

The car has 170,000 miles and the contact surface of the piston was pretty rusted so I sanded it flush again.

I got new pads and rotors, but don't want to throw it all together if its not going to operate perfectly.

The caliper appears to be operating properly when I compress it with C-clamp (goes in smoothly) then push it out by pressing the brakes.

 

[subiesailor]

The pins are known for getting mucked up and causing this. Clean up the pin if you can't get it cleaned up might be time for a new pin

 

[1 Lucky Texan]

doesn't sound normal. they should move around a little, not a huge amount unless you run without the spring clips (some people do on some cars/calipers)

I have read of people who get new pads and have felt the need to grind/file down the backing plate on the new pads' 'ears' or tabs, w'ever - dunno if there's just some extra paint or a burr from manufacturing , ?????

If you swap pads, is it always the inner position on that side? or is there a problem with that pad? (you can ignore the 'squealer' for this test, just see where the problem is)

maybe a clip is bent or, as mentioned something wrong with a slide pin or some other damage.

 

[drewbabich]

When swapping different pads around

When swapping different pads around its still tight on the inside side of the bracket. So its the bracket or shims that are causing the tightness, not the pads. The ears on all the pads are all the same. So no matter the pad, the outside position will slide, but the inside will be tight, so its not really related to the pins....

But thats a good point. I don't understand how the rear calipers work all that well. The pins appear to be where the bolts go into. (the nuts extrude from the rubber accordian thing. The nuts spin, but they do not slide in and out laterally at all. I would think that they are supposed to to compensate for pistion going in and out.)

 

[subiesailor]

Did the old pads have uneven wear? More pad material left than the rear pads?

 

[subiesailor]

Oddly enough I just replaced pads on my a family members 2006 Civic. The front inside pads were not only worn more but were not worn square either. Both sides were the same all the brake gear was clean nearly new looking zero rust etc. My take on it is that its a slight flaw in the actual calipers Honda put on the civics where the rear pad is not held square causing the added wear and the non square wear on the pad its self.

Slightly different set up than the Subaru no pins - pretty basic caliper though the Civic weighs like nothing compared to most cars LOL

 

[drewbabich]

Yes the left inside pad had uneven wear. It was worn to the metal at the bottom and about the thickness of a a nickle and a half up top. The outside pad was even at about two nickel thickness

 

[subiesailor]

Yes the left inside pad had uneven wear. It was worn to the metal at the bottom and about the thickness of a a nickle and a half up top. The outside pad was even at about two nickel thickness

Hmm

Haven't see this on the two Subarus we've had. Are the pads stock pads or aftermarket pads?
Rust on the back side of the pad could have caused the original pads to rest crooked and caused the uneven wear also.

The rear pads generally move with the piston as long as they are not binding up on the slide pins due to slide pin rust or damage they should be OK. Keep in mind the boot on the piston needs to be checked you want to make sure its intact and not damaged etc. A bad boot on the piston can contribute to the piston not retracting / relaxing when your off the brakes etc.

 

[drewbabich]

stock. Say subaru on them even. Not sure if they are original, but maybe. Car has all highway miles.

 

[1 Lucky Texan]

seems like the face of the piston is not seated squarely or there is debris/uneveness/non-coplanarity somewhere.

did the new pad set come with new clips and shims?

 

[drewbabich]

No I got the cheapest pads from advance. The silver ones for 23 billz. They did not come with new clips.


The face of the piston was definitely not seated squarely. The top half of it that wasn't making contact had a lot of uneven rust on it. I sanded it all down. It was only making contact on the bottom point of the piston face, hence the bottom of the pad made more contact and wore out.

I was thinking about taking my grinder to just barely remove some of the material from the ears on the pad on the side that is tight.

I wonder if my bracket rusted or something and thats why it got tight on that one side. The side that is tight is the side that had uneven pad that was worn to the metal at the bottom with about 1/4 inch of pad left at the top.

 

[CNY_Dave]

I have had to hit many subaru pads with the belt sander/file to get them to slide properly, this being after removing the bracket and thoroughly wire-brushing it to bare metal, and thoroughly hand-cleaning the shims.

The die that stamps out the pad backing plate gets a bit old and the material smears down the edge instead of making a nice clean square break.

I assume genuine subaru pads do not require this treatment.

 

[1 Lucky Texan]

sounds like you have a good chance at helping the situation but, it's may be difficult to know which came first, the rust or the pad dragging on one end allowing the rust to develop.

If it's at all possible, could you take those cheap pads back and get some 'daily driver' or OEM equivalent pads? Mid-priced? (name brand semi-metallic, or Centric Posi-Quiet Ceramic?) My experience with cheap pads was terrifying.

 

[drewbabich]

Lesson learned.

I got the rear brakes all together. My one slide pin that has the rubber gasket on it was seized. It would spin, but not move in and out. That is the main cause of the lack of coplanarity is my theroy.

I would of liked to have upgraded to better pads after this experience, but i don't think it was manufacaturing defect since the pad fits fine on the inside side of the bracket, but none fit ok on the outside.

So I grinded down the ears a little and the pad slides great. I bought a new 'pin and bolt' kit for 9 bucks and regreased everything.

I removed the clips and wire brushed all the build of crud off them and the brackets (there was a bunch, but it still fit too tight to slide before grinding)

Now on the initial test drive the pads are making contact with the outside rotor when they were not before. Buuuuut then are only making contact on the outer have diameter of the contact area of the rotor(ie the outside diameter inch is contacting, but the inside diameter inch is still showing surface rust on the rotor.) I figure I just need to wear the pad down some and it will be making complete contact.

 

[1 Lucky Texan]

yeah, if the 'stickiness' with the old pad/caliper interface existed for a long time, the rotor's surfaces may slightly be conical instead of parallel now.

from what I've read, the rear brakes are only responsible for around 30% of braking so, it may not be an issue waiting for the new pads to 'wear in'.