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2015 Acadian Rear Outboard Brake Pad Wear

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New User

Jan 7, 2021, 3:20 PM

Post #1 of 6 (959 views)
2015 Acadian Rear Outboard Brake Pad Wear Sign In

I did a 4 wheel brake job 18,000 miles ago. OEM GM rotors and pads all around. 76,000 miles on the car now.

The right rear outboard pad has worn completely down. When I did the brakes the guide pins looked clean. I cleaned them and lubed them with white lithium brake grease before putting them back together. i did not use any lubricant on the slides.

I will check the caliper and pins again this time, but I think the issue is that the ears on the outer pad are not sliding as they should.

I think that I have the same problem with a 2012 Impala that I just finished. Outboard pad was extremely tight getting it into the slides. 75,000 miles on the Impala.

Not a lot of corrosion on either car. What do you recommend? Filing the slide slots in the caliper (slightly)? Filing the ears on the brake pads (slightly)? Using a small amount of lubricant on the stainless steel slides?

How easily should the pad slide?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 7, 2021, 4:28 PM

Post #2 of 6 (948 views)
Re: 2015 Acadian Rear Outboard Brake Pad Wear Sign In

Couple of many reasons:
White lithium grease isn't listed for brake use! Start over you've ruined rubber parts IMO. It has to be brake lube on label usually a Silicone product AYOR with anything else.

If rubber in pins or around they may not slide on sticky rubber well vs total release. The rubber bellows of brake piston are dust shields not water proof to inside if wet is your common driving scene those allow water in wreck that caliper but your observation is outer pad - not that yet.

Big other just did a couple (other models same idea) the dang pad metal was stamped metal left a seam that didn't belong where they fit in bracket and spindle if a whole piece impossible to install even.
So I extra scraped surfaces where metal of pads with touch and rub. Still a fight. Took pads out (bit ticked now) and filed them down where they are to slide till just right no problems on 8 wheels since.

I take a Q-Tip and lube the metal of the pads plus whole area they are too slide as they are used and when wear are slowly on a new spot. That proper grease better have at lease ceased all corrosion if not still there or when rotating tires see that and fix it again.
That IMO explain outer pads wearing too fast. If design knows it will anyway those would be thicker or thinner so as to wear out evenly,


Hammer Time
Ultimate Carjunky / Moderator
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Jan 7, 2021, 4:32 PM

Post #3 of 6 (946 views)
Re: 2015 Acadian Rear Outboard Brake Pad Wear Sign In

What you're describing sounds clearly like binding slides. Another possibility is the flex hose for that wheel restricted internally.

Make sure the caliper slides freely on the slides when everything is mounted up.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jan 7, 2021, 7:36 PM

Post #4 of 6 (928 views)
Re: 2015 Acadian Rear Outboard Brake Pad Wear Sign In

To add and seem Hammer Time is on the same page. Said there were a list of reasons, some more common.
Quote OP from top ">How easily should the pad slide? <" I think I know what you mean when just done may not now and then bugs me from light years ago find that if thought OK finish, drive the thing and they just do "set" upon a few stops. The Impala anyway rear wheels one at a time should coast when hoisted and spun by hand.

That flex hose issue (don't put a curse on me) hasn't happened in ages but really does. IDK always why but if you let caliper just hang and perhaps fall it's yanking on that it doesn't like that. I've hear some will pinch flex hoses IMO you just wrecked that one. It hydraulic hose don't mess too much them it's holding wild pressures plus must flex. Problem described is they can fail to let pressure in but like a REED valve inside makes them one way hose.
Test for that if you find a wheel that doesn't coast (not always drive wheels) is to loosen bleeder just enough to let some fluid out quickly then tighten up. If wheel goes free that's the hose doing that. IMO both go if so.
Two vehicles seem to do this on YOU (OP) the odds are it's YOU not all just mechanical or bad luck. Find out, you owe it to yourself and here asking bet HT and myself have seen most of this in person maybe don't admit, done it too and learned from it!


New User

Jan 19, 2021, 2:50 PM

Post #5 of 6 (881 views)
Re: 2015 Acadian Rear Outboard Brake Pad Wear Sign In

Thanks for the responses. I took the Acadia apart, and concluded that the problem is the pad was too tight in the slide. I took a file and gently filed the end, so that it slides freely in the slide. My guess is that I took off less than a millimeter.

In the last few years, I have only used GM replacement brake parts, so I was surprised when I had an issue.

Here is my theory: the backing plates appear to be powder coated, which I understand is thicker than paint. Maybe at some point they changed from paint to powder coating and didn't change the spec.

Anyway, I will take the Impala back apart and file the ears of the tight pad(s).

Again, thanks for the help.

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 19, 2021, 4:50 PM

Post #6 of 6 (868 views)
Re: 2015 Acadian Rear Outboard Brake Pad Wear Sign In

You found it, GREAT. Lots of that happens for years now + worse for a couple years. Impossible to fit without removing 1mm like you said.
Other to note: It's a nice feeling with having GM parts for a GM vehicle but not so fast. TMK GM doesn't make any of this stuff it's all farmed out so they just box and mark it. There is just as good or better in this case, the aftermarket.
The "Auto Makers" my whole life (long time sport) they farmed out something. Wiring, motors, shocks, always tires and on and on. None made light bulbs either huge by the untold zillions.
Hard part for you is knowing it or which parts to focus on OE real or I'll just say routine items known coming the aftermarket jumps all over that so do dealers!


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