Rapid Rear Brake Pad Wear

[NMBurb02]

This is for my 2002 Suburban. Here's a bit of history:

5/17/2012, 117,250 miles - Purchased vehicle.
5/5/2014, 135,814 miles - Rear brake pads replaced by a local brake and alignment specialty shop due to cracking of friction material even though there was plenty of material left. New pads were Centric Posi-Quiet Ceramic with a new hardware kit. OE friction material is ceramic. Rotors were re-surfaced at this time and brake fluid was exchanged.
9/2/2015, 154,128 miles (16 mo/18,314 mi on pads) - Rear brake pads shot with metal-on-metal contact on driver side. Pads replaced with new Centric Posi-Quiet Ceramic under warranty by the original shop and new Centric C-TEK standard rotors installed.
2/16/2016, 159,213 miles - New rear axle shafts, diff bearings, and seals installed. Brakes had to be disassembled and reassembled in the process. No mention by the shop of unusual pad wear.
3/5/2017, 175,264 miles (18 mo/21,136 mi on pads/rotors) - While rotating the tires I noticed that the rear brake pads were looking a little thin. I pulled the pads and they measured 4 mm outside driver side, 2.5 mm inside driver side, 6 mm outside passenger side, 5-6 mm inside passenger side (thinner on lower part of pad).

I can't find the original thickness of the friction material on these Centric pads but the pad thickness is 16.3 mm and the backing looks to be about 1/3 of that thickness so the friction material should have been about 10-11 mm thick when new. Eating through a full set in less than 20k miles and 1/2 or more of another set in 21k miles on rear brakes seems pretty extreme. Especially considering that the fronts were replaced about the same time as the shop's original 5/5/2014/135k mile service and have therefore been in service about 34 months/40k miles and are looking great.

What could be going on here?
Did the shop screw something up when replacing the pads both times?
Are these pads just bad? They are ceramic and Centric touts the Posi-Quiet 105 series as "Longest wearing most advanced material available."
Are the calipers sticking? I don't think it is calipers sticking because they were easy to recess when inspecting the pads today and I would think that the shop would have pointed that out when the first set were eaten through in order to get a few more bucks out of me. But what do I know?
Bad slide pins? I did check the slide pins while I had them out today; they moved freely, came out easily, and were greased but I went ahead and cleaned and re-greased them before re-installing. They had what looked like a little bit of surface corrosion but no pitting or real surface damage.

What do I need to do to further troubleshoot?

Edit: I have moved more than 400 miles away from that shop so I cannot take it back to them to check out.

 

[Tomioka]

Looking close at the service history they hadn't bothered to replace the rear brake calipers and lines after seeing premature rear pad wear? The brake calipers uses phenolic pistons which can stick and fail from age and the brake lines can act as a check valve acting as a seized caliper as they age and fail internally.

Sticking rear disc brakes are common in these trucks.

 

[901Memphis]

Sounds like normal wear for hard driving on that tank.

You made no mention of how you drive or the roads. Do you have a lot of hills?

 

[NMBurb02]

Originally Posted By: 901Memphis
Sounds like normal wear for hard driving on that tank.

You made no mention of how you drive or the roads. Do you have a lot of hills?

It isn't driven hard. A little around town driving and 160 mile round trips every two to three weeks with 800+ round trip road trips to visit family every few months. Some hills but nothing crazy and no hard braking downhill. No real hard braking at all and definitely not in a way that would wear the rear brakes much faster than the fronts.

 

[NibbanaBanana]

I have had this problem and it was due to the pads being too tight in the slide ways. The slide ways must have been overly tight from the factory. The original pads were so tight I had to hammer them out. I filed the new pads to fit the slide ways perfectly, so I could move them in and out easily by hand but there was no play.

 

[NMBurb02]

Originally Posted By: Kibitoshin
Looking close at the service history they hadn't bothered to replace the rear brake calipers and lines after seeing premature rear pad wear? The brake calipers uses phenolic pistons which can stick and fail from age and the brake lines can act as a check valve acting as a seized caliper as they age and fail internally.

Sticking rear disc brakes are common in these trucks.

Is there any way to further troubleshoot this before dropping money and spending time to replace both rear calipers?

 

[NMBurb02]

Originally Posted By: NibbanaBanana
I have had this problem and it was due to the pads being too tight in the slide ways. The slide ways must have been overly tight from the factory. The original pads were so tight I had to hammer them out. I filed the new pads to fit the slide ways perfectly, so I could move them in and out easily by hand but there was no play.

That's not the case here because all four pads took no effort to remove from the slide ways.

 

[53' Stude]

I'm a little out of it today so pardon my thought; does the suburban have a proportioning valve by chance?

 

[JHZR2]

Sounds like a rear caliper isnt sliding well. Remove and clean/lube.

 

[901Memphis]

I used to know a guy that loaded up an astrovan pretty full doing carpet business driving like a maniac and some hills in the area and he changed his brakes monthly

 

[Tomioka]

Originally Posted By: NMBurb02
Originally Posted By: Kibitoshin
Looking close at the service history they hadn't bothered to replace the rear brake calipers and lines after seeing premature rear pad wear? The brake calipers uses phenolic pistons which can stick and fail from age and the brake lines can act as a check valve acting as a seized caliper as they age and fail internally.

Sticking rear disc brakes are common in these trucks.

Is there any way to further troubleshoot this before dropping money and spending time to replace both rear calipers?


For this one I'd chalk it due to age considering the mileage on the truck. Like I said it's an extremely common issue and there are tons of pics of the rear brake rotor being worn to nothing all over the internet for these trucks. If the sliding pin bores in the caliper bracket aren't seized or corroded I would buy the caliper only since the caliper to axle bolts are extremely hard to remove.

 

[Rand]

Sounds like they might not be releasing all the way are both sides the same wear?
You could check the brake temps after long trips to see if one side is much hotter than the other.. but if they are both worn the same...hmm. How much roadsalt do they use in UT. Usually around here 2-3 winters and they start getting funky and need cleaned up.

Not familiar with this vehicle.
Does the vehicle have EBD- electronic brakeforce distribution?
I know on later vehicles it can cause the rears to wear considerably faster than the fronts.

 

[clinebarger]

I'm not saying you don't have other issues like sticking caliper pistons or degraded hoses as it is very possible on a 15 year old vehicle.

Use OE GM pads, https://www.amazon.com/ACDelco-171-659-O...Type=automotive

ALL GMT-800 trucks & SUV's with rear disc brakes wear the rear faster than the front, I've seen stranger things than the incorrect friction material causing accelerated wear, I do not believe the OE pads are ceramic.

 

[spk2000]

Those pads are ceramic/kevlar from Akebono and should wear well unless the caliper is seized in some manner.

 

[mehullica]

Buy a brake pressure gauge from Amazon for about $50. It screws into the bleeder valve port & you'll know if you have a hydraulic or mechanical problem right away.

 

[pdxglocker9mm]

Pretty normal really
Gmt 800 front brakes are awesome. Wear like iron quiet and dont really warp. If you did not get over 100k on the front you had corrosion issues. I have seen many with over 135k and factory pads and they still had plenty left.
The rears took all the abuse. Not uncommon to replace every 25-50 thousand miles with most normal drivers going thru a set in 35-45. This was with oem materials. Cheaper materials could wear faster.
You could certainly go thru 3-4 sets in the rear vs one set in the front.
If the wear is even, and the inboard is simular to outboard pad keep driving.
My experience was as a ase/gm certified tech at a buick gmc dealer.
In portland oregon.

 

[silveravant]

Why not jack up the rear and see if the brakes are dragging. Try hot and cold. I'm not sure how the emergency brakes work, but if not separate does it always release completely? Does one or both seem hot after driving?

 

[nascarnation]

I believe they have the rear brakes doing more work to minimize front end dive in normal driving.
With ABS and Stabilitrack, there's no problem with locking up.

FWIW rebuilt calipers are so cheap that if there's any question when retracting your pistons, just replace them. I've always had good luck with Akebono pads, Kentucky's finest.