# Rear disc brakes worn unevenly



## Tomko (Jun 1, 2013)

I'd like to help - but your post doesn't make sense to me. Could you express your observations in different words?


----------



## gt_cristian (Apr 7, 2012)

Hi Tomko,

My rear right brake disc is in bad shape, rusted, and the brake pads are almost finished. The rear left side looks great, I would say those pads look almost like new, same for the brake disc.

I have been using the car for 4 years, 50,000 miles, a lot of highway.

So I am thinking, something had to be causing most of the rear braking to take place on the right side, and very little on the left side. But I am not familiar what could cause this or how to troubleshoot this issue.

Thanks,
Cristian


----------



## gt_cristian (Apr 7, 2012)

[FONT=&quot]This is what I found from my research (in my care, this happens with the rear breakes):[/FONT]
[FONT=&quot]*
Both pads on one side thinner than pads on opposite side

*[/FONT]
[FONT=&quot]This is generally caused by a hydraulic problem, although it may also be caused by a sticky piston.

More often, the cause is a restriction in the brake hose on the opposite side.

The side with the premature wear may also have a brake hose with internal damage that acts like a check valve, preventing the release of the brake fluid.[/FONT]
[FONT=&quot]
It's also possible that there's a hydraulic restriction higher up the line than the brake hose on the side with the pad wear. For example, a faulty ABS modulator may not allow the release (return) of pressure on that side.[/FONT]
[FONT=&quot]
One other possibility is air in the hydraulic line on the side opposite the pad wear.[/FONT]


----------



## MP81 (Jul 20, 2015)

Sounds like a stuck caliper to me - though at such a low mileage/age, that's surprising. 

An easy way to tell is with a thermometer (one of the point and shoot IR ones would be perfect) after a drive. If the caliper is stuck, that rotor should be _significantly_ hotter. Like...a couple hundred degrees more.


----------



## ChevyGuy (Dec 13, 2014)

gt_cristian said:


> My rear right brake disc is in bad shape, rusted, and the brake pads are almost finished. The rear left side looks great, I would say those pads look almost like new, same for the brake disc.


This puzzles me. Rust tends to suggest lack of use - yet the pads are worn out. My guess is that the caliper on that side is stuck. It used to stick in a way that caused excessive wear, but now it's stuck in a position such that it no longer engages. 

Rear brakes tend to lead a very easy life. They'll last much longer than the front. At 50,000 miles, I don't think the left side is loafing - but the right side has been dragging.


----------



## Patman (May 7, 2011)

Sounds like a seized caliper on one side. I had the same problem but on the front. What I did and suggest for you to do is replace the pads and have the brake fluid flushed and bled. Far as I can tell on my at least on my car that fixed the problem. If it continues then look into replacing the caliper.


----------



## Robby (Mar 1, 2013)

Ug.....rear disc systems always seem to have issues like this.

My first thought is the caliper slide pins are corroded (with the outside chance of the caliper piston itself).
In the case of the pins, (slides) hydraulic pressure (brake application) can apply the brakes but pin corrosion prevents the caliper from fully releasing. This causes the affected side to wear the pads rapidly.
As the corrosion advances, the side with little or no binding, applies when the pedal is depressed and the bound side just goes for the ride.
This explains the rusted rotor on the high wear side.

Here in the salt belt, I find myself freeing/lubing bound caliper (and pad backing plate) slides every spring on my sons service vehicles that have rear disc systems.
A combination of road chemicals and little heat production (rear brakes only do about 10 to 20% of stopping power) are, imo, the culprits.

So, sometimes the piston itself does corrode in the bore but the vast majority are bound by the slide pins or the pads are bound in the carrier bracket.....always corrosion.

Last year I began a annual clean and lube maintenance on his equipment just to preserve rear pads and rotors. Prefer to replace brakes for normal wear, not created wear.

I have concluded that as we see more and more rear disc systems this will become a suggested service practice (clean/lube) every year or two.

Rob


----------



## ChevyGuy (Dec 13, 2014)

My dad had a thing against disk brakes. He said drum brakes were designed to prevent problems with contamination.


----------



## JRB'sOilburningCruze (Feb 25, 2015)

Couple of things I would do. First if you are concerned about the caliper being stuck, replace it or rebuild it. An entire caliper is not very expensive. A rebuild kit is even cheaper. It takes all of about 15 minutes to rebuild a caliper. Replace the flex line to the caliper. They can degrade on the inside and cause the caliper to hang. 

When you put it back together lube the caliper pins and I always lube the brake pad mounting hardware. If your new pads do not come with mounting hardware make sure you clean up the old ones before putting back together.


----------



## Robby (Mar 1, 2013)

ChevyGuy said:


> My dad had a thing against disk brakes. He said drum brakes were designed to prevent problems with contamination.


I don't know if they were designed with that intent......more of a result of the systems design.
I had a similar discussion like this on the Miata forum....a member was whining about the complexity of the rear drum brakes he had recently replaced. That turned into a 'what system has the most problems' discussion. Miata's are notorious for binding their rear caliper slides and most owners consider 'disassemble/clean/lube' part of their annual service routine.

The posters that did have daily drivers with rear drums were essentially unanimous in their reporting of no troubles, regardless of where they were operated.

Rob


----------



## NickD (Dec 10, 2011)

Torque plates on mind were very poorly plated, those things that hold the pads, those pad clips would trap road salt, expand and lock the pads. Not only in the rear discs, but the fronts as well. With the caliper guide pins, somebody must have just stuck those in about a 1/4" if at all. Cleaned those off and loaded them with silicone grease, even the boots, helps keep road salt out.

As well as those boots on the piston, last thing put on, I filled the boots with silicone, this helps keep out road salt, pistons are ceramic, but the calipers are iron, rust gets in there to keep the pistons from returning. Also painted the torque plates with anti-seize, the only thing I leaned over the years that works for awhile, tip of the pads that contact those clips also got a good coating of anti-seize, just there, not on the pads. See shops install new pads with a hammer, this is a job for your baby fingers. Also painted the calipers with anti-seize, as well as the hubs where the rotors fit on. Put together dry, raw steel, if you don't with road salt, can't even remove the tire let along the rotor.

If they would only add about 0.5% nickel to the iron, wouldn't be nearly the problem. Use to do this with sheet metal, 1948 was the last year for this, would get surface rust, but no rust through threw. But if they did this, no reason to buy a new vehicle, and today replacement parts, can only use the word, completely outrageous. Ha, even saw some of my stuff that cost us a buck to manufacture on the dealers shelf for 150 bucks.

Not only in automotive, but everywhere. After a long drive, have to get out ans stretch my old legs, at a gas station or rest area, do a quick walk around holding the back of my hand to each rotor or drum, downshift to slow down, if I feel excessive heat, know I have problems.

Like Robby, checking the brakes is always a spring time job. And the only people that do this job right, is us.


----------



## gt_cristian (Apr 7, 2012)

Hi guys,

So I took my car to a shop and they replaced all 4 discs and pads and flushed my brake fluid. They did not find any issues with that side that was rusted. The caliper works well according to them.


----------



## BrandoFisher117 (Mar 14, 2016)

I'm actually running into an issue with the rear disc brakes on the right side only. When I went for my oil change before Lordstown this year, I started hearing a scraping-like sound coming from the rear when stopping. After looking, I noticed that one of my rotors had looked like it had been scraped. After getting the oil change, I received the report from the dealership and they had documented that my rear right brake pad was at 3mm but all others were good. I had inquired about it, and they stated something about driving with the parking brake on (which I NEVER use). They also stated that there was some crystallization on the brake pad and the only thing that would get it that hot was to actually drive with the brake engaged. Now, I am under the impression that the parking brake engages both the left and right rear brakes, not just the right. 

To summarize, the dealership is telling me that I need to get a new caliper, pad, and rotor for the right rear. But they also state the caliper seems to be working fine. Thoughts?


----------



## Blasirl (Mar 31, 2015)

Do it yourself - easy & way cheaper.



If the last time they were off they were not put on on exactly right or the noise clips were not seated properly, that may have exacerbated the issue. About every three or four brake jobs I do end up with a bit of uneven wear on one side. I think usually when I'm in a hurry as it is either freezing, raining or right before work some one says - my brakes are making funny noises...


----------



## BrandoFisher117 (Mar 14, 2016)

Blasirl said:


> Do it yourself - easy & way cheaper.
> 
> 
> 
> If the last time they were off they were not put on on exactly right or the noise clips were not seated properly, that may have exacerbated the issue. About every three or four brake jobs I do end up with a bit of uneven wear on one side. I think usually when I'm in a hurry as it is either freezing, raining or right before work some one says - my brakes are making funny noises...


I'd love to do it myself. Unfortunately, time is a factor and I don't have much (if any free time) at all. I am currently in the process of purchasing my first house as well. 

A bit of wear is fine, but with the rear left side being 7mm+ and the rear right being >3mm, something just doesn't seem right. Along with the fact that my rotor shows what appears to be metal-on-metal.


----------



## Blasirl (Mar 31, 2015)

This is one of the last few things I usually do myself. It takes about the same amount of time that it would take to drop off and pickup my car along with finding a reputable shop.


----------



## mitchd123 (Jul 27, 2015)

For anyone still having this issue with uneven wear on the rear disk brakes, I've had this issue twice. It's looking to be the caliper pin that has the rubber, GM PN 13584090. The first time this happened the brakes on the rear passenger side were fine, but the driver's side wore down to the metal. (around 50k miles) I replaced both side, pads and rotors and made sure to clean out the caliper pins well, and lubricate them with the special disk brake caliper lubricant designed for high temperatures. 

Now I've had the issue now a second time (around 70k miles) The driver's rear pads are completely gone and again the passenger side is fine. Despite having lubricated the caliper pin, one of the caliper pins seems to be binding again. It's almost as if the rubber on the pin has expanded and is causing it to bind. Only one caliper pin has rubber. The one with rubber attaches to the low-frequency noise damper. As an experiment, I'm going to file down the rubber to provide additional clearance for the caliper lube. The caliper itself does not appear to be binding up anywhere. 

Also worth mentioning there appear to be two different rear rotors. Mine is 265mm, not 295mm.

Caliper pin with rubber: GM PN 13584090
Low-frequency noise damper: GM PN 13343688

Stock GM Pictures can be found here


----------



## boraz (Aug 29, 2013)

mitchd123 said:


> For anyone still having this issue with uneven wear on the rear disk brakes, I've had this issue twice. It's looking to be the caliper pin that has the rubber, GM PN 13584090. The first time this happened the brakes on the rear passenger side were fine, but the driver's side wore down to the metal. (around 50k miles) I replaced both side, pads and rotors and made sure to clean out the caliper pins well, and lubricate them with the special disk brake caliper lubricant designed for high temperatures.
> 
> Now I've had the issue now a second time (around 70k miles) The driver's rear pads are completely gone and again the passenger side is fine. Despite having lubricated the caliper pin, one of the caliper pins seems to be binding again. It's almost as if the rubber on the pin has expanded and is causing it to bind. Only one caliper pin has rubber. The one with rubber attaches to the low-frequency noise damper. As an experiment, I'm going to file down the rubber to provide additional clearance for the caliper lube. The caliper itself does not appear to be binding up anywhere.
> 
> ...


2014-15 cruze diesel uses the 292mm rear rotors


----------

