Rear brakes lasting 22k miles????

[Chuck FB]

That certainly seems very odd to me  as well, yes if there is little to no resistance on two pistons I can see where one could easily be a little easier moving and would pop out with little fluid pressure and the other piston take ever so slightly more pressure to extend. 

 

So when you pulled the caliper off and were inspecting the sliding pins for not binding and the pads for not hanging up etc on their bracket assembly, are you saying that one of the pistons appeared like it had never extended out during your initial testing/bedding in of the brakes and was still pushed into the caliper fully. I am not sure so would just be guessing that if lets say too much force was applied to a piston to retract it before fitting the new pads, if it somehow had a way of binding up internally in the caliper. Just thinking out loud mind you, but certainly doesn't seem to make sense that a piston under pressure would stay retracted unless there is an issue inside that caliper. I don't know what it is built like internally in the caliper, if its designed with a small passageway between the two pistons and that some junk is inside the caliper blocking off the flow to the one piston. Again just thoughts without knowing the facts of how they are built and what weird symptoms they can have. 

[AbzDad]

With no resistance on either piston, one piston will extend out and the other one does move. I can put a clamp on the one that does extend and the other one will extend. So I know that both piston move freely and are not seized. Both pistons can be retracted easily.

 

What I don't know is if both pistons, under resistance, extend and retract equally. It seemed like only one one piston was retracting and causing the pads to drag at one end.

 

Pins were good. I cleaned and lubed them when I did the brakes. All new clips, which I lubed as well. 

[Chuck FB]

1 hour ago, AbzDad said:

With no resistance on either piston, one piston will extend out and the other one does move. I can put a clamp on the one that does extend and the other one will extend. So I know that both piston move freely and are not seized. Both pistons can be retracted easily.

 

What I don't know is if both pistons, under resistance, extend and retract equally. It seemed like only one one piston was retracting and causing the pads to drag at one end.

 

Pins were good. I cleaned and lubed them when I did the brakes. All new clips, which I lubed as well. 

 

As far as the various tests you did, yes it sounds like its all functioning but I see where your coming from in wondering what was going on with it before you took things apart again. Like you said, once you reassembled it and tested it again, temp wise anyway things seem to be making sense now. So the question remains, if for some reason that one piston was having an issue sticking and not relaxing as its not like the pistons exactly retract much at all but just enough so there is no pressure on the backside of the pad and therefore no pressure pulling the other side of the caliper into its side of the rotor. Probably for now is keep an eye on it, check its temp compared to the other side and hope that it keeps working ok as it is now. If it all goes sideways though then its more than likely time to replace that caliper. 

 

I do have to wonder if any of this issue goes back to the alarming look of the park brake shoes and if there is any chance moisture/rust found its way past a caliper piston boot. I don't know what those pistons are made out of, these days there tents to be a lot of those ( I will call it plastic but its really Phenolic ) non metallic pistons on some vehicles but I have no idea what an HD truck uses but you may have figured that out as you were working on it. That is the problem with any rust producing crap  on the road, even a bit of it can reek havoc and still blows me away as to how fast that park brake fell completely apart on a vehicle hardly driven on winter roads. 

[Chuck FB]

On 12/22/2025 at 3:25 PM, newdude said:

Looks about right for a salt state.  We do them here in NY all the time. 

 

Gotta open everything up once a year and clean and lubricate everything.  

 

Also something to consider with high rear brake wear on these is your tongue weight and trailer gain settings.  We've seen trucks that drive non stop that eat rear brakes with heavy trailers.  

 

On the topic of working on the rear brakes on the HD trucks, is there a reason or even a method to put the system into "brake service mode" like the half tons have due to their park brake integrated into the caliper itself that has to screw back to allow the piston to be pushed in to install new pads. I believe this gentleman in this instance did nothing in that regard when replacing the park brake shoes and just want to clarify if anything is required either by the vehicles system or requiring a dealer scan tool ?. 

[Another JR]

1 hour ago, Chuck FB said:

Deleted 

Edited January 15 by Another JR
Error

[newdude]

2 hours ago, Chuck FB said:

 

On the topic of working on the rear brakes on the HD trucks, is there a reason or even a method to put the system into "brake service mode" like the half tons have due to their park brake integrated into the caliper itself that has to screw back to allow the piston to be pushed in to install new pads. I believe this gentleman in this instance did nothing in that regard when replacing the park brake shoes and just want to clarify if anything is required either by the vehicles system or requiring a dealer scan tool ?. 

 

 

Parking brake is not a part of the caliper on the HDs.  1/2 tons the parking brake is integrated into the caliper, hence placing them in service mode.  

[Chuck FB]

13 minutes ago, Another JR said:

 

 

I caught a bit of what you said in your post and yes, the half ton uses the actual brake pads to also work as the park brake. The HD trucks using a totally independent system to apply the flimsy brake shoes on the inside drum surface of the brake rotor. I was just not sure if there was still some reason for the HD to be put into a service mode as searching online gets all sorts of comments about claiming it was required, so just getting a lot of conflicting information and want to hear from a tech to know the definitive answer. 

 

Being in an area that uses salt etc on the roads, I can see where its looking like according to this thread that I will have all sorts of fun with the parking brake shoes failing very quickly and having to be pulling the rotors off just to check to make sure what condition they are in. what a pain. Looks like they sell them in sets of two and with minimal hardware so from what I am seeing for prices through a local supplier and they may even be charging dealer price, two sets of shoes and a spring and adjuster hardware kit looks to be about 500.00, one aftermarket rotor 400.00, one set of genuine GM pads for one axle 400.00. Might be able to get some items cheaper if low line rotors and Napa pads but those park brake pads I have to wonder if anyone aftermarket even makes them. Mind you calipers don't last that long either in this environment as they want to seize up or go to bleed the brakes and the bleed screw twists off. Disc brakes are very costly to maintain in a corrosive environment as drum brakes are way better typically, not perfect either but way better. 

 

Definitely with the half tons I came across various comments of having screwed up a caliper by doing the wrong thing by trying to press the piston in when it was not set into service mode to touching the park button with the caliper unbolted and puking the guts out of it because of the park system they use and just not doing the right things due to not understanding how they function. 

[Chuck FB]

44 minutes ago, newdude said:

 

 

Parking brake is not a part of the caliper on the HDs.  1/2 tons the parking brake is integrated into the caliper, hence placing them in service mode.  

 

I must not have explained that part well enough to bring it across that I do realize they are very different on the 1/2 tons.

 

Its the HD trucks that I just wanted to clarify that they are not required or that there is not even such a function as a service mode for the actuator that engages the stand alone park brake shoes. Another words is there nothing that has to be done to replace the park brake shoes aside from removing the calipers so the rotor/drum can be slid off to inspect or replace the park brake shoes ? 

 

 

Edited January 15 by Chuck FB

[newdude]

9 hours ago, Chuck FB said:

 

I must not have explained that part well enough to bring it across that I do realize they are very different on the 1/2 tons.

 

Its the HD trucks that I just wanted to clarify that they are not required or that there is not even such a function as a service mode for the actuator that engages the stand alone park brake shoes. Another words is there nothing that has to be done to replace the park brake shoes aside from removing the calipers so the rotor/drum can be slid off to inspect or replace the park brake shoes ? 

 

 

 

 

No service mode but there is a calibration required when replacing the shoes.  Can only be performed with a scan tool.  

[Pryme]

My poverty edition has received the baby treatment so far and based on current numbers , the brakes should last the life of the truck lol. Around 95% still at almost 3.5yrs. 

[Another JR]

10 hours ago, Chuck FB said:

 

I caught a bit of what you said in your post and yes, the half ton uses the actual brake pads to also work as the park brake. The HD trucks using a totally independent system to apply the flimsy brake shoes on the inside drum surface of the brake rotor. I was just not sure if there was still some reason for the HD to be put into a service mode as searching online gets all sorts of comments about claiming it was required, so just getting a lot of conflicting information and want to hear from a tech to know the definitive answer. 

 

Being in an area that uses salt etc on the roads, I can see where its looking like according to this thread that I will have all sorts of fun with the parking brake shoes failing very quickly and having to be pulling the rotors off just to check to make sure what condition they are in. what a pain. Looks like they sell them in sets of two and with minimal hardware so from what I am seeing for prices through a local supplier and they may even be charging dealer price, two sets of shoes and a spring and adjuster hardware kit looks to be about 500.00, one aftermarket rotor 400.00, one set of genuine GM pads for one axle 400.00. Might be able to get some items cheaper if low line rotors and Napa pads but those park brake pads I have to wonder if anyone aftermarket even makes them. Mind you calipers don't last that long either in this environment as they want to seize up or go to bleed the brakes and the bleed screw twists off. Disc brakes are very costly to maintain in a corrosive environment as drum brakes are way better typically, not perfect either but way better. 

 

Definitely with the half tons I came across various comments of having screwed up a caliper by doing the wrong thing by trying to press the piston in when it was not set into service mode to touching the park button with the caliper unbolted and puking the guts out of it because of the park system they use and just not doing the right things due to not understanding how they function. 

I had initially replied thinking you didn’t recognize the difference in the systems, but after rereading I realized you acknowledged it later in your message.  That’s why I deleted what I had posted. 

[Chuck FB]

2 hours ago, newdude said:

 

 

No service mode but there is a calibration required when replacing the shoes.  Can only be performed with a scan tool.  

 

Dam, thought maybe I was totally in the clear !. Well if/when I do touch the brakes as in replacing pads/rotors I will have to seek out some assistance to make the trucks computer happy. 

 

Thank you for that heads up !, I know you don't often get the credit your owed for answering tech questions we have on here. 

[newdude]

3 minutes ago, Chuck FB said:

 

Dam, thought maybe I was totally in the clear !. Well if/when I do touch the brakes as in replacing pads/rotors I will have to seek out some assistance to make the trucks computer happy. 

 

Thank you for that heads up !, I know you don't often get the credit your owed for answering tech questions we have on here. 

 

 

Changing pads and rotors, you don't need anything.  Its only if you are replacing the parking brake shoes is calibration of the park brake necessary.  

 

Just want to make that clear.  Park brake calibration is needed for replacing the park brake shoes.  

[Chuck FB]

50 minutes ago, Another JR said:

I had initially replied thinking you didn’t recognize the difference in the systems, but after rereading I realized you acknowledged it later in your message.  That’s why I deleted what I had posted. 

 

Yup, I pretty much figured that , its all good.  And thanks to Newdude I now learned that brake service mode is NOT a thing on an HD truck, however one will have to either have or get someone to use a scan tool to reset the system after doing .... and as I am putting an edit to this comment as Newdude caught my error in thinking and that its only required to use the scan tool to calibrate the park brake shoe system if that was worked on. 

 

 

Edited January 15 by Chuck FB

[Chuck FB]

1 minute ago, newdude said:

 

 

Changing pads and rotors, you don't need anything.  Its only if you are replacing the parking brake shoes is calibration of the park brake necessary.  

 

Just want to make that clear.  Park brake calibration is needed for replacing the park brake shoes.  

 

Opps, good thing you said that as I was obviously assuming the foundation brakes needed a reset to know they were brought back to new specs. 

 

That means the original poster of this thread should have that done on his truck since he replace his park brake shoes.