05 STS needs rear brakes

It's pronounced "chassy." Brakes, suspension...things that make the car fun or a death trap
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

05 STS needs rear brakes

Post by kevm14 »

They are done, but prematurely because of what seems to be pin issues, and I had serviced them last year. Or maybe I just did the fronts...I can't remember. Anyway, the inner pads are spanked with heavy inner rotor wear. Outer has much more meat. Annoying. Order:
ACDELCO 1792044 (pins & boots) {#89047759} GM Original Equipment
$23.79 x 2 = $47.58

ACDELCO 17D1020AMH Professional; Semi Metallic; w/Hardware
Rear; GM Brake Code JE5; OE Pad Material is Semi-Metallic
$37.79

ACDELCO 18A2758 {#19288509} Professional
Rear; with 12.54in Diameter Rotor; w/ 5 Stud Rotor
$25.79 x 2 = $51.58

$137 (plus shipping, and tax, sigh) for basically a complete rear axle brake service. I would have gotten Hawk HPS but they don't make it for the rear performance/JE5 brakes. Ironically.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

Did the rear brakes today.

Here are some highlights:
- Both rotors were screwed into the hub and that screw popped right off with my cordless impact. I did reuse it though I didn't crank down on it.
- The rotors needed one whack with my 2.5lb sledge and they wiggled off the parking brake with little drama.
- A pad change takes like 2 seconds, but really if you remove the caliper bracket and clean it out thoroughly, and use new pins, and replace the boots, it takes closer to an hour per rotor.
- These boots actually press into the caliper bracket. I got them out with a small prybar and my sledge.
- I cleaned the bracket pin slide areas very thoroughly. One of the boots was torn and that was the pin that was giving me issues. Surprise surprise. I used brake cleaner, my air hose, and 3 Q-tips jammed into my drill chuck to clean out the caliper brackets very thoroughly. This was not a time for a pad-only job, or even a sloppy regrease of the pins and slap it back together.
- New caliper bracket hardware which came with the pads. The pads looked identical in the picture to the Raybestos which I almost bought, but the AC Delco came with the hardware (where the pads ride on the caliper bracket).
- The new pins and boots came with a blow up of what looked like the front dual piston caliper. But I think the rear uses the same pins and boots.
- For possibly the first time I used the silicone stuff in the packets that came with the slide pin kit, and used the other packet that came with the pads on the caliper bracket hardware. This was a 100% GM brake job for whatever that is worth. Jamie's car is squealing again but I was not as thorough on her car so I may need to refresh some of the hardware (I am sure the pads and rotors are fine).
- Rotors are e-coated which is fancy.

I have not road tested yet but I am about to. I think the brakes are going to feel better than the ever have. For the front I have new caliper brackets and slide pins in the parts funnel but I don't know if I really need to do that right at the moment. I'll see how the road test goes.
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kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

So I road tested. Not great news really. The pedal is a little better but not much. And the squealing appears to be the front. And it seems like the left rear caliper is starting to hang up. The wheel was very hot and I smelled brakes. The right rear was fine. I will keep my eye on it but I may have to do a caliper. That's actually pretty easy, aside from having to bleed everything.

So I may just get my Hawk HPS pads for the front, and do that service at some point (new hardware, new pins, etc.).
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

I did take it down that curvy road near my house. I put it in Performance. I find the tires and brakes underwhelming but the chassis and steering is very willing on this car. And sport mode on the transmission does a decent job holding gears. I find the engine has plenty of power, at least for the current tires and brakes. That all said, my CTS-V can maintain a pace that is startling on roads like that. Not even close. But at less than full bore, the STS feels pretty good for what it is.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

Just took it for another quick ride down the road and back. Left rear wheel extremely hot to the touch, smells like brakes. Other wheels seem fine. It is definitely dragging. The only question is, do I do both rear calipers or just the one with the issue? The labor is almost identical since I will have to bleed all calipers anyway. I would think if it isn't hanging up now it won't hang up later. This also may have been part of the problem with the extremely worn inner pad on the left rear, though a big delta between inner and outer usually suggests a pin issue. If the piston is not retracting, it should put essentially equal pressure on both pads if the pins are sliding freely.

Rob had issues with his 04 SRX like this. He actually had one lock up on his trip down to Berman's wedding and replaced it in the hotel parking lot (it may have been the left rear). They use different calipers but probably the same overall design. He said the piston is phenolic and his theory is over time it reacts with the brake fluid and slightly expands, causing binding issues. I never really tried to do my own research to validate that theory but given that I am having issues after retracting the pistons on a brake job, it makes some sense. And if it was a matter of time, that would suggest I should do both calipers. Now I can't drive this car this week. I guess that's fine.

The rotor looks heat abused. I hope I didn't hurt the rotor or glaze my pads. Freaking annoying. Not good to do on brand new stuff.

Wow, $60 core/each, and around $44/ea after core. They come with caliper brackets, boots and pins all installed, too. New GM calipers are also available for about $115/ea which is a lot more. I'll do reman.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

A very quick internet search revealed that phenolic pistons cause widespread sticking over time. This is dumb. And no, it is not a GM thing. It sounds like the single reason for their use is they provide a level of insulation from heat between the pad and the brake fluid. Which is an issue in overall brake performance, but particularly when old brake fluid is present (absorbs water). Steel would transfer the heat pretty readily. The new GM calipers did have steel pistons. The remans, I am not sure. Makes me wonder if I am going to have the same issue on the front, unless they are not phenolic. Sigh.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

Did the calipers. I reused the slide pins that I had just installed and my old brackets. I am going to chance not sending the brackets back with the core and hope I get my core charge back for just the calipers. I didn't want to send back the brand new brackets since I might want them at some point. They did not seem to be lubricated well at all, and this is sold as "friction ready" which means slap in some pads and go. I didn't feel like re-lubing everything (and did not have any more of the GM stuff that I used before) so meh.

New left caliper.
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Some scoring from when it was dragging when I test drove it last weekend. It wasn't deep but this is obviously not what normally happens right after you install new pads and rotors...
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Right caliper.
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The rotor looks a lot better than the other one since it was not dragging. Before someone says something, no, they don't use all of the available radius for the pads. There is a 1/2" or so of inner radius where the pads do not touch. A little odd but it is as designed. You could make an argument that the outer radius area is more useful than the inner due to the lever arm, so that increases brake torque, plus the larger diameter is good for cooling and mass. And the hub didn't need to be any larger than that. So there you go. These rotors are only shared with the 06-07 CTS.
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I ran out of brake fluid so I had to get some more. You don't see this every day. That is some kind of parrot on that guy's shoulder in Advance Auto. It was real.
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For bleeding I worked with my Mityvac for a while but became frustrated with it. Later I got Jamie outside (had to buy brake fluid anyway) and pressure bled it. I will say I think I actually got all the air out with the Mityvac so that is a good data point. One man bleeding is in fact possible.

While bleeding I did notice that the left rear rotor was still sticking. It was almost impossible to turn by hand while the right rear turned (I could turn it when the wheel was on at least). It was in park so they didn't turn much but it was enough to see it was still binding.

I road tested it anyway. Results? Still dragging though, and I hope I am not being hopelessly optimistic here, it seems better than it was. Though after one test I pulled into a lot and the caliper area was actually smoking. It is possible some spilled brake fluid was burning off but the left rear is clearly still the hottest wheel. It did not do it again and the brake pad smell is also significantly diminished. What's also a little odd is that the right rear is the coolest wheel. I guess that makes sense since rear brakes probably do less than the fronts. Which makes it pretty obvious there is still an issue.

I took it down the highway and stuff and I don't think it is going to strand me with smoke billowing out of those pads. I will try it for a while and see how it does. You may be asking...wtf is the issue then? Well, either it is just a bad reman (doubtful) or there is an issue with the brake hose internally. While there was good flow from the bleeder on the rear left, I may order a brake hose just to have on hand. Stainless braided is way better but even though I care very much about brake feel, I don't think these brakes are ever going to really satisfy me so I should probably not jump through my ass in an attempt to do so. FWIW, the feel does seem a little better than it was, but that is a hard thing to determine after driving the CTS-V all last week (all calipers are 4 piston fixed Brembos = awesome sauce). An AC Delco left rear hose is $8.47. lol. A Wagner is $4.20. I would get the AC Delco...

https://www.rockauto.com/en/moreinfo.ph ... 42&jsn=427

This is the Raybestos:
https://www.rockauto.com/en/moreinfo.ph ... 42&jsn=428

Same pic but the hose is $11.96.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

Drove around town for 15 mins. Came home. Remembered I have an IR thermometer. Left rear rotor around 125F. Right rear was 112F. That isn't bad at all. Hopefully it didn't just glaze over and it's like not actually generating friction or something.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

Did an errand which required driving up the highway where the car said around 94F. Got up to...some speeds on the way back. Front rotors around 220F and the left rear was 140F while the right rear was 120F. I will just resume commuting and I guess check it every once in a while.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS needs rear brakes

Post by kevm14 »

Decided not to chance it and threw in the unused reman caliper brackets. I am risking $60/ea caliper for the core so I did not want to screw myself out of $120.
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