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New brakes did something weird today

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Old 03-20-2017, 02:02 AM   #1
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New brakes did something weird today

Driving down a hill for about a mile with about 7 stop signs. Fairly good grade but not extreme. Wasn't going fast in between, maybe 40 at the most, probably 30 mph mostly.

By the time I got to the bottom, my brakes had faded considerably and the front were smoking. I could smell hot brakes. The car did not pull to either side and seemed to coast just fine (no binding I think).

Front disc / rear drum - factory stuff.

I just finished doing:

new/rebuilt calipers (AC Delco)
new/rebuilt wheel pistons (Dorman)
new AC Delco pads front and back
new brake lines in the front
fluid flush and bleed.

The original fluid was old and brown with stuff floating in it, FYI.

I'm pretty sure the car has better brakes than this. I'm thinking maybe my combo valve is bad or the MC but the car seems fine in normal street driving.

Any ideas?
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Old 03-20-2017, 08:56 AM   #2
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Re: New brakes did something weird today

Stock pads and dinky 10.5" rotors, what you experienced is normal. Had the pads been bedded prior to this?

RBob.
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Old 03-20-2017, 08:57 AM   #3
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Re: New brakes did something weird today

Did you just slap new pads on old glazed rotors and hit the road? Generally you want to have the rotors resurfaced or replace them, and bed the pads to them shortly after replacing so they wear together. Regardless smoking is a bad sign.

Typical stock thirdgen brakes aren't the best, but they shouldn't be fading under normal conditions.
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Old 03-20-2017, 09:03 AM   #4
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Re: New brakes did something weird today

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Originally Posted by RBob View Post
Stock pads and dinky 10.5" rotors, what you experienced is normal.
No it's not. LOL GM used these same brakes on about a billion S10s, G-bodies, Camaros, Firebirds, etc and smoking brakes after a few stop lights in normal traffic has never been considered normal.

WTF.
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Old 03-20-2017, 10:30 AM   #5
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Re: New brakes did something weird today

Thanks everyone. I did reuse the rotors that were on the car. They were straight and didn't have much of a lip on them. But now I'm thinking maybe they were glazed over.

Do you suggest I turn or change the rotors and the pads or just the rotors? Have I ruined the new pads? What do you think about the rear drums? I did not have those turned either.
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Old 03-20-2017, 02:10 PM   #6
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Re: New brakes did something weird today

Did you replace the hoses? I ask because hoses on these cars have a habit of rusting internally, and then they get blocked. What can happen is fluid will push through under pressure, but then it won't release so the calipers stay clamped.

Pull the calipers and inspect the pads and rotors. Grooves would be bad. Signs of excessive heat would be bad. If the pads look evenly worn, and the rotors are still true, you might try buzzing the surface of the rotors with a fine 3M roloc disc to break the glaze. Or have the rotors turned and they should give the surface the same treatment. Really though, for the cost of rotors there's not much reason not to replace them. A fresh, new rotor has more mass than an old one that's been turned. More mass means more capacity to absorb and displace heat.
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Old 03-20-2017, 02:30 PM   #7
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Re: New brakes did something weird today

Yeah. I'll just buy new rotors and drums.

I replaced the two brake hoses to the calipers. The rear hose to the drums was being stubborn so I left it in. It looked OK as far as outside rubber-wise.

I must've flushed at least a quart of new fluid through the front and back using a vacuum bleeder and then topped it off.
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Old 03-20-2017, 02:38 PM   #8
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Re: New brakes did something weird today

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Originally Posted by Drew View Post
Did you replace the hoses? I ask because hoses on these cars have a habit of rusting internally, and then they get blocked. What can happen is fluid will push through under pressure, but then it won't release so the calipers stay clamped.

Pull the calipers and inspect the pads and rotors. Grooves would be bad. Signs of excessive heat would be bad. If the pads look evenly worn, and the rotors are still true, you might try buzzing the surface of the rotors with a fine 3M roloc disc to break the glaze. Or have the rotors turned and they should give the surface the same treatment. Really though, for the cost of rotors there's not much reason not to replace them. A fresh, new rotor has more mass than an old one that's been turned. More mass means more capacity to absorb and displace heat.
While this happens it never happens equally to both left and right, the car will pull to one or the other side.

If the OP just put new pads on old rotors, then what he did was partially bed the brakes in. He wore off the anti-rust coating most likely. And that was what was smoking.

They will likely be fine given a proper bedding.
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Old 03-20-2017, 03:08 PM   #9
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Re: New brakes did something weird today

That's what I was initially hoping that it was just burning off some new coatings but the brake pedal was seriously fading out. So that told me that there was something wrong with the actual contact surfaces.
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Old 03-20-2017, 03:09 PM   #10
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Re: New brakes did something weird today

did you wash them down with brake cleaner? If you didn't, they still had the Zinc coating on there to protect the rotor from rust. Plus the oils that also are on the rotor to protect it while in storage.

That oil will make a SMELLY mess.
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Old 03-20-2017, 04:14 PM   #11
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Re: New brakes did something weird today

Well, I'm using the old rotors. They looked good, but now I'm thinking they were glazed. Do I need to replace my new pads now (maybe 50 miles on them) or will they go with the new rotors (or sanded existing rotors) just fine?
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Old 03-20-2017, 08:58 PM   #12
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Re: New brakes did something weird today

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Originally Posted by Drew View Post
No it's not. LOL GM used these same brakes on about a billion S10s, G-bodies, Camaros, Firebirds, etc and smoking brakes after a few stop lights in normal traffic has never been considered normal.

WTF.
Oh, but it is normal. He didn't bed the pads, and even more so: it wasn't normal traffic. Read the original post, long down hill with multiple stops from speed.

I too have faded the stock OEM brakes, it didn't take much. At a minimum the OP should upgrade the pads.

RBob.

Last edited by RBob; 03-20-2017 at 09:19 PM.
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Old 03-20-2017, 09:19 PM   #13
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Re: New brakes did something weird today

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Originally Posted by Tootie Pang View Post
That's what I was initially hoping that it was just burning off some new coatings but the brake pedal was seriously fading out. So that told me that there was something wrong with the actual contact surfaces.
The stock pads will fade, get something like the StopTech High Performance street pads. It is the D154 pad dimension.

Quote:
Originally Posted by Tootie Pang View Post
Well, I'm using the old rotors. They looked good, but now I'm thinking they were glazed. Do I need to replace my new pads now (maybe 50 miles on them) or will they go with the new rotors (or sanded existing rotors) just fine?
As long as they don't have heat pock marks you can use them. Scuffing them with some 320 emery cloth will help to get the new pads bedded more quickly. Just enough to remove the old pad material.

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Old 03-20-2017, 11:06 PM   #14
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Re: New brakes did something weird today

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Originally Posted by RBob View Post
Oh, but it is normal. He didn't bed the pads, and even more so: it wasn't normal traffic. Read the original post, long down hill with multiple stops from speed.
I read the post. 7 stop signs in a mile, top speed maybe 40mph. Fade maybe, smoke not a chance.

I got my first thirdgen when I was 17, and had at least three by the time I was 21. Even being a master of the jackrabbit start, driving crazy, and standing on the brakes at every stop, I never had a brake issue worthy of a thread post. To get smoke usually takes some serious abuse, like a panic stop from high speed, or a mechanical failure, like a locked up caliper as I mentioned earlier.

Fade serious enough to warrant a thread, and smoke, after a handful of 40mph stops is absolutely not normal.



Quote:
Originally Posted by Tootie Pang View Post
Well, I'm using the old rotors. They looked good, but now I'm thinking they were glazed. Do I need to replace my new pads now (maybe 50 miles on them) or will they go with the new rotors (or sanded existing rotors) just fine?
Give your brakes a good visual inspection. Shiny rotors are normal, glazing will usually show as a hazy or glassy appearance. Any waves, or grooves, and the rotors should probably be replaced. The same applies to the pads, look for signs of damage, shiny smooth areas, cracks, burning, excessive brake dust. If they're flat and dull, and they look new, they're probably fine.

If the rotors do look to be glazed, most auto parts stores, carry a 3M refinishing kit that can be used with a drill, or better yet an air angle grinder.
Amazon Amazon
Harbor Freight sells a cheap version of the same thing, and I think I've even seen the 3M sets on the shelf at Walmart. It doesn't take much, you're just looking to give a non-directional tooth to the rotor surface that the pads can wear to evenly. Like the hone crosshatch in a cylinder, or the random pattern on a new rotor. You can probably accomplish the job with regular sand paper, but where's the fun in that?

The stock brakes really aren't that bad, but they don't leave a lot of room for an error like slapping new pads on old glazed rotors.
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Old 03-21-2017, 08:56 AM   #15
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Re: New brakes did something weird today

If the rotors were glazed, the OP would have had the opposite problem, very low braking effort. He would have been rolling through the stop signs.

As for the smoke, why not, the pads weren't bedded. On top of that, how much was the OP riding the brakes on the down hill slope (fairly good grade) to keep the speed down?

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Old 03-21-2017, 09:37 AM   #16
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Re: New brakes did something weird today

Quote:
Originally Posted by Tootie Pang View Post
Well, I'm using the old rotors. They looked good, but now I'm thinking they were glazed. Do I need to replace my new pads now (maybe 50 miles on them) or will they go with the new rotors (or sanded existing rotors) just fine?
I know I already replied to this, but figured to do it again. The 'new' AC Delco pads may be ruined, as it is I wouldn't use them. What I would do is to pull both rotors and clean them with some 320 emery cloth. Go in a circular motion and get the old pad compound off the rotors. Wipe with a clean dry cloth.

Get a set of the StopTech High Performance street pads (D154 form) and install those. Need to bed the pads, StopTech has a white paper section that describes how to do this. It is making controlled near stops to transfer pad material to the rotor and to bake the resins used to hold the pad material together:

http://www.stoptech.com/technical-su...and-procedures

Then enjoy the better brakes.

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Old 03-21-2017, 09:55 AM   #17
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Re: New brakes did something weird today

Yeah. I should do a "do-over".

Stoptech's website sucks. I'll call them.

Last edited by Tootie Pang; 03-21-2017 at 10:07 AM.
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