If you have had brake issues, then read this.

Helo58

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Well, it has been two weeks, since I had the Stoptech Street Performance brake pads put on the car.
Stoptech Street Performance Pad (Front) Review

Since then, there has been major (to me) development that I would love to get community input on. Since replacing the pads and rotors, I think that there may be a root cause for the pad deposits that was not previously considered in all cases. For the record, I do not use brake hold or my parking brake on level ground in places such as my driveway (where the events below happened).

I have a truck that often acts as my daily driver so the Stinger sits a few days without being driven. After an uneventful day driving the Stinger around (very relaxed scenic driving), my wife and I came home and I parked the Stinger for 3 days. Yesterday (3 days later), when I went to drive it, I put it in reverse and heard a pop from the front of the car and then the car started moving backwards as expected. I drove a short distance (100yds) and then pulled back into my driveway to investigate the "wiiisshhh, whiisshhh, wiisshhh" sound that corresponded with the rotation of the wheels/tires. Both front rotors had a brake pad shape "deposit" that looked like it was slopped on with a wet paint brush. These left and right side "blotches" on the rotor surface were rubbing the pads as the car went down the road making the "wiisshhh" sound for every revolution of the tire. After determining where the noise was coming from, I took the car out to see how permanently the stuff was "baked" on and did some aggressive braking to try and wear the stuff off. This resulted in "thud thud thud thud..." sound and vibration until the car came to a stop. By doing this a few times, I was able to remove the majority of the blotches, but the brakes now still pulse just like they did with the stock pads deposits. I drove the car off and on over those two weeks with no issues until this happened.

This leaves me to think something unavoidable has happened. I think that it is entirely possible that this issue has nothing to do with bedding procedure, driving style, pad composition, brake hold at stop lights, etc. because these are all things I was VERY aware of and have been careful to observe, account for, or avoid since the swap. My new pads were STUCK to the rotors in spite of all of my precautions.

Is it possible that the reason this brake issue has happened to some and not others has more to do with the "setup" of the braking components and less to do with the components themselves? Is it possible that the pads are not fully retracting from the rotor surface on all cars for some reason? Is there something that puts pressure in the line when the car is turned off that puts the pads on the rotor surface? In my case, the pads were on the rotor surface after I parked following an uneventful day of driving. Up until that point, the brakes were performing as desired. I turn the car off and leave and then the brakes start eating themselves after 3 days....
 
Very interesting. Wish I had known this info when I got mine. Mine was one year old and had been on the Kia lot for about 6 weeks when I bought it. I had vibration from the first time I drove it on the Freeway so it is possible it was from sitting on the lot. I wonder if there are any others who got the vibration parked theirs for several days. Were you parked outside or in a garage? If outside did you get rain?
 
Very interesting. Wish I had known this info when I got mine. Mine was one year old and had been on the Kia lot for about 6 weeks when I bought it. I had vibration from the first time I drove it on the Freeway so it is possible it was from sitting on the lot. I wonder if there are any others who got the vibration parked theirs for several days. Were you parked outside or in a garage? If outside did you get rain?
It was parked outside over the three days. It rained a partial day on one day. I can't state strongly enough how much pad material was on the rotors when I looked. Clearly the pad material color with no disk showing through.
 
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Stranger and stranger! So pad material being different has resulted in the same damned thing. I wouldn't be looking at rotors as a contributing factor in any of this. It has to be pads. Now you say that the aftermarket pads you chose are no better, possibly worse, than the OE pads.
 
Stranger and stranger! So pad material being different has resulted in the same damned thing. I wouldn't be looking at rotors as a contributing factor in any of this. It has to be pads. Now you say that the aftermarket pads you chose are no better, possibly worse, than the OE pads.
I am looking more at the braking system controls more than the pads or rotors at this point. I have taken every precaution and corrected the things I can... to no avail. I really think that something in the braking system (on the affected cars) is causing the pads to be pressed against the rotors once the vehicle is turned off. In the old days, I would look at the usual suspects for brake drag such as: push rod length on the brake booster and master cylinder, master cylinder not releasing, and caliper not releasing and start there. I'm not sure how much of that applies in this case. With all of the related systems today such as electronic parking brake, auto hold, etc. there may be many factors that could influence caliper piston movement. I'll let KIA try and figure it out. ;)
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
Did you follow the bed in procedure recommended by the manufacturer? The process is different for different compound pads. I had the new Hawk 5.0 HPS front pads installed with Cquence slotted and drilled rotors and haven't had any issue; this is my daily driver though. These pads came with a substance on them that wore off completely during the bed in process; the brakes gave off a bad chemical odor during bed in. I could see if this was not completely worn off during bedding and the car was parked outside cold for a period of time there could have been adhesion between this break in substance and the rotor creating a high spot on the pads. Have you reached out to Stoptech they are a reputable company.

Also, neither the parking brake or brake hold use the calipers or pads; these brake systems use a drum brake inside the rotor so that would not have been a contributing factor.
 
When I was in the car business it was common for cars sitting on the lot not being drive to get this. But some of those cars might sit for two weeks without being driven. I wonder if the moisture got in between the pad and rotor and caused this after sitting a while. I wonder if those pads somehow leave deposits when moisture gets in there?

One test would be to lift the car and immediately hand spin the wheel and see if it feels like the pads are pressing down too hard against the disk.
 
Did you follow the bed in procedure recommended by the manufacturer? The process is different for different compound pads. I had the new Hawk 5.0 HPS front pads installed with Cquence slotted and drilled rotors and haven't had any issue; this is my daily driver though. These pads came with a substance on them that wore off completely during the bed in process; the brakes gave off a bad chemical odor during bed in. I could see if this was not completely worn off during bedding and the car was parked outside cold for a period of time there could have been adhesion between this break in substance and the rotor creating a high spot on the pads. Have you reached out to Stoptech they are a reputable company.

Also, neither the parking brake or brake hold use the calipers or pads; these brake systems use a drum brake inside the rotor so that would not have been a contributing factor.

I agree with the bed in procedure varying between pads. I put Gyrodisc pads in and their procedure is much milder than some I have seen.
 
The pads on the Stinger Brembo calipers retract mechanically via the plate that sits on top of the pads. The plate has a slope built in to it. It is pressed onto the top of the pads and it is held down by the two sliding guide pins.
Auto Hold and Parking brake have no interference with this mechanism.
See photo reference.

stingerb.webp
 
Did you follow the bed in procedure recommended by the manufacturer? The process is different for different compound pads.
Yeah, I have a separate post where I review the new pads from purchase, bed-in, to use (link above). I've done everything to the manufacturer's recommendations and I am really leaning towards thinking this is a problem with the braking system itself, not the pads or rotors.
Have you reached out to Stoptech they are a reputable company?
I will likely do this at some point, but for now I am going to wait. Just as with the stock pads, many have no issue with the Stoptech pads so I think a conversation with them is premature.
Also, neither the parking brake or brake hold use the calipers or pads; these brake systems use a drum brake inside the rotor so that would not have been a contributing factor.
After reading the maintenance manual, I thought I read somewhere that the systems are linked electronically somehow. In the description of the brake system, there is a condition in which the car's systems sense a grade of "X"% and supplement the rear drum parking brakes with the hydraulic system if the grade percentage exceeds "X." It describes a partial braking force and a full braking force (or something like that). I will track it down when I get home to see if this is correct. As for brake hold, I have personally had the front brake pads creak upon release using that system. This leads me to believe that the system is also linked depending on what is happening with the car. I will also follow up on this when I get home.
 
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From interior to exterior to high performance - everything you need for your Stinger awaits you...
The pads on the Stinger Brembo calipers retract mechanically via the plate that sits on top of the pads. The plate has a slope built in to it. It is pressed onto the top of the pads and it is held down by the two sliding guide pins.
Auto Hold and Parking brake have no interference with this mechanism.
See photo reference.
@robz32 , It was my understanding that the plates/clips were there to keep the pad firmly against the piston as it travels rather than force the piston(s) back into their caliper.
 
Correct. It serves as a double purpose. As the piston extends (when applying pressure on the brake pedal) the pads moves with it. If you look at the shape of the plate where it contacts the top of the pads (from the photo above), as the pad moves out (closer to the disk/rotor) the slope increases on the plate, therefore increasing the pressure on the top of the pad.

When depressing the brake pedal, the piston seal retracts moving the piston away form the pads, this is where the shape of the plate and pressure exerted on the pad become important, as this will keep the pads close to the piston as it retracts away from the disk/rotor.
 
Correct. It serves as a double purpose. As the piston extends (when applying pressure on the brake pedal) the pads moves with it. If you look at the shape of the plate where it contacts the top of the pads (from the photo above), as the pad moves out (closer to the disk/rotor) the slope increases on the plate, therefore increasing the pressure on the top of the pad.

When depressing the brake pedal, the piston seal retracts moving the piston away form the pads, this is where the shape of the plate and pressure exerted on the pad become important, as this will keep the pads close to the piston as it retracts away from the disk/rotor.

It could be that the plate isn't working as it should and allowing the pad to rest on the rotor when the piston retracts. With this latest issue of pad deposits on the new rotors, I think it could also be that the piston itself is not retracting fully. Assuming that the problem is consistent, @itguy61 has a good idea that will rule out the piston retraction question by simply lifting the car and rotating the front wheels. Hopefully, it is simply the plate and not a more complicated issue with the piston failing to disengage fully.
 
That is what I was think. I recently changed my brakes as well and will be paying attention to it. Also it could the that the design at the top of the Stoptec pad is different or flawed and does not allow the pads to slide back via the plate.
 
Does the piston actually retract significantly when you let off the brake? I know when you remove the pads to change them out the piston is right up against the back plate and you have to get a wrench or caliper tool to push the piston in enough to put the newer pads on.
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
Does the piston actually retract significantly when you let off the brake? I know when you remove the pads to change them out the piston is right up against the back plate and you have to get a wrench or caliper tool to push the piston in enough to put the newer pads on.
This would be helpful information. I wouldn't think that they move more than an 1/8th to a 1/4th of an inch or so. The only thing retracting them is the square cut seal on the piston (in the caliper housing).

So at this point, the list of possible causes includes:

1) Bad brake pad retention plate keeping pads to pistons.
2) Faulty piston retraction due to bad "square cut" seal.
3) Residual brake line system pressure causing the pads to remain engaged with the rotor after the vehicle is parked (with no occupants). This could be due to EPB or auto-hold not releasing.
 
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By default there should be a .45mm clearance between the pad and the disk.
 
By default there should be a .45mm clearance between the pad and the disk.
Is this based on piston "neutral" or retracted position (with pad) and maximum thickness for the stock rotor?
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
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