FAQ: Vibration under braking: warped rotors? NO!

Good! You can't overdo "bedding in." Even though I have done so on several vehicles, I still allow time while rolling to let the system cool after heavy braking.
Well, you kinda actually can overdo the bedding in. If you overheat the brakes so much your fluid boils you'll have to bleed the brake system. It would be wise to avoid that if you can. Besides, if you're getting good street pads you don't have to go extreme, many street pads don't even require a break in other than normal driving and expecting slightly reduced braking performance for the first few days.
 
Sorry if it's been asked already, yes i read the faq at least but not the 35 pages since that.

Other than the rebedding process described, is it possible to sand paper the deposits away maybe? I've got some EBC yellow stuff racing brake pads that caused shudder almost straight away after putting them on,then unusable once everything got hot after a few laps at a track day. I'd like to give them one more shot before I give up on them so maybe sand paper the rotors and pads and try bedding again?

Are some pads just never going to work and will give deposits /shudder no matter what?

Thanks.
I've posted previously about this; water-based valve grinding compound smeared on the rotors followed by some nice long stops will get the deposits clean off. I just did this to my car the other day. :)
 
I've posted previously about this; water-based valve grinding compound smeared on the rotors followed by some nice long stops will get the deposits clean off. I just did this to my car the other day. :)
Just get a bit of compound on the disc through the wheel would be enough? Don't even need to take the wheel off...?
 
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Rotors replaced today, pulsation from pedal is gone! Brakes like a normal car now.
 
Just get a bit of compound on the disc through the wheel would be enough? Don't even need to take the wheel off...?
You can do it without removing the wheels, but you drive with it on there only long enough to remove the deposits, and wash it off. It's easiest to fully wash off if you remove the wheels afterward. I've done this to my ZR1 Corvette (I finally decided to say goodbye to it... RIP. Stupid hurricane put a tree on it years ago.) and my Saab after very hard braking left desposits. It does grind down the rotors a little bit but far less than needlessly turning the rotors on a lathe, and avoids having to wait for the pads to re-bed.

Helpful tip: after you wash the rotors off well (wash off any compound that splashes the wheels; it can stain as it oxidizes and the steel off the rotors will create rust stains) go for another short drive to dry off the rotors to reduce surface rust afterward.

As far as how well this works- I went a couple of months without driving the Saab during the pandemic (I parked it after a snowstorm with salt on the rotors - the Saab is our beater), and the rotors were really rusty and making stopping uncomfortable and stopping distances were increased, and attempting to re-bed the pads didn't help. I used this method to grind the rotors down level with the rust pits and it worked like charm but the pits were so bad I had to do it several times and braking is now nearly as good as it used to be, with all pedal pulsations gone. The Saab is due for new rotors anyhow (I usually run redstuff pads which wear the rotors quickly, and 9-3s eat 2-3 sets of rear brakes per front set), so I'm replacing the brakes all around before inspection in February, including rotors-- hopefully the last time I do brakes on this car. After the pandemic is well behind us I'm upgrading, hopefully to a Stinger or G70.
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
Rotors replaced today, pulsation from pedal is gone! Brakes like a normal car now.
I read the original answer--but I was told by KIA that the rotors are not by brembo (they are vented but just bigger normal rotors) and brembo said they do not mass produce rotors for the KIA Stinger.I replaced ALL 4 of my rotors with Geomet cross drilled and vented and they work fantastic now.I have a new 2020 and the KIA dealer actually installed them and complimented on them.Also in freeing cold or rain the brakes bite hard from first stop.I spray my car off weekly and do not notice any brake dust and the brakes are quiet and feel like stock for the most part except they brake better and even.I dragged my car a few weeks ago and had to make a few stops from 105 MPH plus and had ZERO fade or vibration. KIA needs to address this.I had the cross drilled/vented on my old car for a decade--put 25k miles on them and when I traded it in on the Stinger it had 75% pad life and rotors looked new even though they were a decade old. The rotors--stock--are not meant for track use--my new ones are if it makes this any clearer.
 
I read the original answer--but I was told by KIA that the rotors are not by brembo (they are vented but just bigger normal rotors) and brembo said they do not mass produce rotors for the KIA Stinger.I replaced ALL 4 of my rotors with Geomet cross drilled and vented and they work fantastic now.I have a new 2020 and the KIA dealer actually installed them and complimented on them.Also in freeing cold or rain the brakes bite hard from first stop.I spray my car off weekly and do not notice any brake dust and the brakes are quiet and feel like stock for the most part except they brake better and even.I dragged my car a few weeks ago and had to make a few stops from 105 MPH plus and had ZERO fade or vibration. KIA needs to address this.I had the cross drilled/vented on my old car for a decade--put 25k miles on them and when I traded it in on the Stinger it had 75% pad life and rotors looked new even though they were a decade old. The rotors--stock--are not meant for track use--my new ones are if it makes this any clearer.
Which Kia dealer do you frequent?
 
There is a lot Kia could have done; it makes sense that slotted and drilled rotors can mitigate the issue with the soft pads leaving deposits. The real issue remains that the pad compound they chose is far too soft for the application.
 
We will cure cancer before this braking "mystery" is solved.
 
Quick update from RDU area in NC. Just took my 19 GT2 AWD for it's first service and the wire junction box recall. Actually very happy with my treatment so far.

Pretty cool actually, my particular service rep was very honest and said he himself owned a 2018 and traded it in after 22k miles because of the brakes and Kia's inability to fix his shaking after tons of visits and turned/replaced rotors. His problems persisted and he was so frustrated with his own company he just got rid of it.

(I'd assume they never ever properly bedded the brakes or anything and his problems were probably exacerbated by just having the rotors turned over and over and never replacing the pads so their uneven wear issues just made deposit issues happen quicker and quicker....)

BUT he was glad to say that now KIA can actually fix the issue and would do anything I need if I had problems but did say the process is still a pain but at least there's a solution at the end if the problem persists.

1) They will first turn the rotors and resurface (he said "Scrub") the OEM pads.
2) If pulsing returns you'd have to come back and they'd re-turn the rotors and scrub the OEM pads AGAIN,
3) If you still have issues after the 2nd visit THEN they will replace the pads with the upgraded 2020.2/2021 pads and try to re-surface the stock rotors again. ONLY if the front rotors had lost too much material will they ever replace rotors anymore.

Also, they will not warranty rear brakes at all anymore, they'll turn them but won't upgrade the pads or replace the rotors for standard pulsing issues.

(edited - this part is important)
I'll just point out that the process outlined above will actually make pulsing issues that originate from tacky pads prone to uneven deposits WORSE. You'll have smooth operation for a while but unless there was pretty elaborate aggressive bedding, the tendency for uneven deposits from the pad to re-form gets worse as the pad wears. You can't re-surface a pad back to factory spec because heat has so much to do with how the pad material reacts. So even assuming they are truly re-machining the pads back to perfectly flat, some parts of the pad will be harder, other will be softer and the only way to avoid uneven deposits is to do a bedding procedure that gets the system up to temp and under high pressure where the two surfaces are forced together and all pits and valleys get even contact with the rotor.....and even THEN, you're only extending the amount of time before pulsing returns because now the pads are even more worn and heat-cycled which wouldn't matter if they weren't already so tacky and prone to excessive deposits. And frankly we all know that you can't really machine a pad, you rub them on sandpaper on a flat surface unless you're a race shop.

In short, I'd avoid this warranty process like the plague and still buy new pads, at most I'd go through step 1, drive home slowly and just get a free resurfacing out of the deal.

Not sure if this is just this dealer or KIA as a whole. But at minimum I feel this is a good step to confirming the consensus that the stock rotors are perfectly fine and everyone should just get rid of the stock pads ASAP and be happy with it.

<3 everyone.
 
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From interior to exterior to high performance - everything you need for your Stinger awaits you...
anyone have a part number for these alleged OEM upgraded front pads?
 
Just get some Hawk pads and be done with it. Bed them in and you will be good to go, assuming your rotors are still in good shape...
 
rockauto.com has lots of options I haven’t tried any though
 
Quick update from RDU area in NC. Just took my 19 GT2 AWD for it's first service and the wire junction box recall. Actually very happy with my treatment so far.

Pretty cool actually, my particular service rep was very honest and said he himself owned a 2018 and traded it in after 22k miles because of the brakes and Kia's inability to fix his shaking after tons of visits and turned/replaced rotors. His problems persisted and he was so frustrated with his own company he just got rid of it.

(I'd assume they never ever properly bedded the brakes or anything and his problems were probably exacerbated by just having the rotors turned over and over and never replacing the pads so their uneven wear issues just made deposit issues happen quicker and quicker....)

BUT he was glad to say that now KIA can actually fix the issue and would do anything I need if I had problems but did say the process is still a pain but at least there's a solution at the end if the problem persists.

1) They will first turn the rotors and resurface (he said "Scrub") the OEM pads.
2) If pulsing returns you'd have to come back and they'd re-turn the rotors and scrub the OEM pads AGAIN,
3) If you still have issues after the 2nd visit THEN they will replace the pads with the upgraded 2020.2/2021 pads and try to re-surface the stock rotors again. ONLY if the front rotors had lost too much material will they ever replace rotors anymore.

Also, they will not warranty rear brakes at all anymore, they'll turn them but won't upgrade the pads or replace the rotors for standard pulsing issues.

(edited - this part is important)
I'll just point out that the process outlined above will actually make pulsing issues that originate from tacky pads prone to uneven deposits WORSE. You'll have smooth operation for a while but unless there was pretty elaborate aggressive bedding, the tendency for uneven deposits from the pad to re-form gets worse as the pad wears. You can't re-surface a pad back to factory spec because heat has so much to do with how the pad material reacts. So even assuming they are truly re-machining the pads back to perfectly flat, some parts of the pad will be harder, other will be softer and the only way to avoid uneven deposits is to do a bedding procedure that gets the system up to temp and under high pressure where the two surfaces are forced together and all pits and valleys get even contact with the rotor.....and even THEN, you're only extending the amount of time before pulsing returns because now the pads are even more worn and heat-cycled which wouldn't matter if they weren't already so tacky and prone to excessive deposits. And frankly we all know that you can't really machine a pad, you rub them on sandpaper on a flat surface unless you're a race shop.

In short, I'd avoid this warranty process like the plague and still buy new pads, at most I'd go through step 1, drive home slowly and just get a free resurfacing out of the deal.

Not sure if this is just this dealer or KIA as a whole. But at minimum I feel this is a good step to confirming the consensus that the stock rotors are perfectly fine and everyone should just get rid of the stock pads ASAP and be happy with it.

<3 everyone.
Which dealer were you at that gave you this story out of curiosity?
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
Had em on my Lexus. The wheels were constantly dirty and always squealing.

Such a horrible trade-off.

Thanks for the FAQ, OP.
Same with my Cayenne Turbo. Dust was insane and squealing was so embarrassing (given I was driving around in a $100k Porsche) but you’re right, that’s the trade off. Brakes were insanely good and never ever had vibration but damn they still needed to be replaced almost every 15k miles, along with the summer tires. Just physics I guess...5,200lb SUV + 500hp.

On my 2007 Mustang GT Convertible I’ve never had brake issue of any kind, but they do not grab at all, never have. 2020 Stinger started with the brake vibes after only 3k miles but the rebedding solution is correct.
 
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Glad I found this thread. I had my rotors replaced under warranty at 11K miles. by 16K miles the vibration was back. I've been trying to determine what to do. I live in Texas where we have freeways with speed limits of 80 and 85 MPH so my brakes do get a workout. I guess I will try new pads and then bed them in using the methods on this thread. I do wonder if replacing the rotors with the type that have holes in them would help. Wouldn't the holes help "scrape" off the pad residue?
 
Wouldn't the holes help "scrape" off the pad residue?
I'll answer with an opinion: holes are for lightening, slots are for "scraping". Maybe it's all just a fetish for appearances sake. Logically, removing metal from a rotor accomplishes nothing beneficial vis-a-vis heat dissipation.
 
This is a pretty good video on the whole issue, including instructions for rebedding

That said, after I did a few high speed braking runs (being sure to let the brakes cool immediately afterwards) the vibrations came back again after about a week or two. I don’t understand what’s up with that. It’s really annoying and even my “non car” passengers are like “what’s that noise and vibration every time you put your brakes on?” Maybe it really is Kia specific. Idk. I’ve only got 4k miles now after 9 months. Bought it brand new with 7 miles on the odometer. I’m not gonna keep doing high speed runs. Maybe I just need to switch pads. Any recommendations? consensus here says it’s the pads. Not the rotors. Correct?
 
This is a pretty good video on the whole issue, including instructions for rebedding

That said, after I did a few high speed braking runs (being sure to let the brakes cool immediately afterwards) the vibrations came back again after about a week or two. I don’t understand what’s up with that. It’s really annoying and even my “non car” passengers are like “what’s that noise and vibration every time you put your brakes on?” Maybe it really is Kia specific. Idk. I’ve only got 4k miles now after 9 months. Bought it brand new with 7 miles on the odometer. I’m not gonna keep doing high speed runs. Maybe I just need to switch pads. Any recommendations? consensus here says it’s the pads. Not the rotors. Correct?
Here's a forum page I saved because it covers the spectrum of driving style and brands for different kinds of pads. If/when I decide to go aftermarket pads, I'll refer back to this page and start from there. FAQ: Vibration under braking: warped rotors? NO!
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
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