Getting new brakes...

[ThwopKing]

Tahoe had been pad slapped by previous owner and got a discount on em so figured I would give them a shot... Autozone GT brake pads and rotors, both front and rear. Should be going on next week at some point. Will keep ya posted. Random Pic for quick looky-loo

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[jcb2]

I’m not familiar with the GT brakes. I bought the standard Duralast rotors and pads at AutoZone for my ‘07 Yukon XL4x4.But they seemed to warp as I developed that condition where braking wasn’t smooth anymore but rather bumpy.It bothered me to the point where after only a year, I went to NAPA and asked for premium rotors and pads. That was a year ago and they are still very smooth. So paying extra for better quality parts, especially brake parts is worth it to me.

 

[OneofFew]

I’m not familiar with the GT brakes. I bought the standard Duralast rotors and pads at AutoZone for my ‘07 Yukon XL4x4.But they seemed to warp as I developed that condition where braking wasn’t smooth anymore but rather bumpy.It bothered me to the point where after only a year, I went to NAPA and asked for premium rotors and pads. That was a year ago and they are still very smooth. So paying extra for better quality parts, especially brake parts is worth it to me.

The cheap rotors are more prone to warping. Unevenly torqued lug nuts lead to warping.

 

[jcb2]

Oneoffew, I use an air gun but first just snug the lugs then tighten alternate lugs and finally going over all of them again. I feel confident that this gives them the same torgue. I think the cheaper ones warp due to inferior steel. Could I be wrong?

 

[Doubeleive]

it pays to get at least premium brake parts they last longer, work better. I put the GT's and the carbon infused rotor's on mine.
honest opinion---- they stop REALLY well
problems-lots of brake dust, LOTS
squeaks after a while, they are basically carbon fiber racing pads they will squeak eventually it's annoying.
I dumped the GT pads kept the carbon infused rotors, went with the premium ceramic pads, still stops REALLY well, very little brake dust. totally silent.
i've had a new set of GT pads for sale on ebay for $40 for almost a year nobody wants them oddly enough.

 

[iamdub]

Oneoffew, I use an air gun but first just snug the lugs then tighten alternate lugs and finally going over all of them again. I feel confident that this gives them the same torgue. I think the cheaper ones warp due to inferior steel. Could I be wrong?

Rotors don't actually warp. Well, there may be horribly low-quality ones made of a dangerously cheap metal that can warp from the sudden and drastic temperature fluctuations. But, the temperatures required to soften and melt the metal to cast rotors is far higher than what they experience when braking. What really happens is brake pad material burns itself to the rotor's surface, creating a high spot that is only measurable with a precision micrometer. Over time, this high spot(s) collects more pad material and grows. This makes the rotor extra thick in that area/those areas so they grab and release the pads as they pass through the caliper. This causes the pulsating feeling in the brake pedal. Cheap rotor material does play a factor as it can be a lower-quality iron that is more "adhesive" to the pad material. The pad material is what's primarily at fault, though. Sometimes, it's not necessarily a low-quality pad material as it is the pad material not being a good combination with the quality of the rotor's iron.

Improper installation can cause the same thing. If the rotor isn't seated perfectly flat against the hub due to dirt, rust, etc., this will make it wobble. It may be so minor that it's undetectable at first and the brakes may feel perfectly smooth. But the misaligned rotor will drag the pads more on that side that isn't flush and kick start the buildup of extra pad material on the rotor that gradually increases over time until it is able to be felt.

It all boils down to using quality parts and having them properly installed.

 

[jcb2]

Iamdub, Thanks for that information. I never knew that. Everyone mentions “warped rotors” but what you’ve said makes sense.

 

[HiHoeSilver]

Rotors don't actually warp. Well, there may be horribly low-quality ones made of a dangerously cheap metal that can warp from the sudden and drastic temperature fluctuations. But, the temperatures required to soften and melt the metal to cast rotors is far higher than what they experience when braking. What really happens is brake pad material burns itself to the rotor's surface, creating a high spot that is only measurable with a precision micrometer. Over time, this high spot(s) collects more pad material and grows. This makes the rotor extra thick in that area/those areas so they grab and release the pads as they pass through the caliper. This causes the pulsating feeling in the brake pedal. Cheap rotor material does play a factor as it can be a lower-quality iron that is more "adhesive" to the pad material. The pad material is what's primarily at fault, though. Sometimes, it's not necessarily a low-quality pad material as it is the pad material not being a good combination with the quality of the rotor's iron.

Improper installation can cause the same thing. If the rotor isn't seated perfectly flat against the hub due to dirt, rust, etc., this will make it wobble. It may be so minor that it's undetectable at first and the brakes may feel perfectly smooth. But the misaligned rotor will drag the pads more on that side that isn't flush and kick start the buildup of extra pad material on the rotor that gradually increases over time until it is able to be felt.

It all boils down to using quality parts and having them properly installed.

Proper installation includes bedding. Don't forget the bedding. Need to bed them bad boys. Bed em.

 

[jcb2]

Hihoesilver, Please forgive my ignorance but what do you mean by “bedding?”

 

[iamdub]

Iamdub, Thanks for that information. I never knew that. Everyone mentions “warped rotors” but what you’ve said makes sense.

I only recently learned this stuff a couple years ago. I always thought rotors were just sensitive to uneven temperature changes and cringed every time I hit a water puddle after using the brakes.

 

[iamdub]

Proper installation includes bedding. Don't forget the bedding. Need to bed them bad boys. Bed em.

YES. I recall in my youth of getting out and repeatedly stomping the brakes to "test" them right after installing new parts. I've since learned why I was always less than impressed with the new parts. I was glazing over the new pads and setting them up for less-than-optimal performance from the start.

 

[HiHoeSilver]

Hihoesilver, Please forgive my ignorance but what do you mean by “bedding?”

Different mfr will recommend slightly different procedures. Do some searching/emailing or a phone call to ask if you need to. Usually something like repeated slowdowns without stopping and some high pressure stops without "landing" on the pedal.

Basically you are wearing the pads into the rotors without glazing or burning into one spot which, as @iamdub stated, is the real cause of "warping".

 

[jcb2]

Different mfr will recommend slightly different procedures. Do some searching/emailing or a phone call to ask if you need to. Usually something like repeated slowdowns without stopping and some high pressure stops without "landing" on the pedal.

Basically you are wearing the pads into the rotors without glazing or burning into one spot which, as @iamdub stated, is the real cause of "warping".

I understand now. By "bedding," I thought you would tell me I'm missing some application. Thanks

 

[petethepug]

It’s all in the mix of the pad material. Ceramic is the latest blend that hits all the marks across the board. They’re quiet, long lasting, almost zero accumulation and very little visible brake dust.

The benefits of the non ceramic pad materiel is significantly shorter stopping distance that’s a trade off for one of the other beneficial attributes.

The Bosch brand I recently used actually had break/bedding instructions included in the box. Not that common for me in the past but possibly more common now.

Hopefully in the future we can see more brake dyno data relating to particular disc designs, heat cycling and post manufacturing mods like slotting and drilling. GM published some in the last ten years but not sure where it’s located now.

There’s a lot of pictures of cracked rotors on the web. If I posted mine showing the spiders of cracks between the drilling, it’d be an awesome thread.
If I left out the part that I wore the pad down to the bonding material to overheat the rotor, meh ... not so exciting. The geeks that get to be in motorsport because they run machines to put their money where their mouth is, that’s a person with a damn fine job.

https://www.brakeandfrontend.com/br...one-test-is-worth-a-thousand-expert-opinions/

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[swathdiver]

GM uses the term "burnishing" to bed the brake pads.

Accelerate to 30 mph and using moderate to firm pressure bring the vehicle to a stop. Don't lock them up. Repeat 20 times allowing time to cool between stops. I'll add that I do not come to a complete stop, but let off just before she stops and then stop. That was from another GM manual. Works for me.

 

[SnowDrifter]

Rotors don't actually warp. Well, there may be horribly low-quality ones made of a dangerously cheap metal that can warp from the sudden and drastic temperature fluctuations. But, the temperatures required to soften and melt the metal to cast rotors is far higher than what they experience when braking. What really happens is brake pad material burns itself to the rotor's surface, creating a high spot that is only measurable with a precision micrometer. Over time, this high spot(s) collects more pad material and grows. This makes the rotor extra thick in that area/those areas so they grab and release the pads as they pass through the caliper. This causes the pulsating feeling in the brake pedal. Cheap rotor material does play a factor as it can be a lower-quality iron that is more "adhesive" to the pad material. The pad material is what's primarily at fault, though. Sometimes, it's not necessarily a low-quality pad material as it is the pad material not being a good combination with the quality of the rotor's iron.

Improper installation can cause the same thing. If the rotor isn't seated perfectly flat against the hub due to dirt, rust, etc., this will make it wobble. It may be so minor that it's undetectable at first and the brakes may feel perfectly smooth. But the misaligned rotor will drag the pads more on that side that isn't flush and kick start the buildup of extra pad material on the rotor that gradually increases over time until it is able to be felt.

It all boils down to using quality parts and having them properly installed.

I disagree that rotors don't warp.

I've never turned a warped rotor only to have pad schmoo come off. It's always metal.

You can look at the rotor too, for that matter. Check runout, find your high spot, scrape it with a razor blade. That high spot won't go away. Start sanding? You'll get metal dust. Check it with a magnet, check your pad material with a magnet. It's rotor material

 

[petethepug]

Brake warp is a term that helped shops justify the labor costs of turning the rotors. Obviously the rotors don’t bend/warp like damaged pizza pans.

Hot spots, heat spots or metallurgical differences is what’s going on. The iron in the disc is changed metallurgically. Those hot spots expand and/or contract when excessive friction loads the disc beyond its design parameters.

A disc that’s not symmetrical in its metallurgical composition can be turned to remove the shrink/expand on its surface. Once turned, the disc is more susceptible to hot spotting because the pads forged it into a disc that’s heat treated unevenly.

Iron discs composed of multiple iron formulations will never correct themselves. The disc is doomed to self destruction, it’s too hard, too brittle and somewhere in between. When the pads load it up with friction again, the cycle starts all over again. This links says it better...

https://www.brakeandfrontend.com/warped-rotors-myth/


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[ThwopKing]

Ok so I totally forgot to give feedback on these brakes....
Ive got about 7k miles on them and soona s I put them on we took a 1500+ mile round trip to Florida and they did great. Initial break in and lots of heavy traffic on 95 produced a good bit of brake dust. So much so I wasnt sure I could stand it...yeah Im a bit picky and they were dirtying up my new rims lol. But, after that brake in they are actually really low of dust output. They can squeal a bit when cold but once they heat up...they do GREAT! I have had to come to a couple panic stops and man they honestly surprised me.
I can be ******* brakes and so far no vibrations, no odd shudders. Overall I'm happy with them and may put a full set on my 4Runner.