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At 24k miles i had warped rotors and picked up a set of centric premium rotors. i am now at 37k miles and the rotors are warped! i don't ride the brakes and dont stop short, i am very confused as to how a set of rotors can be warped this quick. to have warped rotors after 13k miles is beyond me.

when i got the new centric rotors i replaced the factory brake pads with a set of performance pads from autozone, even though the factory pads had 80% life left in them.

could something else be causing them to warp? such as a bad set of calipers? or another problem with the braking system?
 

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Rotors get warped from just sitting on the shelf. Not much to notice though but i've seen brand new rotors and drums have SLIGHT warpage back in my wrenching days. I machined every drum and rotor before i even installed them on cars. Usually only took about .001 to .003 inches to clean up.

You have no idea how long they've been sitting around before being sold. I know it's hard to believe but the humidity and cold and hot CAN do some damage from sitting on the shelf. They usually have a coating on them though to keep them protected from the humidity and developing rust. Considering the humdity factor over on the eastern side of the country.

See if there's a specification on the rotors and buy a micrometer from harbor freight or borrow one from somewhere. If it's not stamped on the rotors look for a brake spec magazine that you might be able to download or find the car itself online. Rotors don't usually warp unless they're thinner then spec.

What's the symptons your having to suggest warped rotors????
 

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It's pad transfer baked onto the rotor surface, not a warped rotor (unless you hit a puddle while they were smoking hot or something)

Have them resurfaced and get a good quality pad - Akebono ProAct, Hawk, something name brand that isn't their economy formulation.

Make sure the rear brakes are adjusted. The rear drum brakes out of adjustment is common for Cruzes.
 

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I would also add that the hubs must be clean or you will get a brake pedal pulsation. If you get new brakes again, I'd stick with the centric rotors and get some Akebono proact pads. They work great. Before you put the new stuff on, get a wire brush and go to town on the surface of the hub.
 

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Check out this article.

Raybestos Brake Tech School, Part One: Rotors Don't Warp | Hendon Publishing

According to Raybestos, and all other brake manufacturers (whose engineers are more qualified to make these statements than any backyard mechanic on any forum), rotors don't warp, even when driven by the most aggressive traffic officers. Pulsation happens by one of two causes: 1) either the rotors were installed out of true with the hubs, or 2) the wheel was improperly torqued to the hub at the last tire change. Pulsation can start in just a few thousand miles if the wheels weren't torqued correctly.
 

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It's pad transfer baked onto the rotor surface, not a warped rotor (unless you hit a puddle while they were smoking hot or something)
This, one thousand times, this!

Did you properly bed-in the new pads?

FWIW, you could have scoured down the stop pad surfaces a slight amount, and reinstalled them with the fresh rotors, giving both an even surface to bed-in properly.

My Cobalt used to absolutely cook rotors, especially trying to haul the car down from well over 100 with tiny 10.X" brake rotors. Granted, my brake fluid isn't doing much these days (it's brown - it needs to be changed), but ever since installing the 18s I haven't had any hot-spotting. My theory is that the 15" steelies would simply trap all the heat from the brakes in there, and contribute to rapid pad-material-transfer.
 

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Check out this article.

Raybestos Brake Tech School, Part One: Rotors Don't Warp | Hendon Publishing

According to Raybestos, and all other brake manufacturers (whose engineers are more qualified to make these statements than any backyard mechanic on any forum), rotors don't warp, even when driven by the most aggressive traffic officers. Pulsation happens by one of two causes: 1) either the rotors were installed out of true with the hubs, or 2) the wheel was improperly torqued to the hub at the last tire change. Pulsation can start in just a few thousand miles if the wheels weren't torqued correctly.
I"m not a backyard mechanic. And i don't agree with that article. And when I attended a Raybestos class. I was told completely different then what some Media Group is publishing.

Rotors DO warp. It's caused by uneven heating and cooling of the metal. It's also caused by the uneven braking pressure between the fronts and the rears. It SHOULD be a well known fact that front brakes do more work then the rear brakes. Add to that the summer time heat. And as rotors wear down they get thinner. Thinner rotors will warp faster then brand new thick rotors.

I don't wrench now but back in the day. Some cars were notorious for warped rotors. The Ford Taurus comes to mind. Brakes wouldn't last more then 25k miles and that was pushing it.
Back in the day. The average front brake was lucky if it could make 40k miles. While the rear brake shoes would last over 100k miles.

So here's a question.

If rotors don't warp. Then what's the purpose of the brake lathe?
When you mount the rotor or drum. And spin her up. You don't see any abnormal movement. The rotors spin perfectly straight. The drums spin perfectly round. Set your stones and watch as the rotors slowly clean up. First .001 inch. Then .002. Then .003. The thicker rotors usually only required about .005 before a totally clean and smoother surface. Thinner rotors usually required more.

Rotors DO warp. That's the terminology taught by Raybesto's. And other brands. It's more commonly known as HIGH SPOTS. And it's caused by uneven heating and cooling. And witnessed on a brake lathe. High spots diminish braking as they don't allow the pads to touch the rotor surface 100%. The pads are only touch the higher spots. The thinner the rotor gets. The worse the situation can become. To the point of pulsating pedal. And even steering wheel vibration.

Ever had your car vibrate when hitting the brakes at highway speeds?

Back in the really old day. When all 4 brakes were drums. You wouldn't get a pulsating brake pedal. Instead. You got a pedal that felt like hitting a brick wall. And braking performance was very poor. I had a 76 Plymouth Duster that way. I machined all 4 drums and brakes were golden again.

Shops pull wheels off all day long. The only places that might torque are the tire shops. If the problem was as the article stated. We'd ALL be having problems.
I turned wrenches for 12 years. Not once did i ever have a customer come back with brake problems.
I have a friend who owns his own tire shop. Started it when he was 20. He's now 55. I don't think he's ever had a customer with problems either.
Now if some of you want to say rotors don't warp. That's fine. But they DO develop high spots. It's caused by uneven heating and cooling.

I"m long retired now. My toolbox has been locked up for years. You guys could teach me a few things about these newly designed cars. But for rotors.
I'm gonna stick with what 12 years has shown me. And what Raybestos and Bendix taught. Not what some media group publishes on the internet. :)
 

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snowwy66?

I'll take your twelve years and raise you by fourty......and my toolbox is still a daily.......I can't leave the biz....in my blood.

Anyways, for educational purposes (to all readers as well) look up 'zeckhausen racing'. This is a premier supplier of high performance as well as standard brake parts.
From there, go to 'glossary of brake technical terms'........read all that about 'warpage' (alphabetical listings) and go further by reading 'Judder' and "High Spots'.

There is a chance you will reconsider your position on 'warpage'.

Good reading if you are into the tech.

Rob
 

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It all starts with proper Maintenance...A "smooth" clean hub, with a thin coat of anti-seize on it, and Torquing the lug nuts to the proper specific torque and sequence. Also making sure the Caliper "floats" and doesn't bind on the guide pins causing the rotor to heat up unevenly. Doing these procedures on dozens of brake jobs, I've never had an issue with pulsating brakes.
 

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snowwy66?

I'll take your twelve years and raise you by fourty......and my toolbox is still a daily.......I can't leave the biz....in my blood.

Anyways, for educational purposes (to all readers as well) look up 'zeckhausen racing'. This is a premier supplier of high performance as well as standard brake parts.
From there, go to 'glossary of brake technical terms'........read all that about 'warpage' (alphabetical listings) and go further by reading 'Judder' and "High Spots'.

There is a chance you will reconsider your position on 'warpage'.

Good reading if you are into the tech.

Rob
This!

Mechanical engineer here: they definitely do not warp.

The purpose of a brake lathe is to take the surface down to fresh, smooth surface - to remove the unevenness caused by brake pad deposits. NOT because the rotor is physically warped. The brake pad material cooks to the surface, and causes the feeling of warpage, as the surface is no longer smooth. The rotor, being a wear surface, no longer wears evenly. Turning the rotors brings the entire surface down to where it is even, removing the transferred pad material.

Driving on the street, even with repeated hard stops, you're not likely to even see near 1000 degrees F - the annealing point of steel is around 1500 degrees. Not being remotely near that means you are not going to be able to physically warp the steel, especially with how thick they are. It's not going to happen - the only chance you'd have is if you dropped the rotor in a bucket full of water, and even then, it'd still likely not warp.
 

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My stock rotors are still doing well after 70k miles.
Instead of putting new rotors, I opted for having the brakepads wear into the new rotor.
 

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2 questions.

As i explained previously. Even a brand new rotor can be HIGH SPOTTED. It's never been used. So there's no chance of brake material buildup. Yet the surface is uneven. How is that possible?????

How is it possible for thin rotors to cause problems sooner then thick rotors???? A brand new rotor might last 100k miles. But it wears down. STick it on a machine. Make the surface smooth. But now it's beyond specs. So how could brake material cause problems within 5k miles on smooth surface rotor that's too thin. But a thick rotor will last 100k miles.

YOu don't need 1000 degrees to cause heating of material. But they do get hot. And they cool down. Unevenly.
 

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2 questions.

As i explained previously. Even a brand new rotor can be HIGH SPOTTED. It's never been used. So there's no chance of brake material buildup. Yet the surface is uneven. How is that possible?????

How is it possible for thin rotors to cause problems sooner then thick rotors???? A brand new rotor might last 100k miles. But it wears down. STick it on a machine. Make the surface smooth. But now it's beyond specs. So how could brake material cause problems within 5k miles on smooth surface rotor that's too thin. But a thick rotor will last 100k miles.

YOu don't need 1000 degrees to cause heating of material. But they do get hot. And they cool down. Unevenly.
Because a thin rotor heats up quicker than a thick rotor, transferring that heat to the pads, therefore causing the pads to transfer material to the rotor. NOT warp the rotor itself. A thick rotor takes a lot more to heat up, and therefore it's a whole lot less likely to cause hot-spotting due to pad transfer.
 
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Regarding the question about finding a new rotor in need of surfacing........most common reason is how accurately the rotor is mounted on the arbor.
Like anything, there will be a variation from machine to machine......in particular the mounting method for a blanchard grinding process (the method used on the new rotor) and the tool cutting method used in a shop.
The blanchard grinding is an absolute......it is as accurate as possible with the top hat (hub mating area). The rotor is stationary and the cutting head rotates and revolves around the friction surface.......essentially the same as the process used to resurface a flywheel.

This means, the shop resurfacing process (ammco machine) may actually be introducing a variation to a rotor that was dimensionally perfect.

There is another school of thought though rarely discussed.
It is believed that many offshore rotors are machined 'Green'.

'Green' as applied to cast iron means it has not been seasoned. It is said, the molecules in fresh cast iron take several weeks to 'calm down' (my term).
Fresh cast iron is generally put out in the weather, allowed to rust, get rained on, snowed on, just left alone for thirty to forty five days. This is called 'seasoning'.......it is said the part dimensions fractionally change during this time.
After this period of time, the part is cleaned of corrosion, machined, shipped.

So, that being said, offshore rotors that are machined prior to seasoning MAY have variations that develop after the machining process.
Having never blanchard ground one of these I am not in a position to call it a fact......but it does have merit.

The International Harvester engine block/head casting plant was about ten miles from my home......I was always struck by these gigantic racks of cast parts just sitting out in the weather, orange with rust.......seasoning.

Rob
 

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That fits with the rest of the "rust" theme that International Harvesters seemed to have.
 
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