Are cheap rotors more likely to warp, or is it overtightening the lugs nuts that cause it?
Cheap Rotors
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Rapid temperature change before the rotors go through enough heat cycles to harden them and get a layer of brake pad material on them. Don't go too hard on them, brake steadily and get them up to temperature and let them cool down while in motion such as driving on the highway.
You can warp any rotors but cheap rotors do not have as much heat treatment from the factory, are thinner typically and there is less materials concern given to temperature change than more expensive rotors.
Once they are bedded in and go through some heat cycles the worry is mostly gone.
You can warp any rotors but cheap rotors do not have as much heat treatment from the factory, are thinner typically and there is less materials concern given to temperature change than more expensive rotors.
Once they are bedded in and go through some heat cycles the worry is mostly gone.
There are many reasons why rotors warp, but poor material quality could be one of them I suppose.
How cheap is cheap? Who's the manufacturer?
How cheap is cheap? Who's the manufacturer?
$20 rotors by Aimco
Kestas
Staff member
Originally Posted By: MGregoir
... but cheap rotors do not have as much heat treatment from the factory...
This is new to me. What heat treatment is done to rotors? The only rotors I've ever seen are as-cast ferritic gray iron.
... but cheap rotors do not have as much heat treatment from the factory...
This is new to me. What heat treatment is done to rotors? The only rotors I've ever seen are as-cast ferritic gray iron.
Originally Posted By: Kestas
Originally Posted By: MGregoir
... but cheap rotors do not have as much heat treatment from the factory...
This is new to me. What heat treatment is done to rotors? The only rotors I've ever seen are as-cast ferritic gray iron.
Same here.
Bob
Originally Posted By: MGregoir
... but cheap rotors do not have as much heat treatment from the factory...
This is new to me. What heat treatment is done to rotors? The only rotors I've ever seen are as-cast ferritic gray iron.
Same here.
Bob
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Maybe he meant "cryogenically treated rotors."
So throwing the rotors in the oven at 400 for 30 minutes then letting them air cool would help get rid of this problem?
Originally Posted By: moribundman
Maybe he meant "cryogenically treated rotors."
I think those are a joke, as OEM would use them if they work.
"Warped" rotors are usually caused by one or more of the following things:
1. Overtightening lug nuts or not tightening the lug nuts in a "star" pattern.
2. Uneven deposits from the brake pad, although this isn't true rotor warp. This can be cured by bedding in the pads and/or selecting a pad that is less prone to uneven material transfer.
3. True rotor warp from continuous high-speed braking or brake "riding"
Yes, cheap rotors are more prone to warp if and only if the warp is due to situation #3.
Maybe he meant "cryogenically treated rotors."
I think those are a joke, as OEM would use them if they work.
"Warped" rotors are usually caused by one or more of the following things:
1. Overtightening lug nuts or not tightening the lug nuts in a "star" pattern.
2. Uneven deposits from the brake pad, although this isn't true rotor warp. This can be cured by bedding in the pads and/or selecting a pad that is less prone to uneven material transfer.
3. True rotor warp from continuous high-speed braking or brake "riding"
Yes, cheap rotors are more prone to warp if and only if the warp is due to situation #3.
+1 for what Critic said. There was some great stuff posted here about brakes a while back that was very thorough.
With regards to "warping", the biggest culprits for the vibration you feel are rust behind the rotors (and wheels) causing uneven seating and excessive runout, and not tightening the lugnuts equally and in the star pattern.
That said, I've had good luck with standard replacement rotors from AAP on both the Z28 and the CRX. No complaints at all.
With regards to "warping", the biggest culprits for the vibration you feel are rust behind the rotors (and wheels) causing uneven seating and excessive runout, and not tightening the lugnuts equally and in the star pattern.
That said, I've had good luck with standard replacement rotors from AAP on both the Z28 and the CRX. No complaints at all.
I use whatever chinese rotors they sell at the parts store, 25 dollars each for my truck. I've found that they usually warp easily if I have them cut even one time, so I usually replace them about every 18 months. They're cheap enough, so why not.
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Originally Posted By: Brien
So throwing the rotors in the oven at 400 for 30 minutes then letting them air cool would help get rid of this problem?
Huh?
So throwing the rotors in the oven at 400 for 30 minutes then letting them air cool would help get rid of this problem?
Huh?
Of course, YMMV...
I bought a set of cheap lifetime warranty rotors at Autozone form my 1993 Olds Cierra. The price was not much more than machining them, and I've had little luck with machined rotors. The OEM rotors were warped badly. I feel due to not using a torque wrench or stick to put the wheels on or not using the correct patern when tightening them. The shops used an impact with no stick back then.
I put them on with a new set of Peformance Friction Carbon Metalics, and ran them about 75k. I used a torque wrench to put the wheels on, and did my own tire rotations. I even brought the wheels in to have the tires changed, so noone but me touched the lug nuts. The rotors never warped. Before giving the car to my grandmother, I decided to replace the brakes, including the rotors due to the warranty. When I removed the wheels, I realized that the rotors had many radial cracks in them. This was after 75k, and I am not easy on the brakes. Because it was going to grandma, who drives like the proverbial grandma, I put the same type back on, and they have done fine with her. I rotated her tires a while back, and with 25k on the new rotors, they still looked great.
For my Impala, when it came time to replace those rotors, I went with the best stock size rotors I could find. AutoSpecialty directionally vaned, but NOT drilled or slotted. I am VERY hard on this car, so nothing less than the best would do... Sadly, you cannot get the AutoSpecialty plain rotors anymore. I don't believe in reducing the mass of an already undersized rotor with holes and/or slots. The AutoSpecialty rotors were 4 Lbs heavier than the stock rotors, due to thicker braking surfaces, and mass is actually a good thing in a brake rotor. They do still sell the slotted type, now under the PowerStop brand.
I bought a set of cheap lifetime warranty rotors at Autozone form my 1993 Olds Cierra. The price was not much more than machining them, and I've had little luck with machined rotors. The OEM rotors were warped badly. I feel due to not using a torque wrench or stick to put the wheels on or not using the correct patern when tightening them. The shops used an impact with no stick back then.
I put them on with a new set of Peformance Friction Carbon Metalics, and ran them about 75k. I used a torque wrench to put the wheels on, and did my own tire rotations. I even brought the wheels in to have the tires changed, so noone but me touched the lug nuts. The rotors never warped. Before giving the car to my grandmother, I decided to replace the brakes, including the rotors due to the warranty. When I removed the wheels, I realized that the rotors had many radial cracks in them. This was after 75k, and I am not easy on the brakes. Because it was going to grandma, who drives like the proverbial grandma, I put the same type back on, and they have done fine with her. I rotated her tires a while back, and with 25k on the new rotors, they still looked great.
For my Impala, when it came time to replace those rotors, I went with the best stock size rotors I could find. AutoSpecialty directionally vaned, but NOT drilled or slotted. I am VERY hard on this car, so nothing less than the best would do... Sadly, you cannot get the AutoSpecialty plain rotors anymore. I don't believe in reducing the mass of an already undersized rotor with holes and/or slots. The AutoSpecialty rotors were 4 Lbs heavier than the stock rotors, due to thicker braking surfaces, and mass is actually a good thing in a brake rotor. They do still sell the slotted type, now under the PowerStop brand.
Originally Posted By: moribundman
Originally Posted By: Brien
So throwing the rotors in the oven at 400 for 30 minutes then letting them air cool would help get rid of this problem?
Huh?
HECK YEA!!!!! maybe a little BBQ sauce the last 10 minutes or so!!
Bob
Originally Posted By: Brien
So throwing the rotors in the oven at 400 for 30 minutes then letting them air cool would help get rid of this problem?
Huh?
HECK YEA!!!!! maybe a little BBQ sauce the last 10 minutes or so!!
Bob
I too have always been curious wheather or not we can heat treat our own rotors in a kitchen oven or take them to a local place to have them done at a reasonable price. Maybe a place like a high school Art Class that has a KILN for pottery. What we need to know is what tempurature and how long?
Kestas
Staff member
Man, the stuff is really flying today with people pretending to know metallurgy.
If MGregoir meant cryogenic treatment, he would have said so. It's a very specific treatment. It's rarely generically called 'heat treatment'.
30 min at 400°F will do nothing to the rotor metal. It also shows lack of knowledge in heat treating, where most treatments specify one hour minimum PLUS a soak time of one hour per inch of section thickness for the part to come up to temperature as a general rule. If you're talking about stress relieving, this is usually done at temperatures over 1100°F.
CB, other than stress relieving rotors, there's really not much more one can do heat treat to the rotors.
I don't see how cryo-treating helps brake rotors. There's no metallurgical basis for this treatment to have any efficacy on ferritic cast iron.
If MGregoir meant cryogenic treatment, he would have said so. It's a very specific treatment. It's rarely generically called 'heat treatment'.
30 min at 400°F will do nothing to the rotor metal. It also shows lack of knowledge in heat treating, where most treatments specify one hour minimum PLUS a soak time of one hour per inch of section thickness for the part to come up to temperature as a general rule. If you're talking about stress relieving, this is usually done at temperatures over 1100°F.
CB, other than stress relieving rotors, there's really not much more one can do heat treat to the rotors.
I don't see how cryo-treating helps brake rotors. There's no metallurgical basis for this treatment to have any efficacy on ferritic cast iron.
When I replaced the rotors on my Geo Prizm about 100K miles ago, I looked for the heaviest rotors.
100K + miles later, and still no warping. I'm on the same pads too, they appear to have quite a bit of life in them.
I think Oilbabe's Camry is on the original factory rotors and it has almost 181K miles in the past 6 years.
100K + miles later, and still no warping. I'm on the same pads too, they appear to have quite a bit of life in them.
I think Oilbabe's Camry is on the original factory rotors and it has almost 181K miles in the past 6 years.
I put them in our metal recycling dumpster at work.
My town dump has a metal bin and they love old rotors. Iron is worth money. I like to practice my discus throws with 'em. Very satisfying when they smack an old fridge.
I bet if one put them out in their recycle bin they'd get taken. Even if not on the official list of recyclables the driver might just pocket them, knowing where he can dump 'em.
I bet if one put them out in their recycle bin they'd get taken. Even if not on the official list of recyclables the driver might just pocket them, knowing where he can dump 'em.
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