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Are you saying that rotors are not that much different from each other because they are all made of cast iron, are the same thickness and are similar in weight?
Yes, the physical properties of a rotor designed for a specific application are the same across brands and models.
I've seen many a warped rotor in my day, even with Toyota/Lexus stock rotors. I believe the leading cause is riding the brakes, with the second biggest cause being improper torquing of the lugs. I recommend going with a performance brand rotor when replacing stock, but most of the time turning will restore them to flat. However, you end up with a thinner rotor which is even more prone to warping.
I've never heard of bleeding brakes solving a pulsing brake pedal before, but it is always a good idea to change your brake fluid every 4-5 years anyway.
Some of the shops specializing in tires and wheels take torquing seriously and do it right, but not all. Most general repair shops don't torque wheels properly. One more reason to perform this work yourself! The absolute best way to torque wheels is with them off the ground with the brake on. Then, using a torque wrench, come up to the spec gradually in several passes, in a star pattern. I re-torque my wheels every time I get a vehicle back, after having tire/wheel work done. I also check the pressures which are almost always way off. The techs working in tire shops are paid to work fast, not with precision.
Yes, the physical properties of a rotor designed for a specific application are the same across brands and models.
Hmmmm. I will have to ponder that. I know not all Steel is the same. The proportion of iron & carbon (and other elements) effects the end product. Also the fact you can machine used rotors to remove a layer (and make them flat), means it is possible to utilize rotors that are thinner. I think cheap rotor companies take advantage of that and sell slightly thinner rotors straight from the factory.
According to Amazon, the item weight on these two rotors is pretty huge.
Hmmmm. I will have to ponder that. I know not all Steel is the same. The proportion of iron & carbon (and other elements) effects the end product. Also the fact you can machine used rotors to remove a layer (and make them flat), means it is possible to utilize rotors that are thinner. I think cheap rotor companies take advantage of that and sell slightly thinner rotors straight from the factory.
According to Amazon, the item weight on these two rotors is pretty huge.
First, rotors are made of iron not steel. Steel is stronger but it does not dissipate heat as well. Steel is nothing more than iron put through a smelting process. I grew up in Pittsburgh in the 50s and have been to the mills many times. Second, just because it says this on Amazon does not make it so. One of them is wrong. Third, the amount of material removed when a rotor is machined is very small.
Second, just because it says this on Amazon does not make it so.
I agree the huge weight difference could be due to a listing error, but of all the rotors I saw, the weights did vary. Bosch was 5, AC Delco was 8 and Centric was 13.
Even though the metal shaved off is minor, it does create a thinner rotor. When I had my BMW Z4, bmw corporate policy was not to machine the rotor. Their policy was that rotors had to be replaced every pad change. People on the internet boards said it was because BMW designed thinner rotors to make a lighter car and machining them made them too thin and prone to warping.
If a reputable company like BMW designed thinner rotors for "one time use" than I can see how cheap replacements would do the same thing and make a thinner (but meet minimum specs) rotor that could not be machined.
I agree the huge weight difference could be due to a listing error, but of all the rotors I saw, the weights did vary. Bosch was 5, AC Delco was 8 and Centric was 13.
Interesting observation, including the info about the BMW rotor that is supposed to be replaced with each pad replacement. In the racing world, and the "M" world, cost is no object, and every ounce of shaved "unsprung weight" translates to improved handling and performance. Racing is a "pay-to-play" endeavor.
In the real world, and for those of us who aren't independently wealthy, we have to choose a product that fits our budget. I'm always killing myself doing research to find the best part, for the money, so I appreciate a thread like this. If an aftermarket rotor is a little heavier than stock, but has a much higher reputation for not warping, and the cost is fair, I would consider it. If, on the other hand, the aftermarket rotor is a little lighter, is more prone to warping, and cost more than stock, I wouldn't consider it. My first choice is a lighter-than-stock rotor, with a good reputation, that's reasonably priced. Even top brands aren't extravagantly priced, so I would err on spending the $ for good ones.
Not sure what this is going to add to the conversation...
Back in the day when I wanted to be a ball'r and was poor I bought an 1987 or 88 used BMW M5 that needed brakes and a few other fixes.
I decided to fix the top 100 minor problems , LOL, and decided to leave the brakes to the end. After a few months and lots of grinding sounds I decided to get them looked at. I was told I needed new rotors, brake pads and one seized caliper, the rotors had grooves in them from the metal to metal contact.
In my wise decision making phase, I decided to tackle the job. The caliper set me back to the point that I could not go out to the clubs for several weeks, so I decided to just replace the caliper and pads since my car sounded like a 747 landing every time I braked. The rotors looked good to me but YES they had very noticeable grooves in them, oh I forgot to mention that I bought the cheapest pads I could find. I drove on those rotors and pads for a few years and did not notice the difference ( I was young at the time and did not know better), in stopping power...but it was very quite!
On a serious note- I did not feel any vibrations and I know I did not follow proper brake bedding protocol.
In the real world, and for those of us who aren't independently wealthy, we have to choose a product that fits our budget. I'm always killing myself doing research to find the best part, for the money, so I appreciate a thread like this... If... the aftermarket rotor is a little lighter, is more prone to warping, and cost more than stock, I wouldn't consider it. My first choice is a lighter-than-stock rotor, with a good reputation, that's reasonably priced. Even top brands aren't extravagantly priced, so I would err on spending the $ for good ones.
Thanks Wilson for making this statement, This is what I had really meant when I first posted. It comes down to "If you are going to do your brakes yourself, do your research and buy the best rotor based on your use/need"
Slotted rotors are better at avoiding deposits but will cut down on pad life. Crossing-drilling is mainly useful for racing applications and venting gasses that can cause brake float due to high heat.
I replaced my front brakes with powerstop and z23. It was my first mod. Huge difference.
Brake jobs are where mechanics make a lot of money. The parts for basic replacement are super cheap at $60 or less, but you'll pay about 400$ min and a sloppy job will cause issues later.
Cleaning your disks with cleaner and bedding in your pads again is good practice.
I did this and greased all my pins and guides, did flush and gravity bleed, and used brake vibration goop for pad backing, and my brakes make absolutely no noise. My pads leave no dust. And it stops very quickly.
Contrary to popular belief, brake rotors, and especially brake rotors supplied by a reputable manufacturer such as DBA don’t warp, no matter how aggressively a vehicle is driven. Yet, as we know, brake pedal pulsation caused by out-of-true brake rotors is a fairly common problem that is almost invariably attributed to warped rotors, which is almost invariably confirmed by excessive amounts of rotor run out that is easy to “prove” with a dial gauge.
Myths take hold *because either A) they seem completely logical or B) they are so often repeated that they just become common knowledge. The warped rotor myth is a little bit of both. A rotor that contributed to a pulsation condition certainly appears “warped.” Plus, everyone says it — even technicians that know the rotor isn’t *really warped will say it as shorthand.
Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible.
Obviously rotors aren’t invincible. They can crack, break and develop irregularities that lead to pulsation, but all of those problems start to develop in other ways that need a technician’s touch.
Starting today, remove “warped rotor” from your vocabulary.
I'll post another couple of links, since there are still posters talking about warped rotors.
I read both articles and I'm still not sure why we shouldn't use the word "warped" in reference to rotors. The articles substituted the words "excessive run-out," "deformed," "distorted," "unevenly worn," but it's not clear why all of these descriptive words are better than "warped." I don't see a clear justification for this war of words!
Bottom line...if the rotors aren't "true," they need to replaced with high quality rotors, or turned. Personally, I wouldn't turn an OEM rotor if it was causing brake pulsing, as once turned, what's the odds it won't distort again? In fact, when an OEM rotor fails me, I prefer to go with a high-end, quality rotor from a reputable manufacturer, to ensure against a repeat performance.
I was glad to see both articles identify the improper torquing of wheel lugs as one of the contributing factors as that's one we can control ourselves. In fact, whenever I have tires installed, I immediately go home, loosen all the lugs, and torque them myself. I always check and adjust all the tire pressures too because they are typically all over the place!
Another issue that causes warping is riding the brakes. All of my wife's vehicles end up with the stock rotors warping because of this. While riding as a passenger with her, I see her resting her left foot on the brake pedal. She claims she was taught to drive this way so she can more quickly react when needing stop suddenly. I can't change the behavior, so all I can do is change her rotors with higher quality parts!
I read both articles and I'm still not sure why we shouldn't use the word "warped" in reference to rotors. The articles substituted the words "excessive run-out," "deformed," "distorted," "unevenly worn," but it's not clear why all of these descriptive words are better than "warped." I don't see a clear justification for this war of words!
I guess because "warped" rotors imply that they need to be replaced. I'm kind of an a crusade here because I was able to NOT replace my rotors by using a simple bedding procedure. I had the brakes checked last fall, my local indy shop lubed them, said everything looked perfect, but if the pulsation didn't go away, I'd need to replace my rotors. Well, I just saved a few hundred dollars. As mentioned above, brakes don't generate enough heat to warp the iron used in the rotor, so it all comes down to either worn (via metal-to-metal contact) or brake pad material build-up.
To each his own, but I'm trying to share information (that was a complete shock to me!) that can save $$$.
05-09-20, 05:08 PM
