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Thread: How to Protect New Front Rotors

  1. #1
    Campaign Veteran since9's Avatar
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    How to Protect New Front Rotors

    I just replaced the front rotors on my truck, as Ford's factor originals had warped significantly, despite the fact there was plenty of wear left on them and the brakes were only half gone.

    My concern is that the "old" rotors only had 38,000 miles on them, and they were nearly rusted through from the vented interior out! Some of the vent vanes were completely gone. Meanwhile, the vented disk rotors I had on my Acura were still good to go at 180,000 miles, and were free from rust, despite the fact that most of the time they were on the car I was in northern climes with salted roads. I tried to find stainless replacements, but nothing was available in town, so I got some medium-quality ones from Advance Auto.

    My question is this: How do I protect the regular steel rotors from becoming obliterated with rust?

    I'd thought of hitting it all over, inside and out, with Rusty Duck, as it's a high-temp, waterproof, very heavy weight grease, and a thin layer would stay put. Naturally, I'd clean the braking surface with break parts cleaner.

    Anyone else experienced similar issues? How did you solve it?
    The First protects the Second, and the Second protects the First. Together, they protect the rest of our Bill of Rights and our United States Constitution, and help We the People protect ourselves in the spirit of our Declaration of Independence.

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    deleted
    Last edited by Daylen; 11-21-2010 at 05:03 PM. Reason: reduce number of insulted individuals

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    not stainless steel!!!

    brake rotors are cast iron, not steel. Cast iron can take the heat much better than anything else and brakes can get really hot. Although cast iron rotors can and do warp, they are not as prone to this as other metals, such as steel, would be under the rigors of braking.

    What to do??? Buy replacement rotors that have a "lifetime" warranty. One good piece of advice is to make sure that the replacement rotors you buy are NOT from China. The Chinese rotors usually are not properly heat treated to relieve stresses and stiffen the rotors by proper crystalization. Crystalization is the property that gives a material its "stiffness".

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    Regular Member HeroHog's Avatar
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    Mask the bearing holes and the disk faces where the pads ride. Bead blast clean and free of any surface rust. Pick a color and have them powder coated. Finish machine the faces and install after installing and packing bearings and installing new seals. If your rotors are not a part of the hub, then it's a matter of blasting, painting, powder-coating, finish machining and installing. Black is recommended at it sheds heat beater than a lighter color.

    PS: Start with a quality rotor and, if you like, I would Cryo-treat them after blasting and before powder coating.
    Last edited by HeroHog; 11-21-2010 at 04:08 AM.
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    Campaign Veteran since9's Avatar
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    Quote Originally Posted by Daylen View Post
    greasing your brakes!? unless you are trying to win a Darwin award.
    No, and you didn't bother reading my entire post, did you? Particularly, "a thin layer would stay put. Naturally, I'd clean the braking surface with break parts cleaner."

    They come packed in a waxy grease similarly to cosmoline, Daylen. Proper preparation requires degreasing them in varsol, then removing any oils/greases from the varsol treatment by spraying the braking surfaces with brake parts cleaner.

    I never suggested leaving any amount of grease on the braking surface itself. I completely rebuilt four enginess in high school (nearing 30 years ago) and have done all mechanical work on my vehicles ever since, including numerous brake jobs (pads, rotors, drums, brake lines, and master cylinders) with the sole exceptions of transmissions and body/frame repair (it's easier to let the insurance pay the experts).

    I'm not stupid, so please don't assign me a gravesite just yet, particularly one associated with a "Darwin award." That's downright insulting, Daylen.

    Quote Originally Posted by 6L6GC View Post
    brake rotors are cast iron, not steel. Cast iron can take the heat much better than anything else and brakes can get really hot.
    Yes they can! However, dropping from 14,115 feet to 11,000 (15% grade) in about four miles in 55 deg weather and rarified atmosphere never heated them up to more than warm to the touch. Mostly I engine brake down grades, anyway, even around town. I'm sure if I used nothing but brakes coming down from Pikes Peak, they'd get a little more than just warm.

    One good piece of advice is to make sure that the replacement rotors you buy are NOT from China. The Chinese rotors usually are not properly heat treated to relieve stresses and stiffen the rotors by proper crystalization. Crystalization is the property that gives a material its "stiffness".
    That's good advice, but alas, most rotors these days are cast in China.

    There are several types of cast iron, including grey, white, maleable, ductile, and alloyed. The bright hue of my rotors (about like that of nickle) suggest they're either alloyed or simple white iron. White iron is simply cast iron with a lower than normal silicon content that's cooled faster than normal. The result is that the carbon precipitates as cementite (Fe3C) rather than graphite. It's often used in larger casting to provide for a surface with more hardness, while the interior is left to cool more slowly, thereby resulting in greater toughness.

    Ideally, brake rotors should not be white iron, as it's too brittle, though I would imagine it would be ok if the surfaces were quenched to this standard.

    The brightness of my new rotors indicates they're either alloy or white iron. The factor originals were clearly grey iron, through and through, which is one of the reasons they rusted rapidly and deeply.

    Back to the issue: Evidently, rust is common enough inside the vents to warrent an entry in Wikipedia.

    Quote Originally Posted by HeroHog View Post
    Mask the bearing holes and the disk faces where the pads ride. Bead blast clean and free of any surface rust. Pick a color and have them powder coated. Finish machine the faces and install after installing and packing bearings and installing new seals. If your rotors are not a part of the hub, then it's a matter of blasting, painting, powder-coating, finish machining and installing. Black is recommended at it sheds heat beater than a lighter color.

    PS: Start with a quality rotor and, if you like, I would Cryo-treat them after blasting and before powder coating.
    You sound like an engineer! Or at least a machinist. Well, I have to use the rotors I bought, as they're already on the vehicle (I installed them Wednesday). My rotors are also the hubs.

    The powder-coating process you're suggesting... It sounds similar to bluing, but it's not. What's the process called?
    Last edited by since9; 11-21-2010 at 09:30 AM.
    The First protects the Second, and the Second protects the First. Together, they protect the rest of our Bill of Rights and our United States Constitution, and help We the People protect ourselves in the spirit of our Declaration of Independence.

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    Quote Originally Posted by since9 View Post

    The powder-coating process you're suggesting... It sounds similar to bluing, but it's not. What's the process called?
    "Powder coating".

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    Regular Member HeroHog's Avatar
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    It's not too late to do it. It is called "Powder Coating" and what is done is that a special "paint" is applied as a dried powder that is electrostatically applied to the part. That part is then "baked" which "melts" the powder and it bonds with the metal in a VERY durable coating that is chemical, heat and abrasion resistant.

    Cheapest way? Degrease them and paint them with VHT Header paint!
    Speedy: LOCAL League Sec/Treasurer, Information Officer
    AKA: Hero Hog, Dr. Speed, "The Brass Mangler" and "That fat, old, balding, Grey-bearded gimpy guy"

    I don't have NEAR enough ammo on hand. `nuff said.

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    "Stay safe..." - Paul "Skidmark" Henick, RIP

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    What do you want to replace, rotors or brake pads? Your brake pad decision rides on that. In my opinion, I'd rather replace pads more frequently than rotors. Your pad material dictates which component will wear first.
    It takes a village to raise an idiot.

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    Quote Originally Posted by Kirbinator View Post
    What do you want to replace, rotors or brake pads? Your brake pad decision rides on that. In my opinion, I'd rather replace pads more frequently than rotors. Your pad material dictates which component will wear first.
    And with the newer pad materials being more durable (read this as hard) than the brake pads of 15 or more years ago, YOU WILL GET MORE ROTOR WEAR and in my personal experience generally I need to replace the rotors at the same time I replace the pads. There is a minimum safe thickness for the rotors and as the rotors wear with brake use they eventually get worn to the point that you aren't able to resurface the rotors and still have enough thickness left to be safe.

    Softer pads that don't cause as much wear on the rotors also tend to leave more of the nasty black brake dust on your fancy shiny wheels also.

    Initially, I was going to suggest that if you never used your brakes you wouldn't need to replace your rotors either. Be warned that there may be OTHER undesirable results as a consequence of this particular decision!

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    Brake pads are cheaper to replace than clutches, and especially automatic transmission clutches.
    It takes a village to raise an idiot.

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    Quote Originally Posted by Kirbinator View Post
    Brake pads are cheaper to replace than clutches, and especially automatic transmission clutches.
    I was going for "collision repairs"! LOL

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    Quote Originally Posted by Kirbinator View Post
    What do you want to replace, rotors or brake pads? Your brake pad decision rides on that. In my opinion, I'd rather replace pads more frequently than rotors. Your pad material dictates which component will wear first.
    As I said, I replaced both last Wednesday. I choose better rotors and cheaper pads (no metal particles in them, either) guaranteed not to last as long as the more expensive pads. Thus, yes, the pads will (should) wear the most, not the rotors.

    I've concluded that Ford's factory rotors suck on purpose just to sucker owners into the service department shortly after the 3 yr/30,000 mi warranty for a $500 to $800 repair bill.

    Quote Originally Posted by JoeSparky View Post
    Softer pads that don't cause as much wear on the rotors also tend to leave more of the nasty black brake dust on your fancy shiny wheels also!
    Dust is acceptable. We have plenty of it here in Colorado. Brake dust blends right in.
    Last edited by since9; 11-23-2010 at 11:04 AM.
    The First protects the Second, and the Second protects the First. Together, they protect the rest of our Bill of Rights and our United States Constitution, and help We the People protect ourselves in the spirit of our Declaration of Independence.

  13. #13
    Regular Member HeroHog's Avatar
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    My Ford Escape ate rotors. Stock brakes, the pads had PLENTY of life left and the rotors were worn .045 - .070 in different places! I replaced the "hats" and threw on some standard Auto-Zone pads at around 125k miles and they are still going strong at right at 200,000 miles.
    Speedy: LOCAL League Sec/Treasurer, Information Officer
    AKA: Hero Hog, Dr. Speed, "The Brass Mangler" and "That fat, old, balding, Grey-bearded gimpy guy"

    I don't have NEAR enough ammo on hand. `nuff said.

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    "Stay safe..." - Paul "Skidmark" Henick, RIP

  14. #14
    Campaign Veteran kimbercarrier's Avatar
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    Since9, I work part-time for Advance Auto. If you buy the top grade rotors (Wagner, Raybestos, Bendix, etc.) they will last a lot longer than the cheaper ones and without warping. The cheap pads are made out of a generic material and will wear out fast as well as wear out the rotor faster than a top quality pad.

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