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Warped brake Rotors

andys120andys120 Loudon NHPosts: 20,564
I used to own a '91 Taurus SHO. Among the many maintainence issues affecting that car was a repeated ocurrance of brake rotors warping. I was told by a dealer principal with whom I was friendly that this was caused by over tightening wheel nuts when mounting tires.
I didn't believe it because I'd never had the problem recur so frequently with any other car. Most cars I've owned never had the problem but a buddy has had it w. 2 different Tauri.
Oddly it's never occurred on my other Ford product ('86 Mustang 5.0L).
Was he making excuses for Ford or just passing on an old wive's tale, or is there something to it???

2001 BMW 330ci/E46, 2008 BMW 335i conv/E93



  • armtdmarmtdm Posts: 2,057
    New Buick has had a chatter since new, finally took it in at 19,000 miles. They repalced all foru rotors. Seems to have solved the problem However, lug nut came off about a week later but the rest of them seem okay,.
  • 8u6hfd8u6hfd Posts: 1,391
    Sounds like he's making excuses.
  • pjksrpjksr Posts: 111
    For about $55, you can buy a decent click-type torque wrench at Home Depot.

    Lug nut torque should always be checked a couple hundred miles after tire changes--or whenever you let anyone work on your vehicle ;-)
  • jgmilbergjgmilberg Posts: 872
    On some of the cars that only have 4 lugs and even some with 5 lugs on them, an uneven amount of torque WILL cause them to warp. Older cars have studs on the rotors and the wheel bolts to that only making them less likely to warp, on newer cars and most new trucks, the rotor slips on the studs and hub and the wheel bolts down over that. Essentially making a rotor sandwich, and like a sandwich if you put to much pressure in one spot it will flatten it out making it warp. This is really over simplifying how it works, but it gives you a general idea.

    Some other more common ones are using 2 feet to drive, the left one usually ends up resting on the brake pedal causing them to drag. Another one is bad caliper hardware or a stuck caliper overheating the rotor causing it to warp.

    One other common misconception I have discovered is that if you turn a warped rotor to make it square again it only warps again because you have removed more material from one part than the others causing a thinner spot, and that spot is more likely to overheat than the thicker spot, once again warping the rotor. In general if I have a warped rotor I replace it and go over every part of the brake system to make sure it's fixed right. After that all that's left is over torquing.

    I am a GM fan through and through, I have seen this happen on GM cars too, the Cavalier/Sunfire come to mind right away. Watch those tire guys, make sure they use torque sticks and a click wrench to tighten your rims.
  • zr2randozr2rando Posts: 391
    If you get home and wash the car and hit that wheel/rotor with the hose while its hot....
    ther ya go!
    see y'all
  • zueslewiszueslewis Posts: 2,353
    newer ('89 up) T-birds and Cougars, Sables, Mustangs and FWD Lincoln products, Ford had major issues with brake rotor warpage. It happens now with many cars due to two problems: the OEM rotors are too thin to dissipate heat, and warp as they're being used; asbestos is no longer in brake pads - asbestos was very good at stopping cars and absorbing heat, where heat wasn't transferred to the rotors. The new pad materials, mandated by the EPA, stops cars OK, but retains much more heat, damaging rotors sooner. It ain't that your lug nuts are too tight!

    The only cure is to replace the front rotors with Taurus Police rotors from Bendix or another good brake component company, or if you don't mind shelling the dollars, contact Baer Racing - they make a 4-wheel replacement kit with bigger, more gnarly rotors that will lower your braking distances considerably.

  • swschradswschrad Posts: 2,171
    my middle fingertip is healing rather nicely, but I gotta tell you, fastest way to get a dime-sized blister is to drive about five miles, normally, no hammer-em stops, notice some discoloration on the rotor, and touch it to see if this is baked-on crud from the pads coming apart.

    those brakes are converting, in the case of my exploder, 3200 pounds * 40 mph of energy into waste heat in several hundred feet at every stop light. that's a lot of calories. the rotor or drum is the only place to sink that heat away. plenty enough heat to warp a big chunk of solid metal, which is why rotors are made like the Fan Impellers From Hell, and why there are big holes in wheels.

    tire monkeys with air wrenches are public enemy number 1... it's much better if they start on "first click" and star-pattern across the bolts several times to get things tensioned right. that also minimizes the chances of "cocking" the wheel at the edge of the threading on one bolt because the opposite bolt(s) were taken tight right away... that makes the wheel a lever that with the heat is sure to warp a rotor in a relatively short distance.

    and once warped, you are never going to get that rotor straight again.
  • bolivarbolivar Posts: 2,316
    ..that a problem is the pins lose their lubrication, or when brakes are rebuilt the pins are not lubed.

    And the calipers slide on these pens. With no lube the calipers, with the pads, will drag and cause more heat in the rotor, causing warping.

    In general, I think the rotors in the last few years are being made cheep (low quality steel or thin rotor) because you are hearing a lot about warped rotors on all kinds of cars.

    Not long ago I drove a 1998 Caddy Seville with only 4,000 miles just coming off a 3 year lease (yes, you read this right, just a little more than a 1,000 miles a year driven!) and it had badly warped rotors. Sevilles are known for this problem. But in 4,000 miles?????? It did come from Michigan, I wonder if the combination of salt and very low usage caused the calipers to freeze up and cause warping even faster.

    I also drove a 97 Seville at about 27,000 off a 3 year lease and it also had warped rotors.

    Like I said, it's rather common now on a lot of cars. And this is something you never heard of happening until 60,000 or more miles 15 years or more ago
  • andys120andys120 Loudon NHPosts: 20,564

    2001 BMW 330ci/E46, 2008 BMW 335i conv/E93

  • swschradswschrad Posts: 2,171
    if they could make the OEM rotors even thinner, the pads would be riding on each other.

    you have a point on the thread lugs being used dry and dirty, that's another reason why 5-minute-Fred scares me at tire places. the flip side is that I have seen recommendations that the wheel lugs NEVER be lubricated, because excess grease will supposedly also cushion the nut on the lug, and it will shake loose.

    hanging calipers will also definitely beat the rotors up, but there should be some sense of the car "pulling" or extra noise most of the time. I had one hang, barely, on the right front recently, and a car wash and the old self-adjusting drum trick of backing up at about 10-15 mph and doing a firm stop got whatever was sticking on the pin free.
  • andys120andys120 Loudon NHPosts: 20,564
    as on the regular Taurus?

    If they did it's a built in design flaw that any rookie engineer or amateur mechanic could tell you was WRONG.

    2001 BMW 330ci/E46, 2008 BMW 335i conv/E93

  • zueslewiszueslewis Posts: 2,353
    are different, because the SHO has larger diameter rotors and uses rear discs instead of drums like on the regular Taurus. The SHO rotors are made of the same thickness of material, though, and are just as prone, if not more so, to warpage.
  • andys120andys120 Loudon NHPosts: 20,564

    2001 BMW 330ci/E46, 2008 BMW 335i conv/E93

  • bburton1bburton1 Posts: 395
    Older honda cars had awful problems caused by yahoos using air impact wrenches to tighten lug nuts. Had an 80 accord and it got to the point I would take my torque wrench and make the tire change guys use it instead of torque sticks.

    Also older Honda disk replacement is a bear because they are pressed into the front wheel bearing assembly. Supposedly 98 and up rotors are much easier to replace.

    So watch out when anyone changes tires on your vehicle. You could get bent rotors out of the deal.
  • vidtechvidtech Posts: 212
    Not sure if this was posted before.I have found the chinese made rotors are very prone to just shows you can't beat good American steel.I never had problems with replacement rotors or drums until the stores started selling the cheap chinese parts.I cannot even find a store that stocks rotors made in USA anymore.
  • jgmilbergjgmilberg Posts: 872
    It really sounds goofy, but vidtech is right. For me when I use the China made rotors they wear out faster, or warp easier than American/Canadian ones. I know that Pep Boys carries Raybestos brand rotors made in the USA, and that's the reason they cost more, about 20% more in fact when compared to imported (Chinese) rotors. I also have had very good luck with Canadian rotors/drums, I can get them from my local parts store, Murray's Discount Auto Parts, they actually used to carry Chinese and Mexican rotors and drums, but had a lot of them come back warped or not lasting through the warranty period of 2 years. At least they noticed the problem and switched vendors and are finally getting good parts for those who work on their own cars.
  • fdchieffdchief Posts: 10
    Can anyone tell me anything about warping rotors on my 2001 Chevrolet Impala. Purchased new Feb. 2001 - one year and 35,000 miles later only problem has been taking back to shop 5 times for smimmy (rotors each time). They are giving me a line it's because of the 4 miles a day I travel on dirt roads to get to and from home! They have replaced the rotors, trued the rotors, replaced pads and turned rotors. In one thousand miles this baby is mine and not the dealers problem, any suggestion. P.S. For the record, I told them when purchasing the car I travel dirt roads and put a lot of miles on my vehicle working, thus needed one which is comfortable and able to keep up! Help, Help, Help it's doing it again!
  • gslevegsleve Posts: 183
    did not torque the lug nuts to factory specs thereby heat generated by the brakes causes warpage of the rotor. Situation may not be rectifiable due the initial damage may have to opt for new rotors and pads.

    Just a thought
  • zueslewiszueslewis Posts: 2,353
    I can't tell you how many Impalas, Malibus, Grand Ams. etc (mid-size GM products) I seen that have warped brake rotors. It's the quality of the rotors (thickness and material) combined with heat.
  • anon70anon70 Posts: 82
    during my last brake job (at midas), i had my rotors machined. after three thousand miles, i start to hear a low, deep noise of metal grinding when i am at slow speed and come to a complete stop. this continues on and off.

    at that time i was taking automotive classes. my prof said the rotors looked too thin. i got new ones @ $18 each. (Midas is SUCH A RIPOFF. they charged me $50 per rotor to machine them while on the car!)

    10k miles later (my class has ended), the noise has returned. is it the rotors?! how can i tell if it's warped? (my prof didnt say anything about the old ones being warped.)
  • swschradswschrad Posts: 2,171
    it doesn't take many thousandths of an inch to make a big wobble under braking (or to drag once a revolution on the pads), and if you have a runout indicator (dial point micrometer), pull the wheel and fix it to a stand at the side of the rotor, needle in contact with an area near the outside of the contact footprint. a runout indicator shows plus and minus from 0... if your dial indicator doesn't, set it so you are maybe showing .010 inch, aka the micrometer is being compressed where the detector needle is hitting the rotor.

    slowly spin the rotor around. on any rotor, there is bound to be some minor movement of the dial pointer... but it should be under a specified range for the vehicle. for sniffs and grins, let's say .005 maximum runout is the spec on your car. if the needle is swinging from .017 to .002 you are finding a warp out of spec.

    the tool is probably in the $100 range give or take, but any serious mechanic who does brakes will be equipped, because that's how you qualify a warped rotor (needing to make a payment does NOT constitute a test for valid anything.) so any mechanic who works brakes should be able to do this for maybe 30 minutes worth of labor charges and a couple bucks worth of the usual shop rags fee.
  • alcanalcan Posts: 2,550
    Rotor warpage will show up as a brake pedal pulsation, more pronounced at higher speeds under heavy braking. If semi-metallic pads were installed, the grinding noise is probably due to the metal content of the pads. Most manufacturers' specs for rotors are .003" maximum for runout or warpage, .0005" for parallelism or thickness variation.
  • bburton1bburton1 Posts: 395
    If they are really warped, the whole front end will shimmy when you hit the brakes. Before I figured out what the tire change jockeys were doing with their air driven impact wrenches, I had this happen several times on a 80 accord. Helped to just retorque the lug nuts properly. Still shook a bit but no longer a control problem when really standing on the brakes.

    When I have tires replaced now-I take my own over priced torque wrench and watch the tech use it to tighten the lug nuts.
  • zueslewiszueslewis Posts: 2,353
    rotor warpage usually doesn't cause any noise - the grinding noise is either your brake pads or gunk between the pads and rotors. $50 to cut them on the car - that's ridiculous - I'd get a price for cutting rotors from another shop, then return to Midas with the lower estimate and ask for the difference in cash or in-store credit. If the won't do that, make a picket sign!
  • From the time I had 6600 miles to present(71000)
    I have had a major vibration from my front
    brakes.I have had my rotors cut (3) times.
    Has there been any bulletins about this
    problem and/or solutions?
  • zueslewiszueslewis Posts: 2,353
    Galant and Diamante for that reason. The only way to fix it is to use aftermarket brake rotors, like Bendix, instead of Mitsubishi parts.
  • on almost any car these days:

    Accelerate to a good highway cruising speed - say 60-65 mph - brake hard to a complete standstill and hold your foot on the brake pedal for a minute.

    The hard stop puts a huge amount of heat into the rotor (that's what it is there for), but holding your foot on the pedal keeps the hot brake pads in contact with the rotor, preventing that part of the rotor from cooling down as fast as the rest, which is exposed to the air. The temperature differential across the rotor then causes warping.

    Most rotors are quite thin these days, for cost and weight/CAFE reasons, so they can't resist warping like the older thicker ones.

    Warping is felt as a pulsation through the pedal when braking. In severe cases the whole front end may shake, which can be felt through the steering wheel.

    Best way to try and avoid it is to brake hard only when really necessary, and to release the brakes as soon as possible after a stop.

    Dust and dirt will generally cause scoring of the rotor rather than warping.
  • aaceaace Posts: 7
    When I brake at 65mph, I don't feel any brake pedal pulsation. But my steering wheel sometime shake like an earthquake. Is this a symptom of rotor warping or something else? and what you mean by "whole front end may shake?"
  • gqleftygqlefty Posts: 8
    With new pads and rotors on the front of my 1999 Muatang car should the rotors turn freely when you turn the lug studs with your hand ??? Seems to be a lot of drag from the pads, is that normal ????? I still notice vibration when slowing down quickly on a freeway exit ramp. I doesnt do it with normal brake pressure but neither did my old rotors and pads. I spend 300.00 bucks and still have the vibration in the steering wheel on quick slow downs!!! I'm taking it back to him Monday. HELP!!! Could tires affect the problem any ?? Thanks
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Yes, it is normal for the pads to drag.

    Your brake shop can do a simple run-out measurement on your rotors to tell if they are causing the vibration. If they don't do the run out test they are just guessing and so are you.
This discussion has been closed.