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6 Series
The BMW 6 Series builds on BMW's sporty heritage with aggressive lines and an incredible motor to back the design up. Available in coupe and convertible trims with a standard 4.8 liter engine producing 360 horsepower and 360 lb-ft of torque, the 6-series is a popular choice that exceeds expectations.

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  #1  
Old 03-20-2013, 01:58 PM
Diamond_Ed Diamond_Ed is offline
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Angry 3rd Set Of Warped Rotors..Help

I have a 2006 650i , love the car but i have burned through 3 sets of rotors and pads since i got the car. They are perfect for the first 3,000 miles then the shaking starts. It almost stutters to a stop. It came with stock, they warped. I then went after market and got some cross drilled and slotted, warped again. Im now looking at a 3rd pair. The dealer has no clue, I drive this car like a bitch , stuck in traffic all day . I dont think i have broken 100 yet. Any one else ever deal with this. P.s. My other vehicle is a srt8 jeep w 550 hp that has had the needle burried 160+ more times then my dog and his bone. The 6 is a work car / dd . I appreciate all the help.
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  #2  
Old 03-20-2013, 05:08 PM
Skarv Skarv is offline
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No offense intended in this POSSIBILITY... but since you talk about driving in traffic a great deal, and perhaps downhill, could it be related to driving style?

Premise: One of the failure modes for discs is when they are very hot, and then suddenly the car is still. What happens is the pad insulates the disc making it cool at a slower rate under the pads relative to the areas exposed to air. This makes the still hot part expand relative the rest of the disc or the cooler part contract if you like. This in turn warps the disc. Once warped, the disc will eat pads quickly too.

This is why cars at the track tend to do warm down laps. They aren't worried about the engine, but rather the brakes. The discs need to be brought down in temperature uniformly so they don't warp. The way to do that is to do an easy lap or two without using the brakes at all.

So in your case, do you ventilate your brakes in use? By this I mean, apply them intermittently rather than continuously? In traffic, do you ride your brakes for extended periods, and then come to a standstill with them applied? Or do you ride down a long downhill with the brakes applied (heating the brakes) and then get stuck in traffic? Just a thought.

Why might you have this issue with a 650 and not a jeep? Our discs are a very high carbon steel. Makes them grippier, and you will notice they rust with the least bit of moisture. That carbon changes the properties of the steel and may make them more sensitive to this kind of thermal complication. Technically, what is going on has to do with the martensitic transition temperature properties of this alloy of steel... which means the temperatures at which the carbon crystals form in the steel, and and in what size and placement - The metallurgy is very complicated, but bottom line is that the steel's properties change dramatically depending on this temperature treatment, and non uniform cooling can make this happen non uniformly around the disc.

Just a possibility, but if you can find a pattern in your driving where brakes get hot, and then you get into stop and go, or have to park immediately, then this is a good possibility. If you do have this pattern, just use the engine for braking. In heavy traffic, I tend to manually put mine in low gear and then forget the brakes altogether.

Hope this helps.
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Old 03-20-2013, 05:42 PM
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MMME30W MMME30W is offline
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Quote:
Originally Posted by Skarv View Post
No offense intended in this POSSIBILITY... but since you talk about driving in traffic a great deal, and perhaps downhill, could it be related to driving style?

Premise: One of the failure modes for discs is when they are very hot, and then suddenly the car is still. What happens is the pad insulates the disc making it cool at a slower rate under the pads relative to the areas exposed to air. This makes the still hot part expand relative the rest of the disc or the cooler part contract if you like. This in turn warps the disc. Once warped, the disc will eat pads quickly too.

This is why cars at the track tend to do warm down laps. They aren't worried about the engine, but rather the brakes. The discs need to be brought down in temperature uniformly so they don't warp. The way to do that is to do an easy lap or two without using the brakes at all.

So in your case, do you ventilate your brakes in use? By this I mean, apply them intermittently rather than continuously? In traffic, do you ride your brakes for extended periods, and then come to a standstill with them applied? Or do you ride down a long downhill with the brakes applied (heating the brakes) and then get stuck in traffic? Just a thought.

Why might you have this issue with a 650 and not a jeep? Our discs are a very high carbon steel. Makes them grippier, and you will notice they rust with the least bit of moisture. That carbon changes the properties of the steel and may make them more sensitive to this kind of thermal complication. Technically, what is going on has to do with the martensitic transition temperature properties of this alloy of steel... which means the temperatures at which the carbon crystals form in the steel, and and in what size and placement - The metallurgy is very complicated, but bottom line is that the steel's properties change dramatically depending on this temperature treatment, and non uniform cooling can make this happen non uniformly around the disc.

Just a possibility, but if you can find a pattern in your driving where brakes get hot, and then you get into stop and go, or have to park immediately, then this is a good possibility. If you do have this pattern, just use the engine for braking. In heavy traffic, I tend to manually put mine in low gear and then forget the brakes altogether.

Hope this helps.
Brake disks are made of high carbon steel?
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  #4  
Old 03-20-2013, 05:58 PM
Skarv Skarv is offline
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I don't know the precise alloy we have, but I was using the word "steel" colloquially. They are probably cast iron, but I don't know the alloy. I do suspect higher carbon content due to the excess rusting. But the point is that they are a different alloy than your average econobox and will hence likely have a different Martensitic transition.

Performance brakes are known for this tempermentality due to alloys, large brake surfaces (insulation), and because they usually get more heat. This is why the M has drilled rotors... Venting. But they do stop better!
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Old 03-20-2013, 06:13 PM
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MMME30W MMME30W is offline
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Quote:
Originally Posted by Diamond_Ed View Post
I have a 2006 650i , love the car but i have burned through 3 sets of rotors and pads since i got the car. They are perfect for the first 3,000 miles then the shaking starts. It almost stutters to a stop. It came with stock, they warped. I then went after market and got some cross drilled and slotted, warped again. Im now looking at a 3rd pair. The dealer has no clue, I drive this car like a bitch , stuck in traffic all day . I dont think i have broken 100 yet. Any one else ever deal with this. P.s. My other vehicle is a srt8 jeep w 550 hp that has had the needle burried 160+ more times then my dog and his bone. The 6 is a work car / dd . I appreciate all the help.
Issue might be DTV, this might be of interest:

http://www.brakeandfrontend.com/Arti...omplaints.aspx

"Reoccurring pulsation complaints are perhaps the second most common reason a customer returns after having brake service. The brakes operate normally for the first 3,000 to 6,000 miles, but then the customer notices a high-speed pulsation when getting off the exit ramp on his way to work one morning. The customer returns to the shop with the pulsation complaint and leaves with usually one of two “fixes” — the rotors being machined or replaced. The usual explanation given the customer is that the rotors “warped.”
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  #6  
Old 03-20-2013, 06:17 PM
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MMME30W MMME30W is offline
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Quote:
Originally Posted by Skarv View Post
I don't know the precise alloy we have, but I was using the word "steel" colloquially. They are probably cast iron, but I don't know the alloy. I do suspect higher carbon content due to the excess rusting. But the point is that they are a different alloy than your average econobox and will hence likely have a different Martensitic transition.

Performance brakes are known for this tempermentality due to alloys, large brake surfaces (insulation), and because they usually get more heat. This is why the M has drilled rotors... Venting. But they do stop better!
Every brake disk I've ever replaced was cast iron.

I mean this in the nicest possible way, because I'm genuinely interested, but do you have any thing that backs up the statement that a 6 series brake disk is made of any different material (i.e. cast iron) than a Jeep?
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  #7  
Old 03-20-2013, 07:54 PM
Skarv Skarv is offline
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Hey MMM... no worries... I'm just taking an educated guess... from having spent a big part of my career in the metals business but not the brakes business.

Given that they are hollow core they are most certainly cast iron. But there are as many casting alloys as there are points on a line. Carbon content makes iron alloys behave very differently. Generally, high performance brakes have higher carbon content, and I'm not sure why other than ultimately, it makes them brake better.

I'm assuming that we have a different alloy because if I wash this car, the discs turn red in a second. Not so with my wife's Honda... or any other mainline car I've had. But neither did those cars brake like this one.

I'm sure someone could research the answer for us for our cars, but if you go to a performance brakes site, you will find they talk of carbon content as a performance feature.

Otherwise, I'm just a bloke trying to figure out Diamond Ed's problem.
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Old 03-20-2013, 08:18 PM
HerbP HerbP is offline
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Check some of Yorgi's post on the brakes in the DIY section. He would be able to answer this with his knowledge in his racing experience. By chance have you verified that the brake ducts are working properly, allowing air to cool the brakes? The factory rotors are made with hats, to allow for thermal growth. If the rotors were not replaced with the factory type setup, this may be the problem. Any rotors made in China, are not very good.
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Old 03-21-2013, 12:33 PM
Diamond_Ed Diamond_Ed is offline
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Gentlemen I thank you, @Skarv as far as driving style basic high way to a from work, not remotely any driving that would warrent warping , @MMME320w what you are describing is my exact problems. Pulsating to be exact and the only answer is "They are warped" never a cause from bmw. The original rotors were stock BMW replace under warrenty then I went after market from a bavarian auto shop near me. Cross drilled and slotted w ceramic pads. I have never had a problem like this. If a rotor was warped then i knew it was my fault, but not w this car. @herbp ill check out the diy section for help. I thought this would be a common problem but i guess not so much...
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  #10  
Old 03-21-2013, 04:10 PM
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petriej petriej is offline
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There's something wrong with your suspension.
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Jared, why don't you just put "It's Giubo" in your sig? Save a lot of typing.
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this jared guy sounds intimidating lol.
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Old 03-21-2013, 07:46 PM
HerbP HerbP is offline
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When I purchased some aftermarket cross slotted & drilled rotors for my truck, they did not last 20k miles. Some aftermarket rotors made from cheap metal used for brake rotors can warp & wear very fast. When you order online, you never know where the product is made. BMW rotors are very expensive, but last & perform very good. BMW makes a very soft pad, to protect the rotor from premature wear. They are also designed to allow for thermal growth under severe braking conditions. The bad problem with BMW pads are, they are very soft & make a huge dust mess. You have to wash your wheels constantly, to keep them clean.

Maybe a set of new BMW rotors will resolve your issue!

Good Luck!
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Old 03-22-2013, 07:13 AM
Diamond_Ed Diamond_Ed is offline
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@petriej What would make you think suspension, im not disagreeing just curious what you think the problem / cause / solution may be. Im open to any suggestions.Iwill obviously be going back to stock bmw rotors but i did kill a set in about 10k
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Old 03-22-2013, 10:17 AM
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I guess I should ask more questions. Are all of your rotors warping simultaneously? If it's just the front rotors, I'd be concerned about your suspension for sure.

You aren't the first 6er owner to complain of repeatedly warping the rotors. I have forgotten the outcome of the issue, though. It's definitely not normal. Are you bedding the brakes in properly each time? If you don't bed the brakes in they will be more likely to warp.
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Quote:
Originally Posted by hornhospital View Post
Jared, why don't you just put "It's Giubo" in your sig? Save a lot of typing.
Quote:
Originally Posted by e36 miguel View Post
this jared guy sounds intimidating lol.
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Old 03-22-2013, 01:08 PM
Diamond_Ed Diamond_Ed is offline
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@petriiej Yes the brakes were broken in properly. Im replacing the rotors today oem and the caliper carrier. The mechanic feels it cpould be part of the pulstaing problem. We will see. Thank you for all the help.
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Old 03-22-2013, 06:06 PM
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boramkiv boramkiv is offline
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Make sure your wheels are torqued to specs when mounting, make sure your bushings are good, the 'bed in' process should be done after installation of brakes, an alignment should be done. All this to try and remedy the issue, if all fails its the quality of the rotors.
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Old 03-24-2013, 11:02 PM
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Yorgi Yorgi is offline
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For starters you need to find out if you actually have warped rotors or just uneven brake pad deposits on the rotors which is the far more common cause of judder when braking.

You need to have a mechanic measure the rotor runout. If you have more than 0.2mm or runout then they are warped. You can also try to measure it yourself - see section G9 in my brake pad DIY.

Uneven brake pad deposits can be seen by pulling a wheel and looking at the rotors. If they are not perfectly shiny silver all the way around then you probably have brake pad transfer to the rotors. Deposits usually look like rusty streaks or brownish deposits.

If the rotors have deposits that is normally a sign that the pads were over cooked.

If the rotors are warped then there can be many causes. Here are some of the more common causes sorted by most common to least common:
  • Bringing rotors up to high temperature then stopping the car without giving them a chance to cool down (you don't need to get them that hot to cause this)
  • Cheap aftermarket rotors
  • Braking too lightly. Braking lightly results in long stops which heat up brakes much more than quick firm stops.
  • Dragging rotors. If the guide pins are dirty or a caliper piston is sticking you can easily over heat the rotors. Looking at the pads for uneven wear is a good indicator.
  • Uneven lug nut tightening. Rare but is can be a cause due to uneven heat transfer to the wheel.
  • A bent caliper carrier, or other suspension part can also cause uneven braking and warping. Uneven pad wear is also an indicator.
  • Worn wheel bearings or suspension bushings can also cause uneven pad wear.
  • Running rotors past their minimum thickness. Thin rotors cannot dissipate or absorb heat and will warp.

I would use only OEM rotors or StopTech. Most after market rotors are crap, especially drilled rotors. Drilling increases the chance of warping.

Do not try to put warped rotors on a lathe. Once you overheat a small section of the rotor that part of the steel becomes harder than the rest of the rotor and this will result in rotors re-warping after a short period of time.

Also note that if you have worn bushings this will greatly increase the amount of judder you will feel. You may have a tiny amount of warping or deposits but due to play in the suspension what would normally be undetectable will feel like heavily warped discs.
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Last edited by Yorgi; 03-24-2013 at 11:09 PM. Reason: typo
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