Front brake rotors warped at 15,000 miles

[BP1]

I replaced my front rotors and pads 15,000 miles ago. Well, the shimmy started again (normal street driving, not hard, no driving when wet) and I had confirmation from 2 knowledgable shops that the front suspension was tight and that the rotors were warped. The rotors came from Mesa Performance ($52. each) and the pads were PBR's. Nobody i talked to can explain this. Am I missing something? Has anyone else had this issue? Solutions???

1. Have them turned?
2. Replace with another $50 rotor.
3. Go with Zimmermannn's (where can I find these?)
4. Use BMW parts (Tompkinson $122. ?)

Thanks in advance...BOB

 

[HB Chris]

Bob,

They should last longer than that. I use the PBR pads and like them but not available anymore. You can absolutely turn your rotors at least once, try that first.

 

[twistinglane]

See this thread also - Honolulu's post and interesting link http://www.e9coupe.com/forum/showthread.php?t=1426

 

[Nicad]

Check to make sure your calipers aren't binding.

 

[MMercury]

I replaced my front rotors and pads 15,000 miles ago. Well, the shimmy started again (normal street driving, not hard, no driving when wet) and I had confirmation from 2 knowledgeable shops that the front suspension was tight and that the rotors were warped. The rotors came from Mesa Performance ($52. each) and the pads were PBR's. Nobody i talked to can explain this. Am I missing something? Has anyone else had this issue? Solutions???

1. Have them turned?
2. Replace with another $50 rotor.
3. Go with Zimmermannn's (where can I find these?)
4. Use BMW parts (Tompkinson $122. ?)

Thanks in advance...BOB

Can 40,000 knowledgeable shops be wrong? "To every thing, (including rotors) turn, turn, turn?"


I agree with HBChris. I have no doubt that brake rotors can warp, but based upon your description, this is unusual in 15,000 miles of travel. I've heard of second opinions, how about a third, your own? You can visually inspect the rotors while on the car. A dial indicator or even a fixed nail against the rotor would confirm or disprove runout and possibly even establish a loose or overtightened wheel bearing. If the rotors have excessive runout, you might look for other physical evidence such as bluing or discoloration. Are those rotors mirror shiny? Do they evidence obvious signs of wear, including ridges?

IF, there is a problem with the rotors, and the runout is not extreme, I would not hesitate to turn them. But aside from that obvious fix, it is not impossible for rotors to suffer from manufacturing defects. It might also be possible that despite your testament to careful normal driving, the brakes have been over-applied, or the calipers tend to stick, or even the wheel bearings are too tight, leading to extreme heat, or too loose, potentially leading to excessive pad or rotor wear. Food for thought >> http://www.e9coupe.com/forum/showthread.php?t=1927 ; http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths; http://www.brakeandfrontend.com/warped-rotors-myth/

Much of of what I type here has been previously covered on this forum http://www.e9coupe.com/forum/showthread.php?t=1927 . That being said, it is possible that the friction material may have something to do with your shimmy. Could it be that brake pad material is transferring from the pads to the rotors and causing minor changes in rotor thickness and a falsely perceived warpage? Have you examined the pads? Are they worn and/or glazed?

Pads with different names go through constant compound changes and all of them are a compromise of various characteristics, e.g., driveability, noise, wear, dusting, heat resistance and friction coefficients. You mention PBR, if memory serves me correctly, there were at least two flavors, including "deluxe/orgainic" and "metal-masters." You did not specify which you use. I have used both versions with different results on an E3. They both worked fine for normal street driving, but curiously, the Deluxe resulted in a shiny "polished" rotor surface while the MMs left the rotors dull. The Deelux also had a tendency to leave a powdery residue that turned gummy if exposed to water. The MMs left a residue that looked rusty if infrequently washed.





It is probably way off the original topic, but there seems to be many "rebranded" pads available. The old standbys Jurid, Ferodo, Pagid, Repco, Textar and Mintex, seem to be joined by other familiar names, e.g., Ate, Raybestos, Bendix, Wagner, Kelsey Hayes and Beck/Arnley brands, so that it is difficult to determine the real players. I did not forget Hawk, EBC and Porterfield, but they seem to be in their own category.


For those who like to read >> http://www.brakeandfrontend.com/choosing-right-brake-pad-right-customer/



DOT coding for various friction compounds. I was unable to determine the original source or confirm the accuracy of this information, but it might be of some limited value.

DOT Pad Codes
This two letter edge code mandated by the DOT, and painted on all street legal brake pads, will give you some indication of their ability to resist fade. But only if you know how to read them. However, because of the wide range involved in each letter, it is only a rough indication.

Explanation of D.O.T. Edge Codes Located on all Brake Pads Official D.O.T. Edge Code Coefficient of Friction (C.F.) @ 250 F and @ 600 F

EE 0.25 to 0.35 both temps 0-25% fade at 600 F possible

FE 0.25 to 0.35 @ 250 F 0.35 to 0.45 @ 600 F 2% to 44% fade at 600 F possible

FF 0.35 to 0.45 both temps 0-22% fade at 600 F possible

GG 0.45 to 0.55 Very Rare

HH 0.55 to 0.65 Carbon/Carbon only. O.K. up to 3000 F where it glows

Notes: These edge codes are located on the edge of the friction material of every brake pad by government regulation, along with some other codes. The first letter is a grading of the C.F. at 250 F and the second letter is a grading of the material at 600 F. Each letter grade can actually have quite a range of C.F. But a difference in the letter grade from medium to hot temperature could be an indicator of fade. The letters can be in any order. Therefore FE pads fade when hot, and EF pads would not grab when cold.. Also, you should know that Steel on Steel has a C.F. of 0.25!! So EE pads have only marginally more torque than no pads at all! Therefore FF pads are usually considered the minimum for a high-performance pad.

From: http://www.bimmerfest.com/forums/archive/index.php/t-570124.html

 

[BP1]

Thanks for all the input. The PBR's are "deluxe".

Also, the symptom started 3 weeks after I changed my wheels from Coupe King alpina's to BBS RS's (both 16", same tires). I will be doing the visual inspection of the rotors with wheels off in a couple of days.

 

[sfdon]

Check those compliance bushings and the wheel balance Robert.

 

[Koopman]

Warped Rotors.

Hi Guys;
Not sure if this will help.
I remember when I had my second BMW a red 1986 325 ES and bought new snows for winter driving. I had my mechanic put the snows on every winter and immediately I would get warped rotors. It took awhile and I finnaly realized what caused this to happen. The wheels were being torqued wrong,causing the rotors to warp. This would happen both when snows were put on and than again when they were taken off and the reg. tires were put on. I told my mechanic I wanted the wheels put on using a hand tire wrench and the problem was solved.
Good Luck
Koopman

 

[MMercury]

The PBR's are "deluxe".

Also, the symptom started 3 weeks after I changed my wheels from Coupe King alpina's to BBS RS's (both 16", same tires). I will be doing the visual inspection of the rotors with wheels off in a couple of days.

I reread my diatribe and realized I neglected to mention Koopman's suggestion regarding proper torque procedure. We often take these things for granted. He may be on to something since you describe the problem first occurring with wheel changes. A wheel change reminds me of something I once witnessed at a tire store: a mechanic managed to get grease on a brake rotor and, so far as I am aware, made no effort to remove it. As one might imagine, that sort of contamination could lead to all kinds of problems, including brake shimmy - often associated with warpage.

Respecting the "DeeLuxe" pads, I did not mean to suggest there is anything inherently wrong with them. If you looked at the links, there is some discussion about compound transferrence, possibly adding to uneven rotor thickness. Stories abound about cars that sit in humid climates where pads become "frozen" or "rusted" to rotors. Whether this is a cause of "warpage" remains to be seen. A light surface rust would probably have a negligible effect on braking or brake shimmy. Serious, heavy rust would likely have such an effect. Not suggesting this is your situation, but you never know . . .

Best of dust-free luck.

 

[craterface]

Frozen brand rotors

If your rotors aren't being damaged from the wrong wheel torque or other exogenous issues, replace them with Frozen rotors. Stock rotors, cryogenically treated. Have used them on e36 track cars with excellent results. Also on the family van, etc.

http://www.frozenrotors.com/


Scott

 

[BP1]

Wheel Nut Torque

Stopped by the shop that mounted the wheels. They said they torqued to 78-80lbs (their torque chart didn't go back to 1974 so they just used the oldest BMW year on the chart)...51 to 65lbs is what the manual calls for. I know this is not right but is it wrong enough to warp the rotors?? Experienced opinions welcomed....

 

[Koopman]

Warped Rotors

I will almost bet that the torque is the culprit. It happened everytime I changed my wheels. I would end up getting new German rotors from Greenfield Auto Repair for under $25 each and the problem still occured after nthe wheels were put back on the car. There was only one thing to do,CHANGE MECHANICS. That is what I did and the issue was solved.
Koopman
PS By the way I am no mechanic,and have never even changed the oil in any of my vehicles,but not to brag I usually can diagnose a mechanical issue.
Koopman

 

[Ohmess]

Yes, change mechanics.

Two tears ago, I bought a new set of tires for my e39 sedan. I had been planning to pull the wheels off and bring them to the shop; Eddie the manager said "we can take care of that, no extra charge." I get my car home, pull out my big breaker bar and my torque wrench and start checking my lug nuts (which I do every time someone else pulls a wheel off one of my cars). First one, dead on, second one, same thing. Long story short, they are all correctly torqued.

I called Eddie the next morning to give him some feedback. "Eddie, I've owned this car for ten years, this is the first time I have gotten it back from a shop with the wheels properly torqued. This must mean you do a good job supervising the lower level guys who pull off and put on wheels." Turns out they don't hire low level guys for that stuff because they screw it up, creating unhappy customers.

Eddie is doing most of the maintenance on my e39s now while I play with the e9.

 

[lloyd]

Even if they are accurate, the "over" torque numbers presented would not likely warp rotors. Not saying they can't, just that it is unlikely. The more likely scenario IMHO, is when lugs are tightened unevenly, and especially when the wheels are hot. Something rarely discussed is the fact that just like other fasteners, the addition of oil, grease or even water on lug threads can change torque readings. One would like to think that most shops dealing with expensive cars, tires and rims - know enough not to use an air impact wrench capable of 300+ ft./lbs of torque for tightening. This practice might explain so many cars driven with one or two broken lugs. The lug torque specs include enough tolerance for the average Horst to remove and reinstall them for roadside repair - without a torque wrench. This doesn't mean the torque shouldn't be checked, but I submit it is less critical if the star "crisscross" pattern is followed.

I can't speak to the newest electronic torque wrenches, but the more-traditional older mechanical dial and click styles are notoriously inaccurate and most, with the exception of difficult-to-read beam types, require routine recalibration. High end shops and manufacturers have a monetary incentive to use the best and most reliable and accurate tools. It remains an open question as to which mechanics recalibrate or check their torque wrenches for accuracy and how often. (It is another question whether any given mechanic knows how to use the wrench and is familiar with the factory recommended fastener torque tolerances.)

FWIW, different sources list the E9/E3 wheel torque as 65 ft/.lb. The E24, with virtually the same metallurgy, is listed at 75 ft/.lb. http://blog.bavauto.com/2400/bmw-wheel-lug-bolt-nut-tightening-torque/