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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 02-19-2011, 02:03 PM
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stigst3r stigst3r is offline
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Rotor Refinishing does that stuff work?

Hi guy,

i got some rotors on my car. they are fairly brand new less then 100 miles.

i put them on my car a while ago never got a chance to test them out cuz i was waiting for paper work for my car.

i noticed the rotors are warped because when i brake from like 50-80mph the steering wheel shakes violently.

if there a possibility that i can get a machine shop resurface them? would that work at all?


or should i just get different set of front rotors
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Last edited by stigst3r; 02-19-2011 at 02:14 PM.
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  #2  
Old 02-19-2011, 02:26 PM
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bricas45 bricas45 is offline
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If they are warped I don't think you can really get them resurfaced. Keep in mind even after you replace rotors there may still be a shake. Mine turned out to be a bad wheel bearing causing what felt like warped rotor shaking. You can probably take the rotors to a shop to test if they are warped or not first.
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  #3  
Old 02-19-2011, 02:41 PM
xraye39 xraye39 is offline
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Quote:
Originally Posted by stigst3r View Post
Hi guy,

i got some rotors on my car. they are fairly brand new less then 100 miles.

i put them on my car a while ago never got a chance to test them out cuz i was waiting for paper work for my car.

i noticed the rotors are warped because when i brake from like 50-80mph the steering wheel shakes violently.

if there a possibility that i can get a machine shop resurface them? would that work at all?


or should i just get different set of front rotors
I would do some due diligence before condemning rotors.

You are assuming the rotors are warped, read here.

I would look at suspension components first, have you ever had your thrust arm busings replaced? Have you checked your ball joints?
If you search around, more often than not the problem is suspension related.
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Last edited by xraye39; 02-19-2011 at 02:45 PM.
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  #4  
Old 02-19-2011, 03:29 PM
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Fudman Fudman is offline
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+1, warping of rotors is rare. More likely thrust arms bushings or deposits on the rotor. Try a rebedding, first. No cost and easy. Do it until you can smell them. Second, inspect your thrust arm bushings for leakage. Lastly, turning your rotors is OK as long as the thickness is within spec. If they are new, they will be.

Last edited by Fudman; 02-19-2011 at 03:30 PM.
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  #5  
Old 02-19-2011, 03:46 PM
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Just replaced my Pads, and rotors all around, befor this I had a bad case of the shakes. I replaced arms, bearing and still was there....mostly when I braked over 40mph. After the brake job, all is good, hell it feels like I'm stepping on a pillow when I stop now.

I would just buy new rotors, and pads... shop around, did mine for 206.00.

Good luck!
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Old 02-19-2011, 04:00 PM
cn90 cn90 is offline
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Actually, there are 2 kinds of problems:

1. Brand new rotor with UNEVEN friction of coefficient on the surface.
This is from being brand new and not broken in yet.
The rotor is otherwise perfectly flat (mechanically speaking) but it has smooth and "not-so-smooth" surface.
When you brake, the wheel "jerks" a bit causing the "vibration feeling" in the SW but NOT the brake pedal.
This is because the brake pads hit the smooth and "not-so-smooth" surfaces on the rotor.

- If you have a dial gauge, you can measure the rotor runout WITHOUT removing the rotor from the car.
I do not know the current QA (quality assurance) at rotor company like Zimmermann, Brembo: do they check rotor for perfection before leaving shop: who knows?
- Remove the wheel and securely support the car with jackstand.
- Position the dial gauge on a solid stand and measure runout.
the dial gauge and the stand for it are sold at Harbor Freight.
- If no problem with runout, then do the "brake bedding" thingy.

2. Warped rotors:
This does exist, mostly with old rotors with 30-90K miles on it.
Anyone who has fixed brake knows this is true, just put the old rotor on the lathe and you will see the runout.
In this situation, you can resurface it.

My situation was #1 above, as it turned out, my brand new ATE rotor was warped from the factory, I brought it to local autoparts store for machining, and all is good now!

Last edited by cn90; 02-19-2011 at 04:30 PM.
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  #7  
Old 02-19-2011, 04:16 PM
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Try this FIRST (it`s FREE !):

http://www.zeckhausen.com/bedding_in_brakes.htm

Rotors *rarely* warp from street driving, unless you`ve had a sticking caliper, or the tire-shop gorillas had their impact guns set on 600 ft./lbs. when they installed your wheels.

BMW rotors don`t have all that much meat on them even when new, so cutting them is ill-advised....
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Old 02-19-2011, 04:18 PM
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stigst3r stigst3r is offline
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thanks guys for the feed back,

I have replaced my entire front & rear suspension, the ball joints are brand new, the bearings are brand new too, the suspension and brakes have less then a 100 miles on them. the rotors i got are frant

i have these Frenetik rotors:



Combined with EBC red stuff pads.

over all the car is a very smooth ride, only when i try to brake at speeds from 40-70 mph i can feel the vibration at the front and the steerign wheel starts to woble.

im gone inpect them tonight using my dial indicator and see if they is any warpage on them
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  #9  
Old 02-19-2011, 04:32 PM
cn90 cn90 is offline
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The key thing about dial gauge is:
- Car on jackstand so no movement on the body frame.
- Set the gauge on a solid surface such as a piece of brick (tape the dial gauge so it does not move).
Whatever you do, the dial gauge must on on very solid surface because you measure thousandth of an inch.
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Old 02-19-2011, 04:42 PM
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Just resurface them and they will be fine.
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  #11  
Old 02-19-2011, 04:50 PM
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Quote:
Originally Posted by stigst3r View Post

im gone inpect them tonight using my dial indicator and see if they is any warpage on them
Just be aware that any play in the wheel bearings will show up as runout in the calipers....
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  #12  
Old 02-19-2011, 07:32 PM
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FWIW ...

I had brake related vibration after my very first brake job that was solved with the rebedding procedure. After modifying my braking habits, I have not had the brake-related vibration since ... even after my second brake job (with the same rotors that were replaced on the first job).

Details here:
- How to check & replace your BMW front disc brakes and rotors

Those who know me can believe that I searched all over the Internet for every single article I could find on how to change E39 brakes and what the cause and solution to the so-called "warping" was.

Suffice to say, if you can find better references than these below, then you deserve my admiration ... as these are the best on the topic I can find.

I gather these together to help you make your own decisions as to how to identify, solve, and prevent brake-related vibration, starting today:

Articles discussing the term "warped" brake rotors:
- Avoiding Brake Judder at the Track, by Dave Zeckhausen
- Brake Rotor Shake Demystified, by Dali Racing
- The "Warped" Brake Disc and Other Myths of the Braking System, by Carroll Smith
- 8 Myths ... Holding You Back from Performing the Best Brake Job, by Andrew Markel
- Brake Roughness and Vibration: Causes & Solutions, by Dave Mann
- There's no such thing as 'warped' brake rotors, by Michael Block
- Raybestos Brake Tech School, Part One: Rotors Don't Warp, by Police Fleet Manager Magazine

Removing brake pad uneven deposition:
- How to Bed-in Your Brakes, by Dave Zeckhausen
- Removing the Mystery from Brake Pad Bed-In, by Matt Weiss

My personal golden procedure for avoiding brake pedal pulsation:
I. Bed or rebed your pads to your rotors to create an even pad-deposition layer (or turn the rotors, and then rebed);
II. Then, forever after, consciously modify your braking habits so as not to leave uneven pad deposition (i.e., imprints) on your otherwise smooth rotors!


ADDITIONAL REFERENCES:
  • What to do when you experience brake-related pedal pulsation at highway speeds (1)
  • What to do when the lights all work, the key turns, solenoid clicks, but the engine won't start (1) (2)
  • What to do when you have low oil pressure (1)
  • Help! The dealer is charging $500 for a brake job! (where to buy) (what to buy) (price survey) & labor rates (1) (2) (3) & how to find a good mechanic (1) (2).
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  #13  
Old 02-21-2011, 11:03 PM
fadetogrey fadetogrey is offline
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Exclamation

I agree with the OP that it's warped rotors. Why? Because I just got this fixed myself today. I had Zimmerman Coat-Z rotors, and EBC Red Stuff pads installed in July 2010. By September 2010, after primarily highway miles and commuting they were warped and causing a violation front-end vibration. I put up with it for several months thinking that I had a major suspension job due, but no this is not the case.

Today, I replaced my front braking components with genuine rotors and pads - and voila! the problem is gone and my front-end back to being butter smooth. No problems with my control arm bushings, nor wheel bearing.

No more aftermarket parts for me when it comes to brakes. I read these forums up and down looking for a suitable replacement, but it's very clear to me now that the money spent on genuine parts from time to time is not the waste it's advertised to be - I just want things to work the first-time, the right way.
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  #14  
Old 02-22-2011, 09:37 AM
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Quote:
Originally Posted by fadetogrey View Post
I agree with the OP that it's warped rotors.
Rotors aren't made out of putty.

Ever since I researched this way back in June 2010, I've said that anyone who says their rotors actually warped must provide the measurements of the warpage (not just runout, not just pad deposition ... but warpage).

Nobody yet has taken me up on my offer!

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  #15  
Old 02-22-2011, 09:43 AM
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Originally Posted by fadetogrey View Post
By September 2010, after primarily highway miles and commuting they were warped and causing a violation front-end vibration....I replaced my front braking components ... and voila! the problem is gone
Almost certainly you had uneven pad deposition.

It is very likely to come back (yes, even on the new rotors).

You put it there. You'll put it back there. (If you drive the same way as you did before and if other factors are similar).

You will need to change your braking habits.

I need say no more as it's all in the references I quoted.

I do note Jared's comments though ... that's there's more to it than just changing your braking habits ...
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Old 02-22-2011, 09:55 AM
fadetogrey fadetogrey is offline
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Quote:
Originally Posted by bluebee View Post
Almost certainly you had uneven pad deposition.

It is very likely to come back (yes, even on the new rotors).

You put it there. You'll put it back there. (If you drive the same way as you did before and if other factors are similar).

You will need to change your braking habits.

I need say no more as it's all in the references I quoted.

I do note Jared's comments though ... that's there's more to it than just changing your braking habits ...
That is certainly a logical piece of thinking. I thought about that myself - I wondered if maybe I've been braking super hard and not noticing it because I'm so used to it. I do like like fling my car around the odd corner here and there. But... something I've appreciated about the 540 brakes is I hardly need to touch them to get more than acceptable stopping power. So, at least as of late I don't use them hard - and I try to mix in downshifting where applicable since I drive a manual.

Consider this though - prior to my brake replacement I had genuine rotors and pads that came with the car at purchase, and lasted 15 months for me (not sure of pre-purchase condition). If my braking habits are less than ideal, then I should have warped those rotors too, right? I doubt my habits changed any when I re-did the fronts in July.
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Old 02-22-2011, 10:21 AM
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Quote:
Originally Posted by fadetogrey View Post
maybe I've been braking super hard
What people "think" is rotor "warp" is actually something else altogether (whether it be runout or, more often, brake pad deposition building up from the driver's braking habits).

To the OP, it's not braking hard that leaves pad deposition, but braking hard and leaving your foot on the pedal where and when you stop. And all you have to do is do this just once!

From reading the references (and I've read them many times ... and they're not wholly consistent ... nor is my memory) ... but from reading the references, once you have a pad imprint, the deposition grows upon that single pad imprint (for chemical reasons).
- Avoiding Brake Judder at the Track, by Dave Zeckhausen
- Brake Rotor Shake Demystified, by Dali Racing
- The "Warped" Brake Disc and Other Myths of the Braking System, by Carroll Smith
- 8 Myths ... Holding You Back from Performing the Best Brake Job, by Andrew Markel
- Brake Roughness and Vibration: Causes & Solutions, by Dave Mann
- There's no such thing as 'warped' brake rotors, by Michael Block
- Raybestos Brake Tech School, Part One: Rotors Don't Warp, by Police Fleet Manager Magazine

So, if you stopped once, the theory goes, under just the wrong conditions, and left your foot on the pedal, unless you "scrape" that pad imprint off the rotor, it "could" grow to a ten thousandths of an inch mound (or whatever).

That teeny tiny mound of growing pad deposition shows up as highway speed vibration when you brake. In fact, it happened to me, when I did my first brake job in my life (and my first post ever on Bimmerfest) simply because I was ignorant of these facts at that time:
- A user's very first complete 4-wheel brake DIY experience on the BMW E39 (1)

In that job, I bought, begged, and borrowed the tools necessary to check rotor & pad thickness and runout specifications (see photo below). There was no appreciable runout (note, runout is not warp!), and the rotor thickness was well within specifications. Doing my research, I easily solved the problem of severe brake-related vibration at highway speeds.

What eliminated the very severe brake-related vibration was merely a proper rebedding (not easy to do in crowded San Jose California!):
- How to Bed-in Your Brakes, by Dave Zeckhausen
- Removing the Mystery from Brake Pad Bed-In, by Matt Weiss

And, what keeps deposition-related vibration from coming back is daily good braking hygiene!

Think about that. If my rotors had actually 'warped', no amount of rebedding would have fixed them so thoroughly. However, to be fair, as Jared said, it can't be all that simple because you wear down metal when you brake. So where does THAT factor in?

Also, maybe it takes a LOT of hard stops where you hold down your foot on the pedal? Maybe you have to land in the same spot more than once? I do not know (and the articles don't really say).

But, here's my heartfelt advice for good braking hygiene ...
  • If you have to brake hard
  • Lift your lead foot off the brake pedal as soon as you can!
  • When you finally stop ... let the wheels roll a bit (if you safely can)
As soon as you get the HINT of brake-related highway-speed vibration ...
  • Get rid of that pad deposition as soon as you can!
  • Do a quickie rebedding procedure (eight serial ~60-to-10 mph)
  • And then go back to good braking hygiene
As for why it doesn't always happen ... I do not know (reference Jared's comments). My procedure above might be akin to the "miracle in a can". I don't know.

All I know is that it makes sense (somewhat); and that it doesn't cost anything; and that it seems to work; and that I'm not the only one proposing it (it's in all the rebedding procedures).

Up to you what to believe ... but "warp" didn't happen (to me anyway).

And, for those who say they've seen brakes "plenty of rotors warped, right out of the box" ... I say if you put me on a lathe ... with all those lovely cast-iron curlicues of hot metal writhing off the carbide bit ... at the end of the day ... you'd have a lot of lousy rotors (I'd compete with China!).

But badly machined and horribly out of spec rotors with poor quality control is not what we're talking about when someone says their rotors 'warped' in use.

In fact ...

I'd LOVE for one person on the entire Internet to post a picture and/or specs of a truly warped rotor from street use. I'm sure it happens (especially in racing). But not very often. Certainly it's not the first, second, or even fifth thing I'd look at if I had severe brake-related vibration!

Let it be known I have searched the net as mush as anyone and I can't find any reliable measurements of "true non-racing brake related warp" that are believable. To be believable they need to come from a source who knows what they're talking about and that source must discuss both sides of the story (i.e., most warp-related threads clearly show the writer is ignorant of the alternate view).

If you can find believable threads showing rotors often warp in street use, I'd love to see it posted right here!


Last edited by bluebee; 02-23-2011 at 10:42 AM.
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Old 02-22-2011, 11:24 AM
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Gotta go along with the "No Warpage" school of thought here, folks....the thermal load required to warp rotors would be almost beyond audience comprehension. It just ain`t happening in everyday street driving. Frequent track use IS another story, but that`s not where most of us live.
And yes, after a fresh brake job, everything WILL feel smoother....until that nasty ol` pad deposition builds up again, and vibration will once again rear it`s ugly head.
Best solution is to make a concious effort to modify your brake technique, and re-bed your brakes when you feel vibration starting.
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Old 02-22-2011, 11:58 AM
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Well i will just say with over 10 years working on vehicles ive seen ( with my own eyes not on a gauge) many warped rotors . and just yestyerday i had a discovery with a bad case of shaking and pulsation on the brake pedal (new Mintex pads and rotors were fitted just a few months ago ) upon removal of the wheels and calipers you could see the warpage on the front rotors while turning them . sent them to be turned and the shop confirmed the warpage and fixed them better than new .. so it does happen
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Old 02-22-2011, 12:39 PM
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Originally Posted by 525isport View Post
Well i will just say with over 10 years working on vehicles ive seen ( with my own eyes not on a gauge) many warped rotors . and just yestyerday i had a discovery with a bad case of shaking and pulsation on the brake pedal (new Mintex pads and rotors were fitted just a few months ago ) upon removal of the wheels and calipers you could see the warpage on the front rotors while turning them . sent them to be turned and the shop confirmed the warpage and fixed them better than new .. so it does happen
Do you get weak at the knees in the presence of kryptonite?

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Old 02-22-2011, 01:24 PM
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Originally Posted by 525isport View Post
Well i will just say with over 10 years working on vehicles ive seen ( with my own eyes not on a gauge) many warped rotors . and just yestyerday i had a discovery with a bad case of shaking and pulsation on the brake pedal (new Mintex pads and rotors were fitted just a few months ago ) upon removal of the wheels and calipers you could see the warpage on the front rotors while turning them . sent them to be turned and the shop confirmed the warpage and fixed them better than new .. so it does happen
Not to call you out here, but common sense (and a bunch of experience) would dictate that if rotors actually WERE warped to the point *that you could SEE it*, it would take a hell of a lot more than just cutting a thousandth or three off their surface to "fix them better than new"....and, if they DID warp the first time `round, don`t you think that removing more metal from an already worn rotor would invite even more (and faster) warpage due to reduced thickness ?
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Old 02-22-2011, 01:24 PM
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Do you get weak at the knees in the presence of kryptonite?

mw
LOL well im no superman but thats how bad the rotors were warped you could see it with human eyes
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Old 02-22-2011, 01:32 PM
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Originally Posted by Fast Bob View Post
Not to call you out here, but common sense (and a bunch of experience) would dictate that if rotors actually WERE warped to the point *that you could SEE it*, it would take a hell of a lot more than just cutting a thousandth or three off their surface to "fix them better than new"....and, if they DID warp the first time `round, don`t you think that removing more metal from an already worn rotor would invite even more (and faster) warpage due to reduced thickness ?
they were new rotors in the box ..and yes anyone could have seen the warpage and yes turning them fixed the problem ... im just sayin it does happen . Can we accept that ??
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Old 02-22-2011, 02:20 PM
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Actually I have seen many warped rotors in my cars over the years.
They DO exist but usually in old rotor with 40-80K miles.

It is perfectly acceptable to resurface rotor as long as min thickness is observed. Nothing wrong with resurfacing rotor.
However, pricing for new rotors have dropped in recent years, so sometimes people simply install new rotors.

Do new rotors come from factory perfect? NO!!!
I have seen warped rotor straight out of the box.
The Quality Control program of a rotor company is important.
So once in a while you see "imperfect" rotor.
I have learned a new routine now: when I install brand-new rotor, I always do a quick check with my dial gauge (before the brake caliper is re-installed) because I hate removing it again for resurfacing!
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  #25  
Old 02-22-2011, 03:18 PM
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MatWiz MatWiz is offline
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Quote:
Originally Posted by 525isport View Post
LOL well im no superman but thats how bad the rotors were warped you could see it with human eyes
You're too humble.


Quote:
Originally Posted by Fast Bob View Post
Not to call you out here, but common sense (and a bunch of experience) would dictate that if rotors actually WERE warped to the point *that you could SEE it*, it would take a hell of a lot more than just cutting a thousandth or three off their surface to "fix them better than new"....and, if they DID warp the first time `round, don`t you think that removing more metal from an already worn rotor would invite even more (and faster) warpage due to reduced thickness ?
See splanation below:
Quote:
Exposure to the light of a younger blue sun provides Superman with increased physical abilities, and the power of "Superman Vision", which allows him to bestow his abilities on other beings for a limited time.[5]
And also:
Quote:
Super Vision - His senses grant him the ability to see farther and with greater accuracy and detail than normally humanly possible. Sometimes includes the ability to see EM frequencies invisible to humans, such as radio transmissions, infrared light and in some stories, even an energy aura which supposedly surrounds all living things (this originated in Superman: Birthright). Offshoots of this power include Telescopic Vision, which allows him to "zoom in" on far away objects, sometimes hundreds of miles away, and Microscopic Vision, which allows him to zoom in on objects that would normally be too small to see, like those on a cellular or molecular level.
Source: http://en.wikipedia.org/wiki/Powers_...es_of_Superman



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