do i need to turn the rotors?

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  #1  
Old 03-26-02, 03:03 PM
bledsoe
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do i need to turn the rotors?

My buddy's got a '99 Mazda 626 with 112K miles and he needs new brake pads. He says there's no vibration at all when braking, so my question is: can I get away with just replacing the pads and not turning/replacing the rotors? Any advice on this? thanks
 
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  #2  
Old 03-26-02, 03:52 PM
Joe_F
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Good quality rotors are fairly cheap on most FWD applications. Might consider pitching them.

Cutting the rotors is like 20 bucks or so labor. Might put you half way to new rotors. Good idea at that mileage anyhow.
 
  #3  
Old 03-27-02, 03:43 AM
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why turn good rotars

This is a subject that really chaps my hide.
Why do people want to turn a rotor that is NOT out of round or has deep grooves.I think it is a waste of money and shortens the life of the rotor.A thinner rotor will have less metal and warp quicker.I never turn my rotars unless the runout is bad.
The same thing applies for rear drums make them thinner and the risk of warpage goes up.
Brake places I think just want to make a buck and include an automatic rotar turn before they even do a runout check.
 
  #4  
Old 03-27-02, 05:44 AM
Joe_F
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Because pads and shoes need a good surface to "bite" into.

Fact is that old shoes and pads glaze the rotor and do not provide such a surface.

A properly turned rotor each time will have fairly long service life.

Here's a scenario for you:

Back in 1995 or so, my grandparent's Chevy Cavalier needed rotors. Figure that turning them properly is about 45 minutes to an hour's time. Say my time is worth 60 bucks an hour.

New rotors, American made for the car are 20 bucks each. What is the better value considering I want a good service life and surface to mount my pads?

Do the math . Brakes are not something to fool around with. Sure, on an older car, you can probably just sand the rotors smooth with the 1/4" die grinder, but on most modern cars, you should change or resurface the rotors.

In addition, over time the cooling fins rot out and so does the rotor. The rotors on my mother's 93 Saturn SL2 were DUST when I serviced the rotors the first time. Cutting wasn't even an option.

Something to think about...
 
  #5  
Old 03-27-02, 02:29 PM
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brakes are important

I do have to admit that brakes are a very serious part of the car.
but for the sake of turning for no reason I still cannot see spending 20 per side if there are no problems such as you stated such as blown out cooling fins overheating to the point were the color changes on the disk.As far as glazeing emery cloth will remove it with some solvent.Also if you go to a brake shop you know darn well that they jack up the price from a twenty dollar rotar to 40 bucks.the serious DIYer should have the tools to check thickness on the part.And I agree with you Joe if the labor to turn due to warpage is 60 an hour with it probbably is pitch and go with new.
But what I am saying is with a good DIY inspection with the right tools such as calipers,Dial indicators,maybe a magnifican glass for me im kind of old.I still say remove the glaze with emery cloth and some solvent to remove all the oil.
 
  #6  
Old 03-27-02, 11:17 PM
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Glazed roters & drums

I have a bead blast cabinet, and use it to deglaze rotors and drums. I have a brake shop that relines all my brakes and pads with real Asbestos.

Do you remember when we had Asbestos and the brake shops would check out your rotors and drums? If they were just glazed, they would just deglaze them, not cut so much off, that the next time you did a brake job, you had to replace them.

If your rotors and drums are not warped and just glazed have a shop bead blast the glaze and rust for about $15.00 or less for the set.

One reason I work on my own stuff is I can do a better job. A better job means, our stuff works better, and lasts longer. Why would we do a slam bang job on our own stuff?

If this cutting away at rotors, and drums or just buying new ones is the norm, then I am missing the point of Doing it Yourself.

Don't we have an up hill battle with companies, who once paid their workers, to build the best products in the world. Yet today they want their workers, to design parts to break on time, and work faster & faster without reguard to quality, and pride of workmanship.

When we do it ourselves we can take our time, and find aftermarket parts that exceed those light weight break on time parts, that come on our cars that cost as much as a well built house back in the 70s.

If you DIY then you have the choice to do it right, so that puts you in the drivers seat, after all it's your money, so you should have the say as to how it should be fixed.
 
  #7  
Old 03-28-02, 05:21 AM
redneck
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My .02 cents, I have never had rotors cut or "deglazed" if they are not warped, grooved real bad, or worn too thin, then put them back on with new pads and make sure calipers and wheel cylinders are functioning properly, and drive it! If one rotor needs replaced, replace them both. I had used these guidelines on many vehicles, with many miles between brake jobs with no problems!!
 
  #8  
Old 03-28-02, 05:38 AM
Joe_F
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You'll find that most modern FWD rotors rot very quickly. The cooling fins rot out and they warp rather easily.

Cutting them worsens the chance of warping. You might cut them a few times to get it right.

At that point, replacing them is a better option, both part and labor wise.

Marturo: I agree with you, but we're not talking old school GM rotors like you and I have (they last forever and are 80 feet thick...lol). Front wheel drive cars have much thinner and lighter weight rotors .
 
  #9  
Old 03-29-02, 08:46 PM
trendar
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With my 5.0L Mustang, I had a problem with the a front caliper binding, and Ford serviced it under a complimentary program, post warranty. They rebuilt the caliper, and as a routine operation resurfaced the rotors, though it may not have been absolutely necessary. I never had pulsing in my brakes before, but some time after this, it did. The less thickness in the rotor, the more susceptible it is to warping from heat, so it's probably best not to cut the rotor unless there is already a problem with grooves or runout. If it looks and works perfectly except for a glaze, you can just break the glaze with some emery to allow the new pads to bed in properly. Some rotors are softer than others though, so there may be a ridge at the outer edge that cutting the rotor would be able to remove, so it should be looked at to decide which way to go.
 
  #10  
Old 04-01-02, 06:45 AM
bledsoe
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Alright, thanks everybody for your help. I appreciate it. I think for now I'll just replace the pads. As for the "glazing" and using "emery", can someone elaborate more on this? I'm assuming by glazing, you're saying that the rotors just get a bit of a shine to them and that needs to come off??? I have no experience with this, so I'm not sure. Also, what is emery? Lastly, could I just run over the rotors really lightly with sandpaper just to take any rust off and call it the day? thanks!

(joe, to keep you happy, I will measure the thickness of the rotor to make sure they're not getting too thin! thanks bud!)
 
  #11  
Old 04-01-02, 01:22 PM
trendar
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By emery, I just mean emery cloth, basically sandpaper, to try to give it a sort of crosshatch, if the rotor's developed the shine to it. The new pads won't break in as they should if it's all smooth and mirror like, so roughing it up some with the sandpaper will help. Just clean off the rotor afterwards to get the grit off afterwards before putting on the pads.
Of course, as was mentioned, if the rotor's got any runout or noticeable grooves in it, then cutting or replacement would be in order-
 
  #12  
Old 04-01-02, 01:24 PM
bledsoe
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got it. thanks again
 
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