From "AOL Auto Questions"

I ran into this today and thought a couple parts of this article were interesting, particularly the differences between different octane gas and whether to let the car warm up before driving. The top section about
squeeking brakes - almost sounds like they're promoting re-surfacing the roters for each brake job to keep them from squeaking. I've changed brakes before withought re-surfacing and never had a problem. Opinions?
http://tinyurl.com/34du4y
-Dave
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Dave L wrote:

I read the article and thought it was general at best. A lot lacking, and a bit off mis information concerning the topic of hydroplaning.
Yes, you can get away with not resurfacing rotors, but it's not the preferred or recommended manner normally to do a brake job.
If you have a heavily grooved rotor you will notice that the worn pad to be replaced has the exact matching grooves in it.
The new replacement has of course has a flat surface that will have to wear in to the rotor to obtain the greatest breaking surface. That can take time and braking performance in a panic situation can suffer.
Resurfacing also removes any warp.
I could go on, but I'm sure others will have many other reasons as well.
Resurfacing rotors is a good thing.
OBTW, the biggest factors for hydroplaning are speed of the vehicle and tire pressure. Tread and water depth make little if any difference.
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My objection to resurfacing is that many garages do not seem to care for their brake lathing equipment properly.
A dull or mispositioned bit will make an absolutely horrible "new" surface on the rotors. Such a surface can glaze up in a big hurry.
If you are guaranteed a quality lathe job, go for it. But if there is /any/ suspicion of lathe quality, either replace the rotors or just put the new pads on the old surface (provided your new pads are the same as the old ones).
--
Tegger

The Unofficial Honda/Acura FAQ
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Tegger wrote:

You're absolutely right Tegger. Some guys haven't changed a seven dollar insert in years if ever!
Setup by a knowledgeable operator is key as well.
It really a disservice to a customer when you just hog off all the iron on the thinest rotor or largest diameter drum and not take into account the others and just turn them down to the same dimension. Most don't demand it, but on some high end vehicles this must be done and the customer should be informed.
Some guys just want to sell rotors, or how many jobs can I get through this machine to pay for it and the mechanic, not build a new customer to be a return.
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I never considered the equipment used to resurface the rotors. Good point!
-Dave
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It was general but I think that's what they were trying to do to simplify each situation. The topics that caught my eye were the ones I see being debated on these groups from time to time. The use/reasons for the different octane fuel, whether it's good to really warm up a car and whether rotors should be re-surfaced.
I know re-surfacing removes any warp but if the brakes are replaced before any pulsating starts I thought having the rotors turned wouldn't be necessary... Besides, wouldn't re-surfacing increase the tendency for it to warp again?
I agree speed and tire pressure affect hydroplaning - but so do the tread pattern/compound. I used to have the Bridgestone Potenza RE-960 on a Prelude and they were the best tires I've ever used on wet roads. Almost felt like I was driving on dry pavement and cannot remember ever hydroplaning, whether it was light or heavy rain. Very stable and solid. Snow was a different story - they were awful! It was a trade-off. However nothing beats common sense!
-Dave
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I beg to differ. I can't speak for Toyota, but I know Ford and GM specifically says resurfacing is not required when replacing pads unless the rotor is damaged. And then only minor damage can be cleaned up. Significant groving requires rotor replacement. Futhermore, Ford only recommend resurfacing rotors on the car. Unless the brake lathe is in great condition, the chances of it making things worse are significant. Unless the car already has warped or otherwise damaged rotors, I see no reason to routinely turn brake rotors. I know most independent shops routinely turn brake rotors. They usually give a couple of reasons, but in many cases the main reason is extra profit or just habit.
See: http://www.encyclopedia.com/doc/1G1-92137449.html http://www.aa1car.com/library/2003/bf110322.htm http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

Oh boy.......you really need to clarify this. See http://www.nhtsa.dot.gov/cars/rules/rulings/TPMS_FMVSS_No138/part5.6.html . You statement is misleading at best. Speed is a major factor for sure. But tread depth is not the trival factor that you impy in your statement. Tire inflation pressure is a major factor once "water depth exceeds the capability of the tread design to remove water." So for minimal depth of water and good condition tread, tire inflation pressure is not a bigger factor that depth of water and tread. Furthermore the formula used is pretty lame since it does not account for sidewall stiffness. Try applying the forumla to a run flat tire with all the pressure released and get back to me.
See also:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=3
Ed
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C. E. White wrote:

I've noticed the auto manufacturers are in that same extra profit and habit mode as well on every new one pumped out.
All I can say Ed, is never do yours. Most people come into a shop with the pad backing plate, if not a piston ground into at least one of the rotors, wondering what is that funny noise and the vibration in the brake pedal?

8.7 times the square root of the tire pressure is the formula to calculate hydroplane speed in general. It's pretty reliable unless you need to go into some physics calculations.
Tire tread depths vary greatly. Most folks don't buy specialty tires.
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. They usually give a couple of reasons, but in many cases the main

I am not a professional or even a particularly good DIY mechanic (just for the record). I think most shops resurface rotors to avoid 'come back' problems with noise etc. on brake jobs.
On my own cars, I never turn the rotors unless there is a specific need. I know the 'theory' is to make the flat surfaces of the pad/ rotor match, and to take off any rust or other problems with the rotor. But even if a rotor is not perfectly flat after a bit of driving the pads will mate to the rotor and if there were no noise problems with the old pads there shouldn't be any with the new. Any time you cut a rotor you are, of course, taking off metal - why do that if it isn't necessary? Its not just a 'cost' issue.
I also agree with the poster who noted that not all shops use the brake lathe that well - in fact, I think proper turning of rotors may very well be a dying art. In the hands of a skilled operator, a rotor can literally be brought back to life 'from the dead' - but like so many other things you don't just slap the rotor on the machine and take a cut.
My opinion, FWIW.
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snipped-for-privacy@yahoo.com wrote:

Not to mention the $$$ involved (which buys us nothing in most cases). I started replacing brake pads in the 70's on my 1970 VW, 1969 Porsche, 1988 Acura & 2003 Accord - never turned a rotor, never replaced a rotor and never had a problem.
As always, YMMV.
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I had my RAV4's rotors resurfaced only after changing the pads and the squeeling didn't disappear. After resurfacing it was totally gone. I guess my opinion would only to resurface if you are having problems, otherwise don't waste your money fopr the resurface
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wrote:

I had my RAV4's rotors resurfaced only after changing the pads and the squeeling didn't disappear. After resurfacing it was totally gone. I guess my opinion would only to resurface if you are having problems, otherwise don't waste your money fopr the resurface
Exactly how I feel, unless something convinces me otherwise!
-Dave
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