Reaching into the bag of endless Doper knowledge; I just purchased new rotors (front) for my car and the rotors have a thin coat of grease (or something). Question is, do I wipe away the packing grease? If so, can anyone tell me the best way to remove it? Thanks in advance for any help.
If it was me, I’d leave the grease on there until I was just about to replace them, then I’d clean them off really good with brake cleaner(from the parts store). I figure that it should do the trick- it’s supposed to take grease off of brake parts, after all.
Get rid of all of it you can- any grease, brake fluid, etc… will mess up your braking bigtime.
You absolutely want those rotors CLEAN and DRY before installation. The list of acceptable substances to have on the rotors is as follows: NONE whatsoever.
The preservative on the rotors (to prevent their rusting) is probably cosmolene or something equally stubborn to remove. Brake cleaner may help, but in my experience carburetor cleaner works better. Even more effective is gasoline, but it’s dangerous to work with because it can easily catch fire or my God EXPLODE! so I would never recommend using it. Anyway, if you start with carb cleaner or something else, I suggest you then finish cleaning with brake cleaner.
I would call the store I got them from & ask them what to do.
Go to the store and buy a bottle of something called BRAKE KLEEN. There is a protective coating on the rotors (similar to the thin piece of plastic on electronics faces when you buy them). BRAKE KLEEN will remove this (and from what I understand will also kill mice, but I digress). It comes out of the bottle and a high pressure and leaves no residue. Clean it all off and you’ll be good to go. I’m not sure if I did it afterwords or instead, but the last time I changed my rotors I remember washing them with soap and water on the advice of the mechanic at the car place. Like I said though I’m not sure if it was instead of or afterwards. Just read the label on the can, or ask someone for help.
Grease on the rotors is not wise, BRAKE KLEEN or sometimes its cheaper, electric motor cleaner, same stuff, they are usually right next to each other. If your really cheap gasoline or Naptha should work.
For the record the stuff on them is called cosmolene. It’s an anti-rust-while-it-sits-in-the-warehouse chemical. As others have said just rinse them off with carb cleaner or gasoline right before installing them.
Cosmolene is nothing new. It’s been used this way for decades.
Almost any solvent you have on hand should work.
And I strongly suspect that if you skimp on the cleaning step, the worst you’ll experience will be some faintly strange smells, and perhaps a couple of stops during which available brake performance is 97% of optimum.
And I strongly suspect that you have no idea what that cosmolene looks and feels right and that this may be one of the most asinine and potentially dangerous statements made on this board. How about the worst he might experience would be brake performance that is less than 5% of normal? Unless you know for a fact that that would not be the case, it is extremely irresponsible to suggest that cosmolene-contaminated brake pads will perform adequately. Explain your “thinking” to the pedestrian that gets killed when the brakes don’t work.
Arrgh! Should be "…what that cosmolene looks and feels like…
Anyway, back to the OP: this page (http://www.nmia.com/~dgnrg/page_31.htm) says the following (the first part is essentially what all here have recommended):
New rotors come with a cosmolene coating, clean them with solvent, & then thoroughly clean the rotor surfaces with isopropyl alcohol or brake cleaner & wipe them dry with a lint free cloth. Avoid touching the rotor surfaces.
Additionally:
“All the manufacturers of brake pads and rotors now recomend that you do a final cleaning of new or remachined rotors with warm water and dishwashing detergent (use a stiff bristle brush). It seems that particles are imbedded in the surface of the rotor during the machining process and this removes them. They state that this will greatly increases braking effectiveness and reduce break in time also.” (thanks to Bill R. for passing this along). Do this after the solvent wash & dry thoroughly with a lint free cloth.
My perspective on the above: It has long been acknowledged in the auto repair field that resurfaced rotors should be washed with some kind of soap and water. It doesn’t have to be dishwashing detergent, and a stiff bristle brush is not necessary. I have not heard recommendations to do this with NEW rotors, so I’m curious what Bill R.'s source is.
Cosmolene?
Sounds like a personal lubricant for your wacky next-door neighbor…
(Not that there’s anything wrong with that.)
Never mind.
Carry on.
I’ve always used rubbing alcohol, it wipes right off with that, and it’s cheap. I’ve found that it works better than brake cleaner.
I think some folks just lick it off. It would explain alot.
Well, I’ve installed new brake rotors perhaps ten times. Many had a thin coating as mentioned in the OP. None was seriously gooped up, and in my view none would have had much difficulty in service even without the casual cleaning mentioned in my post.
I’ll also note that I’ve never seen a warning with brake rotors along the lines of “Clean these before use or people will die!” In our litigious society, there’s a strong incentive for manufacturers not to booby trap their products with such things as preservative coatings that lead to danger, especially when a thin coating does a more than adequate kob.
I believe that your alarmist tone is either hyperbole or based on a lack of experience with car maintenance (or perhaps some of both). If you can provide a cite for a pattern of accidents resulting from casual cleaning of thinly coated rotors, I’ll cede the point. Until then, I think your comments are out of line.
I’ve installed new rotors hundreds of times. I will admit I never tried leaving the preservative on the rotors, not being curious enough to risk a customer’s safety to find out how much effect it would have. I do know that when brake shoes are contaminated with gear oil or brake fluid, it makes a marked change in their friction characteristics. They get grabby with light pressure and then slip with heavier pressure. They’re treacherous as hell. This site ( http://www.hunter.com/pub/undercar/901701/btest.htm ) shows some research in this area, and says “Contaminated friction material such as grease or brake fluid on the lining can cause a large
percentage difference in left/right balance on a particular axle.” My emphasis – it’s no small thing to have contaminated brake linings.
This site ( http://hawkworks.net/manual/14.html ) says “A contaminated brake disk or pad reduces stopping power. Discard contaminated pads and clean a contaminated disk with a high quality brake degreasing agent.” Not only is stopping force compromised, but the pad cannot be decontaminated – it must be replaced.
**
It is almost hard to believe in our definitely litigious society, but automotive brake components are sold lacking all sorts of possible stern warnings of potentially dire consequences for improper procedures. Nevertheless, poorly or wrongly done brake work can indeed result in serious damage to persons and property.
**
Hyperbole, perhaps. But I about dropped my jaw when I read what I consider a rather cavalier suggestion that cleaning the rotors wasn’t really necessary, and that there would be essentially no negative consequences. Like I said above, I’ve never tried skipping the cleaning because too much is at stake when it comes to brake performance. And considering what is at stake, I would say your comments are far more out of line than mine.
Let’s note that we are not discussing whether clean rotors are a good or a bad thing. We don’t disagree there.
Our disagreements concerns the consequences of doing a casual job of cleaning the thin preservative coating from new rotors. My contention is that this will have minor consequences as compared to a thorough cleaning. Yours is that it can have dire consequences, such as reducing braking effect to 5% of normal and getting pedestrians killed.
The cites you provide obviously support the uncontroversial notion that clean is better than contaminated, but don’t offer any support for the specidic notion that residual amounts of rotor preservative lead to dire consequences.
Your statement about the lack of stern warnings included with brake components sidesteps the point I made: manufacturers have a strong incentive not to booby trap their products – when possible, they seek to provide products that don’t require stern warnings.
Another point here is that after any brake work it’s fundamental to do a couple of test stops to check that everything is working properly. If these tests give satisfactory results, then I’d say the prediction of possible 5% efficiency on subsequent stops is extremely far-fetched.
You seem to be putting forward the notion that in support of important matters (such as having effective brakes) hyperbole is justified. My position is that on matters big and small, truth is truth and hyperbole often gets in the way of it.
I think the OP is aware that we have not seen his particular brake rotors, that his definition of “thin” may not be universal, and that all postings including mine should be interpreted in light of those facts.
And Gary T gets the lesson on the problems with trying to teach pigs to sing to wit:[ul]
[li]It usually doesn’t get good results[/li][li]It can be very frustrating to the teacher[/li][li]It really annoys the pig[/li][/ul]
Xema, Gary T is a professional mechanic and very well respected around this board. In my not so humble opinion speaking as another professional in the automotive business, based on his posts here, Gary T is a damn good mechanic. Yet you continue to slam him. Let’s go back and look over some stuff and clear up a few misconceptions 'k?
First so we know where we stand
Cool, I have done tons of them. Literally. I have probably removed and replaced somewhere over 5,000 rotors during my career. At 20 lbs average per rotor I have replaced tons of cast iron. I have replaced rotors on MG Midgets that were the size of a desert plates all the way up to large trucks that had rotors that weighed over 50 Lbs. Just so we have an idea of our comparative experience.
These three statements do not agree with each other. In the first two you blow off the cleaning step saying that stopping power may only be degraded by 3% At this point I must ask for a cite on this. In your third post you try to back track and say that clean rotors is a good thing.
OK look here is the deal, the cosmolene is not a booby trap put there to trap an unknowing person doing a brake job, it is there to preserve a very fine finish on machined cast iron. Machined cast iron can rust in just a few hours under the wrong conditions. Would you by a set of rusty rotors? I sure as hell wouldn’t. Also for the record I have seen light oily preservatives, thick sticky preservatives, preservatives that looked and acted like a coat of spay paint, and various waxy coating. In your vast experience of replacing 10 rotors how many different types of these coating have you encountered? How do you know which one of the many different types of coating ** WillSantini** has on his rotors? Now as far as your statements about instructions go, auto parts are sold for professionals to repair cars. Professionals have years of training and experience and shop manuals that instruct them in the proper way to do a particular repair. It is not practical to include a shop manual with every part (and if they did, boy would part costs soar). Taking your suggestion to it’s logical end, if you bought a $2.00 rod bearing for your engine it should come with a complete engine rebuilding manual. Riiiiiiiiiiiiiiiiiiiiiiiiiiight.
Thinking over the parts my company sells (I work for a car company) I would guess that way less than 1% of our parts come with any instructions and then usually only a one or two line caution, not a complete set of instructions. Deal with it, this is the way the business is. If you are going to play auto mechanic, they you are saying that you know what you are doing and if you don’t you should look it up.
So comments from a professional in a field to an amateur correcting a miss-statement of fact is out of line? WTF? Oh and nice strawman, not every fact in the world is available on line.
I suspect that you have never ridden in or driven in a car with oil or grease contaminated brakes. I have. Unlike what you might expect, oil and grease on brake linings does not cause the brakes to slip, rather it causes them to grab. Violently, I might add. If one front wheel gets contaminated the car will quite likely spin in a hard stop (this happened to my father, he put our Chrysler into the center divider due to the LF brake being contaminated. Quite a wild ride I must say.
I have also had customers bring cars in with contaminated brakes and had them spin out on a test drive (thanks for the warning when you dropped the car off melon head) So you want a cite, how about my 35 years of experience in the automotive field, is that good enough?
In the days of drum brakes a single greasy fingerprint would cause the brakes to pull to one side during a normal stop. I know this because when I was learning I tried to get out of cleaning off that one lone fingerprint. Then I had to bring the car back in after the test drive and do that side of the car over again. Not fun.
I suspect that if you were to mount preservative covered rotors on both front wheels, the brakes would tend to lock with anything other than the lightest pedal pressure. It should be obvious that this would be a dangerous condition.
Bottom line this is General Questions where we are looking for factual answers, not your best guess. Gary T has provided those factual answers, you have not.
I think that’s fine. But I see no reason not to discuss what’s said with reference to the facts presented rather than to the presenter’s reputation.
I haven’t. I did say that I felt some of what he said was attributable either to hyperbole or inexperience. I now know (in part because he confirmed it) that it is the former, not the latter. I do not think what I’ve said it a “slam”. Taking issue with someone’s points is supposed to be part of what we’re doing here.
I think you are wrong in this. I do not “blow off” the cleaning step - I simply say that being casual about it in view of what the OP mentioned won’t lead to disaster.
Thanks for agreeing with me on this. I strongly suspect that the manufacturers know the properties of the preservative they use, and would disqualify from use one that tended to lead to pedestrian deaths.
All have matched the description in the OP, toward which comments were directed.
I missed the part where I said that rotors or any other part should come with extensive instructions. Please make a point of showing me where I said that.
My “out of line” comment referred to his comments about braking being reduced to 5% of normal and pedestrian deaths. How were these a correction of misstatements?
But I have. I once helped a (seriously negligent) friend replace rotors pads and calipers that were massively deteriorated and contaminated with both grease (from failed half-shaft boots) and brake fluid. The brakes were in a truly shocking condition. But, amazingly, they actually still more or less worked – a good testament to how well designed this essential component really is.
Well, I’ve done it (preservative was thin, as in the OP) and this didn’t happen. Braking was normal, but the faint lingering odor convinced me to do better next time.
My response was based on experience. I don’t have 5000 cars worth of experience; I do have enough to know that the alarmist tone to which I responded was excessive.
BTW: 1000 posts! - congratulations (even if you feel it falls in the category of teaching pigs to sing).
I’d say there are a lot of faintly musical pigs around here.
Considering that most people never even consider that their automobile is, in effect, a lethal missile on the verge of being out of control if even just the slightest of things go wrong, and that further, 100% operational braking is singularly the most important safety feature that any automobile can possibly have - I think it’s rather obvious that maximum pad to rotor friction is utterly desirable.
Xema - sorry my friend - but anything, absolutely anything which clogs your pads is bad news. You can’t win this one I’m afraid. It’s very common knowledge that pads and rotors have to be contaminant free - at all times. It’s part of the reason why it’s good practice to machine your discs and replace your pads every three years - even if your pads have lots of life left in them. Pads pick up gunk and they diminish in their effectiveness as a result.