Talk:Brake fade

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[edit] Observation

Thought this might be considered ancectodal evidence, I must say that I drive, on a daily basis, a vehicle equiped with hydraulically-actuated, four-wheel drum brakes, of the dual-servo, self-adjusting type. Since re-shoeing all four wheels several thousands of miles ago, I have, in a wide variety of braking conditions, experienced no brake fade. Could it be the modern linings?

I also wish to point out that the brakes lack power assist, which the servo action seem to make up for, and, that braking control driving on ice and snow was much better than what I have experienced on ABS and non-ABS power-assist front disc/rear drum equiped vehicles.-WK-139.78.96.115 01:13, 8 March 2007 (UTC)

OK, was your car built in the 1960's (or earlier)? Dan Schwartz, Discpad 04:15, 14 March 2007 (UTC)

Yes, it is a 1968 Chevrolet truck.-WK-139.78.96.83 22:23, 20 March 2007 (UTC)

[edit] Rewrite

I hope you can accept what I have done to your "brake fade" page. Having worked on disk brake development and working with tribology (friction and wear) I came across the items I mention in the rework of that article. The gas bearing and drum expansion are things mechanics, not engineers, cooked up and it is obvious because servo effect is not part of their technical understanding. Jobst 06:40, 17 February 2007 (UTC)

Actually, no. Your rewrite is either original research or simply unsourced. It is counter to the sources presented. For example, you state that only drum brakes suffer fade? Please provide a source. Please do not make drastic changes to the article withou providing sources. Please see these policies; WP:V and WP:NOR. Thank you. --Justanother 03:15, 18 February 2007 (UTC)

I think you should re-read what I wrote and tell me what part you don't understand. The article as it was is based on myth and lore, that you cite from a popular magazine. That is not a valid citation, only a repetition of what you have repeated. I explain why the gas bearing hypothesis is false and defies all reason. Having worked on disk brakes in high performance cars from the outset of disk brakes I can explain how this works and did so. If anythinng, you should show proof that expanding drums and gas-bearing exist. As I mentioned, disks operate at red hot temperatures, ones that gas bearing drums never did, using similar friction material. You should also consider why drums were discontinued when friction materials that cannot out-gas have been designed. Jobst 03:39, 18 February 2007 (UTC)

Hi. I am not arguing your expertise or even "the truth". If you are right then great but you are not a source and you cannot write from the "top of your head" here. You need to provide sources, not assert that the sources provided are wrong because you know better. All due respect, but that is not how wikipedia works. Please see WP:PILLARS. Thanks. --Justanother 03:44, 18 February 2007 (UTC)
Seriously. Please stop adding unsourced WP:OR. Thanks. discuss here. --Justanother 03:49, 18 February 2007 (UTC)

I don't understand what you mean by "you are not the source". The part that you offered is documented more sparingly than mine and as I pointed out, defies physics. That is why it caught my attention. You refer to WP:PILLARS in which is stated:

Wikipedia is free content that anyone may edit. All text is available under the GNU Free Documentation License (GFDL) and may be distributed or linked accordingly. Recognize that articles can be changed by anyone and no individual controls any specific article; therefore, any writing you contribute can be mercilessly edited and redistributed at will by the community. Do not submit copyright infringements or works licensed in a way incompatible with the GFDL.

That you restored the old version seems to indicate that you believe it is correct. I suggest that you give proof that drum expanding or gas bearing causes brake fade. The references listed are not technical support for this physically impossible hypothesis. If you are skilled in the design of brakes you shoudl recognize what the downfall of drum brakes is and why we no longer have brake fade. You shouldn't take this personally and feel insulted but you should also not pass on folklore as encyclopedic information. Jobst 04:25, 18 February 2007 (UTC)

Hi. Yes, anyone can edit but they must play by the rules. Did you see this part (the first part).

Wikipedia is an encyclopedia incorporating elements of general encyclopedias, specialized encyclopedias, and almanacs. All articles must follow our no original research policy and strive for accuracy; Wikipedia is not the place to insert personal opinions, experiences, or arguments.

Please check out the links! I did not say that you are not "the source"; I said that you are not "a source. Please see WP:RS. I welcome your editing here but not if you are disregarding the rules and presenting your unsourced theory and discarding sourced material. I do not have to "prove" anything to you The burden of proof is on you and the only acceptable proof is WP:RS. Nothing personal. Thanks --Justanother 04:38, 18 February 2007 (UTC)
Please stop reinserting your material until you comply with the rules here or I will get an admin involved. Thanks --Justanother 04:40, 18 February 2007 (UTC)

To make the point that you are repeating auto lore, I have asked for references on a few of your unsupported claims. Alternately you could explain how these things occur and their cause instead, but you do neither. Especially the gas bearing item needs explanation or proof, that being a lot of gas with no apparent source. Remeber, after cooling, faded brake pads show no sign of having lost gas or otherwise changed permanently. In fact, they will do it again if put to the test.

Please give what I wrote some thought. Also your talk of high performance equipment has nothing to do with the causes and remedies of drum brake fade. Jobst 05:04, 18 February 2007 (UTC)

Hi. Question. Are those claims that you object to not sourced by the materials presented? Are you saying that the sources mentioned in the article are wrong and those sources are simply repeating misconceptions or lore, as you call it? Thanks.

As you see, justanother, the anonymouse author of this piece, shows no reasonable explanation for the effect of brake drum expansion causing fade, the Coefficient of thermal expansion being vanishingly small in comparison to normal ovalization of drums by braking forces. The gas bearing scenario cannot be found in Dunlop, Girling, Lockheed or any other brake manufacturer's literature. It is folklore. The volume of gas required for such an effect cannot come from friction material, once or repeatedly, brake fade occcurring again as easily as the first time. The citations listed are auto enthusiat magazines, neither of which explain what these gases are and how they keep coming out of brake pads that were originally formed at high temperature in manufacture.

Brake fade is unique to drum brakes because they use self servo action (leading brake shoes) [[1]] whose servo effect relys on the proper friction coefficient, one that reduces at elevated temperatures. I request that justanother cease deleting my re-write of this article and not continue purvey myth and lore. Please note the [citation needed] notations in the article. Jobst 18:31, 19 February 2007 (UTC)

Dear justanother,

Deleteing [citation needed] callouts in your article is not the way to respond to requests for verification of what is known by people in the indstry to be myth and lore. Jobst 19:15, 19 February 2007 (UTC)

Jobst, this is not about what you think or what I think. This is not about me proving anything about brakes to you or you proving anything about brakes to me. This is simply about following the rules here WP:NOR and WP:V. Please read and ensure that you understand those before continuing. Thanks --Justanother 19:21, 19 February 2007 (UTC)
ps. While proving anything about brakes is not the real point here, it is important to note that there are tons of material discussing fade in disk brakes. Here is one that shows a bit more of the mechanism[2]. I think that if you want to contribute to the article then you should a paragraph about how servo effect produces fade in drum brakes. But only if you provide sources. Thanks --Justanother 19:28, 19 February 2007 (UTC)

justanother, I beg to differ. Having worked in the disk brake business I am aware that these folklore stories of gas are some sort of widely believed cargo cult, even though there is no credible explanation, nor any analysis of its existence. You won't find a technical source for proof of the gas bearing or brake drum expansion theory. On top of that, not much is being written on drum brakes these days, except the repition of the gas theory. Please review what I wrote and the proof I gave about drum brakes operating in a narrow friction coefficient between lock-up and fade. How does the gas hypothesis explain drum brakes locking? Jobst 20:07, 19 February 2007 (UTC)

Hi. You are free to provide a WP:RS to support your statements. I went ahead and clarified a couple of the refs you asked for. I also reformated the article. You are more than welcomne to add your insights but if and only if you back them up with source amterial. Thanks. --Justanother 23:24, 19 February 2007 (UTC)

Maybe I'm unclear on the concept, but who is entitled to place [citation needed] references in articles? From my experience it seems to be as open as the rest of Wiki. One of my previous articles was riddled with them even where there were plenty of references. After that the article was deleted by I don't know whom although I can guess from the threats that preceded.Jobst 00:03, 20 February 2007 (UTC)

Jobst, the only thing you really need to do is stop writing unsourced material. If you add something then provide a source so that othere editors can check your work. That is how it works here. If you will do that then you will find that your contributions are welcomed here. Thanks. --Justanother 03:05, 20 February 2007 (UTC)

Justanother, the only thing you really need to do is stop writing unsourced material. If you add something then provide a source so that othere editors can check your work. That is how it works here. If you will do that then you will find that your contributions are welcomed here.

That your article is backed up mainly by another's repetition of drum brake lore does not seem to stike you as odd. That citation contains no explanation of what causes fade, only that it is caused by thermal expansion and gas generation, both of which have not been shown to exist. This is a hypothesis from brake mechanics, not an engineering staff at a major brake manufacturer. Repeating it from auto magazines does not make it credible. We don't need Wiki's to repeat such stories when you can get that from the man on the street.Jobst 03:37, 20 February 2007 (UTC)

Jobst, you are mocking me when I am going out of my way to be helpful. This is not "my article". If you check the history then you will see that I mostly cleaned it up and clarified somewhat based on sources. The bit on drum brakes was already in there and I left it. I also left the fact tag that you put on it. I added a "drum brake" section for you to add correctly sourced material. Regarding what you consider incorrect material, if it has a good source then it stays unless you can provide alternate sourcing. Any published article is considered a good source. Rather than fight with me (I am not your opponent), just learn the rules here and have fun! If you have a question about how the rules work then feel free to ask me on my talk page. --Justanother 14:18, 20 February 2007 (UTC)
Well, I guess a source from 1959 is better than no source at all. Now, instead of rudely destroying the work of other editors, please use the section on "Drum Brakes" to explain, with sources, how the servo effect contributes to fade. That would be great! Your source only mentions it with no explanation. Note also the below from your source which seems to be something that you disagree with?

As the brakes get hot the drums expand away from the shoes and the pedal travel increases. The friction coefficient of the hot linings drops and finally the brakes fade.

I am restoring your destructive edit again. Please contribute sourced material instead of removing sourced material that you disagree with. Disk brake fade is a reality. The 1959 reference had it wrong but can be forgiven for that. We know better now --Justanother 19:11, 20 February 2007 (UTC)
As I said, I did not invent this article and I am not invested in it all being "correct", as-is. Looking at what I could find on the net, I agree with you the the self-energizing design of leading-shoe drum brakes is a major source of fade in drum brakes. Since such brakes rely on a "force multiplier", as it were, of friction leading to more friction then they would be very sensitive to any drop in friction co-efficient. This should be added to the article along with mention of twin trailing shoe designs to reduce fade. I would rather that you wrote that section and I, for one, would not be a stickler for sources at this time (they should show up at some point). But I want to stress that you are part of a team and should not tear apart the work of others without very good cause and discussion here if anyone objects. I would really rather that you became the good contributor that I think you can be rather than someone that tried and got in trouble over here. I am not trying to be patronizing or condescending; I am trying to be helpful. Thanks. --Justanother 20:06, 20 February 2007 (UTC)

Whether it is your article or not, you seem to be its sole defender and thereby assume authorship. Bluntly, it is erroneous and false. Apparently you didn't read the referenced study in which among other findings the following is mentioned:

"Another attempt to beat fade is the two-trailing shoe brake. It needs servo assistance, but it is much less liable to fade than brakes such as the two leading shoe type which depend heavily on a self-servo effect for their efficiency."

"Finally, the disc has no self-servo effect, so it gives a stable and consistent action free from fade, whether hot or cold. It will go on working even when the disc is glowing red with heat."

By reinstating your brake folklore article you ignore logical explanations that should have dissuaded you from the belief in the drum expansion and gas bearing hypotheses, neither of which are physically possible. Editing and elaborating on these fables does the readers of Wiki a disservice. This is not a forum for myth and lore. You have shown no explanation how drum expansion and gas bearing cause fade or that they do so. What I wrote, as well as in the reference citiation from a scientific journal explains how the servo effect of drum brakes causes brake fade.

Is there no one else reading thse pages with comments on the subject? Jobst 20:49, 20 February 2007 (UTC)

Jobst, your reference is hardly a "study". It appears to be an article written in 1959 by a junior or senior is a university dairy program. So now, rather than work together to improve the article, you are putting it up for deletion? All due respect, but if that is your best effort at working with others, well, OK then. I guess we won't be working together to improve the article. I am not "defending" the article against "the truth", I am simply trying to get a disruptive editor, you, to make necessary adjustments to his style of "editing". Do you think I have any hope of succeeding? I am, needless to say, removing the "prod". Your next step if you want to pursue deletion is called WP:AFD. Your next step is you want to work together is leave the parts that you have added "fact" tags to alone for a bit (like a week) and add something worthwhile without destroying the work of others. Good luck. --Justanother 21:29, 20 February 2007 (UTC)


You say you are not the author but you expanded the article to have more sections, mostly not about brake fade and its cause. Since the introduction of disk brakes, more than 30 years ago, fade has no longer been a concern to drivers, making the other parts of the article irrelevant.

Girls, drum brakes are still used on the rear of light trucks & SUV's; and (all but) exclusively on medium & heavy duty trucks. The underlying brake fade mechanisms can differ (brake fluid boiling on disc brakes vs more quickly reaching the "kneepoint" on the temperture-friction curve for drum brakes); but the fact remains that disc brakes cannot dissipate the horsepower (energy) that drum brakes can, without badly warping. Dan Schwartz, Cherry Hill, NJ; Expresso@Snip.Net Discpad 04:13, 14 March 2007 (UTC)
Causes of brake fade
Fade in drum brakes
Controlling fade through driving technique
Brake modificaton to reduce fade
References and sources

A single Brake Fade heading will do, fade being unique to drum brakes and its cause their servo effect. My article recalls the vagaries of servo effect that cause both fade and lock-up. I don't see what part of the existing article you propose to keep.

The report I cited appeared in a peer reviewed Michigan State University technical publication. Your ad hominem of the author is out of place. This is not an auto magazine with conversational fare.Jobst 22:27, 20 February 2007 (UTC)

Your contention that disk brakes do not experience fade is unsupportable. You cannot re-add the prod after I object, you must proceed to AfD if you feel that way. --Justanother 23:11, 20 February 2007 (UTC) --Justanother 23:11, 20 February 2007 (UTC)

[edit] Bendix sources and other sources to improve the article

"Brake fade - There are many types and causes of braking fade. Fade may result, for example, from a reduction in friction between linings and drums caused by exposure to water. Most typically, however, fade involves a reduction in braking force experienced when dragging brakes on a long grade. If brakes are maladjusted, and overheated drum may expand to the degree that push rod travel is insufficient to fully actuate the brakes. This is one example of mechanical fade, which also may result from various mechanical defects (e.g., scored drums) within the foundation brake system. In contrast, heat fade occurs when linings overheat and become less aggressive. Gradual and predictable fade is desirable as a warning."[3]

"At Bendix Spicer Foundation Brake, we developed the metallurgy in our 17-inch rotor and paired it with our advanced friction material specifically designed to optimize friction performance at high temperatures, thus significantly reducing brake fade and maximizing brake pad and rotor life. As a result, there is virtually no degradation in stopping power when brake temperatures rise under heavy use."[4]

OK, what about drum brake fade?! Dan Schwartz, Discpad 04:05, 14 March 2007 (UTC)

Also fade in clutches! Note: these are quotes to point to sources, not for inclusion directly. --Justanother 14:37, 21 February 2007 (UTC)

Lots of great data, esp. on "fluid fade".[5] --Justanother 14:46, 21 February 2007 (UTC)

Justanother, you suggest:
"Jobst, that is a great reference and I wish that you would use it to improve the article rather than to abuse the process here. It is clear from the article that friction fade is a factor on disk brakes and that Bendix has claimed to made a breakthrough to reduce it. Good for them! The issue of fluid fade is not addressed because Bendix is not selling brake fluid in that ad. --Justanother 13:34, 21 February 2007 (UTC)"

Thanks, but how do I merge this with the current article, there being a conflict about the definition of fade and its cause. As I mentioned in my article, friction coefficient is affected by temperature, a change that is magnified by servo action of drum brakes, the bane of vehicles descending steep roads. I believe that loss of hydraulic stiffness between pedal and brake pad should not be called fade. Power assist brakes bridged most of that effect. Fade, as I see it, occurs at the friction interface. As Bendix mentions: "Virtually no brake fade and no degradation in stopping power." is not the fade phenomenon of drum brakes, but a reduction in brake response that is effectively imperceptible. As mentioned, disks work well even at glowing temperatures.

From the beginning of this discussion, the concept of thermally expanding drums and gas bearing was what I believe should not be endorsed in Wikipedia. What I wrote addressed those issues so how do I get my text together with yours without apparent contradiction? I would like to submit what I currently have so you can indicate which parts you believe need modification. I find appending it to the current Brake fade page illogical. I also believe that brake fluid effects should appear under a separate heading of mechanical brake degradation as Bendix does, because otherwise it clouds the issue of resolving what makes drum brakes (friction) fade prone.Jobst 18:46, 21 February 2007 (UTC)

Jobst, your change in approach is noted and appreciated. Thanks. If I may make a suggestion, would you please rewrite this section, Fade in drum brakes, completely to conform with the Bendix source and other sources as appropriate. Make your changes in the article itself. Regarding disk brakes, I would appreciate it if you did not change anything there until we discuss it and I will not be able to do any more here until about 8 hours from now. --Justanother 19:08, 21 February 2007 (UTC)

I'm unclear on where you mean. Do you want me to write that in this discussion page or on the Brake fade page? I notice there is a [citation needed] in that subject, here and on the Brake fade page. Also the section above that title, Causes of brake fade leaves a dilemma in that it states the gas bearing and expansion effects are the cause. Please explain.Jobst 20:00, 21 February 2007 (UTC)

I just copied the section below for convenient reference. I would like you to rewrite that part in the actual article, not here. Let's leave the other sections of the article for later, please. --Justanother 20:17, 21 February 2007 (UTC)

[edit] Fade in drum brakes

In the case of drum brakes the change in dimension of components in response to heat; the curvature of the brake shoes then failing to match the curvature of the brake drum[citation needed].

[edit] Quick note

In light of reading all of your comments in respect to this article, I would suggest taking a look at Requests for comment (RfC). I was also going to suggest taking a look at WikiProject:Automobile construction but it appears to be inactive. (It may be of some use though). I hope I was able to help. Happy editing! Johann...[ T...C ] 00:21, 22 February 2007 (UTC)

[edit] Drum expansion

Jobst: How do you justify this statement:

Fade was commonly attributed to thermal brake drum expansion, reducing brake shoe contact with the drum. This ignores how little expansion a hot drum experiences, (about 0.024 inch for a 400°F temperature rise) far less than normal deformation caused by brake shoe pressure.

when it conflicts with Bendix

If brakes are maladjusted, and overheated drum may expand to the degree that push rod travel is insufficient to fully actuate the brakes.

This is false: The deflection of the very rigid cast iron drum is minimal compared to the mild steel of the web and table of the brake shoe, which is quite flexible. Here, the self-adjusters take up any wear in the brake lining. Dan Schwartz Discpad 03:59, 14 March 2007 (UTC)

Admittedly, adjustment is a major factor, but you cannot simply discard this as "myth"?--Justanother 02:14, 22 February 2007 (UTC)

BTW, Jobst, this is a bit outside our scope here but you might find it interesting. http://fmr.korea.ac.kr/korean/research/results/en25.pdf --Justanother 02:33, 22 February 2007 (UTC)

Another engineering paper http://www.delphi.com/pdf/techpapers/2000-01-0445.pdf --Justanother 02:47, 22 February 2007 (UTC)
Last one http://www.ornl.gov/~webworks/cppr/y2001/rpt/112956.pdf --Justanother 03:40, 22 February 2007 (UTC)

I found interesting that there was no truck drum-brake fade mentioned in these papers although they measured fade of brake materials. The failings of the drum brake seem longer to be studied since passenger cars switched to disks.Jobst 18:44, 22 February 2007 (UTC)

I don't see anything in the Bendix page contradicting what I wrote, consdering that the drum expansion that I chose at glowing hot temperatures giving 0.012" per shoe is insignificant in comparison to drum ovalization under hard braking. We may be putting the cart before the horse in requireing citations for everything stateded. If that were necessary there would be no text and only links to other places. I believe that only if the item is not reasonably credible other justification needs to be cited. Do you believe 0.012" is enough to prevent brake pads from making contact? You are probably aware that unless the contact area is severely compromized, applied force and friction coefficient, independent of contact area, give the drag force? Such considerations need to occur when reading descriptions, otherwise an entire high school physics book would need to be referenced, not to mention higher mathematics and college physics. I believe there is no comflict between Bendix and "Fade in drum brakes" because the "push rod" mentioned is found only on truck air brakes. I also don't believe this Bendix brake is intended for tandem dual axles but mainly for front truck axles judging from the size of its lug bolts.Jobst 06:01, 22 February 2007 (UTC)

By the way, I do not understand who is supposed to delete [citation needed] inserts in an article. I deleted the one in "Fade in drum brakes" but don't know what the procedure is.Jobst 06:08, 22 February 2007 (UTC)

You might want to take a look at Wikipedia:Citation_templates. Happy editing! Johann...[ T...C ] 20:12, 22 February 2007 (UTC)

Could you be more specific? I found no reference to [citation needed] nor who is entitled to inset or remove that flag. I read through a lot of verbiage without making any headway. Could you explain it or give a specific pointer to a description.Jobst 00:26, 23 February 2007 (UTC)

The use of [citation needed] is not required, and if everyone agrees that they are not needed you can remove them. You could also put at the top of the article either:


{{expert}}

{{expert}}

Or

{{Inuse}}

{{Inuse}}


I hope I was of assistance. If you ever need help, feel free to contact me. Happy editing! Johann...[ T...C ] 00:57, 23 February 2007 (UTC)

P.S. This might be of some help aswell Template:Fact.

That page did not make this clearer. It stated that "if everyone agrees the 'fact' template can be remoced"... but by whom and how do I know everyone agrees? The same goes for the two boxes above. I am unclear on how to invoke a spell checker in Wikipedia so I often write on a word processors elsewhere and cut and past. As I wander around in this maze, I begin to feel that I backed into a secret handshake club that wards off newcomers with a depth of procedures. For instance the form of the above paragrafh, seen in edit mode, is utterly cryptic.

What I found difficult was the subjects on which I wrote were themselves unsourced, but when challenged relied on common knowlege that made citations unnecessary. That makes rewrite of aricles diffcult, being held to a different standard than the original article that doesn't disagree common knowlege, regardless of validity. I am glad user:Justanother has been gracious in allowing space on his article for a different assessment of the subject, one that I feel needs to be heard. Both car brakes and engine valve drive are areas in which I worked extensively when these subjects were first subjected to scientific (computer) analysis ca 1960...).Jobst 03:58, 23 February 2007 (UTC)

  • The issues of drum brakes, fade, linearity and control have been around for awhile. See: [6]. Jobst 19:39, 23 February 2007 (UTC)


You can simply ask all editors currently involved in this article to say either 'yes' or 'no'. I understand that some of the code used in writing articles is somewhat confusing, but it may relieve you to know that the majority of the above text is my signature. (In my note that is). Also, 'Justanother' does not have ownership over this article; it is stated below the edit window that "If you don't want your writing to be edited mercilessly or redistributed by others, do not submit it" and also "You agree to license your contributions under the GFDL." I hope this has clarified a few things. Happy editing! Johann...[ T...C ] 01:44, 24 February 2007 (UTC)

I have decided to set up a vote here:

[edit] Vote

This vote is to decide if we should keep the [citation needed] notes in this article. (0/1/0); Scheduled to end 01:40, 2 March (2007) (UTC)

Please keep comments constructive and polite. Thank you.


Type # '''Support/Neutral/Oppose''' ~~~~


Support

Oppose

  1. Oppose I don't think it is necessary. Johann...[ T...C ] 01:44, 24 February 2007 (UTC)
  2. Oppose --Justanother 02:56, 25 February 2007 (UTC)

Neutral

Keep this article: There is a lot of information specific to various brake fade mechanisms that is worthy of its own article. Dan Schwartz, Cherry Hill, NJ; Expresso@Snip.Net


Comments

I am unclear on what "Oppose" and "Support" mean. I am opposed to deleting the sections but I support verifying that gas bearing or drum expansion are causes of brake failure. There has been no technical explanation of these phenomena. People not in the brake design business have repeated them so often that proof by repetition seems to have been achieved. I referenced thermal expansion coefficient and its effect and pointed out that enough gas to float brake shoes is inpossible to generate repeatedly from friction material that shows no material change between incedents of fade and no loss of performance when cooled. Effects of self servo are found in mechanical and electical journals apenty and that the drum brake relies on this to function. My reference to the Michigan University article links servo to the problem unambiguously. Unfortunately there are so few cars with drum brakes that we no longer experience this. Disks have been here so long that no one publishes drum brake research today. Jobst 23:01, 25 February 2007 (UTC)

That is patently false: Rear drum brakes are still used extensively on light trucks and SUV's; and almost exclusively on heavy trucks. Dan Schwartz Discpad 03:53, 14 March 2007 (UTC)
Jobst, this was put here by someone else to show you how you might go about reaching consensus on a disputed issue. This one was if the [citation needed] tags that I think you put should remain. It is kind of moot now as they are gone anyway and no-one wanted them to remain; the new [citation needed] tag I put should stay for a while. The way it really works is if no source is provided after a wait then the info goes not the tag. Thanks --Justanother 23:07, 25 February 2007 (UTC)

I see no [citation needed] tags that I placed. This is getting more cryptic with each turn. The tag in the explanation of thermal expansion and servo is unclear to what it refers, there being citations for both thermal expansion and servo, the subject of the paragraph. Please explain. Jobst 03:07, 26 February 2007 (UTC)

[edit] OR in drum section

I tagged a bit of OR that seems to run counter to sources that can be located so it clearly needs a source. Also, Jobst, when someone makes a change please respect it. We work together here. When you work on the article off-line and then paste it back in you have to be extra careful to include the work of others. --Justanother 03:26, 25 February 2007 (UTC)

I was referring to text that I wrote, not text in other sections of the Brake fade piece. However, I find the two paragraphs before "Fade in drum brakes" misleading and in need of rewrite. When I did that originally, it lead to this bruhaha. The piece overlooked the basic weakness of internally expandig shoe drum brakes, which is at the core of what is commonly known as brake fade, or drum brake failure from loss of servo effect.

Working my way upwards (since it's late at night), the cause of drum brake fade is NOT the loss of servo effect: If this were true, then fixed anchor drum brakes (such as the FMSI part# 501 on the Ford Tempo or 583 on the Taurus/Sable) would not suffer from fade; nor would heavy trucks using the 4311 (Eaton), 4515T (Timken) or 4515F (Fruehauf) cam brake assemblies, nor the 4602 wedge brake assembly, also all with fixed anchors. Instead, it is caused by the friction coefficient curve (friction vs temp curve) reaching the kneepoint where phenolic resin breakdown starts to occur. Please see my entry below. Dan Schwartz Discpad 03:56, 14 March 2007 (UTC)

That makes the rest of the article a bit confusing, because it relies on the unsubstantiated drum expansion and gas bearing hypotheses. Unfortunately this idea has been repeated so often that it passes without challenge or technical explanation and need not be further substantiated. There is no scientific explanation for these scenarios.

I am aparently not able to rewrite those parts without the rewrite being erased and the original resinstated. In the discussion that ensued I was informed that it didn't matterr who is right or wrong, but that the procedures be followed. I'm open to suggestions.Jobst 06:32, 25 February 2007 (UTC)

By the way, who runs the clock on these datelines? It is 24 FEB 07 here.Jobst 06:32, 25 February 2007 (UTC)

You must be on the West Coast. The time is UTC, the same as Greenwich Mean GMT? One of the refs I saw and I think I put a link puts the gas thing as a deposition and redeposition issue rather than a cushion of gas. Also the melting of binders is a factor. And the green fade thing. The expansion of drums should be mentioned, I think, as Bendix says it is an issue if the brakes are out-of-adjustment. Not all myth but perhaps over-stated in the past. --Justanother 06:39, 25 February 2007 (UTC)

I notice that under "history:" you feel that verification is needed to prove disk brakes operate when glowing temperatures. At the moment I cannot find a picture or technical item to cite but many pictures have been in the press showing red hot brake disks on cars to adequately to prove that it occurs without brake failure. If you were to ask readers if they have seen pictures of glowing disks, I think most would say they have. Still looking. Jobst 21:49, 25 February 2007 (UTC)

You misunderstand me. My request applies to the paragraph as a whole, especially any "debunking of myths" that you want to do. Actually, the red-hot disk is the least of my concerns, though, of course, it should be sourced too. --Justanother 22:36, 25 February 2007 (UTC)

As I said, what parts of self servo is not sourced? What I find more important is the concept of drum expansion and gas bearing not held to the standards you demand. I demostrated the temperature falacy with reference to expansion coefficients and explained with citation why drum brake servo is the culprit. Jobst 03:00, 26 February 2007 (UTC)

Hi. It is possible that you need to make an adjustment to your idea of how this wikipedia works. You do not demonstrate or prove anything with explanations or calculations. All proving is done by showing sources. This is NOT about writing explanations. You can write an explanation, sure, but it must be backed up by sources. This is about sourcing. Every single idea should have a source and the source should be mentioned. If not then you can put the [citation needed] tag and ask for a source. But don't discount "popular media" as sources. They are allowable. To clarify. This is unsourced

This ignored how little expansion drum heating causes, (about 0.024 inch for a 400°F change) far less than normal drum deformation caused by brake shoe pressure.

And so is this

they are physically impossible, considering the volume of gas required to generate a gas bearing.

You seem to be wanting to debunk myths there and you are not provinding sources. I am saying please incorporate the Bendix data on drum expansion leading to fade and please take a look at the sources I provided already and see what they say about gas cushion, gasified material deposition, glazing, binder melt. All issues that you do not address but that are covered in the sources I provided. I think that you just want to write this off the top of your head and without sources and that is not what we do here.--Justanother 03:12, 26 February 2007 (UTC)
Jobst, you cannot add links to images. All images must be imported according to WP:IMAGES. Re drum expansion. Per your link red = 1400 F = 760 C. Expansion on a 20" truck drum at that temp works out to 0.18", certainly enough to cause a problem if brakes are out-of-adjustment and that is what Bendix says. --Justanother 04:13, 26 February 2007 (UTC)
And, Jobst, I know the learning curve here is probably like nothing else you ever experienced (it was for me too) but a "source" means a "reliable source". Please read WP:RS to get an idea. Again, the main policies are all at WP:PILLARS. --Justanother 04:13, 26 February 2007 (UTC)

Drum brakes do not operate at the temperature you chose to calculate and cars have roughly ten inch diameter brakes. You'll note, my example took 400°F rise, your example nearly doubled that and doubled the brake diameter. The thermal expansion coefficient is 12ppm/°K. So let's get to the basics. If you believe in the expansion and gas scenario, you should give reasons for readers to believe it and give a reference that explains iut, not just repeat what common belief is. That servo is cause of drum brake failure can be deduced from what the article originally stated, that the friction coefficient decreases with temperature increase and that there is a self servo effect. You'll need to be more specific which source material you don't like. I don't know what you find amiss with my references. Jobst 04:31, 26 February 2007 (UTC)

Bendix. Trucks. "If brakes are maladjusted, and overheated drum may expand to the degree that push rod travel is insufficient to fully actuate the brakes." --Justanother 04:35, 26 February 2007 (UTC)

These are air brakes on trucks that most often lock-up leaving long dual skid marks that we see on highways because they have servo action. That drums as large as these, greater than twice the diameter of passenger car brakes, which are the ones of interest, when "maladjusted" can lose contact, does not contradict that the servo action of drum brakes is the primary cause of brake failure at high temperatures. The "maladjusted" is a major caveat in that sentence. Truck brakes in question use pneumatic diaphragms with pushrods to rotate mechanical cams that spread brake shoes against their drums and are in that way different from hudraulic car brakes. Please stop creating spurious diversions. The claim of gas bearing and brake shoes not making contact on car brakes is unsupported. Jobst 05:41, 3 March 2007 (UTC)

"Please stop creating spurious diversions." Amigo, please do not fight with me or disrespect me. If you cannot "play well with others" then you should not be here and should go to http://www.blogger.com where you can write all you want and not be bothered by others. --Justanother 21:15, 26 February 2007 (UTC)

[edit] Jobst - please stop rudeness

Jobst. My patience is wearing thin. You cannot edit on a word processor and then paste back in and delete all my contributions in the process. That is extremely RUDE! --Justanother 21:57, 26 February 2007 (UTC)

Last time I'm telling you this Jobst. If you cannot edit with another person then you have no business here and I will take necessary measures --Justanother 01:05, 27 February 2007 (UTC)

[edit] Submission to WP:RfC

I hve submitted this dispute to WP:RfC and hope to find a way of resolving the two versions on the origins of brake failure through fade in this article. As I see it, servo effect of drum brakes is the culprit, the reason why they are no longer used in passenger cars and especially racing cars. The loss of drum contact and gass bearing hypothesis should not be validated by Wikipedia.Jobst 02:47, 1 March 2007 (UTC)

[edit] OK guys, I'll try to `splain

I stumbled across this thread by accident: I was chief engineer of Guaranteed Brake Parts Company, in business from 1947 to 1996; originally in north Philly, and from November 1963, Camden, NJ. Among other things, we had the largest bonding oven in the world in the Camden plant; and in in the early 1950's my Grandfather and B.F. Goodrich engineer Leon Fiedler perfected the brake lining bonding process, with the phenolic A602-B thermoset adhesive. Also, our family was heavily involved with the APRA Brake Institute, with my father (Joseph Schwartz) holding the presidency of that body in 1990-1992. As a major rebuilding operation with, at the peak, producing almost a half-million disc pads and 240,000 new and rebuilt brake shoes, we had the choice of various friction material manufacturers, such as Brassbestos, Bendix, Carlisle (truck only), Certified/Lear-Siegler, Krasne, and Nuturn (Turner & Newell/Ferodo) under the Grizzly brand.

There are several causes to brake fade; but at this moment I need to clarify a common misconception about the Friction Material Standards Institute (FMSI) friction coefficient lettering. The codes consist of 2 letters, indicating the cold and hot friction coefficients, usually FF or FE. The misconception centers around the belief that the higher the friction letter (say, FG), the better the quality of the product. Not so: The piece of rubber used on a bicycle rim clamp brake is very high; but if it were attached to a disc pad it would burn right out!

Instead, what we want is a constant friction-vs-temp curve that does not have a sharp drop-off: If the curve is too steep either upwards or downwards, the result is often "grabbing" at high or (usually) low temperatures.

Keep in mind that the temperatures can get quite hot in a braking assembly, as the brake is no more than an energy dump. One of the best illustrations of this is during NASCAR broadcasts from Martinsville, where you see the cast iron rotors glowing so red hot (my estimate from the color is as high as 1100°F) it can actually damage the bead of the tire!

When the brakes get very hot, with conventional phenolic resin & asbestos or Kevlar in the area of 600°F one reaches the "kneepoint" of the curve, where the phenolic resin binder actually starts to break down. By the time the material reaches 850°F the resins "go exothermic," i.e. they catch fire! This is the principle involved with debonding furnaces, where once the lining catches fire, the resins in the lining decompose as does the adhesive. In fact, in our Bayco debonder furnace, which holds up to 4,000 shoes(!), the two main one million BTU gas burners shut down at 850°F and the water sprays kick on, to keep the load temperature under control to avoid warping the steel cores. One time during installation testing of the Bayco oven in 1986, we let a load of 4515 & 4311 truck shoes get to 1100°F to see where the non-asbestos riveted linings would completely disintegrate, turning into powder.

OK, so we've established that brake fade on drum brakes and asbestos disc pads starts from the surface decomposition of the friction material starting at about 600°F. BUT! That is only one mode of brake fade!

Another cause of brake fade started to rear its' ugly head with the advent of metallic disc brake linings: Boiling of the brake fluid. Up until the 1970's, plain old DOT 3 brake fluid was fine for 4-wheel drum brakes, as the friction material would reach the temperature-friction kneepoint long before the brake fluid would boil. However, metallic disc pads were no longer an effective thermal insulator, instead conducting the heat through the pad, through the backing plate... And right on to the cast iron or aluminum caliper and (especially) steel piston(s), boiling the brake fluid. This led to high temperature DOT 4 and silicone-based DOT5 brake fluids, to handle the higher temps yet not boil.

[Alas, DOT5 brake fluids have a tendency to foam when used in anti-lock brake systems from all the "churning," causing fade at operating temperatures... But that's the subject of a whole `nuther discussion!]

We once diagnosed an interesting cause of brake smell (and attendant brake fade) in FoMoCo E/F-350 delivery vans in NYC: Brake balance! Turns out that the proportional valve was set to the factory specs, which put over 70% of the braking force on the front axle when the vehicle was empty. Problem was, when the trucks were (over)loaded, the rear brakes were (all but) tagging along while the front brakes were handling all the load. We solved the smell & fade problem by using a lower friction front pad and a very aggressive rear brake lining originally used in truck brake blocks.

(More to follow in a day or two, after I dig my engineering notebooks out of my parents' basement and dust them off...)

<not a good idea for here> Discpad 03:41, 14 March 2007 (UTC)

Super. Please don't waste your expertise here in the talk page. Write in the article. I will be going on break from editing here soon. Perhaps you and Jobst can work together toward a good article. If you run into trouble or need help then just post to my talk page; I will be checking in from time to time. Later. --Justanother 03:54, 14 March 2007 (UTC)
Whoops. Do not use strikeout or italics in the article. Do not disrespect the sourced edits of others. Merge your material into the existing article so as to explain and provide additional detail but do not remove material unless is is false and. if false, it is better to fix it than remove. Do not write above the head of the casual reader. Or if you do make sure that the layman's explanations are in place too. See WP:PILLARS. Read the policies. --Justanother 04:33, 14 March 2007 (UTC)
The problem is that the information "cited" is patently false: It comes from a Times journalist who is proffering false, unsourced information in his newspulper article. Dan Schwartz Discpad 04:41, 14 March 2007 (UTC)
If the cited source is bad, then cite other better sources. AlistairMcMillan 21:35, 14 March 2007 (UTC)

[edit] This article is so screwed up

After writing up my comments and looking the article over, it is so screwed up with urban legends, half-truths, and other dubious information (including using a "journalist's" article as a primary technical source), I recommend a complete rewrite from scratch. <personal info not good idea> Dan Schwartz, Cherry Hill, New Jersey; Expresso@Snip.Net Discpad 04:44, 14 March 2007 (UTC) (By the way, as pioneers, our family is well known in the brake shoe and disc pad manufacturing industry)

OK, Dan, if you want the spam then leave it here. If you want to improve the article then great. Just realize that you are not the only editor on wikipedia. I imagine you object to the gas cushion bit? Then remove it. I did see some more realistic sounding explanation about gas transport of binder material and deposition and redeposition of same on disks and pads (glazing). Anywho, write a nice bit and do not object if other editors cut it up. ps. Wikipedia is tough on experts. I know because I have my own areas of expertise (not brakes). --Justanother 04:50, 14 March 2007 (UTC)
I already get a lot of spam, and I have a challenge-response spam blocker on my Expresso@Snip.Net public email account. In any case, the phenolic resins used in friction materials are thermoset plastics, i.e. they don't plasticize at elevated temperatures: They disintegrate. Discpad 05:00, 14 March 2007 (UTC)
OK, I will not argue with an expert. How does "glazing" fit in then? Pads glaze, right? --Justanother 05:03, 14 March 2007 (UTC)
"Glazing" is caused when the inorganic fillers (such as the chrysotile allotrope of asbestos) heat and literally turn to glass. But, this is not a transient (fade) effect Discpad 16:10, 14 March 2007 (UTC)


Discpad -- It sounds like you have a lot of good information. Wikipedia requires that any factual claims be supported by a citation to a published work of some kind and furthermore, that original UNpublished research will be deleted immediately. Web sources are preferable, but ANY publication (such as paper journal publications) are acceptable, provide a complete citation is made. See WP:CITE for how to do this properly. IzaakB(my Talk)contribs 15:55, 15 March 2007 (UTC)

I've been out of the brake shoe and disc pad manufacturing industry since 1995; though I've stayed in touch. I'll have to dig down in the dusty shelves in my parents' basement for some of the Grizzly and Bendix TSB's (tech bulletins), especially on the NAO linings & pucks. The problem is that when a customer's customer (like a rental fleet at JFK, or the Atlanta PD, or AC casino limos) would have a problem, I or my father would go out and investigate (most of the time is was installer error, like not machining the rotors when switching to NAO, i.e. just doing a "hang job); but if it was serious, an engineer from the lining manufacturer would join us... Then this information would either be fed back to the manufacturer's engineering for reformulating (like pads crumbling under excessive loads: For obvious liability reasons this would be confidential inside the friction material manufacturers, with silent changes to the formulation and/or "silent recalls" where we would swap out customer stock); or technical information would be conveyed to our W/D & jobber customers, such as the E/F350 brake balance problem on overloaded city delivery vans (see above). We would call the customers who were affected; and also on occasion put a "statement stuffer" to alert all customers. Keep in mind this was all before the Web came into prevalent use (pre-1995); and this was the customary trade practice for decades. Deal with it! Dan Schwartz Discpad 13:40, 17 March 2007 (UTC)
Although there are lots of words under the current discusssion heading (Article all screwed up) I see no reference to servo action of drum brakes or why motorcycles and passenger cars no longer (and Railways never could) use drum brakes. I hope those involved in editing this article can separate changes in friction coefficient, as Dan mentions, from brake failure, commonly swept under the same rug in the past. I tried to capture that in the sub-article "Why drum brakes fade" as Justanother suggested. I hope we can get the whole articel to agree at some time. You can see what I initially proposed in my first edit that got bumped for the original version. I prefer to have change in friction coefficient defined as brake fade and brake failure resulting from such chages identified as a result of drum servo action, the reason we don't use drum brakes any longer where speed control is most needed.Jobst 01:18, 18 March 2007 (UTC)
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