Squealing Brakes

[dwire]

I always thought that semi metallic pads came about to speed up heat tranfer from the braking surface to the backing plate and away. I did prove on my Harley FXE that semi matallic pads were the wrong choice on ductile iron disk. They didn't stop as good as organic on the iron and they ruined the disk in short order. Stainless disks with semi metallic pads are almost as good at brakling as organic on iron and the stainless disks aren't eaten up by the semi metallic pads.

I can't say with 100% certitude as I was ushered in as the panic was dying down as everything was moved to some form of semi-metallic or organic when I was hired into the labs back in that time as to ALLTHE WHY'S. I was told unalaterally time and time again from the new engineers right down to the very oldest one left with a key card; the man to design the very first two viable PRODUCTION hydraulic designs (non-mechanical) for General Motors via DELCO that the change was brought upon due to the safety concerns of asbestos - just like we migrated cad plating out of our processes while I was there. I got chest X-rays even though I hardly ever entered the asbestos production area quarterly, so I would gander there was something to it. Lots of the younger engineers even made crude jokes of some of such things, "Just because some guy with an air hose dies, we have to..." or "Who cares if some Union guy gets cancer; why should we have to reinvent the wheel?"

The statement about semi-mettalics and iron discs could not be more true Sir - or at bare minimum the early ones. No need to repeat what you said your words are spoken wisely and you experienced it. I did daily as they looked for answers and then personally as I went "Oh crap!" with my Buick when said combination equaled four new discs and God knows what else by the time I was done chiseling though discs and replacing broken studs! (Simple brake job gone wrong. )

The rest of your statement is what I have been trying to say ever so poorly I guess, but no one seems to agree, or is somehow trying to make it more complicated. Thank you for your statement, not for reinforcing anything I've said, I only wished you would have posted it earlier, so none of my commentary would have been involved...

Everyone may freely disagree, I'll not be offended or anything. I do my best to share as best as I can recall things. I am fallible as I am human; you need not agree, but with regard to George's statements, they mirror a great deal of experiences I've had both personally and in the workplace.

[Major Softie]

Personally, I find modern metallic HH pads to be superior in braking performance to the old asbestos ones, but they are certainly not as easy on discs - even stainless discs

[dwire]

Not sure what "HH" means with regard to the metsllics, but...

Yeah, they are very hard on discs of any material; some are abbe to take it better than others.

[Major Softie]

HH is a rating of the coefficient of friction. Apparently most stock pads are G, and H is higher. HH means it has a coefficient over .55 both hot and cold (first letter is cold, second is hot). FF and GG are softer and provide a lower coefficient, which is contrary to your belief that a softer pad will give you more braking.

Here's the SAE numbers:

C < 0.15
D > 0.15 but < 0.25
E > 0.25 but < 0.35
F > 0.35 but < 0.45
G > 0.45 but < 0.55
H > 0.55

I believe the best old asbestos pads were mostly rated F or FF with older ones being E.

[dwire]

I would not know what the asbestos "were" back in the day, nor what I have here - wasn't SAE contrived in the mid '70's as a standards and ratings system? That would make all the designs and compounds I am speaking of, auto or our BMW sort of not apply...

[Major Softie]

I would not know what the asbestos "were" back in the day, nor what I have here - wasn't SAE contrived in the mid '70's as a standards and ratings system? That would make all the designs and compounds I am speaking of, auto or our BMW sort of not apply...

Well, the rating system may not have existed yet (don't remember for sure) but companies did know what their coefficient of friction was.

[dwire]

If there are no preventative parts in the brake to stop rattling or chatter (squealing) and all is functioning well (I see none in the ETK) - it would seem to indicate the pads. Unless the design is horrendously inadequate one can greatly reduce the likelihood they will make noise by putting a softer compound in. Of course, perhaps the pads were crap to begin with and a replacement simply with another brand or batch will do. The rest of the story is surely irrelevant as you seem to know more of what I personally experienced, for which is very difficult for me to disagree with anyone with that sort of data on me.

[Major Softie]

I've been talking about brake parts. I now have no idea what you are talking about. I know nothing about what you personally experienced, I only know what you have written here. The only data I know is that which seems to be contradictory to what you have said. I never meant to imply that I know anything about your experience, only that some of what you said is inaccurate: ie. that softer pads provide a higher coefficient of friction than harder ones (more powerful braking). This is simply the opposite of what is true in any pad available today. That softer pads are easier on discs is certainly true; that they provide more braking power simply is not.

I suppose it is possible that everything that is true today is the reverse of what was true in the past with different compounds. Regardless, those older compounds did not provide braking power equivalent to the best current pads. They certainly never needed to, as tires couldn't provide the grip that today's tires can. One may argue that they prefer the feel of the older pads, but that is subjective. In the objective (measurable) qualities, the old pads do not provide more (or equivalent) braking power compared to the best current pads. The fact that you were not familiar with HH pads seems to make it clear that you are not familiar with current brake technology.


Also, on softer pads equaling less squeal: manufacturers claim that the hardness only effects pitch, not amount, of squeal. Certainly a higher pitch squeal is something I find more irritating, so volume may matter less in the perception of squeal than frequency. Ceramic pads (very hard) are supposed to have much less perceptible squeal because they move the pitch of most of the squeal up above the range of human hearing. I have no idea if this means you will frighten all the dogs in the neighborhood every time you arrive at a stop sign, but it would be fun to have someone do some field testing.

[dwire]

MS, you do as you do, think as you'd like. This makes twice now in several weeks I've made observations, that you are free to disagree with. My most recent encounter was the tire thread which I ordinarily would NEVER get caught up in, where I said two things from the get go, 1) Essentially "nice job" [SOME DID GIVE RECOMMENDATIONS WITH NO HASSLES MIND YOU!] for everyone sort of badgering a new forum member off the board for no good reason. and 2) I knew an old friend that had sold these bikes and tires and what not and had once told me that the combination seemed quite adequate for both the bike/tire combination as well as his riding even in that era. That was how that started and you were determined to push that until it was to the point of absurdity.

Now fast forward to this thread. I made one comment inquiring about images or parts brake downs to see if I could see if there were even any counter-measures designed into the break or not and then posted a reply at the top of the following page: --> viewtopic.php?f=1&t=4761&start=40

You won the prize both times by an astute handle and command of how to frustrate me, for unless inquired directly, I'd had noting further to say specifically as I do not have a sample of the brake or better specific data. Beyond that, I must assume this button pushing to the point my writing gets sloppy enough for semantics to play a large role (tire thread) or even care to post to you further such as in this thread. Next to nothing after that post is speaking directly to the problem and you go so far as to tell me how you think it likely companies use an outside ratings firm to make up their own standards, which is impossible as SAE makes their standards from the products only after they are released.

As an example of the waste of time just targeting me for aggravation, I said nothing of the gentleman and I'd like think we are all gentleman (or ladies) here that mentioned that one should wish to drive the heat made by a disc and rotor back into the piston and absorb it into the caliper to be dissipated. We both know that's the wrong way to go as once the fluid is vaporized it no longer displays its normal properties of hydraulics and can thusly be compressed - I.E. no brakes (brake fade) You say nothing to said individual but keep right on after me and none of which is solving or even speaking about fixing a dang squealing brake. lol I'd think a brake with boiled fluid would have tipped your meter, but I did not see any mention from you of it.

I'm not the type to walk around with a chip on my shoulder, nor do I hold grudges; so whatever. I can say, that the engineering practices and standards varied none in other countries either when I was called upon in that role as well, just the language(s).

It's unclear to me if you start the conflict simply to work me into a lather to where I can no longer write with much precision, not to mention then begin to tell me I am incorrect about that which I have observed with me own eyes or performed with my own hands. If you'd like show your superiority over me, or my intellect, be my guest, I may only be in the running with an adolescent anyway, so that bothers me not as well; and says no more for you.

Go look at the history books; look for the change-over from asbestos to metallics. You will see the number one automotive warranty claim OVER ALL OTHERS was squealing brakes - right off the lots. THEN they thought they could do better and found out that metallic pads on a regular nicely finished rotor would allow a chemical reaction to take place underneath the pad on the rotors and every brand new car that sat on the lot for a week had a pulsation problem so bad they needed turned - and the kicker turning them did not solve this. These things are facts, but I would bet you would argue that there is no reason you should not just be able to turn the rotors right? NOPE - WRONG THEY WERE RUINED. So things are not always as they seem.

The link to my initial, not all too helpful post above considering there is too little to go on in the MAX BMW ETK was where I had planned to end interjecting much of anything, why was more required? Should I start a white board with how many beers I need PayPal you or something???

As a final note which applies to tires and brakes and life in general people tell me is there is a device that is enough, then there are devices that are too much; simply a waste of time and or materials. Quad-bore Corvette brakes surely would have more stopping power than the original BMW brakes, why not try for them? Sticky racing slicks, provided the hassle of having to remount your rain tires under a bridge on a super-slab trip would give you the utmost traction; the rain tires would do the same for your rainy travels. You could put a 1KW alternator on your bike and boy would it charge, but how much do our little batteries need? 'nuff said...

[dwire]

The fact that you were not familiar with HH pads seems to make it clear that you are not familiar with current brake technology.

Still not getting it MS. Engineers design then test and the manufacturer makes the stuff. They use THEIR internal specs to make "stuff" to meet THEIR internal needs for a platform, what SAE or "SEE-SAW" or ""Hee-Haw" decides to grade it at is not what is a consideration in development. Things like shore durometer tests, which would be likened to say standard metrology, weights and measures, and metallurgical terms that go back to the beginning of the industrial age, yes; surely, but I guess you must have missed where I pointed out, the objective in design was to make something only as adequate as a company decides they require, which in the end equals make something just over adequate and no more.

That is the cart before the horse, like saying "we are going to build the JD Power car of the year..." (lol Worthless business that JD Power stuff is anyhow, but...