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Discussion Starter #1
Heres why I wouldn't bother;

A smooth (worn-in mated), clutch shoe surface (some dare call it 'glazed' ) presents more net/total surface contact area between the shoe & the clutch bell,
more than would exist between a mechanically (macro) roughened pad surface and the bell.

The job of the clutch shoes is to hold against the steel clutch bell ... in STATIC friction mode.
Static friction can of course be overcome with sufficient sheer force.
Then the interface slips, moving in dynamic or KINETIC friction mode (and dynamic always a lower coefficient of friction than static, ie less "grabby" to be techniwokle about it).

By reducing the total amount of contact surface area, and loading it up the same as always (upon accelerating the bike),
this increases the (break free) force per unit area, bringing you that much closer to slipping.
Kind of the same notion behind running wide slicks instead of narrow tires (that, and to minimize heat...)

Ideally you want the MAX interface area to MINIMIZE that force and the tendency to break free.

This does assume that the surface is not contaminated, and not altered, say by having burned up. Then all bets are off.

Thus roughening the surface will not improve lock up. IT will however increase the wear rate and shorten the service life of the expensive clutch shoes. Are these things even available individually , without the whole assembly ?

Also I kind of sort doubt the de-glaze lasts very long, as a couple minutes of slip during the transition from (slow RPM, take off) slide to (higher RPM) lock up probably does a fine job to smooth out all that nasty deglaze :)

Please use padded brickbatts to dispute my conclusions and hope I didnt abuse any Physics words, its been a few years since MechiMat.
 

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The unglazed clutch shoe surface has more friction than the glazed surface does.

Chris
 

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Discussion Starter #3
I knew you be around to chat it over Chris, thanks !
I bow to your many more miles per scooter but I do enjoy physics. And a nice Gorgonzola.

Your side true only if "unglazed" means "decontaminated" ( and then only if the contaminated surface has a lower coefficient of friction - nowhere near certain ... )
First I would attack the contamination source.

If "glazed" mean "glassy smooth & perhaps fresh but basically UNaltered friction material" then I would let the expensive clutch surface alone.
A wipe with brake cleaner soaked rag at most . But I hesitate to encourage anyone to sand off that precious compound.
(every 0.001 thinner friction surface equals slightly increased spring resistance = lower lock up forces)

Overall I would loath to worry about the couple dozen ponies this engine puts out able to overcome the clutch.

Clean it ? meah, maybe.
Roughen it? I strongly object.

What have you really noticed with a "glazed" surface ?

thanks in advance

BTW are the clutch shoes available other than on a complete unit ?
Springs too ?

Have a goodie, sir
 

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gtgtbangbang said:
I knew you be around to chat it over Chris, thanks !
I bow to your many more miles per scooter but I do enjoy physics. And a nice Gorgonzola.

Your side true only if "unglazed" means "decontaminated" ( and then only if the contaminated surface has a lower coefficient of friction - nowhere near certain ... )
First I would attack the contamination source.

If "glazed" mean "glassy smooth & perhaps fresh but basically UNaltered friction material" then I would let the expensive clutch surface alone.
A wipe with brake cleaner soaked rag at most . But I hesitate to encourage anyone to sand off that precious compound.
(every 0.001 thinner friction surface equals slightly increased spring resistance = lower lock up forces)

Overall I would loath to worry about the couple dozen ponies this engine puts out able to overcome the clutch.

Clean it ? meah, maybe.
Roughen it? I strongly object.

What have you really noticed with a "glazed" surface ?

thanks in advance

BTW are the clutch shoes available other than on a complete unit ?
Springs too ?

Have a goodie, sir
OK.....Have it your way.!!!!!! physics or no physics .etc, coefficient of friction - bla bla bla........!!!! All I know is I used emory cloth on the clutch pads about 6K agao when it had almost zero miles on the clock because of squeal and have never done it again............
 

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The shoes aren't available separately. I've tried using brake cleaner and a rag on the shoes but found it not to do a good job however a few gentle swipes on the shoes with a small piece of emery cloth/sand paper does the trick and only takes about 2 minutes to do all 5 shoes. The problem is the CVT on the 400 (2007+) doesn't have good enough ventilation and causes the clutch bell to get super heated turning it blue in turn causing premature glazing of the pads. To properly correct this issue would to improve the airflow through the cvt housing and or change the material the clutch bell to allow it to run cooler andcool off quicker while withstanding the forces applied to it.
 

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Engineers and theory.....I've said it for years.....Put them out in the real world and let them see what reality really is.
I have worked with engineers for years developing printing equipment and even if the physics and design theoretically work the real world application is often much different.
Your theory is sound until you ad the cosmolene factor in. Yes that protective film of waxy grease that our scoots metal parts are coated with to prevent rust in the shipping crates. The heat and friction of the tranny can and will cause squealing if not de-glazed. So call it decontamination or de-glazing but if your tranny starts to squeal then de-glaze it.
I don't like to argue but I will point out my real world observations every time the need arises. :blackeye:
 

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gtgtbangbang said:
I knew you be around to chat it over Chris, thanks !
I bow to your many more miles per scooter but I do enjoy physics. And a nice Gorgonzola.

Your side true only if "unglazed" means "decontaminated" ( and then only if the contaminated surface has a lower coefficient of friction - nowhere near certain ... )
First I would attack the contamination source.

If "glazed" mean "glassy smooth & perhaps fresh but basically UNaltered friction material" then I would let the expensive clutch surface alone.
A wipe with brake cleaner soaked rag at most . But I hesitate to encourage anyone to sand off that precious compound.
(every 0.001 thinner friction surface equals slightly increased spring resistance = lower lock up forces)

Overall I would loath to worry about the couple dozen ponies this engine puts out able to overcome the clutch.

Clean it ? meah, maybe.
Roughen it? I strongly object.

What have you really noticed with a "glazed" surface ?

thanks in advance

BTW are the clutch shoes available other than on a complete unit ?
Springs too ?

Have a goodie, sir
I agree with all that you have said, but then again I am also an engineer. It should be obvious that the largest possible contact area would be achieved with the "worn" and mated shoes and bell surfaces, the problem is that it is counter-intuitive for non-engineers who equate from empirical observation a correlation between surface roughness and "grip".

The anecdote of using "...emory [sic] cloth on the clutch pads about 6K [ago] when it had almost zero miles on the clock because of squeal and have never done it again" is probably the best argument presented in support your position, as the roughening of the pads no doubt assisted them in wearing into a nice mated ("glazed") relationship with the bell more quickly than the factory finish. In the old days of drum brakes roughening up the shoes on installation was common practice to quicken and improve the mating process (don't go there :) ). On our scoots roughening up the clutch shoes, when new or when problems arise, does the same and "resets the clock" allowing them to begin a new mating process and re-bed (ditto).

I'd wager that if that clutch referred to above were opened up today the shoes would have a nice "glaze", matching quite nicely the surface of the inner bell.

Also, and FWIW, I have found that the semi-metallic pad material chosen by Adige is far superior to that used on the OEM clutch. Like others I too found myself hitting the shoes with Metalite cloth once in a while, and on occasion having to clamp the brake and rev the engine to do away with a shudder on light start-outs. However in almost 4000 miles with the Adige clutch I have not had any squealing, shuddering or any other clutch related issue--zero, zilch, nada...
 

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For what it's worth, deglazing a friction pad ("shoe") (clutch, brake etc) with any sort of abrasive (emery paper etc) will deposit very fine particles of abrasive into the friction pad. These particles turn the shoe itself into an abrasive that will accelerate wear on the metallic friction surface until the abrasive particles have been degraded and are no longer able to cut. Addf to that the fact that the using an abrasive cloth or paper to "deglaze" the shoes is good example of "measure with a micrometer and cut with an axe"; the shoe is never sanded uniformly over its entire surface. Consequently, the arc and profile of its surface no longer matches that of the drum precisely. In the case of a circular metallic friction surface like a clutch drum/brake drum. the abrasive action of the sanded pads against the metallic surface can also minutely change the surface of the drum so that the friction pad and metallic friction surface no longer mate perfectly. Eventually the friction pads clean themselves and wear enough to again match the drum diameter. That's why sanded friction pads no longer vibrate or chatter... they no longer fit the drum exactly.
 

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Now I understand that an unaltered clutch shoe with greater surface area will grab better then one without. But you are stating unaltered material. The action of the clutch shoes spinning and rubbing against the clutch bell when not in full extension in essence polishs the clutch shoe material does it not, hence the shiny appearance. And the heat generated from the friction..I believe someone mentioned bluing of the clutch bell, which I believe occurrs at 575 degrees F. Has to impart some chemical change or carbon build up from dirt and dust in the CVT. Now I ride hills in my neighborhood, so when I was using a stock clutch, I have a stop sign in the middle of the hill on my way home..I come to a stop and give it gas and the clutch slips and slips, then slowly grabs as I creep up the hill. Stop hold the brake, give it some gas..try again, it's better then before. Go home, wait for everything to cool down..pull the clutch bell off, clean the clutch bell, clean the clutch shoes, scuff the clutch shoes..next day same ride, no problem climbing from a dead stop in the middle of the hill. It's an individuals choice what to do and what not to do, but I'll clean and scuff my clutch shoes when I feel they aren't grabbing correctly. Good luck~!
 

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What is the solution for people who have glazed their clutch shoes and the clutch is now squealing loud enough to be heard across the parking lot?

Chris
 

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Fitting heavier clutch springs will minimise slippage but induce other problems as its all to with balance of moving a heavy weight from standstill revs versus grip
Dr Pulley came a long way with their hit clutch that stops slippage by locking the pad to the drum but the use of acceleration has to be smooth not sudden as this will create problems such as flipping the rollers or excessive belt wear as it takes up the forces generated under acceleration. I have been though all this on my majesty which i had modified extensively from big bore kit through to clutch and variator mods. At the end of the day it was to install a hit clutch and sliders from Dr Pulley and experiment with the various size springs on the clutch and pads. I am going to install the same set up on my Burgman soon.
 

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The same principles are at work in both clutch pads AND brake pads -

Pad and Rotor Bed-In Theory, Definitions and Procedures
Removing the Mystery from Brake Pad Bed-In

by Matt Weiss of StopTech and James Walker, Jr. of scR motorsports




In order for any brake system to work optimally, the rotors and pads must be properly bedded-in, period. This process can also be called break-in, conditioning, or burnishing, but whatever terminology you choose, getting the brakes properly bedded-in and keeping them that way is critical to the peak performance of the entire brake system.

However, understanding why the rotors and pads need to be bedded-in is just as important as the actual process. If one understands what is happening during the bed-in process, they can tailor the process to specific pads, rotors, and/or driving conditions. For this reason, we present this generic bed-in overview pertaining to all brake systems, but follow with links to application-specific bed-in procedures to fit most every set of circumstances.



What is brake pad “bed-in” anyway?
Simply stated, bed-in is the process of depositing an even layer of brake pad material, or transfer layer, on the rubbing surface of the rotor disc. That's it. End of discussion. Ok, not really, but although bed-in is quite basic in definition, achieving this condition in practice can be quite a challenge, and the ramifications of improper or incomplete bed-in can be quite a-a-n-n-o-o-y-y-i-i-n-n-g-g.
Abrasive friction and adherent friction


There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction . In general, all pads display a bit of each, with abrasive mechanisms dominating the lower temperature ranges while adherent mechanisms come more into play as pad temperature increases. Both mechanisms allow for friction or the conversion of Kinetic energy to Thermal energy, which is the function of a brake system, by the breaking of molecular bonds in vastly different ways.

The abrasive mechanism generates friction or energy conversion by the mechanical rubbing of the brake pad material directly on the rotor disc. In a crystalline sense, the weaker of the bonds in the two different materials is broken. This obviously results in mechanical wear of both the pad and the rotor. Consequently, both pads and rotors are replaced when they are physically worn to their limit and are too thin to endure further service.

The adherent mechanism is altogether different. In an adherent system, a thin layer of brake pad material actually transfers and sticks (adheres) on to the rotor face. The layer of pad material, once evenly established on the rotor, is what actually rubs on the brake pad. The bonds that are broken, for the conversion of Kinetic to Thermal energy, are formed instantaneously before being broken again. It is this brake pad-on-transferred brake pad material interaction on a molecular level that yields the conversion process.

With the adherent mechanism there is much reduced rotor wear as compared to abrasive mechanism, but it's not a free lunch – pads now become the primary wear element in the braking system. And even though rotors are not mechanically worn down with adherent systems, they still will need to be replaced on a regular basis due to cracking reaching a point of failure if they are exposed to intense, repetitive thermal cycling. This is why race teams throw out rotors that are actually as thick or thicker than when they were brand new. It's due to the an adherent brake pad transfer layer!



The all-important transfer layer


As stated above, the objective of the bed-in process is to deposit an even layer of brake pad material, or transfer layer , on the rubbing surface of the rotor disc. Note the emphasis on the word even, as uneven pad deposits on the rotor face are the number one, and almost exclusive cause of brake judder or vibration.

Let's say that again, just so there is no misunderstanding. Uneven pad deposits on the rotor face are the number one, and almost exclusive cause of brake judder or vibration.

It only takes a small amount of thickness variation, or TV, in the transfer layer (we're only talking a few ten thousandths of an inch here) to initiate brake vibration. While the impact of an uneven transfer layer is almost imperceptible at first, as the pad starts riding the high and low spots, more and more TV will be naturally generated until the vibration is much more evident. With prolonged exposure, the high spots can become hot spots and can actually change the metallurgy of the rotor in those areas, creating “hard” spots in the rotor face that are virtually impossible to remove.



Bedding fundamentals


In general, bed-in consists of heating a brake system to its adherent temperature to allow the formation of a transfer layer. The brake system is then allowed to cool without coming to rest, resulting in an even transfer layer deposition around the rotor circumference. This procedure is typically repeated two or three times in order to ensure that the entire rotor face is evenly covered with brake pad material. Sounds easy, right? Well, it can be if you have the proper information.

Because the adherent temperature range for brake pads varies widely (typically 100°F-600°F for street pads and 600°F-1400°F for race pads), each bed-in needs to be application-specific. One could try to generate a one-size-fits-all procedure, but too little heat during bed-in keeps the material from transferring to the rotor face while overheating the system can generate uneven pad deposits due to the material breaking down and splotching (that's a technical term) on to the rotor face.

In summary, the key to a successful bed-in is to bring the pads up to their adherent operating temperature in a controlled manner and keep them there long enough to start the pad material transfer process. Different brake system designs, pad types, and driving conditions require different procedures to successfully accomplish the bed-in. The recommended procedures below should provide you with the information you need to select the bed-in procedure appropriate for your application.
 

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Sorry but the principles of brake operation /bedding in, is not the same as the cvt clutch operation. both operate differently, one brings the bike to a halt the other accelerates the bike.
 

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Daboo said:
What is the solution for people who have glazed their clutch shoes and the clutch is now squealing loud enough to be heard across the parking lot?

Chris
bump
 

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Muse said:
Sorry but the principles of brake operation /bedding in, is not the same as the cvt clutch operation. both operate differently, one brings the bike to a halt the other accelerates the bike.
DUHHHHHHHHHHH>>>>!!!!!!! Like I really didn't know that!!!!!!!

They both rely on friction to accomplish their given task.......!!!!


Whether it is stopping or accelerating.

REFERENCE: http://www.navsea.navy.mil/nswc/cardero ... 12RevC.pdf
 

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Daboo said:
Daboo said:
What is the solution for people who have glazed their clutch shoes and the clutch is now squealing loud enough to be heard across the parking lot?

Chris
bump
Cleaning with brake cleaner instead of an abrasive would be my only other thought.
 
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