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Old 03-13-2017, 04:04 PM   #1
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Default Sintered brake pad for CCM rotors

After using OE pads with heat cycles - Surface pitting shown.





Two track events after using RB sintered pads.



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Old 03-14-2017, 07:31 AM   #2
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Sintered process is not a new technology but only some are used as brake pad for motorcycles, very few in car application, and none exists in high performance/CCM brakes.

Sometime it s/b easier for general readers to call it as a "Full" metallic brake pad vs."Semi-metallic" pad that is commonly known and widely used.

Making sintered pad is far more difficult and taking much longer time to make than traditional semi-metallic, as it's 100% metallic powder with more than a dozen of ingredients that's molded together via high heat and pressure, no resin nor additive like semi-metallic which certain metallic ingredient are bonded together by resin and the resin (of plastic nature) can only resist to certain temperature, when over the threshold temperature, the resin will melt and the metallic powder can no longer be bonded together so the pad will accelerate its wear, and emit the resin (commonly known as deposit) to the disc surface which can cause all kind of brake issue - vibration, loss of braking power etc.
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Old 04-11-2017, 03:00 PM   #3
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http://www.gtrheritage.com/topic/671...cmcarbon-pads/

Before and after sintered brake pad transfer on worn out carbon ceramic rotor.







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Old 05-14-2017, 07:19 AM   #4
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Default How to restore your damaged CCM rotors at no cost

https://rennlist.com/forums/991-gt3-...t-no-cost.html

The friction couple (pad and rotor) compatibility is very important in the performance of all brake systems, not only carbon ceramic. However since CCM rotors generate much more heat than conventional iron (due to its lighter weight), so it's even more crucial in carbon ceramic application.

To achieve a healthy braking operation it's necessary to transfer a layer from the pad surface on to the rotor face. For iron rotors (with semi-metallic pads) this usually can be achieved with careful selection of iron rotor material and brake pad compound.

However since the CCM rotors brake is running at a higher (~30%) temperature level than iron so using conventional semi-metallic pad becomes challenging due to the temperature limit of resin that holds the friction ingredient together. Resin is of plastic nature so when the pad is heated up it becomes soft and starts losing its binding strength, that's when you feel brake fade and notice resin emitted to rotor surface with uneven/un-uniform layers (bad deposit) that will cause vibration and other ill effect.

Sintered pad on the other hand, uses no resin, and is of full (100%) metallic, it's composed of various metallic powder. Those powder were compressed together under extremely high pressure, under very high temperature, takes days to cure and form together with the steel backing plate which is made of high tensile strength alloy steel so they for more resistant to deformation (warping) under repeated heat cycles.

During bed-in process the sintered pad starts transferring a very "uniform" layers (good deposit) over to rotor surface which also forming a protective coat on rotor surface, from thereon the friction is taken place between the transferred layers between the pad and rotor surface.

If a CCM rotor is already damaged (pitted-rough surface) due to the heat stress & incompatible pads, after bedding in with sintered pad, those surface will begin to heal, and eventually the metallic layer will smooth out the entire disc surface, we used dial gauge to check run out on those healed surface and the run out is within the tolerance of .00013"

During this rotor surface healing (patching) process you will notice the pad will wear out faster than normal, but after the rotor surface is restored not only the rotor life is to be prolonged, but the pad wear rate will become normal.
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Old 05-14-2017, 07:49 AM   #5
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Default Difference of friction methos between Iron and CCM

The method of friction between ceramic discs and pads work differently than iron discs.

With iron discs it is the friction between the disc surface and the pad surface that provides the braking force, but with ceramic discs it is the friction between the pad material that has been laid onto the disc surface and the pad itself that is what provides the braking force.

After properly break in, what you would expect to see on the surface of the rotor is a nice uniform, reflective layer, which signifies the transfer of material from the pad onto the rotor*. If the transfer layer is patchy or streaky then this would indicate that the pad is operating out of its temperature window. Pitting on the surface is the initial signs of disc wear, where the carbon in the disc is oxidizing.

CCM rotor surface is as hard as a diamond, so no brake pad can ever wear the rotor down. The only possible cause that can damage the rotor is from over-heat that causes carbon to oxide and lose its weight, rotor surface becomes pitted which will wear the brake pad down like a sharp grinder. This is the point when the rotor require replacement or re-furbishsing.

OE requires rotor weight check with instrument and complicated process, so to help user better understand we have published an article - "How to determine when to replace CCM rotor ring"

http://forums.racingbrake.com/showth...t=rotor+weight

However we suggest "rotor surface check" is an easy and more practical way to check the healthiness of CCM rotors - If your brakes performs well, rotor surface looks good, and brake pad wear is normal then you should not be worrying about the weight.

*Transfer of layer from the brake pad to CCM rotor is a fusion process which can only take place with a right sintered compound under a high temperature that only CCM rotors can generate (not iron rotors)
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Old 05-14-2017, 07:54 AM   #6
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Some conversations re weight checking:

Quote:
Originally Posted by CAOZKAN View Post
I wanted to update you about my situation. Even after my markers were almost completely gone and we assumed that the rotors needed to change, I went on a trip for 6000km. During this trip I was very stressed about the rotors and everytime I pressed the brakes there was a weird sound and vibrations.
I wrote and complain about rotors to BMW HQ, and Turkey dealer called me and they took the car for inspection. After one week, today I received a call from them, they are saying that they weighed all the rotors and they all had an average around 7.4kg vs min. 7.1kg ; therefore they concluded that there was no necessity for the rotors to be changed.
One side of me is really happy about the fact that even after the markers are gone, there is plenty of rotors left. On the other hand, if this is the case, how in future I will be able to understand the conditions of the rotors and why this sound and vibrations were happening. I really appreciate any comments/guesses about this issue.
Quote:
Originally Posted by racingbrake View Post
Here is RB's comprehensive write up on CCM rotor replacement:

http://forums.racingbrake.com/showth...hlight=replace

Note all presentation are based on published and imprinted numbers w/o subject opinion.

Nonetheless my recommendation to those who run CCM brakes is to use "visual" inspection to the rotor (surface) conditions than those "weight" or "wearing mark" suggestion, because all the braking debris build up in the drill holes do add up to the rotor weight* which can give false signal.

The weight or wearing mark suggested by the CCB rotor mfgr are something quantitative for a consumer to reference and observe, how you "feel" is still more important. I have seen people replace their CCM rotors due to ill operation, but hardly seen anyone replaces their rotors due to below minimum weight.

*Unless you clean up all the holes (clean with a pin and compressed air) after track days which I know only very few track racers doing this to keep their CCM rotor in shape. If you don't this regularly, over the time those accumulated debris becomes as hard as iron bits and block the holes, and can no longer be removed.
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Old 05-19-2017, 08:13 AM   #7
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Default Russ' RB CCM Kit set up

http://www.camaro5.com/forums/showpo...87&postcount=1



OE set up


OE caliper after running RB sintered pad


RB caliper and sintered pad installed


Front set up


Rear set up


Real Brake for the Real People.
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Old 05-19-2017, 03:46 PM   #8
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ZR1/Z28 pads (front and rear) are the standard tooling for our sintered pads.

We are able to confirm that the front ZR1 pad can be modified to fit 991 GT3 OE calipers (yellow or red) as illustrated below.

Original ZR1/Z28 Front Pad (D1395)


Modified to 991 GT3 pccb Pad (D1768)
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Old 07-13-2017, 11:30 AM   #9
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Default Testing RB sintered brake pads on ST damaged rotors

This is a damaged ST rotor set on GTR that were oxidized due to over heat.





Rotors are now re-installed onto our test car (Mercedes CLS550) under RB 6 piston calipers, and a set of new sintered pad.



Previous rotors were installed in a GTR under OE calipers and ZR1 shape pad (w/78mm lining depth), these severely oxidized ST rotors are "un-bearble" during stopping at 25-30 miles for our initial test run, for they would shake violently, but we are carefully and patiently breaking them in with new sintered pads. We purposely trim the pad at the bottom to 60mm depth in order to better observe how effective this repairing process (under 60mm new pad contact surface) can result.

Will post more result back as the the test continues.
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Old 07-13-2017, 03:07 PM   #10
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This right (passenger) side rotor caused a much more violent vibration than the left, so we decided to replace it back to the original iron rotor.

Image of severely damaged right side CCM rotors:

Right Outboard side:


Right Inboard side:


Under the caliper:


Previous iron rotor:


After replacing right side rotor back to iron, the right side vibration is gone but left side CCM vibration becomes noticeable (not quite when both sides are CCM), but it's somewhat bearable therefore we will continue testing/observing this CCM disc surface repairing process by doing one at a time (left rotor first then right rotor).
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Old 07-28-2017, 04:00 PM   #11
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Interim Report:

A pair of ST rotors from a GTR track customer that were severely oxidized and were considered as "discard" or "rebuilt" condition. We put them on to our shop car (2016 Mercedes CLS550) to test with sintered pads (trackabel street compound).

After these damaged ST rotors were installed, the car vibrated so violently (at any speed as the brake pedal was applied) that make it un-driveable, so next day the passenger side rotor was removed and replaced back to iron.

ST CCM-X rotor (Passenger side) removed after one day on sintered pad.



ST CCM-X rotor (Driver side) after 10 days of normal street driving with some occasional hard stops.



Detail view - A more continuous band of metallic finish can be seen.



Since ST discs are made from continuous fiber, the damage is in a "patch" pattern (than Brembo's chopped fiber which is more of a uniform and consistent manner), which makes the restoring process harder (larger spots to fill in) and longer in this restoration process which is somewhat expected.



We have also found that the wearing pattern of pad and rotor surface are in groovy pattern than Brembo's disc in a non groovy surface which coincides to how the respective carbon fibers are structured.

These pictures from the test can not represent what you will actually see with eyes unless taken by pro-photographer, however the effect of rotor surface restoration via the transfer of pad is evident and can definitely be felt by the driver, being the vibration amplitude is progressively getting diminished as the rotor surface looks better (more smooth shining area than spotty patches)

The long process and trouble involved perhaps not worth for a consumer than have it re-furbished, however the point of this test is to demonstrate the effect of a sintered pad can do to a CCM rotor that's severely damaged, better yet is to start the sintered pad in the beginning and avoid it, or mend the rotor with sintered pad before gets so bad.
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Old 07-28-2017, 04:00 PM   #12
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Passenger Side (Iron Rotor)


Driver Side (ST CCM-X rotor)
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