Hi-Tech –300 Degree below zero Cryogenic metal treatment transforms Austenitic molecules to more stable Martensitic:
Tempers matrix structures at the molecular level to resist stress
Brake rotors last longer, increases resistance to warping.
Greatly improves material life and wear resistance. Longer life for
cranks and rods too
Valve gear and transmissions last 2-3 times longer
Springs, both valve and chassis optimized for more consistent
From NASA to NASCAR, the wide spread use of Cryogenic technology in stabilizing a wide variety of metals has been thoroughly tested and documented over the past 20 years. The most advanced process spans over 40 hours in a computer controlled Liquid Nitrogen vapor that slowly takes the target material down to —300 degrees (F) where the carbon molecules are transformed from Austenitic to the more stable a Martensitic matrix.
In real terms, we eliminate residual stress and effectively change the core "default shape", that is changing the memory shape of the base material to a new base configuration. Regarding brake rotors, this means the new default shape is flat and true. As the rotor expands and contracts under thermal stress, it always wants to retain the memory shape thereby resisting distortion. Reduced material wear is another substantial benefit.
All BrakeTech AXIS Design full-floaters are Cryogenically processed in-house to maximize their performance parameters. Considering this process typically costs around $25 per rotor to do yours (plus round trip freight), you'd need to factor in roughly $75 on top of the purchase price of a set of lesser rotors to even begin to compare with the all new, high tech AXIS Design billet rotors.
Does this use of advanced technology guarantee BrakeTech rotors can't be warped? The simple answer is no; but as the only brake manufacturer utilizing this high level of expertise and methodology, we can state you'll not find a better high performance brake rotor. Period.
Correct centering of the double action caliper on the rotor is very important, regardless of the fact that there are live pistons on both sides of the blade supposedly "self-centering" themselves. The fact is, application of the brake intrinsically tries to pull the caliper assembly out of its design plane via the not inconsiderable applied hydraulic forces. On this front, there's two significant actions taking place in the process of braking:
1. Distortion; the hydraulic forces in play not only apply themselves in pressurizing the pistons acting upon the brake pads and working towards stopping the rotational forces of the rotor/wheel assembly, but also play out in the opposite direction as well in attempting to spread the caliper halves. A phenomenon often referred to as the clamshell effect. This usually manifests itself with radially tapered (bottom to top) pad wear, brake howl and piston retraction problems due to this distortion. The new generation calipers, pioneered by Brembo and adopted by Tokico, with their individual pad-per-piston design provides for the incorporation of a rather massive central bridge across the top of the caliper minimizing if not eliminating this effect. As described, this has nothing to do with the caliper being mounted radially or in old-school trailing edge, perpendicular fashion.
Caliper Mount Location; here's where and how the caliper is mounted on the forks becomes a factor, and this is strictly focused on the occurrence of TORSIONAL caliper flex. Bear in mind and heretofore, all conventional calipers are mounted at the trailing edge of the line of force, combined with the fact the energy transfer (to the forks) of the braking forces are focused on just one side of the spinning rotor. Then factor in the normal production tolerances between the mounting faces of the rotor/wheel, fork/caliper, plus perpendicular axle alignment within the wheel to these faces, and more. Of course we can stir the pot with greater possibilities for misalignment with (even just slightly) out of true axles and fork tubes. The end result is there’s always some degree of mating issues that ultimately effect performance potential yet are still within factory tolerance. But it is predominantly the torsional twisting effect of the caliper that is the main culprit for setting the gremlins loose during hard braking. The relatively new radial mount caliper design virtually eliminates this torsion flex problem since it more efficiently spreads the load equally both fore and aft to the line of force. It also offers the additional advantage of better (quicker) release at the end of the braking sequence as an additional design benefit.
Different friction materials have their own personalities and characteristics with some leaving greater material transfer on the rotor surface than others. Ideally, when testing pads, the rotor surface should be thoroughly cleaned between compounds by either bead-blasting the rotor surface or using one of the new Rotor Hones we now stock for this purpose. This is something preached regularly to racers we sponsor to optimize braking performance and minimize excessive deposition layer build-up, which can lead to brake judder and screeching noise. Every shop should have a rotor hone in their service department...a very cool and useful tool.
"Wave" type rotors with longish slots can have interesting if not adverse reactions to the very short length 4 pad caliper designs. These pads having much reduced bearing surface area than a conventionally longer pad create greater opportunity for deflection into those slots and missing parts of the rotor. This thereby creates greater tendency towards negative reactions.
Hole Patterns: the individual brake rotor hole pattern (or sine-wave in the case of the "petal" types) all contribute to producing a distinctive sound. Again some patterns produce more than others. Of course friction material plays a part as well with the sintered metal category usually the noisiest in large part due to their greater density and higher metal content. Our rotors and hole patterns are designed to continually clean the face of the friction material evenly across the radius.
Final note on noise; if not properly assembled, the front wheel can actually bind up in the forks causing alignment issues and excessive brake drag (not to mention much greater fork stiction related problems). Any experienced mechanic should be aware of the proper wheel assembly/installment procedures to avoid this phenomenon.
There's actually another significant factor to add as well; brake pad backplate distortion. If the backplate warps, an occurrence much more common with the longer six pot pads than with the short individual pad per piston model for obvious reasons, major problems will result. Brake drag, over-heating, glazing of friction material, excessive noise, warped rotors, etc. are just some of the anticipated consequences.
The following was copied and forwarded to us by a Ferodo / BrakeTech dealer who thought similarly that confusion indeed exists relative to the questions raised in the letter from Greg regarding sintered metal pads versus organic brake pads on cast iron rotors:
> …actually this was from the "instructions" that came with my rear rotor. This was several months ago and I
> can't say I recall exactly what the issue was, but believe they said sintered pads would cause excessive
> wear on the brake tech rotors. It was immediately followed by a recommendation to use Platinum series
> Ferodo pads (of course).
> Anyway, I forgot about it until I bought a set of brake techs for the front. Called the phone # listed
> on their web site to ask which pads they would recommend and was told that only Ferodo sintered pads
> should be used. Funny how that works, but then what do I know? I've asked people at a shop I trust and
> they've not heard of any reason why sintered pads and CI cause problems. Perhaps it's just marketing.
As such, we'd like to take a stab at clarifying some basic points on this rather convoluted issue:
There's really two very elemental dynamics in play when it comes to material life expectancy [rotor and pad] at the friction couple:
Friction related abrasion [on the rotor pad track]
Thermal stress distortion [i.e.: warping of the rotor and/or backplate]
Although this is the simplistic view, I'll focus here since this forms the basis of our recommendations:
1/ MATERIAL ABRASION.
Most sintered metal pads are designed specifically for use on stainless steel rotors, which is typically a harder material in general than cast iron. As such, some of these friction materials do indeed gall the rubbing surfaces to varying degrees. If this occurs on stainless, the softer cast iron will normally suffer to a greater extent. Since there are so many different sintered materials out in the market (with the vast majority specific to stainless steel) we must as a general rule of thumb recommend to our customers that they not use them on their iron rotors as the potential for premature problems is real and potentially expensive.
Furthermore, using sintered metal pads (any) on Gray iron or individual mold casting rotors can be a recipe for disaster.
2/ THERMAL DYNAMICS.
Regarding sintered pads on Ductile iron, Gray iron, carbon steel or stainless for that matter; using the base assumption that the friction material isn't overly abrasive [causing galling, scoring, etc.], the real issue is thermal capacity.
All conventional metals used in rotors have their own thermal dynamics to deal with; total mass, shape, lightening/venting hole type (placement and quantity) combined with inherent thermal conductivity of the resident material all play an integral role in material stability at peak operating temperatures. What we're essentially talking about here is resistance to distortion [warping, coning, etc.].
This is a complicated and convoluted subject that has few simple answers as there are so many variables to factor in. But one basic truth is that the sintered pads, including our new SinterGrip series, run hotter at the interface than do "most" organic pads...by as much as 150 degrees [F] in our testing. If you're running near the edge of thermal capacity with a particular rotor type and design and high performance / racing organic pads (like the carbon based CP series: 911Star, CP211 and the new CP1), switching to a racing sintered pad will surely exacerbate the problem.
In majority of instances where a problem occurs, thermal stress induced distortion is the culprit.
Another area of potential confusion is the many and significant differences between the classes of iron; the two main categories being primarily the Ductile irons and Grays irons. There simply isn't sufficient room here to expand on those differences here without taking up excessive room...have to leave that for another time.
We manufacture the BrakeTech full-floating rotors from computer controlled Continuous Cast [billet] nodular ductile iron supplied by America's oldest and most experienced foundry specializing in advanced composition cast iron. Cutting from billet is clearly a more expensive process than many others but we do this to have greater control over material matrix, eliminate porosity and have the most consistent micro-structure possible.
Does all this extra care and material selection guarantee they won't warp? Nope. There's very few guarantee's in this world (outside of death and taxes) and in the rarefied atmosphere of racing, even less...we just build our brake rotors to be the best possible given the material technology of today.
In final answer to Greg's question regarding our recommendation of the Ferodo SinterGrip ST pads on the AXIS rotors; we've dyno tested them extensively and have discovered no significant abrasion related issues with this combination. After over 200 dyno runs, they didn't distort either. But bottom line when it comes to thermal stress distortion; as noted above, there's no guarantee this won't happen under the right circumstances.
Hope this provides some insight.
- All dyno testing was performed with Ferodo sintered metal pads
- All BrakeTech full-floaters are Cryogenically treated, substantially improving wear resistance and maximizing their overall performance
- Do not extrapolate or presume that any of the above infers that one can run any sintered metal pad [brand] on the AXIS/Iron rotors without the potential of serious consequences and damaging them as result
What is Full-Floating?Full floating rotors, such as were originally conceived, were designed to reduce the tendency towards thermal stress induced distortion due to uneven thermal expansion under load. Prior to the introduction (by Brembo) of this design, brake rotors in the motorcycle industry were simply round discs bolted solidly to the wheel. You may remember if you've been around long enough, the rotors on the early CB750 and Z-1's were nearly 7mm thick and weighed accordingly. This was in effort to keep them from warping. Now days, the only road bikes coming through with solid mount (front) brakes are the Cruisers and budget bikes.
Today's Sportbikes abound with trick features and hardware in every nook and cranny. Brakes too. The brake rotors on them work remarkably well considering their mass-produced (read: stamped) manufacturing process. These are technically semi-floaters as the outer SS blade is nearly bolted solid to the carrier via the stamped stainless steel rivets.
True full-floaters move on the carriers, this allows them to self-center in the caliper for reduced brake drag and "float" unimpeded for unrestricted expansion and contraction during repeated thermal cycling. The only serious down side is a bit of rattle that reminds you these are indeed full-floaters.
Does all this guarantee they won't distort under severe duty conditions? No, unfortunately, there's precious few guarantee's these days. But they do perform as advertised in improving overall braking performance while significantly reducing that distortion tendency.
BTW: All Superbikes, GP machines and the like unanimously have full-floating brake rotors
Brake Drag and wheel binding?
Excessive brake drag is usually caused by one of several possible culprits:
1) Warped backplates; if your pads aren't flat, you'll definitely experience greater brake drag as when the lever is released and the caliper pistons are retracted from the pads, the you'll still have rotor/friction material contact since the seals can only retract the pistons a very small fraction.
2) Misalignment; if the wheel/caliper/fork assembly alignment is off, binding of the assembly will often occur (bent axles and triple-clamps will be a problem here too). This is particularly true if assembled and tightened while on a front wheel stand (attaching from the fork bottoms). Best way is to have everything assembled but not tightened on the stand, then let it down and bounce the fork/wheel a few times to center everything, then tighten.3) Poor Piston Retraction: Poor piston retraction can be a major culprit and cause of rotor over-heating and distortion, accelerated pad wear, and glazed friction surfaces (creating brake squeal, etc.). Check to make sure all pistons are not only moving freely in their bore, but are retracting as well (when the lever is released). You'll need to block the other pistons to isolate the individual your checking, alternate one at a time. If then suspect, replace all piston seals (we recommend this regardless with a used or suspect caliper).
4) Excessive deposition layer build-up: all friction materials impart a thin transfer layer on the brake rotors pad track. This is a normal part of the bed-in process. But some transfer more than others, creating an excessive and/or uneven build-up that can cause problems with brake drag, brake judder and deteriorating performance. Suspect rotors should be bead-blasted or rotor honed if you don't have access to the blast cabinet (Racers: do this at least every third race weekend, more often if possible). For best results, it is recommended to perform this regiment every time you change friction materials!
5) Disc Thickness Variation: A DTV of over +.0005" can often result in brake vibration. Although not common, is does occur. Suspect rotor should be carefully measured with an accurate 0-1" micrometer by an experienced technician.
For changing material compound of brake pads (organic to sintered or vise-versa), the rotors should be thoroughly cleaned on the pad track area by either bead blasting or employing the easy to use new Rotor Hone.
The easiest way to use the Rotor Hone is to do it on the bike;
With the front end off the ground on a proper stand, get a buddy to spin the wheel. Using a hand held drill set in the low RPM/high torque mode, angle the abrasive balls of the hone at about 10 degrees off of parallel from the rotor surface applying medium pressure to pad track area. You’re looking to remove the darkened burnished deposition layer to the clean and bright base rotor material. Using this process, an ideal circular cross-hatch surface is created. It’s simple and relatively quick. Do both sides this way. Remove the wheel and reverse the rotors by flipping them over (when offset permits), repeating the process to condition the opposite sides.
When down to a relatively clean surface, it’s time to clean the remaining abrasive particles left by the Rotor Hone as the final op. You’ll need a stiff bristle toothbrush and Acetone. Dipping the brush into a small container of Acetone, aggressively brush the rotors pad track area with generous amounts of Acetone (of course use proper eye protection and approved rubber gloves). Again, this a quick and easy way of eliminating contaminants leaving a clean surface ideal for fast and hassle free bed-in of new pads.
The Rotor Hone employs Aluminum Oxide abrasives, which if applied to excess, can cause rotor damage. Do not excessively hone one spot but rather follow the instructions detailed in Step One. Take your time to get the hang of proper usage. Done correctly, the results are most satisfying.
Interesting how things that oftentimes appear to be a radical departure from the “norm” are in fact evolutionary rather than a genuine fundamental revolution. The new buzz on Radial Mount Calipers is straight from the automotive industry with a few minor tweaks. With cars, they’ve almost always mounted the calipers in a fore and aft manner because it’s a straight up simple and strong way to do so. Granted, the new motorcycle version has finally taken that lead and adapted the concept by incorporating a radial mount instead of the commonplace perpendicular (90 degree to rotor face axis) mounting bosses universally prevalent today. In reality, whether calipers are mounted radially or perpendicularly is of little consequence, having only to do with the fact that the new generation calipers can be made a bit lighter via the radial mount set-up (no other significant performance difference here).
I know I’m going to disappoint more than a few technophiles here by stating the Radial Mount design in and of itself offers no real world performance gains beyond improved pad wear characteristics, and that is almost strictly focused on the near elimination of TORSIONAL caliper flex. Bear in mind and heretofore, all conventional calipers are mounted at the trailing edge of the line of force, combined with the fact the energy transfer (to the forks) of the braking forces are all focused on just one side of the clamping pressure as applied to the spinning rotor. Then factor in the normal production tolerances between the mounting faces of the rotor/wheel, fork/caliper, plus perpendicular axle alignment within the wheel to these faces, and more. Of course we can stir the pot with greater possibilities for misalignment with (even just slightly) out of true axles and fork tubes. The end result is there’s always some degree of mating issues that ultimately effect performance potential yet are still within factory tolerance. Depending on degree of misalignment, a torsional twisting effect of the caliper can come into play during hard braking. This usually manifests itself with radial tapered (bottom to top) pad wear, brake howl and piston retraction problems due to this distortion. The relatively new radial mount caliper design virtually eliminates this torsion flex problem since it more efficiently spreads the load both fore and aft to the line of force. It also offers the additional advantage of better (quicker) release at the end of the braking sequence (FYI: brake pad compounds play a large part here, too). Which from the racing perspective provides a cleaner transition when braking into the apex on the edge of disaster. This is a very good thing indeed. But again, something you the average weekend warrior will not likely feel at the lever.
As a sidebar, the single action calipers (live pistons on one side only) such as what came on the CBR600F3 (and is standard on virtually all Motocross bikes) have categorically fallen out of favor for use on Sportbikes. This is primarily due to the fact they suffer from unavoidably greater degrees of flex inherent in the calipers floating pin design and minimal piston area (compared to the modern double action calipers).
The Real World of Greater Performance:
Here’s where it really gets interesting: incorporated into the design of the new generation Radial Mount Calipers is the latest in braking technology led by two basic concepts. Of course there’s more to it than just this, but in an attempt to keep it simple, the elements can be effectively identified by these two separate yet related categories:
1. CALIPER STIFFNESS
2. BRAKE PAD DESIGN AND THE LEADING EDGE
The difference in deflection between the O.E. calipers and the dedicated racing caliper is remarkably quite large. Rigidity plays a major role here. And there’s also a surprising difference between the various O.E. manufacturers in this critical area of stiffness. Bear in mind that on a World Supersport spec heavy braker, we found vertical (up to down) pad taper, just a tenth of mm (.004”) but this is clearly representative of an existing problem. Under severe conditions, caliper deflection is manifest as either inconsistent braking performance and/or a somewhat vague feel at the brake lever. Other factors such as fluid integrity, i.e. relative to water saturation point and resultant resistance to fluid boil (wet vs. dry boiling point), plus backplate flatness and to a lesser extent, friction material compressibility all play a significant role here, too. This is clearly demonstrated on the research dyno where simply changing calipers on the test fixture (with same compound pad and rotor) equates to sometimes dramatically different friction level curves. This is much more pronounced with O.E. calipers than the high-end billet racing counter-parts…but in all fairness, the production O.E. calipers still do a very good job overall, particularly when cost is factored in.
Another fundamental and crucial difference here is with material and manufacturing techniques. Production machines invariably use mass produced cast calipers versus the race-bred gems found in SBK & MotoGP. Those are the real beauties, CNC machined from substantially higher tensile strength billet stock and often sporting ventilated Titanium pistons. The differences are again manifold but paramount is superior rigidity combined with a typically longer and narrower pad shape. The Narrow Track layout focuses the applied braking pressure over a somewhat smaller area, optimizing [in microseconds] the reaction time of the braking forces. Of course another advantage of the race specific calipers is their lighter weight due in large part again to the higher psi capabilities of the premium grade billet material.
With cost always an issue with production bikes; brake designers went back to the drawing boards to boost performance while keeping a bean counters check on cost considerations.
Brembo again forged the way forward with the introduction in late 2000 of their stunning Four Pad caliper, which found a home in both the Aprilia Mille and the Ducati 748 and 998 R models. These were the first of their kind using the individual pad per piston design in a mass produced production caliper. They wisely addressed the performance advantages of increased stiffness with the addition of a massive bridge over the top of the pad cavity opening, greatly increasing resistance to distortion.
PAD DESIGN, the Leading Edge:
The new generation Brembo 4 Piston Caliper design was then further enhanced by incorporating four separate pads operating with larger equal sized 34mm pistons (than their 30/34mm twin pin forerunner). The necessity of using differential bore piston diameters to reduce pad taper (fore and aft) became a moot point when switching to the short individual pad and piston arrangement. Greater piston area mated to a properly sized mastercylinder piston (ratio) improved performance values. But there’s an additional benefit to the individual pad/piston configuration: greater initial bite. Inevitably, as the pads friction material bears down on the rotor during braking, each leading edge acts with greater force than its trailing counterpart, adding additional grip in the process. Think of it in terms of the friction material trying to wedge into the rotor. More leading edges…more bite. Although this is for the most part noticeable mainly in the initial braking sequence, but the end result is another notch up the bar in performance levels. This fact is not new having been around in the Aftermarket for years. Companies like ISR, Harrison, PM and others have and continue to offer these in various combinations. Bear in mind however, you the consumer are going to pay for this improved performance with a notably higher pad replacement cost.
And now Tokico has taken this concept another step by incorporating a beautifully sculpted individual pad/piston design into the trick looking radial mount system, debuting on the new 2003 Kawasaki ultra ZX6R/RR and Suzuki with their revised GSX-R1000 assault weapon.
So bottom line, what does it mean to you the Sportbike enthusiast and weekend warrior? In simple terms, it’s stronger brakes. Evidently the O.E.’s think enough so to warrant down sizing the rotors to improve handling and turn-in performance via reduced rotating mass (less gyroscopic forces). It will surely be of interest to all to see how well these smaller, lighter rotors will like this arrangement. Rotors with less material mass and heat sink capability often suffer more from fatal thermal stress distortion.
Does all this new-fangled brake design mean the current crop of high performance calipers are making a quick exodus to the dust-bins? Not likely. Need proof? The 2002 World Superbike Champion Colin Edwards and the mighty Honda VTR1000Sp2 used the traditional Nissin 6 pot billet race caliper all season…Old World perpendicular mount and all. Could it be Honda was too cheap to fork over the cash for the latest radial mount version? Yeah, right! Sure looked to me like the new Champs brakes were working just fine…
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