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Tech Talk > RADIAL MOUNT CALIPERS; what's all the hubbub?

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  • Tech Talk > RADIAL MOUNT CALIPERS; what's all the hubbub?

    Good Reading from Braketech's website.

    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

    Caliper Deflection:
    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…



  • #2
    Interesting data there Jules.

    Good to see your 998 was the first to use the Brembo 4 pots on a mass produced bike.

    The jap bikes will catch up one day!
    07 MV F41000R
    09 Blazing orange Speed Triple
    07 CBR 600RR trackbike
    sigpic http://www.ozspeedphotography.com/

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    • #3
      Well, brembo being italian and all probably helps. Just because they have "brembo" written on them doesn't necessarily mean they're the be-all and end-all.


      Interesting article - from reading that it would seem that the shift to radial mounts is more about reduced rotating mass and unsprung weight whilst maintaining adequate stiffness, rather than improvement in stiffness - and thus and improvement in handling rather than outright brakng performance.

      Which is fair enough... just contrary to what you might initially think
      “Crashing is shit for you, shit for the bike, shit for the mechanics and shit for the set-up,” Checa told me a while back. “It’s a signal that you are heading in the wrong direction. You want to win but crashing is the opposite. It’s like being in France when you want to go to England and when you crash you go to Spain. That way you’ll never get to England!” -- Carlos Checa

      Comment


      • #4
        Originally posted by thro View Post
        Well, brembo being italian and all probably helps. Just because they have "brembo" written on them doesn't necessarily mean they're the be-all and end-all.


        Which is fair enough... just contrary to what you might initially think
        Nah every Moto GP team and most of the WSBK field are full of it they work just as well as anything else and they seem to nail the feel/performance balance very well.
        Harvey community radio has a motorcycling show listen over the web here www.harveycommunityradio.com.au ,Facebook here http://www.facebook.com/pages/The-Mo...34691323302991 yes I am the goose that hosts it.

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        • #5
          Interesting article but.. 5 years old. What's the 'new' tech these days in brakes?

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          • #6
            ABS
            Harvey community radio has a motorcycling show listen over the web here www.harveycommunityradio.com.au ,Facebook here http://www.facebook.com/pages/The-Mo...34691323302991 yes I am the goose that hosts it.

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            • #7
              Originally posted by Davey View Post
              Interesting article but.. 5 years old. What's the 'new' tech these days in brakes?

              ha Ha!!
              Maybe 5 years old, but tell me what has changed on the caliper side of brakes?

              New Tech in rotors would be CMC Rotors -

              "BrakeTech USA is very pleased to announce the release of the long awaited, ultra-advanced technology Ceramic Matrix Composite brake rotors for the Motorcycle Industry. The AXIS/StarBlade™ is the new and updated MKII version incorporating now de-classified Stealth Bomber Aircraft technology manufactured by Starfire Systems, this revolutionary material will change the way both top-level race teams and enthusiasts alike view their braking systems. The performance parameters in-total make all previous materials and systems dated by comparison, including the vaunted Carbon/carbon brakes. Designed to perform brilliantly with OE calipers as well as the Billet GP race-spec versions. This all-new composite material offers the best features of premium iron rotors with the incredible lightweight of carbon, and none of the Carbon/carbon foibles!

              PRODUCT FEATURES:
              • Patented AXIS Design - featuring Direct-Link™ load transfer system
              • Not thermally sensitive (will work great on the street)
              • Ultra broad torque curve across a very wide thermal range
              • Much longer lasting than C/c
              • Much less expensive than C/c
              • Great wet weather performance - unlike C/c
              • Terrific feel and feedback at the lever
              • Strong braking performance? آ We mean, Really strong: +.6 mu average friction with special Ferodo Racing brake pads
              • Carriers are premium grade billet aluminum bar - not stamped plate aluminum
              • Hard-anodized to military grade specifications
              Brake Weight Comparison (Honda CBR-1000RR, '04-05)
              • Honda OE 310mm Stainless: 3lbs 4.4oz @ 5mm thick [1486grams]
              • BrakeTech 310mm AXIS/Iron: آ 2lbs 15.0oz @ 5mm thick [1332grams]
              • BrakeTech 310mm AXIS/Starblade™ CMC: آ 1lb 5.6oz @ 5mm thick [612grams]
              Brake Weight Stats for 6mm thick Narrow-Band Superbike
              • BrakeTech SBK 320mm AXIS/Starblade™ CMC: 1lb 8.7oz @ 6.0mm thick [700grams]
              • Brembo SBK 320mm Steel: 3lbs 11.4oz @ 6.0mm thick [1684grams]"

              Here is a quote for CMC rotors for my 998 -

              "$2275.00 USD With the pads total free shipping"


              Comment


              • #8
                its not Brembo thats important, its Monoblock..... thats the part that makes all the difference.
                Atlas Performance, dyna pumps, " your name goes here"

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                • #9
                  Originally posted by Nero Diablo View Post
                  Nah every Moto GP team and most of the WSBK field are full of it they work just as well as anything else and they seem to nail the feel/performance balance very well.

                  You kinda missed my point.

                  Bottom of the line brembo calipers != motoGP brembos.

                  Bottom of the line brembos != top of the line other manufacturer calipers.

                  Hence.. the "brembo" badge, whilst indicating they're brembos, does not mean they are "the be all, and end all" of calipers.
                  “Crashing is shit for you, shit for the bike, shit for the mechanics and shit for the set-up,” Checa told me a while back. “It’s a signal that you are heading in the wrong direction. You want to win but crashing is the opposite. It’s like being in France when you want to go to England and when you crash you go to Spain. That way you’ll never get to England!” -- Carlos Checa

                  Comment


                  • #10
                    Originally posted by thro View Post
                    You kinda missed my point.

                    Bottom of the line brembo calipers != motoGP brembos.

                    Bottom of the line brembos != top of the line other manufacturer calipers.

                    Hence.. the "brembo" badge, whilst indicating they're brembos, does not mean they are "the be all, and end all" of calipers.
                    Yes and I have brembo's on two of my bikes the other is a bit of a mix and match. From riding other bikes and my direct experince I'll stand by what I said.
                    Harvey community radio has a motorcycling show listen over the web here www.harveycommunityradio.com.au ,Facebook here http://www.facebook.com/pages/The-Mo...34691323302991 yes I am the goose that hosts it.

                    Comment


                    • #11
                      You still don't get it.

                      Are your brembos better than a lot of other standard brakes? Sure.

                      Are they the best brakes in the world simply because they're the bottom/middle of the range brembos that ducati (or whoever) got cheap, in bulk, factory direct? Perhaps not.
                      “Crashing is shit for you, shit for the bike, shit for the mechanics and shit for the set-up,” Checa told me a while back. “It’s a signal that you are heading in the wrong direction. You want to win but crashing is the opposite. It’s like being in France when you want to go to England and when you crash you go to Spain. That way you’ll never get to England!” -- Carlos Checa

                      Comment


                      • #12
                        Originally posted by thro View Post
                        You still don't get it.

                        Are your brembos better than a lot of other standard brakes? Sure.

                        Are they the best brakes in the world simply because they're the bottom/middle of the range brembos that ducati (or whoever) got cheap, in bulk, factory direct? Perhaps not.
                        OK now ur confusing me...

                        Try explaining in very basic terms...


                        Comment


                        • #13
                          Brakes!!

                          Great info Jules,
                          have you found any info of the same calibre on throttles???
                          I would bemore interested in that.
                          RR VRT #100
                          Sponsors Wanted.
                          Thanks to www.superbikesupply.com.au and ProFlow for assistance.
                          A 1K throttle is like a hot blond, you really want to hit it but you are afraid of the consequences :black eye:

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                          • #14
                            Originally posted by robwas View Post
                            Great info Jules,
                            have you found any info of the same calibre on throttles???
                            I would bemore interested in that.
                            Working on it..

                            Found another good site to get more tuning options
                            on ya CBR!!!

                            Posted.


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                            • #15
                              Originally posted by thro View Post
                              You still don't get it.

                              Are your brembos better than a lot of other standard brakes? Sure.

                              Are they the best brakes in the world simply because they're the bottom/middle of the range brembos that ducati (or whoever) got cheap, in bulk, factory direct? Perhaps not.
                              Yes they are a lot better than standard brakes on other bikes.

                              Are they the best in the world well not the end I'm using the 1200 euro motor GP spec master cylinders and the like probally are but If you organise me a ride on a Moto GP bike so I have something to compare with and I'll give you my opinion. They are still better IMO than the standard Tockio/nissan affairs.

                              There is a trickle down effect from that level of experince, monoblock calipers used to be something that you ordered out of the Brembo catalouge for $1800 a side now they are standard fit on the 1098's. Individual pads per pistion were standard for to the 749/999 series.
                              Harvey community radio has a motorcycling show listen over the web here www.harveycommunityradio.com.au ,Facebook here http://www.facebook.com/pages/The-Mo...34691323302991 yes I am the goose that hosts it.

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