Cycle News - Archive Issues - 1990's

Tech RADICALL Y MOUNTED When it comes to disc brakes, most advances are evo lutionary rather than truly innovative, but Brembo has definitely broken into th e lat ter category with their new rad ially mo unted calipers. "Radially mou nted ca li £e rs appea red first .in Formul a One ca r ra ci n g three seasons ago, th en in Grand Prix last season," explained Fran co Zonned da , a technician from Brem bo's racin g division in Italy. "We hav e a good experience with thi s sy ste m a nd I think it's the right way to mount th e .caliper. We found tha t it had good p erform an ce a nd it was very stable. Th e caliper is more rigid, so in a hardbraking track, y o u have more progressi ve braking and the pad wear , for sure, . is much better - not uneven like the axial -m ounted ones. " Zonnedda d escribed how conventional axially mounted calipers twist d ov.;nward and inward under braking forces, and the pad wear is badly tapered as a result. Pad taper gives yo u a longer lever travel because the pistons extend furthe r out of th e ca liper, and the further the pistons come out, the more lever travel is required and the more likely the pistons can cock in the caliper. "Normally, the leading edge of the pad will have more wear," said Brembo North but th ey were hea vily invo lved and had m ore peopl e o n s ta ff . W e u sed their equipment instead of ours. " Bu t th e American te am w as st ill o u rs, so we wen t o ur own direct ion, because th at' s w hat we were going to be racing in the fu tu re. It wa sn 't that we d idn 't kn ow w hat eac h o the r were d oing, but th ey had th eir id ea s a n d we h ad o u rs. A n d in a ll h on esty , I bel iev e tha t because of Doug' s inp u t, our bi ke ended up being a be tter bik e th an w ha t we h ad (in World Su perbike)." America 's Rafael Santiago. "And if yo u hav e two equal-size pistons, then the leadingedge pa d ta per will be greater. We design our calipers wit h the leading-ed ge pis ton smaller to compensate for this. Th e radial bol t pattern dis tributes the load mo re equa ls ly across the caliper for le s flex. With the axially mounted caliper, th e flex movem ent is minimal at the bo lts but much gr eater at the end of the calipe r. By locati ng it at both ends and with the bolt s centered side to side, th e flex is minimized and pad -wear characte ris tics and braking performance improv e accord ing ly." While th e radiall y mounted caliper s appear to hold mu ch promise, th ey' re not d eveloped for ma ss production. "We need to make sure it works properly and do the right devel opment before it's widely produced," Santiago cautioned. "Hope fully, we'll see it here (in the AMA) next seaso n. Maybe we'll test it at the end of the year." The AMA Series has its own bit of exotic brake equipment, though you'd have to look more carefullv to see it on the Vance & Hines Ducatis. "That calipe r is" also not completely developed," said Zonnedda, "The Ducati factory in Italy gave permission to use it here." "I think a good way to put it is," Santiago added, " because of Gobert's ability, we are developing this caliper with Ducati. Gobert takes the brakes to the limit , let' s put it that wa y. He will put the calipers to the utmost test, so we will get a lot of feedback from tha t. The four -pad c~liper is more effective because there's twice as many leading ed ges and it allows all four pistons to be the same siz e." Aside from differences in calipers, riders also choose between rotor sizes as we ll. " We u se 320mm discs or 290mm discs - these are most co m mo n," Zonnedda detailed . "Lagu na Seea is not so hard, but hard enough on braking, so we use 320m m. The 290 is better for the not-so-hard braking track due to less gyroscopic effect and lighter handling." Of his current d eal, Muzzy sai d : "It's easy to feel at a d isadvantage, but I'v e bee n d oing this d eal for so lon g th at I' m aware of th e fact that the g rass isn' t greener. Ii's real simple to say, 'A h, th ey got all this stuff over th er e and we' re not getting it, blah, blah, blah: And I'm THE TRICIfEST .,TS . en en en 44 The Cas tro l Honda team is wi dely rumored to have a $10 million annual bu dget, and from the look s of some of the pieces around the pad dock, we don' t d oubt it. From their exotic ai r-chamber reservoir for ks to th e fro nt-e nd hu b tha t bo lts in place to align the brake pad s and pistons properl y, little expense is spared . We talked w i th team rid er Co li n Edwa r ds o n Su n day mo rni ng in h is motorhome, "My race se tup is good," Edwards said. "Maybe no t as good as so me of the loca ls," he added wi th a ch uc kle, "but we'll have to ge t o ut there and see wha t happens. The local . team has alwavs been on Dunl ops , too: a nd this has a lways been a Du nlop track: (John) Kocin ski was th e on ly o n e w h o made it a Michelin track." About th e reservoirs on the Showa fork, Edwards said: "It's just a bigger air chamber, you know, instead of having it all included in the fork. lt just allows for a smoo the r ride, is a ll it is . It jus t seems to soa k everything up and then, wh en yo u take those ai r cham be rs o ff, it just gets h arsh . It ju s t basic ally a llows for less work. When you don't have the air chambers, yo u' ve got to tune it more precisely. With the chambers, it's more forgiving, is all it is. You can be in the range instead of on the line and it will still be good." Late last season, Edwards and his crew hit upon a change in the fork tuning that made a major improvement. "The big difference was that before," he explained, "as soon as you let off the brakes the thing (front end) would just pop up and everything would go onto the rear and it wouldn't steer. Aaron (Slight) could ride the thing because he's way over the front of it and keeps his weight over the front and keeps it down. He just adapted to it. I was always trying to change it for my style and then once we figured out what it was - it was internal, it wasn't just as simple as closing the rebound down - once we did that, it.was night and day. I found out since then that (Tadayuki) Okada had came over and tested the 5uzuka (8 Hours) bike and said, 'Hey, this thing turns better than my 500: He took some of the internals back to EurOJ?e,wi andfhe won ~ race. I Eion't know hew interchangeable it is, because we run 4Zs and the.Y run 46 . I}; swili ~ around:~~J ~~~:i~~~~1 N n ot go ing to say that w e d on 't go throu gh that, be cause it is fru strat ing for us now. We kn ow they have so me thing that's better but it jus t hasn 't trickled to our level, and it's fru str at in g. I believe th at there a re s o m e thi ngs that th ey have th at would ben efit us ." _

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