Cycle News - Archive Issues - 1980's

~ ~ a: ~ :I: ~ 0 U ...J 0 ~ ~ =; 0 z < :I: U It'') - ...J 00 => z 0 ., ~ )0- -.:::f"t C'J m - (/l 0 ... 0 ... . ~ :I: c, 0.. -< (Below) Works Performance bu ilds the monoshock damper/spring as- : sembly for Champion. A f ull six i nc hes of axle travel is ava il able. (A bov e) Monoshock geometry loads the frame behind the cylinder; note l ig ht w ei g ht rear frame which on ly supports the seat an,d exhaust. . (left) Designer/racer Bud Carroll. (R ight) Adjustment at this point allows for f lne -tun tnq swingarm angle to suit track conditions. The Champion.monoshock d irttrack frame By Jim Wolcott T hough monoshock rear suspensio n s are seen on T eam H onda 's flat track bikes, p riva teers interested in cam paign in g this su sp ension con fig uration h ave h ad to desig n and \veld th eir own frames and th en find a suitable spring! damper a ssem bly to m at ch th e . frame geometry . 26 But n ow Carroll R acing P roducts , which manufactures Champion Racin g Fram es, has fini sh ed developmen t of a monosh ock frame kit , and o ffers it for sa le as any th ing from a bare fram e to a race-read y motorcycle . The new frame is a dedi cated mono sh ocker : not an exis ting design with a rear suspen sio n tr ansp lant. The fram e is co ns truc ted o f T IG welded 4 130 ch ro me-moly steel -a nd is a two piece unit th at is bolted together. The front su p po rts th e steer ing head, th e engine, a nd ca rr ies the swingarm pivot. Up from th e pivot, o n th e left side o f th e frame a nd behind th e en gine is th e fo rward (u p per ) shock m ount; sturdil y reinfor ced with tubul ar a nd sheet meta l g usse ts. T he rear sec tion o f th e frame bolts 'to 'rh e-fro n r.rits o rrly job -is to -locate the seat a nd th e exha us t 'p ipe, since the swinga r m m ounts 10 th e frame a nd th e rea r o f th e en g ine. T he top o f th e swinga rm has a can tilevered bra ce, whi ch a lso serves a s th e rear m ount for the monosh ock . T he two-pi ece design means th at -ea ch part is sma ll and light enough 10 be sen t via o verni ght U PS sh ip p ing; a crashe d bike co u ld be made race-ready in two da ys. Bud Carroll did th e design , devel o p me nt, a nd testi n g o f th e new fra me - mak ing h im th e o n ly ac ti ve ra cer ( Expert pl at eholder fo r AMA C lass C racing) in th e desi gn bus iness . Bu t wh y build a mon osh ock ? " T he big ad vant age is adjusta bilit y. The a ng le of th e swinga rrn can be a lte red between 5° a nd 10° - wi tho u t changing th e geo me try a t th e sp ri ng . Of co urse yo u ca n cha nge the sw inga rm a ngle with a twi n-s hock suspen sion by mo ving the shock mo u nts . forward a nd ba ckward - but tha t cha n ges th e leverage fo r the spring, a nd affects th e dam pi ng rat es. With ' .• rnv - rno noshock geo metry: yo u' ca n di a l-in th e bike fo r a n y track . More an g le on th e swingarrn makes th e bike hook up bet ter and sit up qui cker: less ang le makes th e bik e slide bette r. " T he actua l monos ho ck un it is made for Champion by Works Performan ce, and features ex te rn a lly -a dj us ta ble rebo und damping; a quick twist of a n allen wrench cha nges th e dampin g . With th e present sus pe n sio n geome try, six in ch es o f rear axle travel translates to a bo u t 1.5 inche s of p isIOn movement in th e m onoshock . According to Carroll, th e limi ted travel is ac tua ll y an ad van tage . " So me peopl e are sa ying i t doesn 't move enoug h to work - o ne gu y even told me it's a pi ece o f junk . But it 's tr an sferr ing so littl e o il tha t it doesn't ge nera te th e hea l th at o the r shocks do ." For developing this new fram e, Carro ll built a specia l adj us ta ble p ro tot yp e which em p loye d a n o versized steerin g head . Ma chin ed plates were fitt ed into thi s h ead to all ow for different steering a ngles. Similar test ing was co nd ucted for swin ga rm leng th a nd ride height. Wh en asked a bo u t manufacturing suc h a n adj us ta ble fram e, th e designer a nswe red , " No wav, No mail er wh o bu ys th em , th ese ' fra mes have my nam e o n th em . My job is to set the frames u p so the y work; so I kn ow th ey'll work . Add 100 man y adj us tmen ts a nd it 's hard for a racer to d ial a bike i n . If th ere is a p robl em with com p lex a d j us t m ents, th e fram e would p robably be blamed for it. " Wh ich ' brin gs us 10 th e bott om lin e: d oes th is new mon osh ockIrarn e work? Aa ro n Hill rode th e bike in th e Jun ior Nati o na l a t th e Ca mel P ro Series T T ra ces a t Ascot Park on March 30, and p laced third overa ll . Wh at 's signifi cant is that Hill 's bike was eq u ip pe d with a 500cc Rot a x engin e; firs t and seco nd place bikes were eq u ip pe d with 560cc a nd 600cc eng ines . In fourth p lace behi nd Hi ll was an o th er560cc bike. Considering th e differen ce in disp lacement. Carrotl say s, "the Champion monoshock frame was doin g its part. " T he basi c frame kit inc ludes both frame pieces, th e Works Performan ce shock, th e swinga rrn. rear axle. cha in adj usters, h ead heari ngs, brake peda l, m o tor m ounts a nd oil lin es, and (d ep e n d i n g o n a p p lica tio n) co sts a bo u t $ 1500. The fram e is a va ila ble to su i t th e 500 Rotax , 500 Honda . 600 Honda a nd 600 Yamaha engine s. Th e fra me is designed to use ex isting Champio n fib erglass bod ywork, and will accep t m ost front sus pe ns io ns. Carroll will mak e specific co mponent recommendati ons based on his expe rience; a nd for a n ex tra fee will parti all y o r co m p lete ly asse m ble th e bike. All ha rd ware aside, probabl y th e most int eresting feature of th e new Champion monos hock frame is that its design er is o n ly 24 years o ld. BUI • Bud Ca rroll has been ac tively racing fo r more th an half h is life, a nd has been tin kering, designin g and brain . stor m ing al ong th e way . " I may be yo ung," said Ca rroll . "but I list en . If I hear a n idea th at makes sense . I' ll tr y it. I don't kn ow everything, bUI I do n' t have a ny prejudices. either. " For furth er informa tio n co n tact Ca rro ll Racing Produ cts , 18700 No rmandi e Ave.. U n i t C. Garden a, CA 96248. (2 13) 327-3432.

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