ClassicMotorcycleMechanicsJune2020

Simple solutions:Takeabitofmaterialoffatatime,notgreatchunks!

theadjusterblocksweresuppliedwiththe

frame,whichmadethingsabitsimpler.The

processwassimilartothefront,measuring

fromtherimtotheswingarm.Importantto

notethattherearwheeladjusterblocksare

positionedthesameonbothsides,asa

discrepancyherewouldthrowoutthe

measurementandthusthealignment.The

spacerontheright-handsidewasjustmade

solidwithnoprovisionatthistimeto

includethebrakecallipermountingbracket.

Theaimwastogettherearwheelcentralin

theswingarmandbothwheelstolineup.

Also,thesprocketanditsdrivehubwereleft

out...notenoughroom!

Oncethewheelwascentralised,Icould

turnmyattentiontothesprocketandhub.

Evenaneyeballmeasurementidentifiedit

wasgoingtobeverytight.Theother

considerationtofactorinwasthechainrun.

ThinkofthewidthofaGT 750 rearwheel

andengineandthena 600 Bandit;alotof

difference,butbothruna 530 chain.

AstraightedgeofftheinsideoftheGT

frontsprocketshowedIneededtogetthe

rearsprocketasclosetothewheelas

possible,butleavingenoughchain

clearanceforthetyre.Nowtherearwheel

wascentralised,thesprockethubwastoo

widetofit...allabitmarginal.

Firstthingwastogetthehubtofitin

place.Alotofmeasuringandhead

scratchingplusaleapoffaithsawthehub

onmymill.AsfarasIcanrememberany

rearwheelI’vetakenouthasaspacer

runningonthebearinginnerandanoilseal.

Logictellsmethataspaceronthebearing

innerisnodifferentfromrunningdirectlyon

thebearinginner,it’sjustanextension

throughtheoilseal.Withtheoilsealprized

outandverycarefullythehubsetflatona

rotarytable,Imachinedtheallydownuntil

thebearingjustsatproud(photo 1 ).Back

in,theswingarmthisjustfits,thebearing

innernipsupontheswingarmandthe

wheelstayscentralandrotatesfreely.A

sealedbearing(lateron)willnegatethe

needforanoilseal.Straightedgesfrontto

rearwheelsshowgoodalignment.Result,

butthesprocketnowclipstheswingarm!

TheamountIcanmovetherearsprocket

overisdictatedbytheinsideofthechain

clearingthetyreandtheamountofmetalI

canremovefromthehub.Moremeasuring,

hubbackoutandthistimemountedinthe

lathe.Asmuchaspossiblewasmachined

fromthesprocketmountingfaceofthe

hub(photo 2 ),leavingthecentralringthe

sprocketlocatesonmaintained,asthis

centralisesitonthehub(photo 3 .)Itfits

andclearsjust,butenough(photo 4 ).

Shortersprocketmountingboltsare

requiredwiththeheadsslightlymachined

downtogainalittlemoreclearance.

Straightedgeontherearsprocket

showsthefrontsprockethastocomeover

toachievealignment.Ameasurement

dictatedthefrontsprocketneededa

further 7 mmoff-set.Atemporary 530

sprocketwasmadeupwiththerequired

off-setsoachaincouldbefitted,asthere

isnothingofftheshelfthatcouldbe

bought(photo 5 .)

Chainalignmentisok,tyreclearanceis

tight,butok.Butthechainjusttouches

therearshockatthebottom(photo 6 ),

runsonthegearchangeshaftandthe

framebehindthegearshaft(photo 7 )!

Deepjoy!

surprisedathowwellsomeofthecheap

stuffworks.No,they’renotaswellmadeor

asrobust,butifyou’reonabudget...

TherearwheelwasaBandit 600 witha

160 reartyre,mainlyasIcouldnotseehow

a 180 wouldfit.Therearspindlediameter

wasthesamesizeastheBandit;bothitand

Thanks this month to:

TheRacin gMotorcycl ebyJohn

Bradley. ISBN 9780951292921&

ISBN 095129 35

PeteO’Dell.The Motorcycl eWorks.

01735578883

Reducing sprocket

off-set on the lathe.

It's tight, but withabit more

work...

Machining finished, does it fit?

Couple of sprockets and some tube

and the right off-set!

The chain touches: what next?

Chain supported by gear shaft and

frame.

94 /classicmotorcyclemechanics

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