WORK­SHOP: HUBS AND BEAR­INGS

Scoop on this es­sen­tial el­e­ment!

Classic Motorcycle Mechanics - - CONTENTS -

You can make sort­ing wheel bear­ings hard or easy for your­self, reck­ons Scoop. Let’s see how he did!

very mo­tor­cy­cle de­pends on its wheel bear­ings for a de­cent qual­ity ride. Up­grade to the stick­i­est tyres out there, fit the best sus­pen­sion avail­able, blow the bud­get on ad­justable fork-an­gle yokes but if your wheel bear­ings are knack­ered you’ll be wast­ing your hard-earned cash. In al­most ev­ery wheel fit­ted to a mo­tor­cy­cle there’s two pairs of ball races car­ry­ing the en­tire weight of both you and your bike. Whether that’s a nifty fifty or a fully dressed Gold Wing your for­ward mo­men­tum is en­tirely reliant upon just a hand­ful of in­di­vid­ual ball bear­ings at any given mo­ment in time. And those balls and the races that house them are lu­bri­cated by a splodge of grease ap­plied by the man­u­fac­turer how many years ago? Boiled down to their ba­sics it’s amaz­ing the amount of work wheel bear­ings do yet we take them to­tally for granted. You prob­a­bly pay more at­ten­tion to the spokes of your wheels than you do to the bear­ings: out of sight, out of mind etc. as they say. Most of us will prob­a­bly only ever look at our wheel bear­ings dur­ing the course of a re­build, a restora­tion or ma­te­rial fail­ure. If you’re re­ally dili­gent you might check them for wear at ser­vice or MOT time but that’s as much at­ten­tion as they ever nor­mally see. And, ar­guably, that’s how it should be; prop­erly lu­bri­cated they should and can last the life of a ve­hi­cle but if one starts to wear, what do you do? Project Kawasaki Hy­brid had sat out­side for years and as a con­se­quence its wheel bear­ings were less than happy at be­ing moved. Tak­ing no chances they were go­ing to be re­placed come what may. As the bike is the sub­ject of a full re­build I’ll be work­ing with the bare hubs; the spokes and rims have been re­moved. If you were car­ry­ing out a ‘run­ning re­pair’ then you’d have to fac­tor in space to ac­com­mo­date the wheel com­plete with tyre yet the same rules ap­ply. Every­one has their own pet way for jobs like this but what fol­lows is a method­ol­ogy that’s worked well for me.

1/ A pair of stout wooden blocks sup­port the hub out­side of the bear­ing area. A de­cent punch with­out burrs and a large but con­trol­lable ham­mer are the tools of choice 2/ Care­fully lev­er­ing the in­ter­nal bear­ing spacer to one side, the drift is en­gaged with the edge of the in­ner race. When it’s se­curely in place the ham­mer is called into ac­tion with one de­fined firm strike. Care­fully and pre­cisely work­ing around the pe­riph­ery of the in­ner race, suc­ces­sive blows move the bear­ing slowly out of its hous­ing. As it be­gins to move the pres­ence of the bear­ing spacer be­comes less in­tru­sive. 3/ And be­fore too long the bear­ing is free of the hous­ing along with the spacer. Some hubs run dif­fer­ent sized bear­ing on ei­ther side so it’s im­por­tant to note which one goes where.

4/ When a bear­ing is stuck fast con­trolled heat can of­ten help. Ex­per­i­ment with dif­fer­ent sized punches and if one bear­ing is al­ready out con­sider an ap­pro­pri­ate sized drift to aid re­moval. 5/ Seals and cir­clips need to be re­moved be­fore bear­ing evic­tion is at­tempted. The circlip has cor­ro­sion welded it­self into its reg­is­ter. Pen­e­trat­ing fluid and heat may be needed here. 6/ Even though, even­tu­ally, the circlip was freed off it was still dif­fi­cult to re­move due to cor­ro­sion. Only ever use de­cent circlip pli­ers – never at­tempt to prise cir­clips out with screw­drivers.

7/ The four bear­ings are all full of dirty grease and most show ev­i­dence of rust. Fac­tor­ing in how long they lay out­side they will be re­placed but not be­fore I’ve cleaned one up to il­lus­trate fit­ting new ones. 8/ Bear­ings must be in­stalled per­pen­dic­u­lar to their hous­ings. At this an­gle it’d never fit but just a few de­grees out of true can per­pet­u­ate a dis­as­ter when the bear­ing be­comes stuck at an an­gle in its hous­ing. Time spent here get­ting ev­ery­thing true will be dis­pro­por­tion­ally re­warded later. 9 & 10/ Heat­ing hubs and freez­ing bear­ings makes the job so easy. The fam­ily oven may be a big ask but the vapour blasted hub is spot­lessly clean – hon­estly! A few days in the freezer sig­nif­i­cantly shrinks the bear­ings.

11/ Al­ter­na­tively heat the hub up out­side with a hot air gun if ‘the real boss’ ve­toes the oven idea!

12 & 13/ With the bear­ing true at the top of its hous­ing or reg­is­ter it needs to be driven into place via force ap­plied to the OUTER race not the in­ner. Ei­ther a suit­ably sized socket or pur­pose-made bear­ing drift are fine. With a hot hub and frozen bear­ing the job should only take min­i­mal ef­fort. 14 & 15/ With the first bear­ing in­stalled, drop in the bear­ing spacer, flip the hub over then line ev­ery­thing up us­ing a wheel spin­dle or man­drel. 16/ The old circlip ac­tu­ally cleaned up sur­pris­ingly well but if there’s any doubt buy a new one for peace of mind and your own safety. 17/ And there they are; a pair of cleaned Kawasaki KH250 hubs with new bear­ings ready to be sent off to Cen­tral Wheel Com­po­nents to be mated to new rims with stain­less spokes. When wheel bear­ing re­moval and re­place­ment goes as planned it’s a re­ward­ing task to un­der­take; get it wrong and it can be pure pain. If a bear­ing won’t drift out make sure no seals or cir­clips have been missed. If there’s any rust or sus­pi­cion of cor­ro­sion, use a pen­e­trat­ing fluid. Never at­tempt bear­ing re­moval on a flimsy bench as you’ll be squan­der­ing most of your ef­fort. If all else fails, beg ac­cess to a hy­draulic press and let it work its magic. The in­stal­la­tion of bear­ings needs to be or­gan­ised; have the hub hot, the bear­ing cold and all the tools you need to hand ready. Ex­pand the for­mer, con­tract the lat­ter and ev­ery­thing should al­most fall into place.

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Do get your­self one of these!

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