In our shed

Alan em­barks on low vol­ume ally wheelspacer pro­duc­tion for TDR250, like no vol­ume (as yet). But wait...

Practical Sportsbikes (UK) - - Contents -

MY MYFORD ML7 is a re­as­sur­ing if some­times ac­cusatory pres­ence in the cor­ner of my work­shop. This ven­er­a­ble lathe, now at least 50 and prob­a­bly more like 60 years old, is my most ex­trav­a­gant work­shop pur­chase to date.

It’s worth at least what I paid for it, so in cap­i­tal terms I shouldn’t feel too bad. It’s an as­set, and one that has proven its worth on many oc­ca­sions. Still it mocks me, be­ing so much more ca­pa­ble than I am of churn­ing out lit­tle mar­vels of en­gi­neer­ing ge­nius. Maybe one day I’ll use it to its full po­ten­tial, mak­ing work­ing mod­els of mo­tor­cy­cle en­gines when I’m too in­firm to ride the real things [Bet­ter get on with that then – JM].

In prac­ti­cal terms it’s got me out of a hole more than once. I’ve be­come some­what ex­pert in the ma­chin­ing of spac­ers. When it came time to swap the cast TZR wheels my TDR used to wear for a pair of re­built wire-spoked ones, I ob­vi­ously lacked the cor­rect spac­ers for the proper rims. Or at least I thought I did, as will be­come clear. Cast wheels are gen­er­ally nar­rower than wire-spoked ones as the lat­ter re­quire wider hubs to pro­vide suf­fi­cient an­gle be­tween hub flanges and rim cen­tre to give the wheel lat­eral strength.

The TDR, as was, had ex­tra spac­ers to take up the gaps be­tween fork legs and swingarm spars, as well as crude ally spac­ers to move the brake calipers in over the discs. Its sis­ter bike, Project Light­weight TDR (see page 104) came with the cor­rect spac­ers po­si­tion­ing its wire-spoked wheels and I elected to use these rusty, pit­ted relics as pat­terns for repli­ca­tion in fresh alu­minium.

The only bar stock I had was nearly 50 per cent larger in di­am­e­ter than re­quired but I’ve come to en­joy the gen­tle hyp­no­tism of work­ing a lathe tool back and forth. I made a pair of rear spac­ers first then got to work on the nar­rower front. A mountain of scrap alu­minium curls filled the lathe’s drip tray as the work pro­gressed. Front wheel first and the top hat I’d made showed the nar­row­est of gaps be­fore the spin­dle was tight­ened up. Per­fec­tion. Turn­ing my at­ten­tions to the rear I re­alised my work was re­dun­dant. A pair of stock spac­ers were in place, aug­mented by a thick ally ring to take up the con­sid­er­able slack. Still, noth­ing goes to waste and the alu­minium rear spac­ers I’ve made can go into Project Light­weight TDR. Mean­while my Myford still sits sen­tinel, won­der­ing when the real en­gi­neer­ing work is go­ing to start.

Pinch-per­fect job from the son of Corn­wall Nipped up to a nicety, an­other Cor­nish tri­umph

No short­age of swarf at the fi­nal cut

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