STOP­PING SUG­GES­TIONS

Real Classic - - Letters -

Re­gard­ing John’s brak­ing prob­lem in RC194. Are the shoes cor­rect? This may be a fault I’ve met be­fore. They need to be fit­ted the cor­rect way round, with the brake cam run­ning on the al­loy side of the shoe, NOT the flat­ter ‘U’ steel shoe on the other side of the shoe. It’s what is called a float­ing shoe. On ap­pli­ca­tion, the trail­ing shoe moves back and be­comes a lead­ing shoe. Hope this helps. Dave King, mem­ber 4895

The rear brake on a T100SS has a lead­ing shoe and a trail­ing shoe. It’s easy to get these wrong as they look very sim­i­lar. They have dif­fer­ent part num­bers (lead­ing W1406, trail­ing W1407. It sounds like he has them in the wrong way around. I have a T100R and a T100C with the same brakes and I have no prob­lem lock­ing the rear wheel. Denny Chap­pell

John Stu­art should try fit­ting the brake shoes the other way round, so that the shoes have the op­po­site lead­ing edge. The only bike I ever bought new was a 1973 Tri­dent T150V, which came with a full work­shop man­ual. The back brake was so bad that I had to use the front brake to bring me to a halt at traf­fic lights on a very greasy patch of Mitcham Com­mon Road, re­sult­ing in a tum­ble to the great amuse­ment of a po­lice mo­tor­cy­clist op­po­site.

Upon in­ves­ti­ga­tion I found that the man­ual de­scribed the shoes as be­ing one way round, while show­ing a pic­ture of them the other way round, so I tried re­vers­ing them and it worked. Alas, Metropoli­tan Po­lice Z Di­vi­sion lost their sense of hu­mour about the bike over the next cou­ple of years when it gained clipons, rearsets and a tuned mo­tor and I spent the glo­ri­ous sum­mer of 1976 on a push-bike... Phil

When we checked, we dis­cov­ered lots of eBay traders of­fer­ing one type of brake shoe to ful­fil both orig­i­nal part num­bers ( W1406 and W1407), when they should be dif­fer­ent. So this is one of those mo­ments when it is prob­a­bly wise to con­sult an ac­tual Tri­umph parts spe­cial­ist, rather than sourc­ing brake shoes on­line from sup­pli­ers who don’t re­ally know what they’re sell­ing. Try chat­ting to Monty (01822 617010) or Andy (01434 820752). R&F

I think Mr Stu­art has dropped a ge­o­met­ri­cal clanger. By ex­tend­ing the brake lever arm length to the brake rod pivot, he’s re­duced the me­chan­i­cal ad­van­tage not in­creased it. Jim Lugs­den

Some­thing I of­ten see in photograph­s of mo­tor­cy­cles fit­ted with 2ls front brakes is that the op­er­at­ing arms are not par­al­lel. I have found that set­ting them up par­al­lel, by shift­ing the lever around on the splines, gives a much firmer feel and evens the wear on the shoes. If the levers are not par­al­lel then dif­fer­ent forces are ap­plied to each brake shoe cam. The­o­ret­i­cally, max­i­mum brak­ing ef­fect is achieved when the cable and lever are at ninety de­grees, but it is bet­ter to aim for about 80 de­grees to al­low for a bit of wear on the shoes.

This even worked on Yamaha XS1s, which were no­to­ri­ous for hav­ing poor front brakes. As the shoes wear then the levers can be ro­tated on the splines to re­turn the levers to their op­ti­mum op­er­at­ing an­gle.

I hope some­one finds this use­ful as it can no­tice­ably in­crease the ef­fec­tive­ness of twin leader brakes, ex­tend the life of the lin­ings and it may just save some­one’s life. RealClas­sic is about the best value mo­tor­cy­cle mag­a­zine avail­able, with a huge range of in­ter­est­ing ar­ti­cles on all as­pects of mo­tor­cy­cling. Please keep it up! Paul El­liott

Back in the late 1950s and 60s, I and oth­ers had sim­i­lar prob­lems with back brake fade. I had it on my rac­ing Nor­tons, both Dom­i­na­tor SS mod­els, and on a Manx back brake. Af­ter talk­ing to a well-known rider I started to re­line my brake shoes (rear only) with a brake lin­ing called AM4. It was a green com­pos­ite im­preg­nated with al­loy ma­te­rial. These lin­ings were known to be a lit­tle bit too good, so we were ad­vised to add a slightly longer lead cham­fer, and put a longer cham­fer on the back end of the lin­ing.

In­stead of mess­ing around with ful­crums, piv­ots, brake rod to brake pedal levers, etc, I think that John could go back to the orig­i­nal Tri­umph brake lay­out and try some bet­ter lin­ings. It worked in the old days, there’s no rea­son why it wouldn’t work 50 years later. Mick Madell, mem­ber 12,297 Ah, well, odd you should say that, Mick. In our on­go­ing strug­gles with con­i­cal hub drum brakes – which can be ran­domly aw­ful or awe­some – we’ve no­ticed that brakes which re­tain the orig­i­nal brake lin­ings tend to per­form bet­ter than those fit­ted with mod­ern lin­ings. We have a sus­pi­cion that mod­ern high-tech lin­ings are pos­si­bly made of some­thing su­per­safe which doesn’t gen­er­ate car­cino­genic par­ti­cles… but which doesn’t gen­er­ate quite so much fric­tion, ei­ther…

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