A mas­ter­piece in Amaranth Red

Old Bike Australasia - - 1938 TRIUMPH 5T SPEED TWIN - Story Jim Scaysbrook Pho­tos Ian Fal­loon, Jim Scaysbrook

Eighty years ago, one of the most sig­nif­i­cant mo­tor­cy­cles ever cre­ated emerged from the Tri­umph Engi­neer­ing works. Although an in­trin­si­cally sim­ple de­sign, it forced the hand of vir­tu­ally ev­ery other ma­jor man­u­fac­turer to fol­low suit.

When ques­tioned as to why he had cho­sen to de­sign a 500cc ver­ti­cal twin in­stead of an equiv­a­lent dis­place­ment sin­gle, Tri­umph Man­ag­ing Di­rec­tor and De­signer Ed­ward Turner replied, “A twin gives bet­ter torque – twice as good in fact, if, as in this case, the fir­ing in­ter­vals are equal. It has a ca­pac­ity for run­ning at higher rev­o­lu­tions with­out un­duly stress­ing ma­jor com­po­nents, and on ac­count of its even torque it pulls bet­ter at low speeds. It starts eas­ier and re­quires no ex­haust (valve) lifter. It is eas­ier to si­lence, has bet­ter ac­cel­er­a­tion, bet­ter fuel con­sump­tion for the same power, in­creased re­li­a­bil­ity and dura­bil­ity, and is bet­ter cooled. In fact it is a much more agree­able en­gine to han­dle.” So there you have it – any fur­ther ques­tions?

Tri­umph was in very bad shape, at least fi­nan­cially, when Jack Sang­ster bought the com­pany in 1936 for a re­puted £50,000. Sang­ster was a shrewd busi­ness­man and a tal­ented de­signer in his own right. His fa­ther Charles, also a de­signer of note, had gained con­trol of the mo­tor­cy­cle di­vi­sion of Com­po­nents Lim­ited and he took con­trol of the Ariel works around 1905. By the early 1920s, Ariel was lag­ging be­hind cur­rent mo­tor­cy­cle trends, and when Jack joined the com­pany he im­me­di­ately lured the im­mensely tal­ented de­signer Valen­tine Page from J.A.P. But in 1932 the De­pres­sion claimed Ariel, and Jack Sang­ster pur­chased the as­sets, although the re­struc­tur­ing meant that Page left to join Tri­umph. But Sang­ster al­ready had a re­place­ment in young Ed­ward Turner, who had sketched the de­sign of the now-le­gendary Ariel Square Four some years ear­lier. Turner had hawked his de­sign around the traps of the Birm­ing­ham mo­tor­cy­cle in­dus­try but had found no tak­ers un­til Sang­ster took him into the Ariel fold. With Sang­ster’s pur­chase of Tri­umph, Turner packed his draft­ing board and moved from Selly Oak, Birm­ing­ham, to the Tri­umph works at Coven­try. Tri­umph had ac­tu­ally de­signed and built a side­valve ver­ti­cal twin en­gine back in 1914, which fea­tured a 180-de­gree forged crank­shaft, and an in­te­grally-cast iron head and bar­rel with the valves op­er­ated from a cen­tral camshaft driven by skew gears from the cen­tre of the crank. It was a promis­ing de­sign but the war ef­fort meant that it was never pro­duced as a com­plete mo­tor­cy­cle. In 1933, Val Page, now at Tri­umph, penned a 650cc twin, the Model 6/1 which had bore and stroke di­men­sions of 70mm x 84mm, dou­ble-he­li­cal geared pri­mary drive (the crank­shaft turn­ing back­wards) and semi-unit con­struc­tion with the four-speed hand-change gear­box bolted to the en­gine. This power plant was dropped into an ex­ist­ing chas­sis with a Glo­ria side­car at­tached in time for the In­ter­na­tional Six Days Trial which was held in Wales. The 650 out­fit per­formed ex­tremely well, win­ning rider (and Tri­umph de­signer) Harry Per­rey a Sil­ver medal, and later cov­ered 500 miles

in 498 min­utes at the Brook­lands cir­cuit un­der the su­per­vi­sion of the Auto Cy­cle Union, win­ning for Tri­umph the cov­eted Maudes Tro­phy. But Tri­umph needed more than a sil­ver tro­phy to shore up its op­er­a­tions, and although the 6/1 did pro­ceed to pro­duc­tion, it was very ex­pen­sive at £75.00 and, at 187kg, rather over­weight, be­ing re­ally only suit­able for use with a side­car. It is be­lieved only around 500 were man­u­fac­tured in the two-years of pro­duc­tion. By the time Turner ar­rived at Tri­umph the 6/1 was gone, and un­der Page’s su­per­vi­sion he be­gan to ex­per­i­ment with what amounted to half his Square Four de­sign. What even­tu­ally emerged was a very neat over­head valve par­al­lel twin with di­men­sions of 63mm x 80mm (the same di­men­sions as Tri­umph’s 250 sin­gle), an iron bar­rel with a one-piece iron head. The built-up crank­shaft, patented by Tri­umph, was made from man­ganese-molyb­de­num steel al­loy run­ning in 2.75” OD ball bear­ings, with each crank half flanged at its in­ner end and bolted to a cen­tral fly­wheel. The con-rods, forged in RR56 alu­minium al­loy, ran di­rectly onto the crank jour­nals with white metal-lined steel caps. Com­pres­sion ra­tio was 7.2:1. Camshafts were lo­cated front and rear of the crank­case mouths, with the shafts run­ning in bronze bushes, gear-driven to the pushrod fol­low­ers. The rear-mounted mag­neto was gear-driven from the in­let camshaft, with a peg driv­ing the twin-plunger oil pump that pro­duced a con­stant 6o psi. Of­fi­cially, the en­gine pro­duced 26hp at 6,000 rpm, with a top speed of 90mph. The new twin was so com­pact that it fit­ted straight into the sin­gle-down tube frame used on the Tiger 90 493cc sin­gle, with a girder front fork and rigid rear end. Front wheel was 20-inch and rear 19-inch, both with chromium plated rims. The four-speed foot-change gear­box was also iden­ti­cal to the Tiger 90. Turner’s state­ment that the new twin pro­duced the same bal­ance as a sin­gle of the same ca­pac­ity proved to be a lit­tle wide of the mark, due to the flex­ing of the crank­shaft and the loss of rigid­ity due to the wider spac­ing of the main bear­ings. Nev­er­the­less, vi­bra­tion was not seen as an is­sue, and fuel con­sump­tion, or rather, lack of it, as a bonus. Turner added, “For a given power out­put it is pos­si­ble to use a far smaller choke, which im­plies bet­ter va­por­iza­tion and at­om­iza­tion. Whereas a sin­gle of 27hp would re­quire a 1 1/8” di­am­e­ter choke, the twin would need a di­am­e­ter of only 15/16”. The ver­ti­cal twin with cranks at 60-de­grees (in line) was cho­sen as the best all-round lay­out as it has the best car­bu­ra­tion pos­si­bil­i­ties of any type of twin ow­ing to its even fir­ing im­pulses and short in­duc­tion pipes.”

The fan­fare

The sparkling new Tri­umph 5T Speed Twin, re­splen­dent in Amaranth Red for all cy­cle parts with a chrome and red petrol tank, was shown to jour­nal­ists in July, 1937, to univer­sal ac­claim. Be­hind the scenes how­ever, Turner was qui­etly at log­ger­heads with Sang­ster over the lat­ter’s pro­posal to float Ariel and Tri­umph on the stock ex­change, with Turner as Man­ag­ing Di­rec­tor of both com­pa­nies. Ap­par­ently, Turner’s opin­ion of his worth dif­fered from Sang­ster’s, but the dis­cus­sions were kept pri­vate as they both strove to en­sure pro­duc­tion of the eleven-strong 1938 Tri­umph range re­mained on track.

The Au­gust 1938 Mo­tor­cy­cle Show was held for the first time at Earl’s Court in Lon­don in and the Speed Twin was un­ques­tion­ably the belle of the ball. The first road tests be­gan ap­pear­ing in Oc­to­ber 1937, and while The Mo­tor Cy­cle mag­a­zine achieved an im­pres­sive top speed of 93.75 mph, an­other jour­nal­ist, rid­ing with a strong tail wind, was clocked at an amaz­ing 107 mph. Soon the new model was be­ing pressed into ser­vice for record at­tempts ev­ery­where; as far afield as South Aus­tralia where Les Fred­er­icks set a new 12 Hour record at Coorong, near Goolwa, cram­ming 805 miles into the half day. At £75, the re­tail price was only £5 more than the Tiger 90 sin­gle, and such was the clam­our for the new twin that Turner ad­vo­cated drop­ping the sin­gle from the range. To ex­tend the ap­peal of the twin and to has­ten the demise of the sin­gle, Turner quickly be­gan work on a sec­ond model, named the Tiger 100, which ap­peared in the same sil­ver and chrome dé­cor as the Tiger 90. The new twin used forged al­loy pis­tons of higher 7.8:1 com­pres­sion ra­tio, pol­ished in­let ports with a one-inch car­bu­ret­tor, a slightly mod­i­fied crank­shaft and si­lencers with ta­pered ends that could be re­moved to ex­pose open mega­phones. To cope with the ex­tra power, the sixs­tud fix­ing for the bar­rel gave way to an eight-stud ar­range­ment that was car­ried over to the 5T. Post-war, Turner’s de­sign ap­peared in the form of the Grand Prix, based on the tuned T100 model that had won the 1946 Manx Grand Prix, and in 1949 as the Thun­der­bird – a 650cc ver­sion with bore and stroke of 71 x 82. Tes­ta­ment to the strength of the orig­i­nal de­sign is that the ba­sic en­gine, in 350cc, 500cc and 650cc sizes re­mained in pro­duc­tion from 1937 to the in­tro­duc­tion of the unit-con­struc­tion mod­els in 1963. Ivor Davies, who worked in the Tri­umph Ad­ver­tis­ing and Mar­ket­ing depart­ment for 16 years, said in his fa­mous book, It’s a Tri­umph, “It (the Speed Twin), started a ver­ti­cal twin band­wagon onto which al­most ev­ery other man­u­fac­turer in UK and abroad has since jumped, and it en­abled Turner to build Tri­umph Engi­neer­ing into a com­pany which, at the height of its fame, prob­a­bly made more profit per pound in­vested than any com­pany be­fore or since. It also made Turner a rich man…a dom­i­nant char­ac­ter whose pres­ence could not be ig­nored.”

A Down Un­der de­light

The fea­tured mo­tor­cy­cle here be­longs to Jon Munn from Clas­sic Style Aus­tralia in Seaford Vic­to­ria, and is an­other ex­am­ple of the metic­u­lous restora­tion work car­ried out by res­i­dent re­storer Ge­off Knott. “A few years back I was ap­proached by a Qan­tas pi­lot from By­ron Bay who had a bike that his fa­ther had orig­i­nally owned and he wanted to know if I was in­ter­ested in buy­ing it”, says Jon. “He sent some pho­tos and I could see it was ba­si­cally as de­scribed so we agreed on a price. It had been ‘re­stored’ by a friend of his some time be­fore, and although the job wasn’t too bad it was not re­ally what I con­sid­ered ac­cept­able for a mo­tor­cy­cle of this sig­nif­i­cance – this is one of the very first Speed Twins pro­duced in 1938 with the six-stud bar­rels. So Ge­off and I looked at it for a few weeks and then de­cided to do a ground-up restora­tion. We work strictly from the fac­tory parts book, so it was com­pletely dis­man­tled and ev­ery nut and bolt was in­spected. Ge­off is fas­tid­i­ous in this way – he will not fit a nut if it has the slight­est ev­i­dence of span­ner rash.” The Speed Twin was mostly all there, but there were still parts to be sourced, such as the pri­mary chain case which was dam­aged. Jon says that a good source of early Tri­umph parts is Ace Clas­sics in Lon­don (www.ace­clas­sics.co.uk) who were able to sup­ply a good chain case as well as sev­eral other parts. Clas­sic Style it­self has a vast store of New Old Stock parts and much of what was needed came off their shelves, and in other cases Ge­off was able to

re­claim items. The fuel tank for in­stance, had to be stripped of its chrome plat­ing and Ge­off spent many hours work­ing with his set of dol­lies and spe­cial metal work­ing tools to re­move ev­ery tiny im­per­fec­tion be­fore the tank was ready for plat­ing again – a spe­cial­ist job done by A.A. Vin­ney Elec­tro­plat­ing in Dan­de­nong. Al­most in­evitably, the in­stru­ments con­tained within the tank top panel re­quired ma­jor at­ten­tion. The in­cor­rect am­me­ter was re­placed with the cor­rect one from their NOS, while Ge­off re­stored the oil pres­sure gauge and the map light. The speedome­ter was also in­cor­rect but one was lo­cated which was in re­stor­able con­di­tion. Var­i­ous other pro­cesses were farmed out to ex­perts, mostly in and around Mel­bourne. “Phil de Gruchy from Light­foot Engi­neer­ing did the wheels,” says Jon. “He al­ways does a bril­liant job and did the wheels on our Vin­cent (fea­tured in OBA 71) as well. We for­tu­nately had some new orig­i­nal parts still in wrap­pers which were painted in the Amaranth Red, so we were able to get the colour ex­actly right. The paint­ing was done by Pres­tige Auto Paint who are only min­utes away from us in Seaford, they also did our Vin­cent. Greg Wood at Woody’s En­gine Ser­vices at Highett did the hy­dro blast­ing. Ge­off did pretty much ev­ery­thing else. Once he had had the bike apart he pro­duced a list of what was re­quired, and once we’d gone through our own stock he gave me a shorter list of stuff I needed to chase up. Phil Pil­grim at Union Jack Mo­tor­cy­cles is an­other very good source of Tri­umph parts, and we got a brand new carb from Burlen Fuel Sys­tems in Eng­land.” And so around three months af­ter be­ing dis­man­tled, the Speed Twin was back to­gether again, and look­ing ab­so­lutely splen­did. Ex­hib­ited at Mo­tor­clas­sica 2017 in Mel­bourne, it drew rave re­views – a ma­chine of enor­mous sig­nif­i­cance and one that lit­er­ally changed the face of mo­tor­cy­cling.

Am­me­ter, oil pres­sure gauge and light switch are con­tained in a Bake­lite panel in the fuel tank. The top­most item in the panel is an in­spec­tion light with a wan­der lead.

Lycett sad­dle was stan­dard fit­ment for many makes and mod­els. The el­e­gant pri­mary chain case, with the flared bump for the en­gine shock ab­sorber.

The very early Speed Twins had painted head­light shells, but this soon changed to chrome plat­ing to match the rim. Ini­tial road tests showed that the Speed Twin would ac­tu­ally wind the speedome­ter off the clock.

ABOVE Lord Mont­gomery ex­am­in­ing a 1949 Tri­umph Speed Twin. His Lord­ship had just of­fi­cially opened the Earls Court Show and look­ing on are Tri­umph Chair­man Jack Sang­ster and Man­ag­ing Di­rec­tor Ed­ward Turner. (Photo from Rus­sell McIvor)

LEFT An­nounce­ment of the new Tiger 100 in Novem­ber 1938.

ABOVE The tri­an­gu­lar plate would be­come syn­ony­mous with the Tri­umph mar­que and con­tin­ues to cur­rent pro­duc­tion.

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