A sec­ond Roarer roars

Read­ers were in­tro­duced to the re­mark­able Dan Smith in is­sue 75 with the fea­ture story on his V-4 AJS. Now it’s time to look at an­other cre­ation from the mod­est Smith work­shop in Van­cou­ver BC.

Old Bike Australasia - - CONTENTS - Story Jim Scaysbrook Pho­tos Den­nis Quin­lan and Jim Scaysbrook

As noted in the AJS story, Dan con­sid­ers the 1930s to be the zenith of the Bri­tish mo­tor­cy­cle in­dus­try, con­sid­er­ing the post-war prod­ucts and their same­ness. So af­ter com­plet­ing the her­culean task of build­ing his AJS V-4 from a sin­gle pho­to­graph, Dan set about mak­ing his own ver­sion of an­other of his favourite de­signs, the 500cc su­per­charged twin Ve­lo­cette known as The Roarer.

Now, for those not fa­mil­iar with the saga of the Roarer, it’s worth a brief run­down here. In the ‘thir­ties, thanks mainly to the rapid de­vel­op­ment of su­per­charg­ing that be­gan in WW1, cram­ming in­creas­ing vol­umes of air and fuel mix­ture into cylin­ders was pro­ceed­ing apace. Mil­i­tary en­gi­neers had long grap­pled with the prob­lem faced by their air­craft, which had to cope with cooler and less dense air the higher they flew. ‚

The higher the al­ti­tude, the lower the vol­u­met­ric ef­fi­ciency, with the re­sul­tant drop in power. The best way to over­come this was to ar­ti­fi­cially in­crease the amount of mix­ture go­ing in, and the favourite method was by su­per­charg­ing. The same prin­ci­ple ap­plied to ground-based en­gines. Bent­ley had done much work in this field, as had Mercedes Benz in car rac­ing, and BMW had suc­cess­fully su­per­charged their record breaker, the WR750. Sig­nif­i­cantly, those in charge of the rules for in­ter­na­tional mo­tor­cy­cle rac­ing made no dis­tinc­tion be­tween ‘at­mo­spheric’ (non-su­per­charged), and ‘boosted’ (su­per­charged or tur­bocharged) en­gines. As the thir­ties pro­gressed, sev­eral Ger­man and Ital­ian fac­to­ries tried su­per­charg­ing, not just in the 500cc class, but also in smaller dis­place­ment cat­e­gories. Ve­lo­cette had dab­bled in boosted en­gines as far back as 1930, with their blown KTT (us­ing a Foxwell blower) which was quaintly known as “Whif­fling Clara” that ran in the Ju­nior TT in 1931 and 1932, and of course, so had AJS with their wa­ter-cooled V-4 500cc racer. Both of these en­gines had be­gun life as nor­mally-as­pi­rated de­signs, with su­per­charg­ing later grafted on, but what be­came the twin-cylin­der Roarer was de­signed by Harold Wil­lis and Charles Udall at Ve­lo­cette specif­i­cally for su­per­charg­ing. To over­come the BMW’s in­her­ent torque re­ac­tion and the gy­ro­scopic pre­ces­sion ef­fect from the hor­i­zon­tally-op­posed lay­out with its large fly­wheel (which be­came even more marked and vi­o­lent when boosted), Udall’s de­sign placed twin crankshafts, geared to­gether along the frame axis, with the cranks ro­tat­ing in op­po­site di­rec­tions, thus elim­i­nat­ing both the torque re­ac­tion and the gy­ro­scopic ef­fect which in BMW’s case, af­fected the cor­ner­ing char­ac­ter­is­tics. One crank­shaft drove the su­per­charger, which sat be­hind the crank­case, while the other drove the trans­mis­sion com­po­nents, in­clud­ing the shaft to the rear wheel. A skew gear from the front of the left side crank­shaft drove the oil pump which ran at one-third en­gine speed. The choice of shaft drive was in­ter­est­ing, but Udall’s rea­son was that it kept the rear of the mo­tor­cy­cle free from the oil that was nec­es­sary to lu­bri­cate the usual drive chains. In­deed, Udall’s in­sis­tence on shaft fi­nal drive vir­tu­ally dic­tated that the en­gine would need to use lon­gi­tu­di­nal crankshafts. The top end of the Roarer en­gine was more or less con­ven­tional, with sin­gle over­head camshafts for each cylin­der. One un­usual as­pect of the de­sign was that the ex­hausts ran from the rear of the cylin­der head, with a long, curved in­let man­i­fold run­ning over the top of the en­gine and into the lead­ing side of the cylin­der head. This al­lowed the in­com­ing mix­ture to shed some of the heat gen­er­ated in the blower, and to re­duce the in­her­ent pulses also cre­ated by the vanes. To as­sist in cool­ing the ex­haust area of the cylin­der head, a pair of ducts was bolted to the sides of the heads.

By 1939, Gil­era was rapidly com­ing to grips with its su­per­charged four-cylin­der 500 which even by the mid ‘thir­ties was pump­ing out around 85hp when in trim for record break­ing, and in 1937 set a new world record for the fly­ing kilo­me­tre at 170.15 mph. De­spite the in­her­ent pe­cu­liar­i­ties of the op­posed twin de­sign, the su­per­charged BMW had taken an em­phatic 1-2 in the 1939 Se­nior TT, while the Gil­era won the sea­son’s fi­nal Grand Prix in Ul­ster and rider Darino Ser­afini be­came that year’s Euro­pean Cham­pion. The Roarer, on the other hand, com­pleted a soli­tary lap of the TT course in 1939, dur­ing a prac­tice ses­sion in the hands of TT mae­stro Stan­ley Woods. The fac­tory claimed the lap was not timed, which seems highly un­likely, and Woods re­ported that the ma­chine han­dled ex­tremely well and was in­cred­i­bly smooth, but there were con­cerns with over­heat­ing and the Roarer was with­drawn from the Se­nior TT. A fac­tor in the de­ci­sion to with­draw the ma­chine may have been the ab­sence from the TT of Harold Wil­lis, who had en­tered hos­pi­tal suf­fer­ing from menin­gi­tis. He passed away on June 11th, just two days af­ter that sin­gle prac­tice lap.

Udall orig­i­nally planned to use gly­col cool­ing for the Roarer, but this was ve­toed on cost grounds. Then when peace re­turned and rac­ing strug­gled back onto its feet, the FIM in­ter­vened and banned su­per­charg­ing out­right in 1947. There­after the Roarer gath­ered dust in the work­shop, un­til in 1956 the en­gine and

gear­box were stripped to per­mit jour­nal­ist Vic Wil­loughby to in­spect the de­sign and in­ter­view Charles Udall. At the same time the artist Frank Beak cre­ated ex­ploded draw­ings of the en­gine – some­thing that would prove in­valu­able in the fu­ture. The Roarer was ex­ter­nally re­fur­bished and re­assem­bled, mi­nus its en­gine com­po­nents, and was trot­ted out for var­i­ous mo­tor­cy­cle shows dur­ing the ‘fifties. It is be­lieved the in­ter­nals were placed in a box un­der a bench in the Ve­lo­cette work­shop, from where they grad­u­ally dis­ap­peared. When Ve­lo­cette fi­nally went un­der in 1970, the Roarer car­cass (an the pro­to­type Model O) was ac­quired by jour­nal­ist John Grif­fith who ex­hib­ited it in Stan­ford Hall Mu­seum in Le­ices­ter­shire, which he had co-founded. Fol­low­ing Grif­fith’s death in a mo­tor ac­ci­dent in 1975, own­er­ship of the Roarer passed to John’s son Stephen, and it was sub­se­quently sold in 1983 to Ivan Rhodes in Derby, who be­gan a long and painstak­ing task to re­build the bike – a task that in­volved recre­at­ing the miss­ing en­gine in­ter­nals which fell to his son Gra­hame. Luck­ily, Charles Udall was liv­ing in re­tire­ment in UK and still had his note­books from 1938 and 1939. Since its com­ple­tion, the orig­i­nal Roarer has ap­peared around the world, in­clud­ing Aus­tralia and New Zealand, much to the de­light of Ve­lo­cette afi­ciona­dos and those who ap­pre­ci­ate this im­mensely sig­nif­i­cant piece of rac­ing his­tory.

Mean­while, in Canada…

Just as he did when cre­at­ing his V-4 AJS, Dan Smith be­gan at his draw­ing board, in ‘The Base­ment’ un­der his mod­est house in Van­cou­ver BC, where he worked out the di­men­sions from pho­to­graphs and cut­away draw­ings taken from mag­a­zines which needed to be scaled up in iso­met­ric pro­jec­tion. It was a long and ar­du­ous process that in­volved draw­ing up every com­po­nent in­di­vid­u­ally, and of­ten more than once, be­fore he was con­fi­dent that ev­ery­thing would fit to­gether as it should. How­ever un­like the AJS project, Dan was able to get some as­sis­tance along the way, as Ivan Rhodes hap­pily vol­un­teered to check Dan’s draw­ings against his own. Still, it was no cake­walk, and get­ting the crankcases right was the first task. “The cases are made up of five sep­a­rate cast­ings,” says Dan. It had been doc­u­mented that the bal­ance fac­tor of the cranks was 100%, a fig­ure con­firmed by Ivan Rhodes, whereby the pis­ton move­ments are ex­actly matched to those of the crank­shaft bob weights, giv­ing per­fect pri­mary bal­ance. Af­ter mak­ing the wooden pat­terns for the crankcases sec­tions, Smith had them cast by a Van­cou­ver com­pany in alu­minium al­loy, al­though the orig­i­nal Roarer cast­ings were mainly in heat­treated mag­ne­sium. He ma­chined the cast­ings in his base­ment work­shop and then moved on to the top end of the en­gine, first tack­ling the com­plex sys­tem of bevel shafts and gears used to drive the camshafts. In­side the en­gine he opted for off-the shelf parts in sev­eral ar­eas (“Why make what you don’t have to”, is Dan’s motto) such as Suzuki pis­tons, a BSA oil pump and NSU Max valves and hair­pin valve springs. The lu­bri­ca­tion sys­tem was an­other as­pect that oc­cu­pied count­less hours, with myr­iad oil­ways that needed to be drilled and matched up. Then there was the gear­box to deal with! Un­like con­ven­tional Bri­tish de­signs with a coun­ter­shaft, the Roarer gear­box has just two shafts, for in­put and out­put, with the for­mer sit­ting be­low the lat­ter and con­nected by large gears. The in­put shaft is splined into the clutch cen­tre, while the out­put shaft is splined into a con­stant-ve­loc­ity uni­ver­sal joint on the axis of the swing­ing arm

pivot. The fi­nal drive shaft runs in­side the left side of the swing­ing arm fork. A suit­able CV joint could not be found in Bri­tain, so Ve­lo­cette Manag­ing Di­rec­tor Percy Good­man used his con­tacts in the aero in­dus­try to ob­tain a cou­ple from the Bendix Cor­po­ra­tion in USA. One was in­stalled in the Roarer, the other lost. Many years later, new owner Ivan Rhodes lo­cated it, still in its wrap­ping, un­der a bench where it had been for over 40 years. Next came the most unique fea­ture (for a Ve­lo­cette) – the su­per­charger. Dan’s re­search con­vinced him that the orig­i­nal Shor­rock blower had been specif­i­cally made for the Roarer, so there was no chance of find­ing one of those. What to do? Make his own of course. “I made the whole su­per­charger but I had no idea when I was start­ing. When I made the vanes for the su­per­charger I ended up with a bit more clear­ance than I would have liked but I wasn’t about to re­make them. Velo used a Shor­rock and you can still buy those, but there’s none that would fit in, and you’ve only got so much room. To me they had to have gone to Shor­rock and said we need a blower that will fit in this cav­ity, so they made it, and the pic­tures show six vanes, but I couldn’t put six vanes in, it was too short. There isn’t room for the whole stack to go on the shaft, so I made four vanes which doesn’t re­ally mat­ter be­cause you don’t get any more pump­ing, it’s dis­place­ment per rev as it goes around. If I was go­ing to pur­sue it I would have to cut the clear­ance down on the vanes but I’m not rac­ing it so I didn’t. The cams were shaped wrong for the blower – you should have zero over­lap with a blower. When they (Ve­lo­cette) were run­ning it on the bench they talked about hav­ing trou­ble get­ting the blower pres­sure up. I’m get­ting 6 pounds boost on it at 6,000 rpm but I haven’t been able to spin it up fur­ther, but I think I’ll get 8 pounds if I get it to 7,000.” With the power unit and trans­mis­sion ba­si­cally com­plete, it was time to turn to the chas­sis, which was nat­u­rally built in the Base­ment work­shop by Dan – a process he de­scribes as be­ing, “Just a whole bunch of straight tubes, fairly straight­for­ward.” Straight­for­ward it may have been, but it was still a case of trial and er­ror, and im­mensely time con­sum­ing, com­bin­ing as it did the swing­ing arm with the in­te­gral drive shaft tube. The en­gine is clamped into place at four points, act­ing as a stressed mem­ber and con­tribut­ing to the rigid­ity of the chas­sis. Thanks to the in­her­ent vi­bra­tion-free na­ture, no head-steady is nec­es­sary. “I got a set of Webb forks out of In­dia. They were re-pop­ping Webb forks for the 16H Norton so I got them back here and con­verted them to the Webb TT forks but they must have made the pat­terns off an old set and it was just about as much work to fix them as it would have been to start fresh. I was a month or more build­ing the fuel tank by hand out of steel.” Dan also made the hubs and brake drums, ex­act repli­cas of the orig­i­nals, but us­ing Suzuki brakes shoes.

Three years af­ter the project be­gan, the replica Roarer burst into life. It was time to put his work to the acid test, so man and ma­chine ven­tured south to Seat­tle In­ter­na­tional Race­way. “When I was on the track at Seat­tle, which was two years ago, I was a wreck when I fi­nally came off and I said, ‘That’s it, I’ve had enough’. You don’t know what to ex­pect, down the straight­away and I’m watch­ing blower pres­sures and mix­tures and I haven’t re­ally got­ten en­thu­si­as­tic enough to go back and do it again. I haven’t put many miles on it, and then I’ve come back and I’ve made some changes but I haven’t been back out again. I’m go­ing to be 80 next year so go­ing 100 mph is not for me. The gear­ing they (Ve­lo­cette) used for the one lap they did at the TT was very high, and I’ve got the gear­ing lower in the fi­nal drive. I couldn’t fit in the lower gear (in the box) be­cause you don’t go through four gears you just cut through one gear, up and out so you have to do all your ra­tios just be­tween two, they’re not com­pounded. So in the fi­nal drive you get a choice of 3:1, or 4:1. I couldn’t get full revs out of it be­cause they short­ened the straight, so I couldn’t re­ally get it wound out. It was funny; I’m in third gear and it won’t rev and af­ter many times around the track I’m get­ting used to it so I thought I’d try fourth gear and see what that’s like, and it went down into third! I’d made my cam plate so it went first, sec­ond, fourth, third! I re­mem­ber hav­ing to change my gear sets in or­der to fit ev­ery­thing in there and I swapped third and fourth around and I guess when I made the cam plate my draw­ings and sketches got swapped around, you for­get these things. The cam plate is cor­rect now but I haven’t rid­den it, apart from in Mon­tano on a lit­tle short track but I couldn’t get it out of sec­ond gear. It won’t pull up any sort of hill with­out a good start; it needs a lot of clutch.” With the Roarer now a com­plete and run­ning

item, Dan has moved onto his next project, a Norton-framed café racer us­ing one of his own HRD Se­ries A Rapide en­gines, and he has de­cided to put the Roarer up for sale, to a buyer “who has deep pock­ets”. “I’m slow­ing down, but I’m still in the Base­ment eight hours a day.” You get the im­pres­sion that while ever the sun rises, Dan will not be able to stay away from the draw­ing board and the ma­chine shop for long.

Dan Smith and his hand­i­work. A painstak­ing re­cre­ation of the pre­war su­per­charged twin with which Ve­lo­cette hoped to chal­lenge Ger­man and Ital­ian supremacy.

Ex­ploded view of the gear­box by artist Frank Beak.

Roarer en­gine in the Ve­lo­cette work­shop. Clamps for the frame tubes can clearly be seen, with the rear hub on the bench.

MAIN The orig­i­nal en­gine ex­posed, show­ing the con­tra-ro­tat­ing cranks. BE­LOW Roarer en­gine on the Heenan & Froude DPX2 dyno spe­cially bought by Ve­lo­cette to test the new en­gine.

The Roarer in the race or ex­per­i­men­tal shop 1939. Percy Good­man, Tommy Mut­ton and Harry Thorne pre­par­ing the Roarer for the 1939 TT. Ivan Rhodes with the Roarer at Bankstown RSL night dur­ing a trip to Syd­ney.

Gra­hame Rhodes and Stan­ley Woods with the re­stored Roarer. Stan­ley Woods, re­united with the ma­chine he rode in 1939.

LEFT The lu­bri­ca­tion de­part­ment. BE­LOW LEFT CV cou­pling in the left side swing­ing arm tube. BE­LOW RIGHT Like just about ev­ery­thing else, Dan made the hubs and the com­plex fi­nal drive.

The en­gine in­stalled in the un­painted frame in Dan’s work­shop. Webb-pat­tern, front forks came from In­dia. ABOVE CEN­TRE En­gine is clamped into frame on the bot­tom rails. ABOVE Unique gear­box with the cam­plate in the hous­ing on top of the main cast­ing.

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