MONTLHERY VINCENT: 100MPH FOR 6 HOURS

Coming to the Bonhams Stafford auction April 28th; the Montlhéry Vincent Black Shadow

The Montlhéry race circuit, just 15.5 miles south of Paris, holds a place much like Brooklands in England in the hearts of European speed-fans, but the track isn't a fractured memory from pre WW2, its a living thing in continuous usage since constructed in 1924.  Today the track is regularly pounded by automotive companies, being engineered to withstand 5,000lb racing cars traveling at 150mph - a far-sighted vision for 1920s engineers.  But then, French engineers of the early 20th Century were exactly that, out on the exploratory limbs of technology, making double overhead camshaft four-valve multi-cylinder motorcycles even in the 'Teens.  What Montlhéry became best known for, though, was long-distance record-breaking; while nearby Arpajon was an excellent spot for Land Speed Record attempts in the 1920s and 30s, Montlhéry was a perfect venue to circulate for hours around its steeply banked oval, being relatively smooth (well, smoother than Brooklands...) and amenable to 24-hour full-bore, unsilenced riding.

The most visible modification from 'standard' spec is the large capacity racing fuel tank.  The Shadow is a matching #s machine with History...

On May 13 1952, a pair of mildly modified 1,000cc Vincent Black Shadows arrived in Paris to attempt a new 24-hour speed record, with a slew of Vincent factory employees (including 18 year old apprentice John Surtees), a few pressmen, plus a French team contingent of riders, the record-attempt team manager, and timing officials from the FIM.  One of the machines was a 'test hack' which circulated for hours during testing, on which modifications were made for an average/acceptable riding position for the 11 riders participating; Phil Heath, John Surtees, Robin Sherry (AMC factory racer), Cyril Julian (TT rider), Vic Willoughby (infamous writer for The Motor Cycle), Dennis Lashmar,  and Danny Thomas, plus four French riders; Ken Bills was team manager.  All the riders save Danny Thomas were able to keep up the 100mph pace, so he was relieved of duty.

The Montlhéry Vincent Black Shadow in 1952, at the track

 Paul Richardson, the Vincent-HRD Service Manager, described the record-breaker thus:

"The record breaking machine is a standard Black Shadow with 8:1 compression as supplied to the American market. ... We used 1-5/32" T.T. Annals in conjunction with two inch open pipes, the fuel being non-leaded 80 octane... Lightning cams... We removed our front brakes and rear flap, fixed rearward foot rests were fitted... special five Gallon petrol tank and a Feridax perspex flyscreen. Modified handlebars gave a very flat riding position and riders lay on a Sorbo 'mattress' fastened to the tank top...Avon...Standard 300 x 20 front racing and 3.50 x 19 rear racing tyres..."  His complete (and delightful) account of the attempt can be found here on the VOC site.

Ted Davis, the Vincent competition manager, originally built the Montlhéry racers with a caged big-end bearing, an improvement over the standard crowded-roller item, but Philip Vincent insisted the standard item was good enough, and ordered them changed back to standard, 'to demonstrate the reliability of the standard Black Shadow', which of course it did, but not with the intended outcome!  It didn't help that France was having its hottest May on record - so hot that the Avon rear tires on the pair of Black Lightnings (brought over for high-speed records) shed their treads at high speed, and the Castrol XL oil was described by Davis (read here) as 'dirty hot black water' when drained from the engines.  

After ten hours forty minutes, the standard big-end of the Vincent crankshaft failed, and a deafening silence rang in the speed bowl; the team ran to the far side of the track (a mile!), and waited 20 minutes to push the bike over the 'line' to take the 11hour record.  While a Vincent never took the 24hr/100mph record (it took a Velocette for that one), the Vincent team still took and impressive eight World Records, including the six-hour record at 100.53mph and 1,000km at 100.67mph, and 10 hours at 99.17mph.   Other records were 7 hrs @ 99.73mph, 8 hrs @ 99.73mph, 9 hrs @ 99.40mph, 10 hrs @ 99.17mph, 11 hours @ 91.98mph, and 1,000 miles @ 99.20mph.

I mentioned above that TWO Black Shadows were taken to Montlhéry...one a 'test mule' and the other used in the attempt; both were tuned and prepared for the attempt, and both machines survive.  One is coming up for sale at the Bonhams Stafford sale on April 28th.  Apparently there is no record of 'which bike was which', but both can rightly claim to be part of the attempt at Montlhéry...

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OEC, POST LSR

After a successful career housing a supercharged 994cc JAP engine for several attempts at the Motorcycle Land Speed Record with Joe Wright aboard, the unusual OEC chassis built for the specific purpose of breaking records was host to another blown engine, this time from a car.

The Aug. 30, 1934 edition of 'The Motor Cycle' has a short article on a 'A New Racing "Four"', detailing the attempts by J. Granville Grenfell (what a name!) to create a 500cc machine, with the specific intention of being the first motorcycle to achieve 100mph for an hour, and win a 'Motor Cycle' sponsored trophy for a multi-cylinder/100mph/1hour British motorcycle.  While the OEC was being built, a New Imperial 500cc v-twin took the prize with 'Ginger' Wood the brave rider - it was said he was the only person willing to risk his life aboard the evil-handling New Imp, which spat him off with a tank-slapper at 100mph on the Brooklands banking, while practicing for the record. By comparison, the OEC was a far safer bet at over 100mph; the 'Duplex' steering system being almost too stable at speed, taking some effort to deflect from a straight-line course.  Of the two possibilities, I'd take stable over wobble.

As the raison d'etre of the revised OEC had passed, the Grenfell's (under the sponsorship of Minnie Grenfell, a trials rider) entered the machine in the 'Hutchison 100' race at Brooklands that August of '34.  F.W.S. Clarke was the pilot, although the machine 'failed to distinguish itself' in the races, as the engine was yet 'too tight'...although building a record-breaking engine to 'tight' clearances is dubious. The motor in question is an Austin 7 four-cylinder sidevalver, sleeved down from the original 742cc to 490cc, making a very long stroke indeed at 46mm bore x 76mm stroke.  The crankshaft, notoriously prone to breakage on 'sporting' Austin 7s, was an especially strong one-piece item, yet retained only one main bearing at either end (in '36, Austin introduced a '3-Bearing' crank).  The crank end held a sprocket, presumably between the main bearing and flywheel clutch, which drove a Centric supercharger, mounted above the Morgan 90degree bevel-drive box, which 'turned the corner' and made a rear drive chain possible.  There was no gearbox per se, making the OEC a supercharged four-cylinder single-speed racer!

More technical points on the modified engine: the Centric blower began puffing at 25rpm, giving maximum pressure of 20lbs/sq" at 6000rpm, producing an estimated 46hp 7000rpm...about twice the safe revs of the standard Austin engine, and nearly 3 times the original 17hp.  A sporting Watmough cylinder head gave a better combustion chamber shape, although the compression ratio remained a lowly 4.5:1...not an issue with a supercharger, which needs neither high compression nor radical valve timing to produce maximum power.  In fact, a very tame camshaft with little 'overlap' of valve openings produces the best results with a blower, as it's the job of the compressor is fill the cylinder completely with fuel/air mix, no fancy engine tuning is required, other than the ability to hold the engine bits together, after a dramatic increase in horsepower.

To keep the engine cool, a Scott radiator fits snugly at the front of the engine; hopefully a waterpump was used rather than the 'thermosiphon' system of the Scott, notoriously prone to boiling, although the OEC used glycol rather than water for cooling - a novelty at the time.  The OEC frame was modified to fit all this machinery, and it was estimated the bike would be good for 118mph, and although 'nothing like this speed' was achieved during the 'Hutchison 100', the 60" wheelbase chassis was reported to handle 'extraordinarily well'.

Of course, the OEC wasn't the only motorcycle using an 'Austin 7' engine, as Brough Superior used the engine as well - see the Road Test here.

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OEC, ZENITH, AND THE STOLEN RECORD

In a funny twist of lingering history, the FIM book of Motorcycle Land Speed Records notes that on 6th November, 1930, Joseph S. Wright took his Temple-O.E.C. (Osborne Engineering Company) with supercharged JAP 994cc engine to 150.7 mph down the rod-straight concrete pavé at Cork, Ireland. The 1930 record was a significant advance on the Ernst Henne/BMW record of 137.58mph, achieved only weeks prior at Ingolstadt, Germany, on a supercharged 750cc ohv machine.  But in this case, the history books are all wrong.

150 MILES AN HOUR ON A MOTORCYCLE!

 (Click on the image above to see the film from the Record attempt)
The O.E.C. was an unusual motorcycle, using 'duplex' steering; an OEC trademark, although not all of their bikes used this system.  The advantages of this arcane steering system on these early motorcycles was great stability at speed, plus the possibility of front wheel suspension which didn't alter the steering geometry when compressed by bumps, giving totally 'neutral' steering under all conditions.  In practical use, the OEC chassis was reported to be very stable indeed, although resistant to steering input!  So, while potholes and broken surfaces brought no front wheel deflection, neither did a hard push on the handlebars...perfect for a speed record chassis actually.

A pair of machines was present at Cork that day; the OEC which had been prepared by veteran speed tuner Claude Temple, and a 'reserve' machine in case it all went pear-shaped.  The second-string machine was a supercharged Zenith-JAP, of similar engine configuration to the OEC, but in a mid-1920s Zenith '8/45' racing chassis.  Zenith at that date was technically out of business, so no valuable publicity could be gained for the factory from a record run, nor bonuses paid, nor salaries for any helpful staff who built/maintained the machine.  While Zenith would be rescued from the trashbin of the Depression in a few months, and carry on making motorcycles until 1948 in fact, the reorganized company, with its star-making General Manager Freddie Barnes, never sponsored another racer at Brooklands or built more of their illustrious special 'one off' singles and v-twins, which did so well at speed events around the world - from England to Argentina!

Joe Wright had already taken the Motorcycle Land Speed Record with the OEC, back on August 31st at Arpajon, France, at 137.32mph (see top photo with news story), but Henne and his BMW had the cheek to snatch the Record by a mere .3mph, on Septermber 20th. That November day was unlucky for Wright and the team, as the Woodruff key which fixed the crankshaft sprocket sheared off, and the OEC was unable to complete the required two-direction timed runs to take the Record.  As you can see in the photo below, the engine mainshaft drove the supercharger as well as the primary chain/gearbox, and was a one-off for which there was presumably no replacement, with probably no time for repair in any case.

Supercharging a v-twin motorcycle is a difficult business, as the compressor blows fuel/air mix at a constant rate into a shared inlet manifold for both cylinders, but as the cylinders aren't evenly spaced physically (as they are on a BMW, for instance), one cylinder inevitably gets a much bigger 'puff' of built-up pressure.  Figuring out how to accommodate a different charge for each cylinder led to all sorts of compromises, from restricting the inlet port of one cylinder, to the use of different camshafts/compression ratios/valve sizes for each cylinder, in an effort to keep one cylinder from doing all the 'work' and overheating.  It was an imperfect science, as supercharging was still relatively new to motorcycles, and only a handful of blown motorcycles were truly 'sorted out' for racing or record-breaking before WW2.  Typically, these had flat-twin or four-cylinder engines, with even intake pulses!  (Although, of course Moto Guzzi, typical of their genius at the time, had a lovely 250cc ohc blown single-cylinder which worked a treat).

With the OEC out of action, and FIM timekeepers being paid by the day, as well as the complicated arrangements with the city of Cork to close their road (and presumably police the area), a World Speed Record was an expensive proposition, and the luxury of a 'second machine' (above) was in fact very practical...although this may be the only instance in which the second machine was of a completely different make.  Imagine Ernst Henne bringing a supercharged DKW as a backup for his BMW; simply unthinkable!

But, such was the English motorcycle industry at the time; several very small factories (Brough Superior, Zenith) competed on friendly terms for national prestige the in record books, while the largest makes (BSA, Triumph, Ariel), nearly ignored top-tier speed competitions such as the Grands Prix and Land Speed Records.

In the event, Wright did indeed set a new Motorcycle Land Speed Record with his trusty Zenith (above, setting the record, quite clearly on a different machine than the OEC below) at 150.7mph, although the press photographs and film crews of the time were solely focused on the magnificent but ill-fated OEC, as Zenith was out of business and OEC paying the bills.  Scandalously, all present played along with the misdirection that the OEC had been the machine burning up the timing strips, and the Zenith was quickly hidden away from history, a situation which still exists in the FIM record books!

Photographs from the actual event show the Zenith lurking in the background (above), while Joe Wright poses on the OEC, preparing himself for a blast of 150mph wind by taping his leather gloves to his hard-knit woolen sweater, and wrapping more tape around his turtleneck and ankles to stop the wind stretching them, and dragging down his top speed.  His custom-made teardrop aluminum helmet is well-documented, but the protective abilities of his wool trousers and sweater at such a speed are dubious at best...but there were no safety requirements in those days, you risked your neck and that was that.  Nowadays, when any young squiddie can hit 150mph exactly 8 seconds after parting with cash for a new motorcycle, Wright's efforts might seem quaint, but he was exploring the outer boundaries of motorcycling at the time, and was a brave man indeed.

The record-breaking Joe Wright Zenith was a rumor for decades, becoming a documented story only in the 1980s via the classic motorcycling rags, the whereabouts or existence of the Actual machine known only to very few.  I've had the great pleasure of making the Zenith's acquaintance, it does still exist, and is currently undergoing restoration, to be revealed when the time is ripe.

As the OEC also still exists and is in beautiful restored condition, a meeting of the two machines is almost a certainty, at the right event.  If motorcycles could talk, I bet the Zenith would have something to say to the OEC...

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