Any time I see an 'ex-TT Works Racer' coming up for auction, my ears perk up and I start pulling books off the shelf and making phone calls to Australia. It's really rare that any machine claimed to have been built specially by a factory for the TT (1.) comes up for auction and (2.) is genuine, for the simple reason that so few have been built, and even fewer survive the rigors and modifications of racing in the subsequent years. And to be generous, sometimes owners are confused or optimistic that their racing machine was a unique bike created by the factory for a special race.
The ca. 1934 O.E.C. (Osborne Engineering Co.) ex-Works Racer coming up for sale at the MidAmerica Las Vegas auction is a real rarity, from a company which only sporadically competed in the TT at all. OEC is better known for it's 'odd engineering contraptions' than for any racing dominance, yet they periodically threw their hat in the ring at the TT, and in chasing the World Land Speed Record. Their most famous design is a form of hub-center steering (which they called the 'Duplex' system), which was introduced in 1929 to a skeptical public...just like the one today which won't buy Yamahas or Bimotas with hub-center steering!
Little is documented about the mid-30's foray into racing by this tiny company (they only produced around 300 motorcycles/year), but we do know that between 1933 and 1935 they produced perhaps half a dozen machines for the Isle of Man TT, using genuine racing J.A.P. ohv engines of 250cc, 350cc, and 500cc. The '33/'34 engines had aluminum crankcases, whereas the '35 effort used magnesium. Students of motorcycle history will recall that these were dismal years for the JAP racing engine, with lots of failures at the TT, which led to their prestigious client base seeking other engine makers to fill their chassis, notably Brough Superior (who found AMC engines more reliable) and HRD-Vincent (who made their own).
OEC chose to use two types of chassis for the TT; a single machine used the 'Duplex' frame (almost inconceivable given their well-documented tendency to hold and keep a straight line unless muscled over), while the other machines used Webb girders (as seen in the photo above - Freddie Clarke at the '35 Lightweight TT). These Works bikes were the only OEC's to use Webbs, and the particular fork is unique to these bikes, as the steering head on an OEC is considered to be the longest on any motorcycle; something like 9 inches, requiring a new jig at Webb's and a host of one-off links and tubes. An 'OEC' Webb girder won't fit any other motorcycle, so you'll know if you stumble across one.
The back end of the OEC frame is their own version of a swingarm frame, introduced in 1929 (see drawing), which uses a full 'loop' at the back end for stability, and the swinging fork situated between compression and rebound springs housed within the frame tubes. The Works machines also used Harwal wheels (same as the Excelsior Manxman and OK Supreme racers), and special petrol/oil tanks. The auction machine appears to have all the right stuff, although I haven't seen the crucial engine/frame numbers yet. The crankcases look to be correct, but the cylinder barrel is alloy, and the cylinder head looks to be a scantily-finned Speedway item - but in the racing game, everything is up for change in the name of speed.
I've only seen one other OEC Works racer, which turned up at a swap meet in Australia, housing a Suzuki dohc 4 cylinder engine! Yes, the owner is restoring it!
Many thanks to Mitchell Barnes for his information.