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Douglas Mark V
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This 1951 Douglas 350 Mark V was featured in the June 2008 issue of RealClassic, but there wasn’t space in the paper magazine for all the lovely photos of it… so here you are, a feast for your eyes...

The Douglas Engineering Company began life in Bristol in 1882, and company built its first motorcycle engine in 1905. Douglas specialised in horizontally-opposed twin cylinder machines which they produced throughout the ’teens and Twenties, and became famous for their speedway winners. Before the Great Depression undermined the economics of the industry, Douglas expanded their range to include 350, 500 and 600cc models, then the shaft-drive Endeavour (which was the first Douglas to carry its engine positioned across the frame), and finally the Aero which arrived just before WW2.

This space reserved for the Vicar's car. It says... 1951 Douglas 350 Mark V

During the Second World War Douglas made many stationary engines, and then restarted motorcycle production with the T35, another ohv flat-twin 350cc, set across a duplex fame with torsion bar rear suspension. Various Sport and Competition offshoots were built in the next few years, including the 90 Plus and 80 Plus, and the standard bike evolved through several incarnations to become the Mark V. The Mark V was built until the introduction of the Dragonfly in 1955.

The handling is so light you need to tie the bike down when it's parked. 1951 Douglas 350 Mark V

Douglas found plenty of ingenious methods of solving problems which led to a raft of patents, not only for Radiadraulic leading link forks (1948) and torsion bar rear suspension (1944) but also a butterfly valve carb (1945) and gearbox with final chain drive for transverse twin engines (1947).

Look closely and you can see the inlet valve stem from here... 1951 Douglas 350 Mark V

Douglas were very proud of their oil-damped Radiadraulic forks which offer 5.5 inches of travel through variable rate springs, while keeping unsprung weight to a minimum.

Note 'Reaction Link' to prevent brake drum forces affecting suspension movement. Oil-damped Radiadraulic forks - Exploded View - 1951 Douglas 350 Mark V

You’ll find torsion bar suspension on some modern 4x4s, but in 1934 Citroen were among the first to use it on their Traction Avant. When the Douglas sprung frame arrived it ‘set a new standard of comfort’ and was a massive improvement over the competition: ‘handling was excellent by any standards and particularly those of the day’.

Torsion bar suspension twists a rod (the torsion bar in the diagram) around its centre to provide sprung movement. Torsion Bar Suspension - Exploded View - 1951 Douglas 350 Mark V

Douglas reckoned that ‘the 180-degree cylinder disposition assures a power curve free from vibration – the crankshaft accepting a power impulse for every revolution’ and, as Steve Wilson once commented, flat twins offer ‘inherent good balance, low centre of gravity and smoothness’.

More tea, Douglas? 1951 Douglas 350 Mark V

By modern standards the Mark V is a tiny little bike; it barely comes up to your knees. It’s also not the fastest motorcycle Douglas ever built: quicker than the Dragonfly which replaced it, but still happier at 50mph than 60. In common with other Douglas engines of its era it likes to be revved, which riders of big Brit singles can find somewhat disconcerting.

Jeff Clew has said that; ‘There’s something special about just sitting on a Mark Douglas. I swear that if I was led into a completely dark room full of motorcycles and asked to locate which one was a Douglas, its riding position and feel would immediately give it away’

Knees not shown... 1951 Douglas 350 Mark V

According to the Douglas brochure; ‘The Mark V represents one of the most highly developed models in the industry and has no rival for the motorcyclist who needs efficiency, comfort, reliability and perfect road-holding. A twin is best and Douglas is the best twin’

Purpose built... 1951 Douglas 350 Mark V

Douglas Mark V Fact Pack

  • Built: 1951 to 1954
  • Engine: OHV horizontally-opposed twin
  • Capacity: 348cc
  • Bore/Stroke: 60.8 x 60mm
  • Compression: 7.25:1
  • Gearbox: 4-speed, unit construction
  • Frame: Duplex cradle
  • Electrical system: Lucas Magdyno
  • Front suspension: Radiadraulic forks
  • Rear suspension: Swinging fork with torsion bars
  • Brakes: 7-inch
  • Wheels: 3.25 x 19-inch
  • Fuel capacity: 3 gallons
  • Wheelbase: 54.5-inches
  • Ground clearance: 5.25-inches loaded
  • Weight: 365lb
  • Owners’ Club: LDMCC

  • Douglas stuff on
    (Douglas were also Vespa importers)


    Want to read more? The full history and details of the Douglas Mark V are in RealClassic magazine, May 2008, and you can buy a copy here…


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