Triumph Quadrant

Triumph Quadrant Special Road Test

Triumph Quadrant Road TestThere is talk of many secret or enigmatic machines, often steeped in biking folklore, road legal racers, or machines that produce so much power that a mere mortal could never be allowed to cock a leg over. From futuristic designs that never saw the light of day, or would have transformed motorcycling as we know it, to the down right foolhardy that if actually put into production, could never have survived in the market place.

While the Japanese factories often spend millions just to see if an idea actually works, for the British bike industry such creations were usually fabricated from existing parts to save cost and development time and resembled cobbled together home built machines at best. Triumph during the mid 70s toyed with a super sporty 350 twin (more of that in the future) and several ideas that they hoped would help compete with the Japanese influx of Supebikes. One such machine is the Quadrant, an amalgam of T150 triple parts built at Triumphs Kitts Green factory in Birmingham, and Doug Hele, Triumphs legendary design chief was the man behind the idea. A welded up cylinder block was joined to a common case to create a modern looking four-cylinder, albeit in reality using dated pushrod technology; while the competition had long since been implementing overhead cam and chain driven gear trains. Because the transmission and power take off from the crank shaft could not be altered without a complete redesign the four was created by simply adding the 4th cylinder on the outside of the engine giving it a lopsided look, but fit for purpose none the less.

Triumph Quadrant SpecialFrom the outset the 987cc machine was never going to give Honda and the other Japanese manufacturers much to lose sleep over, although a top speed of 125mph was reported despite little testing time being allocated to the big Triumph. It is largely thought that the time spent on the Quadrant was simply a waste of effort that could have been used more productively on the big bore 900cc triple variant waiting in the wings, but it was all too late and the difficulties within the Brit bike industry soon meant that no further development would take place on any machine not currently in production and achieving sales.

Those that rode the Quadrant expressed much pleasure in its abilities; the engine was smooth and powerful, if dated by the time it had been built.

The machine seen here is one mans recreation of the concept, a completely home built version of the Triumph Quadrant. George Pooley, from Mansfield, has owned many of Triumphs triples and in 1993 showed his mechanical prowess by creating a 1500cc V6 by using two T150 top ends on a common casing. He then turned his attentions to the Quadrant just to see if the project could have worked in practice.

Triumph QuadrantTriumph Quadrant – Too little Too late?
George’s Quadrant looks nothing like a home built special, a testament to his work ethic and undoubted skill; in fact the big four looks every bit the factory produced production item. The hardest part was the engineering that had to go into the one-piece crankshaft, milling it himself in his home workshop. Then two casings, barrels and rocker covers all had to be machine allowing them to be welded together to make one bigger engine assembly, and after much work the four-pot engine started to take shape. It is powered by a Boyer Bransden electronic ignition for reliability and the finished power plant now rests in a modified T120 frame albeit with wider lower frame rails and engine plates to take the larger engine. T160 triple brake discs complete the cycle parts and the whole look is one of a very special motorcycle indeed, making us think what could have been were it not for politics of the 70s and its effect upon the UK motorcycle industry.

Triumph Quadrant Specifications

Engine – Air-cooled OHV four-cylinder four-stroke
Capacity – 987cc
Bore/stroke – 67 x 70mm
Power – 75bhp @7250rpm
Torque – 54ft-lb @ 6000rpm
Carburation – 4 x 27mm Amal
Transmission – 4 speed, wet-clutch, chain final drive
Frame – Steel tube
Suspension – 43mm telescopic forks, Twin shock rear
Brakes – 2 x 250mm discs twin opposed piston AP calipers, 250mm disc opposed piston AP caliper
Wheels – 4.10 x 18, 130/90 x16
Weight – 261kgs
Top speed – 125mph
Wheelbase – 1400mm
Fuel capacity – 22lts

Triumph Quadrant Gallery

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