MIKE CASTS HIS MIND BACK TO THE DECADE WHEN MULTI-ENGINED MONSTER BIKES RULES THE STRIPS
Nicksy on the decade when multi-engined monsters ripped up the drag strips
‘RUBBER WAS AS VITAL TO PROGRESS AS HORSEPOWER’
Of all the people who’ve done crazy things on motorcycles, the Top Fuel drag racers of the 1970s rank second only to Isle of Man TT racers in my books. The ’70s was a period of frantic technical change on the drag strips – twin-engined bikes powered by Triumph and Norton motors were tussling for supremacy with a new wave of double-engined Harleys, rear tyres were getting fatter, wheelbases growing longer and two- and three-speed transmissions had started to appear.
The bikes were getting faster by the week – TC Christensen achieved a terminal speed of 180mph on his 1500cc double-engined Norton, and the top contenders were vying to set the world’s first seven-second motorcycle run.
I never got to see one of the big US bike drags in the ’70s, but at least I met the famed TC when he made a short British tour. He named his bike Hogslayer because it took over from Boris Murray’s twin-engined Triumph as the most feared machine in the USA, and consistently humbled the single-engined Harleys.
That drove the Harley contingent back to sketching on their Coors beermats, and the result was the Harley doubles – W-fours, really – and a flood of tumbling elapsed times. TC’S fastest at that point was an 8.37sec run. Carl Ahlfeldt was fielding the biggest Harley double at 236 cubic inches (3.7 litres), but Joe Smith was the world’s fastest drag-bike rider at 8.201sec and a terminal speed of 176.47mph on his 3700cc Harley. Coming up strongly was Russ Collins, who wedged three Honda CB750 engines into a motorcycle frame. With the machine still in an early stage of development, he ran 8.47sec at 171.42mph. Danny Johnson and Marion Owens were other twinharley exponents who were also running in the 8.3sec bracket. TC and his engineer John Gregory, running out of their Sunset Motors shop in Kenosha, Wisconsin, were under pressure. “I’ve got 300 horsepower in my Norton and I can use it all,” he told me at the time of his British visit. “The Harleys are putting down about 400 horsepower and they’re only using 70% of it. They can’t find the traction to get all the power on the ground. They could be doing sevens now if they knew how to use the power.”
Rubber was as vital to progress as horsepower. Tyre manufacturer M&H offered the quickest riders so many combinations of compound and section that “it would take me a year to test ’em all,” according to TC. A six-inch rear tyre was the standard size, but when M&H produced an eight-inch rear, new challenges arose. In the early development stages of the fatter tyre, only TC, Russ Collins and Johnson used it.
The eight-incher, a two-ply design, 28 inches in height, caused handling problems for Collins and tossed TC onto the strip at 150mph, leaving him with cracked ribs, a crushed heel and calf and severe body abrasions. He had been experimenting with different tyre pressures, starting with 16psi and going down in 2psi stages. At 8psi, the Norton laid down on its side after TC had completed an 8.8sec run – the tyre walls had flexed too much. M&H responded by working on a fourply version with a lower height – and by developing a 10½in version. At the time of our meeting, TC was testing with M&H to develop this tyre, and was also tuning 850cc Commando engines and a threespeed transmission, in an attempt to get back ahead of the Harleys.
Not getting to see these amazing dragbike wars in the US in the ’70s is one of the things I regret in life. I only read about it from afar, and sat enthralled by TC’S tales. He and his clan were constantly pushing technology to the edge, never knowing when something was going to break, with unpredictable consequences. They did it under the floodlights, on a Saturday night, the pits awash with eyestinging nitro fumes and raging exhaust sounds. They did it with barely no manufacturer backing, and no one made serious money out of it. True heroes.