The Final Featherbed: 1967 Norton Atlas

Norton Guru Colin Kelly revives and restores a 1967 Norton Atlas to show-winning perfection.

| November/December 2017

Colin Kelly's 1967 Norton 750 Atlas.

Photo by Robert Smith
1967 Norton Atlas
Claimed power: 49hp @6,800rpm
Top speed: 110mph
Engine: 745cc air-cooled OHV parallel twin, 73mm x 89mm bore and stroke, 7.6:1 compression ratio
Weight (dry): 395lb (180kg)
Fuel capacity: 3.2gal (12ltr)
Price then/now: $1,050(est.)/$4,000-$12,000

Not many production motorcycles are notable for the frames they use.

Apart from Norton’s famous double-cradle frame from 1950, I can think of only Lino Tonti’s long-running design for Moto Guzzi and Miguel Angel Galluzzi’s trellis frame for the Ducati Monster as defining each model. (Though Philip Vincent’s Series B, which had no frame at all, certainly warrants a mention!) But perhaps only the Featherbed has achieved legendary status.

The Featherbed

It’s a well-known story, but it bears repeating. During World War II, Cromie McCandless and his brother Rex owned an engineering company in Belfast, Northern Ireland. Rex was also one of the best known and most successful motorcycle racers in Ireland, but was dissatisfied with the lack of suspension in the rigid-rear frames fitted to most motorcycles at the time. Thinking that motorcycle frame design had been left behind by the increases in engine power, McCandless designed a rear subframe that incorporated a swingarm and spring/damper units from a Citroen car. He fitted it to his race bike, and it worked. Before long, competitors started inquiring about his rear frame. After partnering with fellow racer Artie Bell, McCandless began offering conversion kits and modifying frames for other riders.

In the early postwar years, reports of the McCandless conversion and its racing successes reached the mainland, eventually attracting the attention of Norton’s managing director, Bill Mansell. Working under contract to Norton, McCandless was able to devote his time to developing a new frame for the Norton Manx to replace the unstable and crack-prone “Garden Gate” plunger frame. What McCandless came up with was an elegant dual-cradle, steel tube frame in which two continuous loops encircled the engine with ample triangulation at the head stock. It was light, rigid and strong, and with McCandless’ rear suspension and Norton’s own Roadholder fork fitted, it provided outstanding handling.

Successful testing was carried out at the Montlhery circuit in France and at the Motor Industry Research Association’s test track in England. It was at the Silverstone track in 1950 that works racer Harold Daniell made the now famous comment that the new McCandless Manx was like riding on a “feather-bed.” The name stuck. 

The racing Featherbed frames were rather special, being made up from Reynolds 531 high-tensile tubing that was SIF-bronze welded. When the Featherbed was introduced on production machines it was made from mild steel, with the rear section bolted in place. But the Featherbed frame endured for close to 20 years on numerous Norton models with only two major changes: from the “wideline” design, which used straight tubes for the top frame rails, to the “slimline,” in which the top tubes were necked in at the front of the seat for a more comfortable ride; and from the bolted-on rear section to a fully welded frame.

11/9/2017 4:19:34 AM

Look forward to seeing it in person in 2018. But just a tip, the vibration only has a little to do with higher compression. The real culprit is Nortons bottom ends. They ALL suffer from bad rocking couple, as well as rather loose manufacturing standards. I have found stock cranks that had slightly different strokes by up to 40 thou Left to right, as well as bikes with loose flywheel fasteners. pistons differing by several grams in extreme cases also check the pins for weight! All contribute to vibs.. So the real fix is DYNAMIC BALANCING. Not a static balance by DYNAMIC. Will transform ANY Norton and I have built a lot of them. A good balancing guy can fix the rocking couple issue as well as put the inherent design vibes you cant get rid of into a RPM range you dont use. Simple! Dont forget to ALSO balance the alternator rotor. Its surprisingly how much they are out and thats a LOT of weight flopping around on the end of the crank.

bike on highway

Classic Motorcycle Touring and Events.

The latest classic motorcycle events and tours.