The Norton CS1
By Rick McDowell
“At low speeds one can liken its performance to that of a steam engine, so sweetly does it gain revs …. it can be driven like a lamb in traffic or like a lion on the open road ….”
Yes, that’s right, another example of a road tester getting carried away with the job, but, as the reference to a steam engine should indicate, these aren’t the words of a modern day test rider on some fuel-injected, plastic-encased, space shuttle.
Rather, the reporter from once famed British motorcycle paper, Motor Cycling, was talking about the new production version of Norton’s first overhead-cam machine which went straight from the workshop to victory in the Isle Of Man Senior TT of 1927.
The CS1, as the production bike was named, is something of a landmark in the history of motorcycling and you certainly won’t find too many examples of the very first model CS1 like this beautifully restored (and admittedly slightly modified) unit that belonged to Ross Lowe in Western Australia when we first featured the bike on MCNews.com.au at the turn of century. Email us if you know where this bike is now?
Ross had his work cut out restoring the bike, which, with its positive-stop gearbox, larger fuel tank and close ratio gearbox, appears to have been imported into Australia as a pure racer. The standard production model CS1 only had a three-speed box and no positive stop mechanism, plus the fuel tank was much flatter than on Ross’ version.
This particular 1929 model CS1 could well be the only example of its type in Australia, because within three years of this first version being released in 1928, the model was completely re-vamped after its designer defected from the Norton camp.
In fact, the whole story surrounding the CS1 is a melting pot of intrigue and scandal, making for a truly great yarn that can match any of today’s soapies.
The death of James Lansdowne Norton (the founder of Norton) in 1925 was a sad event in more ways than one. ‘Pa’ Norton as he had become known suffered from bowel cancer in his later life, yet it didn’t prevent him from being involved first hand with his bikes and those who rode them.
Always present at meetings and not afraid to get his hands dirty either, Norton was well known and even loved in two wheel circles.
The treatment of his family by the Board of Norton Motors at the time of his death is therefore hard to understand. Lansdowne, Norton’s eldest son, was sacked from his drawing office position shortly after his fathers death and the family as a whole vowed never to talk of the matter.
Walter Mansell took over as the head of Norton Motors when Pa Norton died, yet it was the passenger in the Norton sidecar outfit that won the 1924 Sidecar TT who is probably more important to our story.
Walter Moore was a well known trouble shooter of the day and was contacted directly by Mansell. After some negotiation, Moore became Team Manager for the works racing squad, but Mansell also gave him special responsibilities on the technical – or R & D – side.
A submerged pump driven by worm gears off the crank was one of the first items Moore designed in his new position and it featured on the 490cc, OHV model 18 ‘Works’ Nortons at the 1925 Isle Of Man TT.
During the winter of 1926 / 1927, Moore set about designing a brand new Norton engine that would feature not only overhead-valves, but overhead-cams as well. At the time, many manufacturers (including Norton), were still building side-valve engines, but there was a growing trend towards overhead-valves and placing the cams above the head was starting to attract interest too.
Moore’s new design was to an extent based on the company’s top of the range Model 18 machine and accordingly retained Norton’s traditional 79 mm x 100 mm engine dimensions to produce 490 cc.
However, instead of pushrods on the timing side of the engine, Moore employed two pairs of bevel gears and a shaft to create a direct drive to the overhead-cams which were on a single camshaft.
The upper, non-camshaft bevel carried the weight of the drive-shaft, while the separate cams actuated two-piece rockers that extended out of the cam-box to work the semi-exposed valves.
Tappet adjustment was performed by the screw-and-locknut method and the exhaust port was off-set slightly so as to provide an easier route for the header pipe. Perhaps even more interesting from a technical point of view, was that a 2 : 1 reduction ratio operated between the upper and lower bevel pairings, meaning that the shaft between them ran at a considerably lower speed than the engine.
The lower bevel arrangement saw the bottom of Moore’s shaft splined into a bevel gear which ran in a ball race. This lower bevel gear was naturally driven by another off the crankshaft and the whole arrangement was placed in a housing bolted to the crankcase.
On its debut at the 1927 Isle Of Man TT, the overhead-cam engine also carried Moore’s new oil pump in a separate housing underneath the lower bevel arrangement.
When the CS 1 production version was released though, the two housings and their contents had become one unit. Moore’s pump is a double-diameter rotating plunger type that is driven by a worm directly off the crank. Oil is sucked in to do its thing in the crankcase, which is supposed to have a dry-sump but which can in fact have a wet sump effect thanks to a knurled oil flow adjuster on the inlet line.
Oil is also pumped up to the cam box from where it returns to the crankcase by flowing down the hollow bevel shaft housing and lubricating the bevel gears in the process. A return oil line then feeds the lubricant back to the oil tank before another round.
However, as with many 1920s designs, the valves are left unlubricated. When you look at the photographs, it’s not hard to see that Norton’s first overhead cam engine was quickly dubbed the ‘Cricket Bat’, although it’s not hard to believe that it was also called ‘The Clanker” ! The new engine performed with distinction in its first outing, winning the 1927 Senior TT beneath a Canadian-Irishman called Alec Bennett.
However, it wasn’t as straight a victory as it sounds and there’s even some debate as to whether the ’27 TT was in fact the Cammy Norton’s first outing. So, it’s here that we’ll introduce one of the all time legendary figures of motorcycle sport to our story, the late and very great Stanley Woods.
Dubliner Woods had been a travelling salesman who raced on the weekends and who’d had some success in the early 20s at The Island. His results combined with the right people getting together at the right time saw Woods drafted into the Norton fold for the 1926 Senior race.
On a Model 18, Woods was the victor and he soon began working as a salesman for the company. In early 1927, Moore organised a transfer for Woods into the R & D department to help with the new overhead-cam engine. Whilst the duo initially got on well together, Woods didn’t think that Moore put a great deal of thought into the design of the new engine and although praising it for being reasonably reliable at the time, indicated that it never finished a race with the full compliment of teeth on the bevel gears!.
Woods’ opinions came through in a variety of interviews he gave more than half a century after the first overhead-cam Norton was built. Woods was known for his sharpness and vitality in later life, making his comments more than credible.
It’s therefore interesting to note too, that while Walter Moore in later life claimed to have rushed the first overhead-cam engines straight from the workshop to the TT, Woods said that he rode one of the machines at a meeting in Germany well before the 1927 Isle Of Man TT.
Woods remembered the event because the con-rod broke and he had to rush the engine back to Moore.
But the intrigue doesn’t end there, as it appears there was some form of inter team rivalry between Woods and Bennett at the TT that year. Whilst Bennett won the senior race, Woods actually set a new lap record of 70.9 mph on the fourth of six laps. His time was 31-minutes, 54-seconds and it was the first under 32-minute lap anyone had ever done on the circuit.
Woods took a re-fuelling stop between the fourth and fifth lap and although he was told by his crew that he was in the lead, nobody mentioned that he was out in front by a huge four-minutes! Unaware of his massive lead, Woods maintained a cracking pace – until the clutch on his works overhead-cam Norton expired at the end of lap five.
Afterwards, Stanley Woods blamed Walter Moore and to a degree Alec Bennett for the clutch failure. Apparently, on the evening before the race, Bennett and Woods had a passing conversation in which the former indicated that he’d beat Woods come the race. Woods just shrugged the comments off, but after his let down he learnt that Walter Moore knew about some weakness with the clutch and after practice for the big event had advised Bennett to install a new unit. Nonetheless, Woods did go on to score race wins for the new Norton at the 1927 Dutch, Belgian and Swiss Grands Prix.
Racing politics aside, the buying public were in September of 1927 given the news that a replica of Bennett’s Isle Of Man TT winning machine would be available as part of the 1928 model line-up.
Not only would the CS 1 machine feature the all new overhead-cam engine, but a new cradle frame which had also featured on the TT winning race bike. This cradle frame was also used with Norton’s 490 cc overhead-valve engine for the first time at the 1927 Isle Of Man TT races and the production version of this set up, dubbed the ES 2, went alongside the CS 1 as Norton’s top of the range duo in 1928.
Essentially, the new frame was simply an update of the single down-tube, single spine-tube and single seat-pillar-tube frame being used across the board by Norton at the time. As can be seen from the photographs, the new frame was called a cradle simply because it had a member that ran underneath the crankcase.
To be fair and considering the period, the new frame was a vast improvement, because with extra struts in its rigid rear end and with a good deal of webbing around the head stem, it did offer a huge improvement to stability under riding conditions.
The improved handling on the CS 1 can also be attributed to the Webb front forks which only a few years previously had started to be used by Norton. Other up-dates over previous Nortons included a new position behind the cylinder for the magneto (previously in front of the crankcase), a rounded oil tank under the seat and a new ‘saddle’ fuel tank.
A three-speed Sturmey Archer gearbox was fitted to the CS 1, with the long change lever laid flat so that it could be operated by foot. Hand operated gear levers were common on motorcycles at this time and a foot-shifter quite unusual.
Despite the handling and engine improvements however, the CS 1 didn’t have much in the way of stopping power, although, incredibly, the front drum brake carried by the new Norton was only starting to overtake the stirrup bicycle brake that had stayed with the motorcycle since its invention at the end of the previous century.
Not surprisingly, Ross Lowe doesn’t like to get into heavy traffic situations when he rides around Perth, preferring instead to take the bike out on Vintage club runs. Not that this necessarily means sedate Sunday rides, because make no mistake about it, this CS 1 flies. Stanley Woods managed the equivalent of 110 kph back in 1927 and as Ross kindly demonstrated after the photo shoot, his CS 1 is capable of the same, if not more.