Perhaps the premier sporting single in the world, the o.h.v. Norton remains practically unchanged, though an exact T.T. replica is now obtainable, with the special lubrication and large tank. Other interesting models on this stand are the 4-speed 490 c.c. o.h.v. machine and an extremely massive and sturdy outfit embodying the 588 c.c. o.h.v. engine and 4-speed gear in the " big 4 " frame. Published in Motor Sport Magazine
The Norton T.T. machines look very formidable with their enormous saddle tanks, 8 in. brakes, and prominent steering dampers. The oil tank, too, is of very large capacity, and a small auxiliary tank feeds oil on to the chains. A special form of dry sump lubrication is used, their being no adjustment of the mechanical pump itself, though the " dryness " of the sump can be varied. Apart from these modifications the machines are practically standard, the equipment including Terry saddle, Webb forks and B. & B. carburetter.
The Norton team is very strong, as it includes A. Bennett, S. Woods (two previous winners), and J. Craig, one of the premier Irish road racers.
Excerpt from Reports on sports machines of 1926
Two 3 1/2-h.p. o.h.v. Nortons were put through their paces, one a 1925 O'Donovan racing job with Druid forks, the other a 1926 model with Webb forks. Summed-up the Druids gave heavy steering and great sense of security, the Webbs light steering, not quite the same feeling of security, but a more pleasant action for turning in a road or on sharp corners, albeit without the rock-steady, self-centring action of the Druids. As to the bicycle itself, the frame tended to be to whippy when cornering, well over, at 50 and taking a hump-bridge too fast gave rise to a slight steering wobble.
The 1925 job did approximately 80 m.p.h., the newer Norton just over 70. The latter had slightly lower and wider ratios and had better standing-start acceleration. Both machines were completely vibrationless and had bags of reserve-power. The older one had a noisy gearbox, but, curiously, the quieter valve gear. The 1925 gear-change possessed the snag of tending to stick in bottom, this being in the centre of the quadrant and calling for a voyage through it when changing from second to top. The 1926 box was free from this bother, but tended to stick in second gear. The brakes were not too good, inasmuch as adjustment became necessary during a short test, the pedal brakes being very powerful but fierce. The front brake had insufficient leverage of the handlebar lever to be effective. When out of adjustment the pedal fouled the exhaust pipe. Comfort, troublefree lubrication by the Best and Lloyd mechanical pump and cleanliness were of a high order. Motor Sport Magazine (1949 article)
The 3 1/2 h.p. O.H.V. Norton. By "THE RABBIT."
THESE notes are the results of brief but enjoyable experiences on two separate machines of this type. Although of similar type the two machines in question have a very different history ; the one is a sparkling 1926 model, delicately nursed, and as yet scarcely emerged from its teething stage, while the other was a 1925 veteran with a lurid past, composed of a year on the road, races at Brooklands, and it is whispered, of even a furtive and highly illegal road race. For the loan of this machine we are indebted to O'Donovan Motors, Ltd., of Gt. Portland Street, W.
Apart from the difference in age the two machines were similar in most respects, except that the 1925 model was fitted with Druid forks and B. & D. stabilisers, whereas the other had the latest Webb forks, incorporating its own shock absorber. There has been great controversy with regard to the rival merits of different fork designs, so perhaps a few remarks on these two types may be of interest. In the first place, the writer is not one of those hardy souls who can cheerfully " flatten " a strange machine over a bumpy road and round acute bends in order to test its steering qualities ; he is essentially a timid person and this should be remembered if he makes any remark that might imply that the steering of a machine leaves anything to be desired.
But "revenons a nos Nortons," our chief impression was of heavy steering with the Druid forks, particularly at moderate speeds, and the comparatively light steering with the Webb forks ; as one would expect, a greater sense of security results with the Druid forks at high speeds, it being quite possible to ride "hands off" at 75 m.p.h. with the steering damper slightly screwed down. The writer is quite willing to believe that this can be done with the Webb forks, but somehow he did not feel inclined to try the experiment.
On the other hand, for sharp corners, for turning in a road, and for negotiating twisty lanes, the Webb forks feel much pleasanter, though lacking that rocksteady, self-centreing feeling at high speeds, inspired by the Druid.
However, the results of races on road and track in the past show that there is nothing seriously wrong with the steering of the Norton, although occasionally it succeeds in " throwing " quite famous riders. The only unsteadiness experienced by the writer (a comparative "rabbit," as explained above) was once when, owing to the high gear and deceptive speed of the Norton, he inadvertently took a hump back bridge at about 10 m.p.h.. above his normal speed for this bridge, and once when negotiating a bend at about 50 m.p.h. with the inside footrests not very far off the road; on the first occasion a slight wobble resulted and on the latter a curious whipping sensation seemed to be felt as if the two wheels were only connected by a laminated spring and were free to move in a lateral direction; this would seem to indicate the desirability of stiffening the frame, which point, it is understood, is receiving the attention of the manufacturers.
As regards performance on the road, both machines, as one would expect from thoroughbreds, left little to be desired ; the older machine was capable of approximately 80 m.p.h. and the newer machine of something just over 70 m.p.h., this lower figure being, no doubt, due to the fact that the machine was still comparatively new and untuned. The 1926 model, however, by virtue of slightly lower and wider gear ratios, was faster in accelerating from a standing start, but both machines displayed a reassuring reserve of power, a whiff of throttle being ample for any main road hill, even when approached slowly on top gear. Engine vibration was noticeable only for its absence on both machines at all speeds, and enough, although the overhead rocker gear on the machine was considerably worn, this machine was decidedly the more mechanically silent of the two.
The same cannot be said of the 1925 gear box, which on the machine tested wonderful tram-like noises on the indirect ratios, gear being the chief offender in this respect ; slight criticism of this gear box is that it is necessary to pass through bottom gear when changing from second to top, an excellent arrangement for speed work, but unless a very decisive kick is given to the lever it is inclined to stick in the bottom gear notch, which of course is in the middle of the quadrant, with rather disturbing results if one happens to be travelling at anything above 40 m.p.h. ! On the more normal type of gear box fitted to the 1926 model this cannot occur, though occasionally second gear can be missed unless care is used. The Norton back brakes both appear to be very powerful, but on the fierce side, and both needed rather more adjustment than should have been necessary during the short period of our test ; if this adjustment is neglected the brake pedal " bottoms " on the exhaust pipe without appreciably retarding the progress of the machine ! The handlebar control for the front brake does not seem to possess sufficient leverage to permit of powerful application, though the design and size of the brake itself are well up to modern requirements ; now that riders are beginning to realise the utility of good front brakes the question of better operating gear should be considered by designers.
The Best and Lloyd mechanical oil pump, fitted to all o.h.v. Nortons as standard, worked with unfailing reliability and was observed and then forgotten throughout our test. Comfort being merely a matter of a good saddle and correct adjustment of handlebars and footrests the writer will not discuss it, except to say that both Nortons possessed all the points necessary to secure the maximum comfort. The machines were both reasonably clean to ride, the engines retained their lubricating oil well and the sports mudguards were considerably more effective than they looked, though it must be admitted that the weather during our test did not give them very much chance to prove their worth.
In conclusion, the writer would like to explain that in view of the world-wide fame that the o.h.v. Norton has attained in every branch of the sport, he has purposely refrained from saying much about performance, but has rather tried to draw attention to the secondary and less obvious features of the machine ; which after all are of more interest to the prospective owner than a reiteration of already well-known racing successes and constant eulogies of the tremendous speed and power of the machine. Anyone more interested in the latter points should refer to the results of road and track races and the list of world's records, in which sphere he will find that the Norton is indeed "unapproachable."
Prospective purchasers of Nortons who desire to achieve fame in the racing world would do well to communicate with O'Donovan Motors, as this firm numbers among its staff such well-known speedmen. as D. R. O'Donovan, A. Denly and L. P. Driscoll, who specialise in the preparation of Norton machines for competition work.
N.B. It will be noted that Webb forks are mentioned repeatedly.