Friday, October 31, 2008

Velocette data from a variety of sources....

Over the years I've collected lots of Velocette data, some from the usual sources such as Bob Burgess's red book on Velocette ( more on this in a later book review blog ), others from proprietary suppliers catalogues, lots of which I photocopied and pasted onto cardboard pages, making up a folder and from there I further photocopied into files to share with others... so I'm going to run a series from them, not in any particular order and this next lot are from The UK Velocette Owner's Club magazine "Fishtail", a sheet supplied in the past by Ivan Rhodes, Veloce Ltd and Alpha Bearings Ltd, Dudley, West Midlands, UK, "MotorCycling".........

Credit for their use is acknowledged to all of them.

Left Click on images to enlarge...

Saturday, October 25, 2008

Velocette's 24 HOURS AT 100.05mph.........

Velocette have had several goes at world records...the first being 100 miles in the hour on a 350cc, titled "The Century Velocette" around 1930...then "a long time between drinks" as the saying goes in 1961 they mounted an attack on the worlds 24 hour record for motorcycles and for a week or so, until a BMW 600cc attempt came along, they held the absolute world record for 24 hours at 100.05mph.
Following the BMW attempt and subsequent others, Velocette held and still hold the record for 500cc motorcycles at the mentioned 100.05mph.
During 1963 they attempted the 24 hour record again with a Velocette 349cc Viper, but suffered defeat by mechanical problems and never tried again.
February 1971 saw Velocette fade from the motorcycle scene into insolvency and oblivion, but not forgotten by a long shot ......

The managing director of Veloce Ltd, Bertie Goodman and "MotorCycling" journalist Bruce Main-Smith headed a team of French riders for the successful attempt and his report in "MotorCycling" follows.
John Griffith, fellow journalist on "MotorCycling" produced a three book series by Temple Press, then owners of "MotorCycling"..."Built For Speed" (1962)...."Famous Racing Motorcycles" (1961) and "Historic Racing Motorcycles" (1963).
I'll feature these in a future blog.
In "Built For Speed" he featured the "24hr Record Velocette 500cc" and his article also follows.

I've included illustrations from these publications below and acknowledge copyright and thanks to Mortons Motorcycle Media UK, current owners of "The Motor Cycle" and "MotorCycling".

Reprinted from " Motor Cycling"- March 23. 1961
OUR 24 HOURS AT 100,05
Bruce Main-Smith on the main straight.....

WELL, we did it! World's Records at both 12 and 24 hour levels have been broken-by driving a virtually " stock Venom” at full bore. Absolutely against the stop, for all those arduous hours, both by day and by night at Montlhéry, near Paris last week-end. For a push-rod " 500 " on a mere 8.75 : 1 c.r. to scuttle round in flying laps of the 110 m.p.h. order, on perhaps the worst track anywhere, is something of which not only Veloce must be very proud but the entire British industry.
The 24-hr. record has not only been wrested from a foreign machine-and by nearly four mph but it has been hoisted to over the 100 m.p.h. mark. If only you could know the appalling condition of the track and the organizational handicaps over which the Velocette triumphed you would realize just what this record means.
As a participating rider, I can report that the machine had to do more than stand continuous full-bore-it had to go quickly enough to make good deficiencies arising front insufficient preparation not attributable, I am glad to say, to anyone hailing from this side of the Channel.
Veloce spent months carefully proving an almost standard “Venom". As any private owner could do, they took it from stock as a normal “Venom Vee-line Clubman," tuned to give both torque and power rising to peak at 5,800 to 5,900 rpm. Using the 1 3/16”in. Amal G.P. as rich as possible, it developed 39.8 bhp. On its 3.92:1 top gear it was able to lap at 110 to 112 mph. which it held for all of every lap-no throttling back anywhere for anything other than pit stopping. A good lap is done in 52 sec. and a poor one in 54½/55.
Now a word about the circuit de vitesse de Montlhéry. It is a bowl-shaped, concrete-banked slice of medieval punishment. It has two minute straights, and two torture-inflicting pieces of bump infested purgatory described as high-speed banking,. On this anti-clockwise course is painted a yellow median line which is the official distance. One must not go below this according to the regulations.
In fact, at 110 mph the line is about the lowest point of the banking at which to ride and during the actual attempt most pilots were about a yard-and-a-half higher to avoid the bumpier track lower down. One is then too high and stays up by leaning over to the right (relative to the banking), which unfortunately hastens tyre wear.

Bertie Goodman flat out on the back straight.......
The bankings are concrete, cast in 25-yd. sections. Between some of them it is possible to insert one's clenched fist, often the flat of the hand, and regularly to we see daylight through the gap from the yellow line to the top. The two straights are flat and hardly worthy of the name.
There is a rapid change of contour from banking to straight.
I had under 10 practice laps, of which half were done at night by the standard illumination of 50 car headlamps provided by Marchal ;
the " Venom's " electrics were dispensed with.
This was totally insufficient for an utter stranger to Montlhéry. It was a thoroughly chastened B.M.-S. who came in from his last permitted practice period and I was seriously doubtful of my ability to do more than 10 laps at a stretch, let alone an hour's worth (60 laps). Back at my hotel I stripped off in front of a mirror to study the extensive bruising on the rib cage.
On the strength of the few laps on the second session (in the dark). the riders were selected. the faster ones to be used. They were Pierre Cherrier. Alain Dagan, Bertie Goodman, André Jacquier-Bret, Robert Leconte, Bruce Main-Smith, 55-year-old Georges Monneret and Pierre Monneret.
Pierre Monerett pushs off for a night stint.......
For weeks beforehand it had been insisted that March 18-19 would be excellent weather. Therefore it was not necessary to make use of the perfect days immediately preceding. At 7.30 a.m. it was raining. By 8.27 the attempt was set in motion by Georges Monneret who was supervising matters for the French end.
Georges dashes round in the 51-52 second bracket. His son Pierre takes over and is even quicker. I walk round to the back half of the course invisible to the control tower (a wood intervenes) and study la ligne de Pierre. Riders meanwhile change over every hour and the speed remains well above 105 m.p.h. To run for longer intervals would not be possible anyway with a touring tank of 3.7 gallons capacity.
Dunlop’s Dennis Durbridge wields his depth gauge during pit stops and estimates tyre consumption at two front and four rear, and notes that wear was related to riders. The rear was actually changed at six hours in three minutes. a tribute to the Velocette q.d. wheel system.
At 5.30 Georges is in the saddle again and has some trouble starting. Carelessness in filling the tank from the two polythene buckets of Esso has left a pool under the machine through which the machine’s driving wheel rolls. Consequently, the rear wheel skids.
After dark Alain Dagan takes over and Circulates in 52.8 sec at 107.8 m.p.h. When Pierre Monneret pulls in at the end of his stint, in which the 12-hr. record has fallen, both tyres and the rear chain are changed and I am kitted up to be dispatched. On attempting to select bottom cog for the bump start it is realized that the internal gear mechanism has been bent by some rider stamping on the pedal.
Jack Passant has the trouble rectified and the total deficit is 33 min., all of which I have spent outside in the dark to help the eyes. I hop in the saddle, shout Allez. Allez, the feet of the pushers patter, the motor catches first drop of the clutch and I feed it in doing a cautious entry on to the dark circuit. To save the clutch I drive through the megaphonitis to get onto the trumpet and,
although I cannot see the rev-counter in the track lighting, I know the power comes in at 4,500.
I take it very easily through the gears and hope that the gearbox trouble is nothing very serious and that the box doesn't lock up. As I come down the home straight I am on full song in top and
the motor is running superbly, not a tingle of vibration and giving an impression of utter indestructibility. Frankly, at 110 mph up on the bumpy banking, in the dark on a strange bike and track I am genuinely frightened. The lights at the pits come round amazingly soon on each lap, but the punishment from the bumps is awful. My nose and mouth run on to the chin pad on to which I press my head to keep it behind the screen, through which I look for the entire lap. Through the perspex I can just see the yellow line. I cannot use either the main footrests or the pillion ones properly, but pull a muscle in my right thigh when I try the latter. I try to relax the arms
completely, as Pierre advised me, but find this difficult to do, though I know it is quite safe, for the Velo is steering over the atrocious surface in the way this marque always does, taut, waggle-free, 100% safe. But I have to hold on to the bars for how else to keep on?
The pits signal that my speed is good, but I wonder how long I can stick it. I get to know exactly which bumps will cause the front forks to deflect fully and where these " friends" will be.
Anticipating them with the certainty of their presence I find to be bad and try to forget.
It seems an eternity. I watch a bright star gradually sink below the north-west banking and reason that some slice of time must have elapsed. But how much? The noise from the mega. chases me
round the track like a wild beast. I decide to pack it in. No, keep the British flag flying-show the French that we too can do it. . . . I manage three laps on the patriotism theme. Next I try the Duty to the Readers one. Also good for several laps. Then I’m paid to do this (So help me!)---result, more laps. Then argue with myself about whether I use opposite lock to lift up from the banking. By now (though I do not know, of course) some 45 min. have elapsed. The next problem is the sameness of the course at all points. The rhythm of one's fast, regular, monotonous progress. I realize I am getting hypnotized by the pattern of what I see. I look at the Velocette, the fairing, the red lanterns, the illuminated score- board and the stars,. always coming back speedily to the yellow line 3 ft. to my left under the spinning front wheel.
After 52 m.-some 60 laps that is-I know it would sabotage the attempt if I continued. I come in, remembering the advice to shut off very early because of the misjudgement that results from the monotony of set high speeds. Somebody helps me off the bike as I shout un autre pilot. An English voice says "Good show!” - Mentally I thank him for his kindness. but know that 60 laps is not a full stint and feel that I have let the side down.
Another Frenchman goes out and is pulled in after several laps as not being quick enough. André Jacquier-Bret lasts for 35 laps and retires with eye trouble. Pierre Monneret does a full stint at
172 k.p.h., the scoreboard says. Cherrier tries his hand and after a few 170kph laps gets off the trumpet in a low gear and crawls. He ignores pit signals and after three laps comes in talking of
fog on the course-eyes once more. Georges Monneret fits a stint about here while I cat-nap and he too packs in after half an hour with blurred vision-but he's fast. Robert Leconte, a little slow
it is true. stays on for a long while. At 5.30 a.m. I go on again. Just my luck to get the time of
lowest ebb of one's vitality. I last 30 laps but seek consolation .. in seeing 173, 174 and even 175 k.p.h. on the scoreboard and being officially credited with the fastest night-time lap of 52.4 sec. Bertie Goodman, who has not ridden at Montlhéry before in the dark, sets a formidable full stint of 54-sec. 170-k.p.h. laps. Alain Dagan does yet another hour of rapid, consistent laps.
The piston at strip down, following the succesful attempt.
After the dawn I offer to go out again-less frightened now, know the track a bit better and some blimps like old friends. Bertie puts in another hour. Then Monneret Snr. again, to beat the mileage of the old record by 8 o'clock. Another 10 minutes and he is stopping with cold hands. Dagan staunchly jumps off and finishes the remaining time.
I watch the official measurement. The engine comes down in perfect shape. I feel damned tired. I make for my hotel and the largest, softest bed they have to offer.


12-hour: 2,021.181 km., 168.431 k.p.h., 104.66 mph

24-hour: 3,864.223 km., 161.009 k.p.h., 100.05 mph
(Subject to official confirmation.)
From "Built for Speed"...
First Machine in the World to Average the Ton for a Day
Reprinted from “Motor Cycling” March 30, 1961
By the time you read these words, the “world's fastest” 24-hour title may well have changed hands again. But if it changes hands a hundred times in as many days the name Velocette will stand out from all the rest, for to this English factory goes the credit of producing the machine that first exceeded 100 m.p.h. for a day - on March 18/19 at Montlhéry track in France.
Last week we carried "Motor Cycling" staffman Bruce Main-Smith's story of his gruelling ride as a member of the record-breaking Anglo-French team. Now we can tell, literally, the inside story of the machine.
And that machine is amazingly close to standard specification-in fact, I would go so far as to say that there are hundreds of " Venom " riders in this country who could have converted (if that is the right word) their stock machines to put up just the same performance.
Let's get it straight. Unless otherwise stated, everything mentioned in this article is STANDARD, either as original equipment or as an optional extra.
Basically, the machine is the equivalent of the production " Venom Clubman Vee-line " model. I say "the equivalent" because the record-breaker was built last June, before the announcement of the production job. and was ready by August, having completed some 1,400 miles at over "the ton" in Practice runs.
The fairing fitted then, specially produced by the Amesbury factory of Mitchenall Bros., was-and still is-the prototype used for the "Clubman Vee-line" models. Why didn't the factory fit a production version for the record attempt? The first maxim of successful record-breaking is to limit changes to a minimum.
The same reasoning applied to the retention of the old-type tank. Both these items had been proved to the hilt and half a yard beyond, and to have carried out similar tests (far more rigorous than those needed for the equipment of normal machines) would only have caused unnecessary delay.
The engine was very carefully assembled and bench developed last June. It had not been stripped-not even the head had been removed until the record was in the bag. Then, of course, it had to be dismantled for measuring. That meant 1,400 miles of testing and 2,400 miles of' record, all at over the "100" mark, without “opening up".
The motor is, of course, on now “traditional” Velocette single-cylinder lines with a gear-driven high-camshaft and short-and so light push-rods; an extension of the gear train drives the magneto, just astern of the barrel. This design, incidentally, was introduced (as a “250") almost 30 years ago.
The crankshaft assembly runs on Timken taper roller main bearings; it has an Alpha big-end with 18 caged 3/16” x 9/16” rollers.
A Nimonic 80 exhaust valve and EN52 Silchrome inlet valve are controlled by hairpin springs. Valve timing is: inlet opens 55° before TDC; closes 65° after BDC; exhaust opens 75° before BDC; closes 45° after TDC-all checked with .030”. tappet clearance. Running clearances used were: inlet .008”, exhaust .010 “. (just for safety).
Manually controlled ignition is provided by a B.T.H. magneto and, for the record attempt, a non-standard Marchal plug (arranged by the French members of the équipe), was timed at 38° before TDC on full advance.
The Amal G.P. carburetter, of 13/16” bore, has a 310 size main jet-which was too rich, but gave an ample safety margin, even at night. A ¾” packing piece, non standard, was fitted between the cylinder head and carburetter, as it was found to be beneficial when bench tests were carried out. The 1¾” bore exhaust pipe is 34” long and terminates in a KTT pattern megaphone, 12”. long and with a 41” outlet.
Close-ratio gears are used (identical incidentally, with those employed on the last of the factory KTT racers) and sprocket sizes, front to rear, are 23T. 44T, 22T., 46T,. which give a top gear ratio of precisely 4:1. (Even 1 can do this one: gear ratio is product of driven sprockets' toothery divided by product of driving sprockets' ditto 44x46/23x23 =2 x 2).
Dunlop racing tyres were used for the record attempt; actually, Dunlop provided some "special" tyres for early tests but these were found to be unnecessary. Brake lining material is Ferodo MR41, a racing material used on all big Velos, and the wheels had alloy racing rims. Only change to the frame was the addition of a centre stand, to help with quick wheel changes; even the sidecar lugs were left on!
As the model had no electrics (non-standard), the top fork covers, which have integral headlamp brackets, were dispensed and rubber gaiters from a Scrambler were fitted. The clip-on bars are non- standard, as are a set of pillion footrests fitted for an alternative riding position.
Non-standard also are the rubber-mounted of the oil tank and the float chamber carried front of it ; non-standard is the open primary chain with two-pipe oiler from the engine's oil tank, and rubber-mounted guard which replaces the standard chaincase.
The rear chainguard is retained and the chain is lubricated by the oil-tank breather.
The record machine ran on 94-octane fuel supplied by Esso and multi-grade (S.A.E. 20/40) engine oil. The oil tank was topped up at 4- or 5-hour intervals only to make good the drip to the chain; the oil wasn't changed. S.A.E. 50 lubricant was used in the gearbox.
I asked why 100 octane fuel was not used.
Answer: it's not available in France.
Fuel consumption at a maintained 107 m.p.h. was 35-36 m.p.g. (13½ litres per hour) and maximum speed on the chosen gearing was a shade under 115 m.p.h.
If you want to see the machine, it's on show this week at the Pinks of Harrow showrooms (It was at Stevens of Shepherd's Bush last week-end). It is not far sale. . . .
Printed In England by Temple Press Limited. Bowling Green Lane, London. E.C.I. 7816---61
Engine: Single-cylinder OHV; light alloy head ; 86 mm. bore x 86 mm. stroke= 499 c.c.; c.r. 8.75:1 : 39.8 BHP at 5,900 rpm.
Transmission : Velocette gearbox with close ratios; 4:1 top.
Fuel : 3.7 gal. steel tank.
Oil : 4.5-pint steel tank.
Wheels: Light-alloy rims with Dunlop rating tyres, 3.00”x 19” front, 3.50” X 19” F rear.
Wheelbase : 53.75”
Rear Suspension : Girling hydraulically damped spring units.
Left click on images to enlarge.

Tuesday, October 21, 2008

The BMG Desmodromic valve operating kit for the 86x86 Velocette engines….

BMG motorcycles were a motorcycle dealer in Ilford, Essex, on the outskirts of London.
When I lived in the UK in the early 1970s, I occasionally rode over to there and purchased the odd part.
I never really became interested in the desmodromic valve set-up they marketed until I returned to Australia and wrote to BMG.
I’d read a little of the information over their kit and recalled seeing a Venom Clubman at the Southern Cross motorcycle rally at Burrumbeet Park, Ballarat in Victoria, Australia in February 1966 with one fitted.
The reply from Mr. Woods of BMG, which I still have, was quite scathing of Veloce Ltd and their lack of interest in his kit, following his sending one to them for evaluation. He claimed it was dusty when returned and obviously hadn’t been used.
A disappointment to him.
But the claims made by BMG really stretched ones imagination…9000rpm
…acceleration such that you could lift the front wheel in top gear at 60mph…
BMG actually patented the principle of using push-pull rods to actuate the valves in an engine in a desmodromic fashion…that is, without valve springs. The patent application is illustrated here.
But the BMG kit did have torsion bars fitted inside the hollow centre of the upper rockers, claimed to finally close the valves to get a gas seal for starting.

The kit was suitable for use only in the 86mm x 86mm Venom and MSS or 72mm x 86mm Viper engines.
The UK motorcycle magazine, “MotorCycling” did a test of a Velocette Viper in September 1963 and journalist Bruce Main Smith who rode it for over a week around Britain wrote it was the tool for the rev happy rider.
Acceleration and top speed figures, taken at MIRA, were given, but really couldn’t be compared with anything…the bike was fitted with an after market Butler fairing which contributed to any final speed claimed and as BMS commented, prevented a direct comparison with earlier Velo Viper tests..
The true test would have been to take the bike to MIRA, run it around in normal trim, obtaining figures, then fitting the kit and repeating the test.
The cost of the kit at the time was £46/10/- including fitting by BMG, or £38 in a box. The full price of a Viper in early 1964, including VAT was £262/4/-. ”MotorCycling” tested a Viper in early 1964 and it’s top speed at MIRA was 90.6mph.
The highest one way speed of the desmo Viper at MIRA was 93.9mph, with as mentioned the fairing fitted. The rev-counter reading at this speed was 6200rpm.
Main-Smith commented that the desmo Viper was geared one tooth higher than standard and that he felt with the right gearing 93-95mph would be expected.
In all it seems a bit “iffy”…
You make up your own mind….
The Australian Velocette Owners Club has a kit (damaged) and their technical officer, Norm Trigg, sectioned an engine and fitted the kit so it could be hand operated to see it’s operation.
I took photos at a Velo rally some years back and they illustrate this blog, together with details from the patent application, US “Cycle World” advertisements, drawing from “MotorCycle” and “MotorCycling”, to whose copyright holders, Mortons Motorcycle Media, I make due acknowledgement.
Want to read more on desmodromic vale operation, especially in motorcycles?
Dutch enthusiast Henk Cloosterman has a website, titled “Desmodromology” well worth a visit.

In Australia there were two other major efforts at making a desmo operated motorcycle…
In the early 1950s, Velo racer, Sid Willis converted a KSS cylinder head to desmo operation and fitted it to his KTT racer.
Australian Norton supremo, Harry Hinton had one made by his nephew and it was fitted to an ex works Norton 350 Manx and used in practice at the 1960 NSW TT races, Bathurst, NSW, Australia.

These stories for a later blog…..
Reading- “Testing the BMG Desmo Velocette”, MotorCycling, September 4 1963.
Left click on the images to enlarge.

Saturday, October 18, 2008


The first description of the Velocette adjustable rear suspension system which incorporates several extremely clever features….the article written by Graham Walker and featured in “Motorcycling” August 20 1942.
Reproduced with acknowledgement to Mortons Motorcycle Media, holders of the copyright for "The MotorCycle" and "Motorcycling".

Left click on the images to enlarge, although the quality of some will be suspect, as they were scanned from newspaper.

PATENT specifications can hardly be regarded as light weekend reading, yet sometimes they can prove just as exciting as the most thrilling detective novel. True, like the sorcerer's horoscope, they hint at the shape of things to come in an involved jargon. Warranted to blind with science the poor ignorant layman who can only read English, the strange phraseology employed is presumably designed to provide pitfalls for the wily copyist and an honest crust for the lawyers in the event of a dispute, but the effort needed to strip the wealth of verbiage from the salient facts is well worth while, for every specification is evidence of mankind's ceaseless efforts to improve his lot.
Seen in '39
What is all this leading up to? I will tell you. Some time ago I became involved in an argument anent spring frames and, being obstinate by nature, searched the Patents files to, prove my point. By accident I came across a specification for rear suspension regis­tered in the joint names of Veloce Ltd., and Phillip Irving. There was something reminiscent about the draw­ing attached to the description which puzzled me for a minute or so until the penny dropped-I'd seen a similar coil spring device on F. J. Binder's Velocette in the Island during 1939 T.T. Race week. Enter the detective atmosphere ! Hot on the trail, a little more research brought to light two more patents taken out in the same names and dealing with the same subject.
Obviously, something had to be done about this. A letter to Veloce, Ltd., produced a most courteous invitation to visit the factory and to test the model. Thus it came about that, one dampish day recently, I listened to Phil Irving describing the many good points in the ingenious design and watched him demonstrate the ease with which the springing can be adjusted and if necessary, dismantled.
Patent No. 1 deals with this matter of adjustability, the basic idea being to provide a suspension system
instantaneously adaptable to widely varying loads. As with most good ideas, the method is simple in the extreme. The rear wheel is mounted in a swinging fork. Hinged to each fork end, slightly above and forward of the wheel spindle, is a straightforward telescopic plunger surrounded by a stout coil spring. And now comes the cunning part-the top end of each plunger is mounted on a transverse rod passing through slots formed in the rear frame member and the rod can be, locked by handwheels in a number of positions ranging from the nearly vertical to one where the spring mem­bers are inclined forward considerably.

Variable Resistance
In the upright position the springs exert their greatest resistance to wheel movement; in the forward position the freedom of wheel movement is increased. Intermediate positions, of course, permit of settings between these extremes. The curved slots are so plotted that virtually no variation takes place in the position of the main frame relative to the rear wheel, thus the steering remains unaffected by variations in setting. Incidentally, a later design provides for arcuate slots which make the transverse bar self­locking at the peaks of the curves.
Chain Adjustment
Patent No. 2 is so simple as to make anyone who sees it chuckle-and then go into a quiet corner and kick himself for not thinking of it first! It permits of rear chain adjustment with­out the slightest fear of the rear wheel getting out of line. Method? Simple, my dear Watson! The pivot upon which the rear fork swings is mounted eccentrically on its bolt; thus, partial rotation of the eccentric slides the com­plete fork slightly forward or backward, leaving the wheel spindle location undisturbed.
This eccentric plot has been applied to dynamo chain adjustment for some years and the primary chain adjustment on the Lea-Francis consisted of a circular gearbox with the shell offset in relation to the mainshaft, but it has been left to Messrs. Veloce and Irving to apply such a common-sense adjust­ment to the secondary chain.
Patent No. 3 provided the real eye-opener, being none other than the employment of a stressed-skin rear frame, in which suitably formed sheet metal replaces the tubular construction usually associated with the job of sup­porting the rear wheel and accom­modating road shocks. As the photographs and drawings show, a single sheet of metal, bolted to the tubular centre frame at several points, acts as mudguard and support for the top ends of the spring plungers and base for pillion seat and saddle. The rear half of this member can be arranged to hinge, thus giving access to the rear wheel, whilst toolbox, battery carrier and other " cupboard space " can also be combined in the one pressing.
The Friction Dampers
Another particularly interesting detail consists of the built-in friction damper incorporated in each spring plunger. The male member carries two Ferodo rings standing proud of suitable supporting steel collars which are firmly attached to the plunger. These act as guide bearings. Placed between the collars are two semi­circular pieces of Ferodo, forced out­wards and into contact with the female outer sleeve by a circular clock spring, which exert a predetermined pressure. The assembly is designed to run dry ­indeed, lubricant obviously has a deleterious effect on brake lining material-and has proved entirely satis­factory and devoid of wear.

Lest that last statement be taken with a grain of salt, may I add that Irving demonstrated the test machine, which has covered over 90,000 miles without any replacement in the suspen­sion system, when I gained ocular proof that no wear has taken place over this great mileage. As Phil emphasized the fact in no uncertain terms, I had better state at this stage that the machine under discussion is, in his own words, " A lash-up intended to prove principles and not to win beauty prizes." When experimental work is completed and a production prototype is built, the appearance will probably be very different.
Lash-up or no lash-up, a road test soon proved the efficiency of the design. For purposes of comparison, the experi­mental " springer " and a standard rigid-frame model were ridden out by Phil and myself to a vile, unmade road on a housing estate, the surface of which deteriorated rapidly from uneven cobbles to cobbles with gaps and then to gaps with exposed manhole covers and other aids to aviation. I first tried the " springer " with the plungers in the forward, or most resilient, posi­tion and then had a second run with the plungers in the back notch. Even in the former case there was no " bottoming," but it was surprising to note what a difference was made to the swinging fork action by such a com­paratively small variation in the plunger angle.
On Rough Going
Having several times galloped down the stretch at some 25 m.p.h. on the spring heel, meanwhile deliberately aiming at the worst obstructions, I nearly cast myself off when I attempted the same gait on the rigid model. Hitting the edge of a particularly dreadful pothole a resounding clout-it seemed more like a pitshaft-I felt the back wheel rise to such an extent that I thought for a split second I was going over the bars. The incident must have looked funny to Phil, riding along behind me, as he said something about " What a pity the photographer is not with us." So far as I was concerned, however, it taught me a lesson; after that I did what one usually does with a rigid frame in such conditions picked out a crooked, but more com­fortable, path and took things con­siderably slower.
Manfully hiding any qualms I might have, I then mounted on the pillion device behind Phil. This, I thought, was to be the acid test of the springing, to say nothing of my courage! The result was even more impressive than when I had been in the saddle. I weigh, roughly, 15 stone, but only once did the springing " bottom " over the aforesaid pitshaft and even then I suffered no discomfort and there was no subsequent " life on the ocean wave " rocking reaction such as might have been expected.
Again it took the rigid frame to demonstrate just how efficient is the spring-heel design. Even following the excrescence-dodging path at a much reduced speed the bumping was so severe that the headlamp front fell off and I acquired a severe " headache " in reverse. The demonstration was very convincing, my only regret being that I failed to take Phil on the pillion of the rigid-frame model after the shaking he gave me!
Some spring frames are good, others are all " spring " and others might be solid for all the benefit obtained. The Veloce type tested definitely qualifies for the first category. It has all the perfect steering qualities of the maker's excellent rigid frame, combined with first-rate comfort for rider and passenger. The lateral rigidity of the wide pivot bearing and the deep stressed-skin rear frame member must be ample for the purpose, as there was no visible trace of shake and certainly none could be felt even over rutted three-ply lanes. And let it not be over­looked that more than 90,000 miles had been covered on this machine since it was put into commission in the autumn of 1938.
Regarding ease of maintenance, the problem seems to have been solved by giving the rider no maintenance to do. The bottom bearing in each spring leg consists of a floating Oilite bronze bush, which has proved ideal for the niggling semi-rotary motion to which it is subjected. The fork pivot bearing is equipped with a simple grease nipple with suitable passages in the member leading to the bronze bushes, whilst, as has been previously stated, the Ferodo guide-cum-damper assembly runs dry.
The assembly of the spring leg is very simple. First, the bottom Ferodo guide, with its steel collar, slips down to a shoulder formed on the inner mem­ber. Next, the semi-circular pieces of Ferodo and the little clock spring are nipped into position with a piece of string. Then the top Ferodo-and-steel collar is screwed on. Next, the spring is screwed on to the helix on the plunger and, finally, the sheath is slipped over the plunger and inside the spring. As the sheath slides over the damper segments the string is removed and then the sheath is given a half turn so that its external bayonet catch engages with the top spring coil. That's all!
To sum up, as an attempt to provide a suspension system instantly adjust­able to solo or pillion loads, allied to ease of maintenance and long life, the experiment appears to be a complete
success. I am very glad I found that patent specification. There is always a thrill in testing something new, and more particularly when the something new indicates that war-time conditions have not been allowed to cry " Halt " to post-war progress.

Wednesday, October 15, 2008

More pen and ink from the Motorcycle Media...

Time for another

As I mentioned in a previous foray into pen and ink drawings from the motorcycle media, graphic art has changed dramatically …. lets have another look into the 1930s and later when graphic artists, cartoonists and the like, armed with pen, ink and pencil recorded the images of the day in concert with the film camera.Acknowledgement is made to Mortons Motorcycle Media owners of the copyright for "The Motorcycle" and "MotorCycling" and to the families of the artists for use of the images.

Left click on images to enlarge.....

Saturday, October 11, 2008

Pictures from my Archive… a frequent dip into some more photographs that I want to share with you….

This blog's selection is a bit of a "pot-pouri" selection.... I suffered the old "blue screen of death" with my computer during this last week, so have been off the air rebuilding it... thus a hastily cobbled up group of photos this time... but all good viewing just the same....

The rotary valve NSU 125cc engine is a bit of an enigma to me...I took the photo at Veloman Heinz Limber's friends storage place near Neckarsulm, Germany around was an experimental attempt by NSU with this form of valve arrangement.

This is a favourite shot of mine...erstwhile managing director of Veloce Ltd, "Bertie" Goodman, flat on the tank of a cobbled up KTT special testing the new Velocette telescopic forks.Likely around 1950... he was a real "racer's racer"

Hard men in the 1950s...... road racing with ribbed front tyres on gravel road circuits...pictured at Quornhall, Tasmania, during the Junior TT. #21 ridden by D.Powell, Mk.8 KTT e/no. KTT1015 with #74 Max Stephens, Mk.8 KTT e/no. KTT1025.

Below, Pietro Taruffi, Rondine Gilera, sets a new world record..but where and when?

Left click on images to enlarge...

Sunday, October 5, 2008

Pictures from my Archive…Graham Walker and Rudge

Continuing with another selection from Allan Schafer's literature collection, now in my custody....
Allan Schafer of Grafton, a town in northern NSW, Australia as a young man was a prolific letter writer to overseas motorcycling "greats". This one is a reply to his letter together with an autographed photo, from Graham Walker, a factory Rudge rider, winning the Lightweight TT in 1931 on a Rudge and the photo shows Graham in the paddock at the TT after the 1930 Junior TT in which he finished 3rd on the 350 Rudge. Rudge machines finished 1st,2nd and 3rd in the Junior TT that year.
The gentleman in the hat in the photograph was John V.Pugh, the Managing Director and designer for Rudge in 1930.
Graham's racing career spanned 1920 to 1934 in the IOM. He then is better known as a motorcycle journalist, editing the Temple Press paper "MotorCycling" for many years.
His son, Murray Walker became a well known TV commentator of F1 car races.
The photo is credited at the time to "Sport and General" Press Agency, London.

Left click on the images to enlarge.

Thursday, October 2, 2008

349 c.c. MAC Velocette...the so called "Alloy MAC"....

An Analysis of a Successful Single, with Questions by GEORGE WILSON and Answers from CHARLES UDALL, Velocette Development Engineer.
This following article was published by "The MotorCycle", London, in a series "Motor Cycle Engines" Second Series, 1955....

In 1932, by introducing a four-stroke with push-rod-operated valve gear, in the motor cycle design field. The design incorporated numerous new and praiseworthy features. One of these was the high-mounted camshaft which permitted the use of short, sturdy push-rods. But perhaps more important was the fact that the valve stems and springs were totally enclosed. This feature caused widespread discussion. Many claimed that valve enclosure would prove to be a mixed blessing. Certainly, it was said, greater external cleanliness would result, and it was agreed that dust and road grit would be kept away from the valve guides. But, against these points, it was argued that the valve springs would receive inadequate cooling and, in the long run, exposed valve gear was to be preferred. How unfounded those views were has been proved beyond all doubt in the ensuing 20 years. The original engine with totally enclosed valves was of 248 c.c. capacity, and it was “square,” with a bore and stroke of 68 x 68.25 mm. Later, the stroke was increased to 96mm. To bring the capacity to 349 c.c. Thus, the MAC Velocette, a “sports” three-fifty, was born. From then on, the engine remained unchanged until June, 1951, when the top half was extensively redesigned to bring it into line with modern trends. However, the basic design remains, and in my questionnaire I decided to delve into the “reasons why” behind the illustrious original engine as well as those concerning the more recent version. Since the first World War, incidentally, Velocettes had marketed only two-strokes and overhead-camshaft four-strokes; this engine was their first “modern” design employing push-rod-operated valves.
Why a Push-rod Engine?
In view of this, my first question was: “What made you decide on a push-rod type four-stroke ohv.? You had already, in 1932, the KSS engine, and I would have thought that going from ohc to push-rod valve operation was a retrograde step.” “Basically,” answered Mr. Udall, “the push-rod four-stroke is a type of engine that can be produced more cheaply than the overhead-camshaft type. Moreover, the first type, perhaps on the score of cost, has a rather wider appeal than the second – a fact which has been clearly borne out by our sales figures.”
Question: “What, then, made you decide on a high camshaft location and, that decision made, to employ gear drive to the camshaft and magneto? I have a good reason for asking the second part of this question. As you know, you have a reputation for producing engines which are mechanically quiet, and I would have thought that it would have been easier to obtain a higher standard of quietness by using chain drive.”
Answer: “The decision to locate the camshaft ‘high’ was made for several reasons. Obviously, one reason was to reduce the length of the push-rods. That, of course, reduces valve spring troubles, and differential expansion between the barrel and rods is reduced. When I say that high camshaft location reduces valve-spring troubles. I mean, specifically, because of the lower reciprocating weight, it is possible to use lower-strength valve springs for given rpm. “The decision to use gear drive was based on the fact that, provided the gears are manufactured accurately, and mounted correctly, the drive maintains its efficiency for the total life of the engine. It is more difficult to make to make a gear drive as quiet as a chain drive, but it is a question of maintaining the necessary degree of accuracy in the gears. A chain drive, however well it is arranged, suffers from the fact that the chain stretches during its life and, ultimately, must be replaced.”
Question: “About 1932, you may recall, the Magdyno was in its heyday: the acetylene light had long disappeared, but separate magnetos and dynamos were not widely used. What made you decide on your set-up of magneto behind the crankcase and dynamo in front? I cannot believe that at that time you foresaw that this would be the fashion in 1952!”
Answer: “So far as the latter part of the question is concerned, we did not obviously, foresee that this would be the fashion to-day! But there were excellent reasons for adopting this particular layout. Positioning the magneto at the rear worked in well with the gear drive and allowed us to use a very neatly shaped timing cover. It also meant that as the magneto was well up on the engine, it was safe from any possible water troubles in normal use. A dynamo is less susceptible to water, and the forward mounting made it easy for us to arrange a neat and most satisfactory belt drive.”
Question: “Dealing again with general features first, could you tell me why the change was made to a light-alloy cylinder head and barrel last June? I know from experience that the original engine would withstand hard driving, and I was rather surprised at your making the change at a time when supply difficulties discouraged such modifications, and secondly, because the original job I should have thought, would have been less expensive to produce.”
1951 rigid model Alloy MAC
Answer: “The question of changeover was dictated by two considerations. In the first place, the light-alloy head is a far easier machining proposition and thus allows the production of cylinder-head assemblies at a greater rate than was possible with the old design. The construction is an easier job, and it is a more up-to-date arrangement.
“When the original M-type of engine was designed, enclosure of the valve gear with air-cooled engines was not
widely used, and there was very little known about the subject. Casting a one-piece head would have been possible at that time, but tit was thought that to cast a large valve-spring chest on top of a cast-iron head would lead to troubles. Hence our original scheme of using thin steel cups and separate rocker boxes. It would, of course, have been possible to use this new one-piece design while retaining a cast-iron head, but obviously, a light-alloy head is much better from the point of view of good cooling and general weight reduction. The use of a light-alloy cylinder barrel follows automatically. In fine, the basic reasons for making the change were to bring the model right up to date and to reduce machining difficulties as far as was practicable.”
1954 US model Alloy MAC
Question: “The new cylinder employs very deep fins; does this mean that you subscribe to the theory that it is better to get heat right out of the air-stream and that it is better than trying to get moving air circulating around the barrel at the root of the fins?”
Answer: “Quite honestly, with this type of engine, it does not matter one way or the other. The real reason was to get away from the ‘skinny’ 1932
look and thus to have an engine which looks bigger. Appearance is improved by a nicer balance with the remainder of the machine. There is some slight advantage from having an increased fin area but, I repeat, the primary reason was to get the machine proportionally right aesthetically.” Question: “Would you tell me what is the pitch of the cylinder fins and whether there is any point of interest in connection with the fin shape?”
Answer: “The pitch is 3/8 in. There is nothing unusual about the fin shape and no point of interest arises.”
1956 Alloy MAC
Question: “In the KTT engine, the silicon aluminium-alloy jacket, with its very deep fins, is cast on the nickel iron barrel which has a corrugated outer wall. The barrel is, I believe, heated and placed in the mould before alloy is poured. Would you like to explain the advantages of each of these systems-this on and the new one?”
Answer: “Well, the real underlying answer is that at the time the KTT barrel was produced, there were only two ways of obtaining a composite barrel. One of these was the method adopted for the works’ racing machines: that is to say, a fully machined liner was shrunk into the machined bore of a light-alloy jacket.
mentioned. Nowadays, both have been out-moded by the very up-to-the-minute Al-Fin process used on the MAC. Besides being more modern, the AL-Fin barrel has the advantage of a much better heat transfer.”
Question: “Have any changes been made to the bottom half of the engine at all since it was first introduced? If the answer is ‘No’ and the flywheel inertia was scientifically correct for the two-fifty engine, I should have thought that flywheels of greater diameter would have been necessary for the larger engine.”
Answer: “The answer to the first part of the question is ‘No’. But in fact, the two-fifty had very heavy flywheels that were rather heavier than they needed to be, with the result that the MOV engine was extremely smooth. Owing to the decision merely to increase the stroke it was impossible to inveigle flywheels of greater diameter into the existing crank case, in spite of the theoretical advantage. In any event, and I think you will agree, the standard flywheels are perfectly adequate for this particular engine.”
The late Ron Owen, Australian VOC stalwart aboard his beloved "Alloy MAC", Aust.Nat.Velo Rally, Bright, Victoria
High Safety Factor
“And the big-end……..? Inertia and centrifugal loadings must be greater with the three-fifty than they were originally---and they are possibly now greater again with the light-alloy engine, because of the increased power output.”
Answer: That is quite correct, the loading on the big-end is much greater with the three-fifty ---but it is a different big-end. This one is the same dimensionally as that fitted to our three-fifty racing machines. The safety factor, accordingly, is extremely high.”
Question: “I cannot remember ever having seen a full technical description of the flywheel assembly. Would you describe the assembly to me?”
Answer: “The flywheels themselves are 0.25 per cent carbon-steel forgings. The timing-side mainshaft is 3 per cent nickel steel, oil-hardened, and the driving-side shaft is 3 per cent nickel steel, case hardened. Both shafts are pressed into taper holes in the flywheel centres and are pegged. As you no doubt know, the crankpin is of two-piece construction, with the central portion which carries the nuts made of 3 ½ per cent nickel steel, oil-hardened and a separate roller track made from 1 per cent carbon chrome steel.”
Question: “Arising from that would you explain first why you oil-harden the timing-side shaft and case-harden its opposite number, and, secondly, why you favour having separate shafts and wheels? Could the flywheels and shafts not be forged as single units?”
Answer: “The reason for case-hardening the driving shaft is that it is splined to locate the shock-absorber sleeve. In this case, the shock absorber works directly on the mainshaft which must obviously be given a case to minimize wear. Regarding the second part of your question, it is, of course, possible to have the axles in one piece with the flywheels. In this particular instance, however, there are several objections.
“One of these is that, as I have just said, it is necessary to case-harden the driving shaft, and doing this with a shaft that is in one piece with a flywheel is almost an impossibility. Thus, the decision made to use a separate shaft on one side, there is no reason for using an integral shaft on the other. Equally important, however, is that by using separate components one can select the type of steel which has the best properties for each particular job. The 0.25 per cent carbon steel in which the flywheels are forged would be unsuitable for the shafts.”
Question: “Why do you favour using a separate roller track for the crankpin?”
Answer: “Because it is a much easier machining proposition. If we used a one-piece pin --- as we do on the KTT --- it would mean that it would have to be manufactured from a case-hardening steel. It is essential, as you well know, to have a case-hardened roller track, but the shanks have to be left soft because of strength considerations. Therefore, the use of a one-piece pin would mean that machining and hardening processes would be unnecessarily complicated; it would involve a lot of handling and increased production time --- and, therefore, increased cost.
“The sleeve, incidentally, is pressed on the pin in an ordinary mandril press and ground finally to size after being pressed on; it is, of course, ground before and after hardening, both on the periphery and in the bore. The final operations are to the roller track and side faces.”
Crankcase Breathing
Question: “I note that the crankpin nuts are not locked. Is this because you feel that additional locking ‘safeguards’ are unnecessary?”
Answer: “Yes. The real answer is that provided the hexagon faces are square and flat, and they are put up to the correct degree of tension, they will never come loose. We used to lock the nuts with a grub screw, but the immediate question to that is, ‘What locks the grub screw? Putting a centre-punch indentation on the end of a shaft or pin is an excellent means of locking a nut in certain circumstances – but not in this particular case.”
Question: “Would you describe, please, how crankcase breathing is achieved and why you use this particular system?”
Answer: “Breathing is achieved through a hole in the middle of the driving shaft. This leads to a cross hole which mates up with a recess in the engine sprocket, and the gases
are discharged through slots in the sprocket. The reason for our using this particular type of breather is that if any oil is thrown out with the discharges gases, it helps to lubricate the engine sprocket. Finally, of course, the oil is thrown out to the chaincase, where it assists in primary chain lubrication.”
Question: “The connecting rod, I believe, is manufactured from a 3 ½ per cent nickel steel, heat-treated to 50-60 tons per square inch tensile strength. What is its length between the centres in relation to the stroke, and has the figure any special significance?”
Answer: “The stroke is 96mm or 3.779in. The connecting rod measures 6.875in and is, therefore, 1.82 times the stroke. The figure has no special significance. I have found no great variation when using either long connecting rods or short ones.”
Question: “To what extent is the reciprocating weight balanced?”
Answer: “70 per cent. Incidentally, each flywheel is individually balanced, with the result that each flywheel assembly is balanced to perfection.”
Question: “Returning to the timing gear, is there anything unusual about the tooth form?”
Answer: “Yes, there is something. In the first place the teeth are of every fine pitch and, of course, as we have already remarked, they are helical cut instead of being the more usual type of spur pinions.”
Question: “The reason you use helical gearing is, presumably, because you want to ensure mechanical quietness. But in the L.E. Velocette you use spur gears accurately machined by modern methods, are just as quiet as helical gears. It is not a fact that spur gearing in this case would be as quiet and yet prove less expensive?”
Spur or Helical Gears?
“I would not go so far as to say that your pinions are less expensive than helical ones are, but the new methods of machining spur gears have been developed since the MAC was originally designed. While we could today produce spur pinions for the MAC in the same way as we do those for the LE, we have no wish to make a change, thus introducing a service problem, at this stage.”
Question: “Do you make any provision for adjusting gear centres?”
Answer: “The intermediate gear centre spindle is capable of being moved to adjust the centre distance of the gears. Thus, on assembly, we can produce backlash in the timing pinions to a minimum. Incidentally, the gear pinion material is 3 per cent nickel case-hardening steel, which is given a light case. We use this particular material because the high tensile strength of a nickel steel is necessary in view of the very small gear teeth. In the interests of quietness again, the magneto pinion is made in Tufnol. We have a hunting tooth in the intermediate pinion so that wear is evenly distributed among the teeth.”
Question: “Does the tooth form compensate for variation between the centres, due to expansion and contraction of the crankcase?”
Answer: “As with most involute gear teeth, it is possible to operate them on centres other than the theoretically correct ones, so there is no special compensation --- for none is necessary.”
Question: “Your cam-wheel arrangement is unusual.. The cams, which are manufactured from case-hardening mild steel, have an integral boss which is a press fit in the pinion bore. The assembly is plain-bushed and rotates on a stationary shaft. Would you please explain why you use this system in preference to the more orthodox one?”
Answer: “It is easier to maintain correct gear centres by this method and, in addition, it is just about the only system that one can use for the moveable intermediate gear centre.”
Question: “Instead of the push-rods being operated through straight tappets, the MAC engine employs a system of cam followers, or, as you call them, bottom rockets. Has your system any real advantage over the other one?”
Answer: “If we used straight tappets with this type of cam, valve operation would be noisier. Our method is used chiefly with a view to achieving the maximum degree of operational quietness. Were we to alter the cam design we could, of course, obtain just as quiet running in conjunction with straight tappets. Indeed, broadly speaking, it is true to say that with modern knowledge and production methods, it is possible to make almost any type of valve gear quiet.”
Question: “The valve seats, I note, are of austenitic iron, shrunk in as on the KTT. But on the racing engine, different materials are used for the inlet and exhaust seats. Would you explain the reason why the difference does not appear on the MAC unit?”
Answer: “The iron used for both MAC valve seats is similar to that used for the inlet seating on the racing engines. But, owing to the much less arduous conditions under which the MAC engine works, it is not necessary to provide an aluminium-bronze seat for the exhaust valve. Another very important factor is that austenitic iron is much more hardwearing than aluminium-bronze. A point here is that the KTT engine is likely to be worked on much more frequently than the MAC!”
Question: “Can you tell me if the choke diameter was decided upon with a view to high performance or good power at low revs, or, as with all design problems, is it a compromise between the two?”
Answer: “It is compromise between the two. One aims to get as good power output as possible at the top end without spoiling the power at low revs; and, of course, the reverse holds good. It is a compromise to obtain the best possible performance at both ends.
Question: “The rockers operate in separate DTD 424 light-alloy brackets. Could these brackets not have been incorporated with the rocker posts in the head castings, since there would then, I should have thought, have been even greater rigidity than at present? And would you explain why it has not been necessary to line the rocker housings with some form of hearing material?”
Bearing Pressures Low
“The reason is that in the original design of the engine, the rocker bearing surface was made of such ample proportions that the bearing pressures were already down to a very low figure, thus permitting the rockers to be run directly in the aluminium rocker box, avoiding, again, separate components. When the engine was redesigned with a light-alloy head, similar rockers were used, which meant that we could operate them in light-alloy housings quite successfully. The housings could not be incorporated in the head casting, since that would render two of the cylinder head studs inaccessible. It would also make the machining of the housings very difficult.”
Question: “Are the bearings split purely because of considerations of ease of assembly and dismantling?”
Answer: “They are split because it is the only way of getting a bearing on that particular design of rocker. The use of solid bearings would mean that a two-piece rocker construction would be essential. The disadvantages of that are obvious: there would be more component parts to machine and there would be, also, the possibility of slack developing between the two components of the rocker.”
Question: “And the power output …?”
Answer: “It is approximately 15 b.h.p. at 5,500 r.p.m. We make no attempt to obtain a higher power output although we have done so by tuning on special occasions. We have what we believe to be an excellent compromise, bearing in mind the poor quality of the fuel in Great Britain and the high quality obtainable in some overseas countries. The engine is so arranged that it will run on any of these fuels with a high degree of efficiency.”

Left click on images to enlarge.