Scott Cranks

[Roger Moss]

Moss Engineering are to manufacture a small batch of the high strength (110 tons tensile fatigue resistant steel) cranks. We will manufacture 21 sets of long stroke cranks only. No short stroke cranks will be made as these have a tolerable, if not perfect, fatigue life. 4 sets of special long stroke cranks to go with ball race main bearings with 1.500″ bores that we use with our high strength crankcases will be also made.
Since 1997 we have made 100 sets of long stroke cranks 20 sets of short stroke cranks and 10 sets of big bearing cranks, plus steering head spindles for super type machines where the same material and thus heat treatment is used
If anyone requires anything else in this special aerospace steel, please contact to discuss. Kind Regards
Roger

[BRIAN MARSHALL]

Hi Roger, Any thoughts on the wheel spindle used by Scott in the ‘kite’-shaped forks fitted to TT Reps, Flying Squirrel Deluxe, and 1928 and 1929 works TT machines ? Only 3/8″ diameter, and push-bike size, in a heavy machine doing over 85 mph !!! I know they go through a hollow sub-spindle that gives a little support. I have used EN16 in recent years, but they still worry me…
Brian

[Roger Moss]

Hi Brian Yes I agree, but I do not hear of them breaking. If I had to select a readily available steel that does not need subsequent heat treatment, I would choose EN24T in preference to EN16T, Both are quite strong, but the nickel in EN24T gives it more ductility. EN 16T tends to be a little more granular and brittle but, of course, not as bad as “Silver Steel” which is more brittle and should be avoided at all costs
The material I use for cranks is quite special, expensive and needs unique heat treatment in controlled atmosphere furnaces in several stages. I have to hire a furnace at about £1500 and I can put in the box whatever I can get in for the one process. I remember a Vincent sprinter asking me if I could make some head / barrel bolts to highest strength possible. The material and machining were not cheap, but were reasonable considering what was asked, but when I added on the heat treatment at £1200 the customer thought I had gone mad. I had to explain that it was not possible to consolidate with other customers and I had to hire a box whether there was a lot or a little in it. That is why I always ask about steering stems and if anybody has any special requirements before we start as afterwards, like the Vincent barrel studs, it will be too expensive. When I first investigated the material for the cranks, I knew that I had to go for the absolute optimum material to make cranks that were so far superior to the originals as to put the possibility of breakage beyond reality. Richards bike on dope is putting out 42 bhp on a standard overhung crank and certainly nobody has broken one made in this material. Several years after I started using this steel, I heard that Air Bus had chosen to use the same steel for their landing gear, so the punch line is, when you hear that the wheels have been falling off the AirBus aircraft, then you can start worrying! I have been very lucky to have had such a wide variety of engineering challenges in my life and this is very helpful to me. I have no idea where anyone can get such a comprehensive engineering education nowadays, but then starting to work machinery at nine years of age at weekends was unusual even then. OK back to work. Kindest Regards Roger

[BRIAN MARSHALL]

Since 2002 there have been 19 undercarriage ‘incidents’ with the Airbus A310 and A320, but Roger will be relieved to know that none were due to metal fatigue ! All nosewheel problems, and mostly the wheels pointing sideways instead of ahead when lowered. Lovely….
Brian

[Dripfeed]

I owned a Triumph that did things similar with its wheels Brian . regards D F .

[BRIAN MARSHALL]

My first legal two-wheeler was a 1959 Dayton Albatross, with a Villiers 2T 250cc twin engine, Earles type forks, foot-change, etc., sort of half bike, half scooter, an idea also perpetrated by DMW as the ‘Deemster’. The Albatross should have been called the Albatrocity… It was hypersensitive to front tyre pressure, but nobody warned me. As a stupid 16 year old, my first ride was flat out, to see what speed it would do. At about 50mph it went into a violent tank-slapper, so violent that after three or four oscillations it was going from lock to lock, and one of the fork stops broke off, enabling the front forks to go 90 degrees to my direction of travel. There was an equally violent deceleration, and I went over the handlebars, with the clutch lever going under my watch strap and ripping it off as I parted company with the Albatrocity. I slid down the road, and clearly remember it overtaking me on its side, showering sparks.
A little lad kindly handed me my watch, with the bracelet still intact, and spectators helped me up, with the elbows out of my jacket, and the backside out of my trousers. The Albatrocity was also picked up, and wheeled into the nearest house garden. The householder gave me a very stiff drink, probably whisky or brandy, but I was not yet a drinker of alcohol so had no real idea what I was drinking. He asked where I lived, and said that he would give me a lift home and look after the Albatrocity until I could recover it. He then proceeded to don a crash helmet and riding gear, and the lift home was on his Lambretta, which I was VERY apprehensive about due to my ‘accident’. Happy days ?
Brian

[Dripfeed]

The brother of the man that I worked for in the late 50 s was road testing a customers Albatrocity he had the same ill luck but was in hospital for several weeks with head injuries that he never fully recovered .Another heap of junk that sometimes came in for repair was a Swallow gadabout ,, don’t swap your Scott for one of those,,.D F.

[timetc]

I had similar forebodings when I made a wheel for my kite forks
I put 2 Bantam hubs back to back and the hole in the wheel bearings for a bantam spindle was far bigger than a Scott!
then I reasoned that a bantam has a pretty poor version those pathetic things called tele forks so each leg can do its own thing while a kite fork ‘legs’ are almost braced as one component. anyway I got some drawn steel tube and some En24T bar for the spindle and made one a smooth fit in the other and a smooth fit in the bearings finally I a put a slight countersink in the inner faces of the legs and a slight chamfer on the tube ends and was very exact about spacers and tube length and bolted up the spindle.
At that point I stopped worrying about that and found something else to worry about (-:

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