Lucas KVFTT Magneto
|The Lucas KFVTT differed in specification from
the standard magneto in that it was fitted with a manual advance retard
mechanism and (I believe) a better quality Stainless Steel armature than
standard. In addition, the earlier magnetos were made from a lightweight
magnesium alloy, although I am told later ones used a more standard competition
alloy (similar to K2FC's I would imagine). I think they were also fitted
with Platinum points, although I gather these were also fitted to KVF magnetos.
I have absolutely no idea how many of these magnetos were made in total but I would guess that probably no more than 50 - 100 in total. I have talked various people who, like myself, have tried to research the magneto and to my knowledge no one has found any literature produced by Lucas mentioning them or listing their components.
Identifying a KVFTT
· Magneto body made of lightweight alloy (sometimes magnesium
based). Armature pickups parallel to each other (K2FC's had one pickup
at an approximate 10 degree angle to the other).
|Recreating a KVFTT
I think because of their rarity, I have always been interested in the KVFTT magneto, therefore I decided very early on that it was important to fit one to my bike, as it was a very distinctive feature of the Lightning specification. Indeed, you see very few Vincent's racing today with one fitted.
I spent many years scouring autojumbles and the classifieds in the hope I would find one, but they definitely resemble the proverbial 'hens teeth'. Even if I had found one, it is very doubtful I could have afforded it, bearing in mind some of the prices I had heard been paid to obtain one.
When I was sprinting in the late eighties I took a close look at Tony Brown's Nero, and noticed it was fitted with a KFVTT, which I photographed. Examining it closely I decided that it might be possible to create my own KVFTT using a more standard competition magneto as a starting point.
I know that some people object to building replica's, as they are easily be passed off as the real thing. However in the end I saw this as being the only alternative, and I intended that this replica would be as close to the original specification as I could make it.
As a final point for those interested, I have stamped it underneath as a replica and my initials, so no mistake can be made.
The body started life as a (comparatively rare) K2FC competition magneto. It came my way because one of the three mounting flanges was cracked and it was considered unusable (for those that have tried, most will tell you it is almost impossible to TIG weld a magneto body as the cast in magnet's deflect the arc). Fortunately, I was able to de-magnetise the body enough for my local welder and friend, Arthur Sosbe, to successfully repair the cracked flange and also weld up the left HT pickup hole and top face, which are different to the very distinctive KVFTT model. To anyone in the Leicester area who does not know Arthur, he is probably the finest welder in Leicestershire, his business repairs all kinds of exotic car/bike engines, including rare racing cars from the Donington collection. He is also very fairly priced and a motorcycle enthusiast to boot!
Once the body had been welded up, I was able to re-machine the left HT hole parallel to the right, as per photos and pictures I have taken from the genuine article. At the same time, I also machined the top face flat, to take the Lucas Racing plate. The only other magneto that I think could have been fitted with a similar nameplate could possibly be the rotating magnet variety, fitted to late Norton Manx's, however I would be interested to know if there were any others. I do actually possess another Lucas Racing label, slightly longer, that was obviously designed to be fitted on the flange, presumably in place of the normal Lucas plate, giving model and serial number details. The genuine KVFTT examples I have seen do not have a nameplate on the flange, instead having the model type/model number/year of manufacture stamped directly on to the flange. As you can hopefully see from the photograph I have replicated this as faithfully as I can.
Side view of a genuine KVFTT.
Another point worth menitioning is that the safety gap screws on a KVF magneto are on the opposite side to a K2F magneto (again, clockwise rather than anti-clockwise). While having the above work done I also had the original holes welded up and then drilled/tapped new holes on the opposite side.
Finally I stamped the direction indicator arrow on the top of the magneto, and very fiddly it was to replicate as well! To achieve this I had to make about 4 very small chisels using Silver Steel rods, each one representing a different length of straight line, I then stamped each component of the arrow seperately. Obviously, the arrow signifies a clockwise rotation which does not seem to be stamped on standard K2F and K2FC magnetos, presumably as this was the only magneto at the time with that rotation. (Actually, I also own a Royal Enfield Constellation which, although of a slightly later period, also has a clockwise magneto direction).
|Manual Advance/Retard Mechanism
The manual advance/retard casting is (as far as I know) exclusive to KVFTT magnetos. A similar casting was made for other racing magnetos but I believe these were all anti-clockwise in rotation, and therefore the cable exited from the left, looking endcap on. The other difference between this and an anti-clockwise casting is that the depth of the casting that abuts with the magneto body (ie the bit that has the copper spring screwed to it) is shallower in depth. I only found this out much later, when talking to Dave Linsdley, who has worked on many genuine ones.
|With little possibility of ever
finding one of these castings, I decided the easiest way to overcome the
problem was to take an anti-clockwise casting from one of my other magnetos
(a Lucas NR1) and make up a mirror image pattern from which I could have
a casting made. I had never done this before so I visited one of the best
known foundries in Leicester called Harrisons to get some advice. The people
there were extremely helpful and also seemed very keen to help, once I had
explained what I was trying to do. Once they had shown me the casting process
one of the pattern makers took me over to their drawing office and gave
me some of the wood used to make patterns. This is a very light wood, which
if I remember rightly is called Jelamine.
With this wood I spent the next two nights carefully turning and carving a very close copy of the NR1 casting, making it slightly oversize to allow for shrinkage. As I was doing the job anyway, I took the opportunity to make an anti-clockwise pattern up as well as the clockwise, as the NR1 casting is quite rare in itself.
|I painted the bare pattern in red primer and
sent it off to be cast in aluminium, which turned out to be a relatively
painless process. It was then a case of machining the casting to match the
dimensions of the original casting. To ensure that the bearing housing was
absolutely true to the cam ring housing, on the opposite side, I first of
all machined the cam ring side, and screwcut the thread to take the endcap.
I then machined a jig (see photograph) which fitted 'size' into the cam
ring hole, secured by threaded ring. This jig was then held in a collet,
ensuring the casting ran absolutely true to the cam ring.
I also made a simpler jig to ensure that the 3 mounting points were drilled true to the magneto.
Final job was to drill and tap holes to take the small copper leaf spring that is used on competition magnetos to secure the endcap.
(Incidentally, my lathe is a Smart and Brown Model A toolroom lathe, which I think dates back to the 1950's. It is a beautiful lathe, massively built and very accurate for its size. I have some old engineering friends who fondly remember it as the Rolls Royce of lathes. That apart though, for a lathe of this quality it is not fitted with a clutch, which makes screwcutting a test of nerves! Because of this I have set the belt to slip at quite low torque, however it is still a very easy thing to break the workpiece/tool/lathe gears . . .
I already had a K2F armature in good condition and was just in the process
of sending it off to be rebuilt when I decided to check it in the magneto
body. Good job I did, as it turned out that the drive side armature shaft
was a smaller diameter than the inner race of the bearing.
|As well as the armature and bearings,
Dave very kindly took the trouble to draw me a detailed picture of a mandrel
and sleeve that would be invaluable for inserting a new bearing into the
magneto body. This bearing is inserted from the inside but is an extremely
fiddly job as it has a paper insulator washer around it and an oil seal
placed behind it first. As this is approximately 3 inch's inside the body,
without a special tool it would be almost impossible to hold all the components
in line and place the bearing absolutely square.
The idea of the mandrel was to hold the outer bearing, paper insulator and oil seal in the position they need to be mounted. Then a sleeve is placed over the paper insulator, pushing it against the outer face of the bearing and holding it in place. The mandrel is then carefully inserted all the way down the magneto body, until the bearing comes up against the bearing housing. A gently tap and the bearing/seal presses into place, while at the same time the sleeve is pushed further up the mandrel body, revealing the paper washer which insulates the bearing from the bearing housing.
It required quite a large piece of aluminium bar with numerous different diameters machining on it, but it worked superbly. Again, it was one of those occasions that most engineers know well where it takes 2 hours to make the tool but 5 minutes to do the job. Thanks very much Dave, excellent advice!
In comparison, inserting the other bearing into the manual advance/retard housing was very simple, and was achieved in the normal manner without the need of any special tools. (I think I might have used my bench press actually to ensure the bearing went in square).
|Cosmetics and Final Assembly
I had decided to paint the magneto body gold, partly because this I am told was done with the earlier magnetos, but also because I think this colour looks great on competition magnetos!
Painting was not too difficult, starting first with a 2-pack aluminium etch primer, then a gold topcoat and finally a clear laquer to protect it. It certainly looked very smart when complete.
|Assembling the magneto was relatively straightforward.
Dave Lindsley was able to supply sundry screws and washers as well as the
correct shims for ensuring the endplay was correct (it is a year or so since
I assembled but if I remember correctly, this is set as zero thou).
I fitted new bakelite pick up housings and brush's and the correct competition hexagonal screws. The advance/retard retaining screws were also of the hexagonal competition type, drilled for lockwiring. As with the carburettors, all reclaimed parts were replated in my dull nickel bath.
I have fitted new Lucas points but unfortunately the rare platinum variety
are no longer available. If anyone has a set I would be interested to
The Finished Article
The Finished Magneto