Saturday morning I went to start it to warm it up for practice. At first it didn't fire, so I stopped and tickled the float again. I push it again and, when it fired, there was a loud bang and now I had 6 neutrals. The gearbox had failed. I pulled the motor out of the frame and Bill took the drive side crankcase half off and it was immediately obvious.
|failed gear on the layshaft|
My friend Aleksey Kravchuk let me ride the Velocette Thruxton that I've left with him for a couple of years and into which he's put a tremendous amount of work and money. Most recently, he's had the Lucas K1FC magneto rebuilt and bought a 1 1/2" Amal GP carb. The carb required cutting up the fuel tank for clearance.
|Velo Thruxton with tank modified for carb clearance.|
When I started it for the race, the clutch was dragging again, but there was no time for any adjustment. On the warm-up lap there was some indication of clutch slip. I was able to get the gearbox in neutral when I came to the grid and I made a pathetic start when the flag dropped. When I would shift, the clutch would slip, though it seemed that if I then backed off, it would hook up, so I carried on. Then, I lost all clutch release, with the lever dangling on the clip-on. So, I started shifting without the clutch. Then the motor started misfiring. This got progressively worse and I pulled off after two laps. First we found that the magneto flopping around, the nuts holding it to the timing case being loose. This was fixable, with some difficulty as there is limited access. But, the clutch was a different matter. When we took it apart, we found that four balls from the big ball bearing between the inner and outer clutch basket had somehow gotten out of their race and were jammed in the plates.
|Somewhat hard to see, but there is a gap in the balls near the top of the bearing in the middle of the clutch. They have scored the surface outboard of the outer race and left a lot of debris on the outer perimeter of the basket.|
|Doug Wood repairs magnetos and generators and had his 1938 Velocette KTS in front of his booth|