Didn't Even Make It To The Start...

[paul.wirdnam]

...of yesterday's VMCC Dorset Section annual Blandford Run.

I'd been looking forward to it for ages, a friend was riding my '46 Red Hunter and I on my '35 Cammy. The weather was great. So off we set for the 8 mile trip to the Corn Exchange where the run started at 11. But I got as far as Shillingstone which is about halfway between my house and Blandford. Was doing about 30mpg and engine suddenly died.

Did as much as we could at the road side. Seemed to have a spark, stripped down carb but found nothing amiss, cleaned and checked mag points, changed plugs, took off dissy cap and checked rotor etc. In the end, gave up and the Red Hunter towed me home, probably not legal but we successfully limped back at about 10mph.

Always suspected ignition but not quite this:

[Steven.Carter]

Wow Paul, that looks a differcult repair. Towing isn't much fun but if your close to home it saves a lot of extra hassle.

Hope you have better luck next time.

Steve

[paul.jameson]

Well blow me down (or something similar). I had exactly the same problem on my OHC four on the LDR about 10 years ago.

[john.whiting]

Well,metal fatigue after only 80years use.All the Lucas bashers must be right,after all.Regards John.

[paul.wirdnam]

Had a closer look at the break today. The steel shaft has not broken and on this version of the Lucas armature the steel shaft is pushed into the boss on the brass end cap. There looks to have been an old crack (brown area) between brass boss and brass base...which finally gave way.



Seems like the earlier design (below) where the steel shaft goes all the way through the brass end cap and is then peened over would be much more robust:

[nevhunter]

The magdyno shaft is sticking a long way out from the support bearing, so gets a fair bit of bending load on it especially if the chain is too tight . Over time these things deteriorate. They are way out of the warrantee period. Nev

[paul.wirdnam]

Cammy back on the road. Found a suitable end cap, very lightly skimmed in a lathe and a shimmed out the bearings to adjust the end float.

[bruce.carrad]

Yes,I had the same thing happen to my BSA B31 many years ago, at the brass to steel shaft join, but I managed to limp home as the rough edges of the break kept the armature spinning. Had to stop and advance the points quite a few times though as there was a bit of slippage. I remember the Late Les Graham had the same thing happen in, I think, the 1949 Senior TT while leading on the last lap on the Porcupine AJS. I believe the AJS works switched to BTH magnetos as a result!

[Ian.Taylor]

In 1992 my ol 32 cammy let me down once. The one screw to the distributor cap fell out leaving it loose and took out the rotor
Glad to see your back on the road again Paul. Nice cammy