Last weekend, a strange noise occurred when I closed the throttle of my Model 50. It was a strange whining/rubbing noise. Like something was spinning on an axle or grinding against something. Best way to describe it would be the sound of a bicycle rim brake when the two blocks hit the rim and start squeaking with a sort of resonation in it. It seems like the noise was coming from the primary gear, from the oilbath. But with the noise of the engine, carb and exhaust, combined with earplugs and a helmet, that diagnosis could be faulty.
It stopped at idle and then occurred sporadically when I decelerated, or sounded constantly for a while... or not at all. I feared the crankshaft sprocket nut had come off, but did a little dance when that wasn't the case. The clutch was also fine.
As I did the timing the weekend before, the most likely suspect now was the MO1 magdyno. I've never liked the sharp tap you have to give the magneto sprocket to seat it on the conical shaft. After checking, the recently tensioned (without tension) timing chain was now slack again and there was quite a bit of radial play on the magneto shaft. A spinning bearing could explain the sound I guess. The most likely suspect is the insulating washer, so fingers crossed it will be that easy.
But when I removed the E3L dynamo on top, I found that one had quite a bit of axial play, yet no radial play. Just to make sure I get the terms right: when holding the gear, I can't move it up and down, but I can push and pull it a little in and out of the housing. Could someone please tell me if this is this normal or do I need to a bit of shimming or adjusting?
A bit of a long story to get to the dynamo question, but you never know if somebody recognises the explained sound at the start of this post and will say: 'You're looking for something completely else, have you checked your left footpeg?' or something more sensible. There's no Lucas manual (that I could find) that even speaks of shimming. It's all about the electrical stuff.
P.s. I put this in GENERAL, as it's not really ELECTRICAL.
Cheers,
Tim
Noise such as you describe…
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Noise such as you describe needs investigating further.
End float is axial movement and needs to be kept in check to avoid damage.
For peace of mind strip the component and look for witness marks such as shiny metal or metal dust is an indicator of too much end float, check the bearings for wear and or lack of light grease within.