timing wheel?

[orabanda]

Some of my A10 mags have the carbon brush in the back of the brass plate, some don't.

[MG]

Hm, funny. Maybe there had been a version without the front earthing brush available at some time? That would be the only reason making sense to me. Might also have been an "universal" points plate for different mags, one without any other earthing brush.
Where is Joseph Lucas when you need him...?

[LJ.]

Joe and his 'dark' secrets eh? 

[muskrat]

If he is where a lot of riders wished him over the years it would be very hot.

[MG]

If he is where a lot of riders wished him over the years it would be very hot.

...and dark

[LJ.]

... But someone else says... "Let there be light"! and there was light, and everything was good. If only it was 'that' easy Joe. 

[MG]

Did you guys know that Lucas built vacuum cleaners once? It was their only product that did NOT suck.

[groily]

I think we're too hard on Uncle Joe sometimes. He made his stuff to suit the tightwads at the factories - they could have had better quality and better longevity, but I reckon they didn't think we were worth it. In light of that, Uncle Joe's magnetos do work pretty well, or I think they do anyway. Even our under-sized over-stressed little dynamos aren't all bad, although I don't think much of the regulators myself.

I don't know why some brass cb backplates have the brush fitting either - just that some of them do. Never seen a K2F without the standard earth brush either.

As a lot of folk here have said a few times, the first thing to do with any newly-acquired beast of unknown provenance is to get the mag rewound, sort the charging out from end to end, and you're half way to having a reliable bike. I've no idea what the stats are, but I bet well over half of all classic breakdowns bar punctures are down to optimism winning out over prudence in the electrical department. (I know mine have been!)

[MG]

groily - absolutely agree. We have to bear in mid that these things are 50+ years old. I want to see today's motor control unit or microprocessor-ignition-module in 50 years. Well, maybe I even will...

[trevinoz]

If you have a look at the Lucas parts book, all brass point plates have an earthing brush and spring.
It must have been unnecessary as it was dropped when the steel plates were introduced.
If my points don't have a brush, I don't worry about it and fit them anyway.
As already stated, the brush plate makes contact with earth through the shaft.
Trev.

[olev]

Did you guys know that Lucas built the first English fridges?
and thats why they drink warm beer.

[emilios]

If you have a look at the Lucas parts book, all brass point plates have an earthing brush and spring.
It must have been unnecessary as it was dropped when the steel plates were introduced.
If my points don't have a brush, I don't worry about it and fit them anyway.
As already stated, the brush plate makes contact with earth through the shaft.
Trev.

But if brass point plate makes contact with earth through the shaft...what for is spring with brush there??
It doesnt make any sense to me.

[a10 gf]

all brass point plates have an earthing brush and spring

nope!
Am also interested in the answer to the riddle (why some with and some without?)