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MG Midget and Sprite Technical - Whining Dynamo

I've got a whine coming from the rear of the dynamo on my 71 Sprite, that increases with engine revs.
I put it down to the rear bearing needing replacing but found that if I disconnect the electrical connectors to the dynamo, the noise stops! Seems strange..Anyone else had this?
Harvey '71 Sprite

Brushes?

Worn down wearing away the springs?

You know what Harry Hill says

"there's only one way to find out…"
Bill 1

When you disconnect the connectors don't you effectivly remove the 'load' from the dynamo (i.e. it is no longer producing current that is going somewhere) therefore less load on suspected knackered bearings.

Just a hypothesis this, could be utter nonsense! It's been a while since I tackled or thought about any electrical systems.

Cheers,
Malcolm

P.S. Or when you disconnected the connectors you nudged something back into place that was whining and it was just a coincidence that it stopped!
M Le Chevalier

Harvey - Sounds like you dynamo is ready for a rebuild - new front bearing, brushes and rear bushing. Once it is rebuilt, make the fan belt very loose. Dynamos don't need a tight fan belt like an alternator does and all a tight belt does is cause accelerated wear on the rear bushing. See the article, Keep Your Belts Loose in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave
David DuBois

This thread was discussed between 24/08/2011 and 25/08/2011

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