c15 Crank nut alternator side

Started by bushy, 28 Sep, 2025, 17:32

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bushy

Anyone know the large nut that holds the stator on the crank ? It NOT what Dragonfly say , cycle 5/8th 20tpi as I have one and it will not thread..
thanks for any suggestions

Rupert

It is 5/8 20 tpi cycle. Likely to be dahage to the thread on the shaft or inside the nut if they won't screw together.

bushy


rhyatt


courtney

Quote from: bushy on 28 Sep, 2025, 17:32 Anyone know the large nut that holds the stator on the crank ? It NOT what Dragonfly say , cycle 5/8th 20tpi as I have one and it will not thread..
thanks for any suggestions

Did you buy it from someone on ebay - "lister" something or other was the seller name, if I remember correctly. I think the threads are the wrong angle. I think there is a topic on here from a few years ago where I asked the same thing.

If so, I bought one from him and it claimed to be the right thread, but it wasn't. It would screw down a bit and bind. When I emailed the seller he claimed he'd sold loads and not had complaints, but it was kak! The one from Draganfly should be right.
1965 BSA C15
1970 BSA B25 (US spec.)
2004 Aprilia Tuono

limeyrob

Measure and confirm is is 5/8 x 20 just in case someone has forces a wrong nut on or recut it. If it is they get a 5/8 x 20 CEI die, they are only about £12 and you can carefully re-cut the thread.

rhyatt

I've had the same issue with "correct" nuts etc

also be careful on the drive side lock tabs that the correct nut is used - to allow the nut to securely hold the rotor tight.
some lock tabs do not allow the nut to pull onto the threads.
some nuts have a waist and some are plain , so take care - I had a dreadful "bottom falling out of the engine sound" and all it was , was the nut not pulling the rotor tight  !!

bushy

Dragonfly are in stock now - have ordered one will see ..