AJS & Matchless Owners Club

I have run into an issue with the bike I'm assembling. It is a 1962 Matchless 650 twin motor.

I'm installing the relevant bits on the drive side of the crankshaft and there are a couple of problems.
1. The breather “nut” fouls the outer chaincase when everything is assembled.
2. Although the nut fouls the chaincase it actually bottoms out on the thread with at least a ¼” space between the nut and the alternator rotor.
3. There is about a 1/8” space between the end of the crankshaft and the chaincase when assembled which doesn't appear enough to cater for the size of the nut.

As I see it there are several possibilities-
1. There is more than one version of the breather nut.
2. There is more than one version of the alternator chaincase.
3. I am fitting a new alternator rotor and perhaps these are a different width than the original rotor.
4. For some unknown reason the Crank spigot protrudes too far.

I am of the opinion there is two problems not necessarily connected. One is the nut fouling the chaincase and the other is the gap between the nut and the rotor when the nut is seated.

Both issues could be resolved by cutting about 1/4'” of the end of the crank spigot but this seems a bit drastic..... and hopefully unnecessary.
I have attached some photos to show the issues.
Any suggestions you might have would be appreciated.

No photos

Are you sure it's an alternator crankshaft, and not a dynamo crankshaft with an aftermarket extension fitted (but either too long or not screwed in far enough) Maybe it's just the threads in the breather nut or the end of the crank that need cleaning? Have you got a measurement of another breather nut to check the thread depth?
Dave.

Can you try again posting some pictures?

Thanks

Hi All
I think my problem has been solved.
Armed with info from Steven from AMC Classic Spares I conducted a very close inspection of the crankshaft and I am fairly certain it is an added extension of incorrect length- a conversion of a dynamo crank to an alternator crank.
It would also appear that the rotor is narrower than the original fitment.
Thanks to everyone for their help.

Barry

Did you get a solution to this? I have just fitted a new 74mm rotor to complete the conversion to 12v and the new rotor is narrower than the original. My nut also bottoms out on the threads before tightening up fully.
I assume there are spacers to be fitted to lock the rotor in place?