Auto advance removal

[tonyairconchap]

I assume someone before my time had stripped the thread on the bolt and aa unit. Tightened the aa on the shaft, taper , and set timing up.Now after 23 years i have got the bodge to sort out. Trouble is as the aa units thread is also knackered.
 So now do i have to hit it hard to try and free the taper off the shaft? 
New aa unit then i guess, unless someone can point me in the direction of someone that can repair it.
then i have the cost to repair the mag which is why i was trying to remove it first of all

Or do i approach this differently and convert to electronic ignition, the thorspark looks ok?  At least then i know i only have a one off cost of the kit. Dont need to remove the mag to install it .....or so they say.

Any thoughts on this ?
cheers
tony

[bsa-bill]

You should be able to get a new bolt
Have you been trying to take it off with inner cover on, from memory I can't recall if this is possible, would have thought it should still be possible to at least break the taper,

[tonyairconchap]

Hi bsa bill,  not sure if the thread is ok in the aa unit , so a new bolt might not help,
what thread is it, left or right hand, what size? Anyone know?

[muskrat]

^^^^^^ pretty much what I was going to suggest. As the bolt is buggered screw it back on the shaft a few turns to protect the thread of the armature.
Good luck.
Cheers

[berger]

i'd have a go as musky says with the nut on having got rid of any interfering remains of the outer left hand thread  or try and get to the solid bit behind the bob weights and springs even if you have to take off the inner cover and hit that like you would on a car ball joint taper to shock it off ....... not literally

[tonyairconchap]

Trouble is if i damage the  mag shaft threads by hitting the bolt firmly i will need even more work on the mag to repair that,  thats if the aa unit comes off .
if i convert to electronic ignition the mag and aa unit can stay where they are.  Fingers crossed the bearings dont fail , then i will have to hit it hard to remove it.
shame , as i like magnetos, got two other bsa with them on and i get no issues. 1934  m34 and a wm20
thorspark any good?
tony

[RichardL]

Tony,

Welcome to the forum.    When this problem is solved and life has meaning again, please tell us a bit about yourself and your bike, like how you two came to be a couple, etc.

If the nut is now sacrificial, maybe you could turn out the inside and outside threads so that the end of the nut sits on the shoulder of the armature when you hit it, thus sparing stress on the armature threads. In all the threads (that is, "discussions") we have on this topic, I haven't heard of anyone trying this and I don't even know if there is enough meat on the nut. Contrary to what Bill said about the three mag securing nuts, unless you remove the points housing and bearing race, I don't think you will get anywhere with the mag securing nuts tight while hitting the AA nut (maybe to eBay or Priory to find a replacement mag). (Sorry, Bill, if I've misunderstood you.)

Also, I think it would be A good idea to do all this with the inner timing cover removed so you can see what the backside of the mag gear will be pressing against when you hit the armature. This way, you should be able to install spacers behind, if necessary.

 Since you haven't been inside the timing case in a long time (if ever), try not to let the idler gear pull out when you remove the inner cover. this will save you some trouble aligning the timing dots on the three gears when you go to reassemble.

Good luck,

Richard L.

[tonyairconchap]

Yippee... one hefty sharp blow and the aa unit released itself... thanks gents for all your help and guidance.

Got the faulty mag out now, first time in over 23 years.
Have ordered an easy cap as a first try....fingers crossed
Will then need to retime, anyone got a step by step help guide, settings etc.
i have done my single cylinder side valves before, hopefully a twin is not too complicated.

Thanks again all, tony

[a10 gf]

Congrats with the success.

Will then need to retime, anyone got a step by step help guide, settings etc.

Yes (see attachment :O)

You may post in an existing topic (or eventually start a new timing topic if something is special with your setup).

[tonyairconchap]

Thanks a10gf ,   still getting used to the web site.  Know doubt every question and answer have been asked  and responded to over the years.

Suns out off for a ride on the BSA M34   

[Greybeard]

Well done!

[muskrat]

A new bolt/nut/extractor might be a good idea as well. £14 from Priory Magnetos. https://sites.google.com/site/priorymagnetos/magneto-atd-spares
Cheers

[tonyairconchap]

Trouble is i think the thread has gone in the aa unit, so will have to tap it back on the mag shaft ....no different than my early BSAs.
Thanks for the link to priory,  they may be very useful

All the best for now
tony

[RichardL]

You almost certainly will go insane trying to set the timing without being able to use the extractor thread every time you have to try again to get right.

Richard L.

[Greybeard]

Thanks for the link to priory,  they may be very useful

Might be good to mention this forum when you contact Andrew/Beezermac at Priory.