The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => Lucas, Ignition, Charging, Electrical => Topic started by: tonyairconchap on 30.05. 2018 21:20

Title: Auto advance removal
Post by: tonyairconchap on 30.05. 2018 21:20
Hi  all,  new to the forum   i need some advice please on my 1958 A10
After 20 years my magneto has given up so i need to remove it for repair. It has the auto advance retard setup.
I have removed the bolt which secures it to the pinion. I assume its fitted on a taper, but how do i remove it.
Do i need a bolt to screw into the hole, if so what size is the bolt and thread size?
How far do i need to screw the bolt in?  Do i tap it once its screwed in?

Any help would be greatfully received

Thanks
Tony
Title: Re: Auto advance removal
Post by: muskrat on 30.05. 2018 21:48
G'day Tony,  *welcome*.
Wow, you mean after 20 years this is the 1st removal of the aa unit  *surpr*.
The pinion and aa unit are joined (as in riveted together). The nut in the center is a self extractor so once it is lose you keep winding and it is supposed to pop the unit off with the pinion.
Cheers
Title: Re: Auto advance removal
Post by: chaterlea25 on 30.05. 2018 21:53
Hi and welcome to the Forum Tony  *smile*

Have a read here

https://www.a7a10.net/forum/index.php?topic=11841.msg91082#msg91082


John
Title: Re: Auto advance removal
Post by: tonyairconchap on 30.05. 2018 22:05
Thanks for the quick replies.

Yes 23 years at least since its been off,  think the warranty has run out now!

Muskrat, you say the centre nut is a self extractor,  what do you mean by loosening then continue to wind...all i end up with is the bolt in my hands...is that wrong?

John, am i right that i just undo the bolt a turn and give it a sharp tap to loosen from the taper.

Tony
Title: Re: Auto advance removal
Post by: muskrat on 30.05. 2018 22:22
After you undo the three mag mounting nuts.
Cheers
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 18:24
Gents, i have tried loosening the 3 mag bolts and then tried to wind in the centre bolt, self winder? The only thing that happens is that i turn the aa unit. Nothing frees up. Am i right in thinking that the aa unit is on a taper?

Also tried what John suggested, giving it a good tap with a hammer after loosening the 3 securing bolts. Still no joy..

What am i doing wrong?

Any u tube videos on the removal of the aa?

Tony
Title: Re: Auto advance removal
Post by: bsa-bill on 31.05. 2018 18:49
I'm not sure giving it a tap will have  the desired effect if the magneto is loose ( three nuts slackened), try tightening them up again, then unscrew the central nut, when it becomes tight again then give it a tap (small hammer please), to assist you could lever behind the gear with a thin flat bar as you do the tap (very positive tap)
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 19:18
Hi Bill,  thanks for the reply.
when i unscrew the centre nut all i am doing is unscrewing it off the armature shaft, it does not go tight as i unscrew it.
do i need an extractor tool to remove the auto advance unit?
tony
Title: Re: Auto advance removal
Post by: Greybeard on 31.05. 2018 19:20
Hi Bill,  thanks for the reply.
when i unscrew the centre nut all i am doing is unscrewing it off the armature shaft, it does not go tight as i unscrew it.
do i need an extractor tool to remove the auto advance unit?
tony
I know this is a repeating query here. Have you tried searching the forum?
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 19:32
Hi Greybeard, yes , searched for hours over the last few nights, searched the net, all i can find  is that the centre bolt is a self extractor which muskrat suggested.  But tried that and still not doing as suggested.
so sorry if this subject may be repeated time and again, but i do research before asking.
Tony
Title: Re: Auto advance removal
Post by: berger on 31.05. 2018 19:54
I am going to get a slap! your not at the points end are you, as dido said , its just a thought definatley going to get slapped ive just read the first post , oh well pub tmow
Title: Re: Auto advance removal
Post by: Greybeard on 31.05. 2018 20:11
Priory Magnetos website may be useful for tips. I found this PDF to download and read: https://sites.google.com/site/priorymagnetos/tech-tips-1

Did you find this page? https://www.a7a10.net/forum/index.php?topic=9333.msg67521#msg67521
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 20:21
Hi all,  think i have found an issue with the centre bolt.
from what your saying is that as i loosen the bolt from the main shaft it should go tight again.  I think the thread further up the bolt shaft has failed, almost completly missing,  . Also what looks like a thread  in the auto advance is almost  gone.
so bugger, what do i do now?
tony
Title: Re: Auto advance removal
Post by: Greybeard on 31.05. 2018 20:26
I'm glad to say I've not had this problem. I hope someone comes along with a definitive answer for you.

I'm wondering if a slide hammer could be screwed into the thread in the ATD and used to jolt the thing off the shaft
Title: Re: Auto advance removal
Post by: berger on 31.05. 2018 20:37
undo mag nuts completely get someone to steady it, try and get some wooden wedges between auto unit and inner case, get hardwood dowel or very soft brass drift onto mag armature shaft and bash it,, no don't bash it play with it gently while muttering let go you bastard
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 20:38
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

Title: Re: Auto advance removal
Post by: bsa-bill on 31.05. 2018 20:40
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,
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 20:44
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?
Title: Re: Auto advance removal
Post by: muskrat on 31.05. 2018 21:46
^^^^^^ 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
Title: Re: Auto advance removal
Post by: berger on 31.05. 2018 22:03
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
Title: Re: Auto advance removal
Post by: tonyairconchap on 31.05. 2018 22:16
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






Title: Re: Auto advance removal
Post by: RichardL on 31.05. 2018 23:49
Tony,

Welcome to the forum.  *welcome*  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.
Title: Re: Auto advance removal
Post by: tonyairconchap on 02.06. 2018 14:38
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
Title: Re: Auto advance removal
Post by: a10gf on 02.06. 2018 14:50
Congrats with the success.

Quote
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).
Title: Re: Auto advance removal
Post by: tonyairconchap on 02.06. 2018 15:02
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   *smile*
Title: Re: Auto advance removal
Post by: Greybeard on 02.06. 2018 17:07
Well done!
Title: Re: Auto advance removal
Post by: muskrat on 02.06. 2018 21:28
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
Title: Re: Auto advance removal
Post by: tonyairconchap on 02.06. 2018 21:57
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
Title: Re: Auto advance removal
Post by: RichardL on 02.06. 2018 23:22
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.
Title: Re: Auto advance removal
Post by: Greybeard on 02.06. 2018 23:29
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.
Title: Re: Auto advance removal
Post by: tonyairconchap on 19.06. 2018 22:24
Just a little update  for you.
I managed to buy a complete kf2 mag with a good ATD ...  good price  thank goodness from one of those odd internet selling sites, always worth the time searching.
so my Mag has just been wrapped up to be send off to be overhauled, plus now i also got a spare magneto.

Dont know how long turn around time  will be,   but i have at least got a couple more BSA to ride for now,

Anyone doing the Westland  mcc coast to coast ( lyme regis to burnham on sea ) this sunday  (24 June)
if so come and say hello,  i am number 2 in the start up.

Cheers for now
tony