The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Retired Fireman on 01.10. 2013 05:26

Title: tapered drive shaft loose on K2F armature
Post by: Retired Fireman on 01.10. 2013 05:26
Hi all, my K2F mag armature has developed a "loose shaft" on the tapered drive shaft. I can wriggle the steel shaft where it meets the brass body of the armature. Question= is the armature knackered or is the steel shaft held onto the armature body by a internal screw/bolt?  Can I  dissasemble the armature by removing the bearings, slip ring then loosen the screws that hold the armature body together then just apply some loctite and tighten the screw/bolt that holds the tapered shaft onto the end of the armature. I have never dissasembled an armature into its componants and can't find a diagram anywhere showing the armature broken down to it's bare parts.
Title: Re: tapered drive shaft loose on K2F armature
Post by: orabanda on 01.10. 2013 07:25
For what it is worth, I had an identical problem.

The shaft was cracked, through the parallel portion beyond the taper.
A throw - away  job.

I have heard of it happening to others as well.

Title: Re: tapered drive shaft loose on K2F armature
Post by: Retired Fireman on 01.10. 2013 09:49
It looks like a crack because it is jaggard, it runs around the shaft but does not run around in a straight line, if it is scrap can I replace the earth end that incorporates the tapered drive shaft as the armature has not long been rewound and a new capacitor fitted. As I said have not dissasembled an armature but it appears to be 3 pieces with the centre part that is wound. Can I replace the drive end then just true it on the lathe as I have another armature for a donor?
Title: Re: tapered drive shaft loose on K2F armature
Post by: groily on 01.10. 2013 18:20
I think 'throw-away' is right as Richard says.
You can do the swap though, yup, but with mix 'n match parts you'll almost certainly need the lathe for truing, and you may find you can't get one or other or both small steel dowel pins into the bobbin through the drive-end brass cheek owing to the parts not belonging together. On the other hand, sometimes it's a piece of proverbial and no problem at all.
Withdraw the dowels for trial assembly, rather than trying to force the drive-end on with them pre-fitted on the bobbin and forcing the through-screws to align and do up as well. Filing to a 'D section' on half the length of a 'near-fit' dowel can be done, and worst case, there are plenty of mags running around with the dowel(s) missing.
Things to watch out for are internal clearance for the armature (absolutely minimal cuts to get it to turn freely if it binds, because you don't want to increase the air gap), shimming to get not just the right end float, but also the slipring centralised in the HT pick-up apertures after changing a key part, and then it's a real 'must do' to clock what run-out you have on the drive-end taper/shaft. A lot of shafts are a bit bent owing to heavy-handed gear extraction, and others are untrue because of people having had to mix 'n match in the past. More than a few thou run-out at the thin (far) end of the taper (at the base of the thread) is very visible in a lathe at low rpm, but perfection isn't always an option.
There's always a little bit of flex in the mag, usually some wiggle in the spigot that registers the mag to the rear of the timing case when fitting it, and there's always a bit of clearance on the teeth of the pinions in the gear train  . . . . . A value judgment, or suck it and see. What would make some people feel unwell doesn't bother others at all!
Good luck with it anyway, Bill
Title: Re: tapered drive shaft loose on K2F armature
Post by: trevinoz on 01.10. 2013 22:08
The steel shaft has been known to come loose in the brass casting.
I have seen them brazed internally but with the number of armatures floating around I wouldn't bother trying to repair it.
I would be inclined to transfer the new coil etc. to another set of ends.
As Bill states, the dowels may not line up but you can remove them, true it up and drill new dowel holes in the assembly.

Title: Re: tapered drive shaft loose on K2F armature
Post by: Retired Fireman on 01.10. 2013 22:31
Thank Richard and Bill, I take it that the shaft was pressed into the earth end brass part of the armature when manufactured and as such when it works loose or in my case develops a crack in it's shaft then that the end of it. I have a spare mag that I cleaned the slip ring and lubed the bearings and now it throws a good spark on the bench BUT as we know when heated to engine temps the windings might leak or the condenser fail. It costs about $400 from Peter Scott to recon the spare mag or I could go to option 2. I have a "mag conversion body" that I bought on Fleabay some time ago, it is one of the components that the electronic conversions use. I see on Fleebay a 6V dual output coil rated at 3.5 ohms that the seller claims would work using 6V coils on a 12V Boyer set up, also see that Boyer make a kit in a 6V version of their electronic ignition. Has anyone used the Boyer 6V electronic kit? I could hide the dual output coil in the tool box near the DVR2 I fitted and of course get away from adjusting cam rings etc to get my ignition timing spot on each side, the advance curve would be more acurate as well BUT  I am puting my faith on long trips to a battery made in China and my expeariance with Chinese batteries is that 1 in 3 are rubbish and fail on their first long trip (All British Rally in Victoria April this year on my TR7 Triumph then on the A10 going up to Queensland BSA Club's British Rally last month) both were new batteries and properly charged before leaving both blew a cell on the trips. Decisions decisions any suggestions or personal experieances with electronic ignitions on A10's out there?
Title: Re: tapered drive shaft loose on K2F armature
Post by: Retired Fireman on 01.10. 2013 22:33
Thanks Trev your replied while I was typing!!
Title: Re: tapered drive shaft loose on K2F armature
Post by: Topdad on 02.10. 2013 16:17
I think Musky runs at least one of his bikes on electronic ing and poss Bill over here in pomland,they'll let you know the pros and cons, regards BobH
Title: Re: tapered drive shaft loose on K2F armature
Post by: bsa-bill on 02.10. 2013 19:28
Did I hear my name??

Hi Retired Fireman
I fitted a Pazon electronic ignition to my Rocket type as I could not get to the bottom of the magneto problem, two magnetos that both work on the Flash proved totally unreliable on the Rocket so I fitted the Pazon unit and it's works just fine, first kick starting and runs without pinking but you do need a reliable battery and as you already mentioned Chinese C**P seem to be every where I've had three two on the Flash that just died and refused to be charged and a twelve volt one on the Pazon that refused to hold more than ten volts.

I eventually bought three of these  -

I can mix and match between the Flash and the Rocket 6 and 12 volt, and they are guaranteed to hold there charge when in circuit ( not sure is it for two years ?) and so far I'm fully satisfied with them, wont fit into the battery bit both upright but they're totally sealed so I just turned one upside down.

Pazon I think is an Ozzy or NZ firm, with the Burlen batteries starting is a doddle, If you prefer the look of a Magneto (I do) then maybe not for you OTOH if you like to ride then it's a good mod
I have had an offer from a member here to examine my maggie which I will do when I get my life, shed and a few other things put back in order but for now Pazon good for me

All the best - Bill
Title: Re: tapered drive shaft loose on K2F armature
Post by: muskrat on 02.10. 2013 21:46
G'day Steve.
I have Boyer in my 3 BSA's and love it. Mine use a mag replacement body. I think Pazon do a kit for the mag body, and their just the other side of the ditch.
If your running a DVR2 then why not go for 12v? Much easier to get globes etc and two sealed 6v 4amp prawning light batteries fit in the dummy battery case. If the dynamo packs up I get about 1 hour running (legal speeds *sad2*) out of the batteries. And the best bit, set and forget the timing.
Title: Re: tapered drive shaft loose on K2F armature
Post by: Retired Fireman on 03.10. 2013 07:58
Thanks Bill but I just looked at the link and they state that "the batteries can no longer be sent by airmail to some countries" well considering that there is no longer any convict ships coming to Australia guess I can't get one sent out here! lol. But thanks for the information guess I will have to look over here to see if some simular other non motorcycle sealed batteries that might be suitable that will fit in the A10 battery holder, don't care about putting it inside a dummy battery case my main concern about going electronic is reliability on long trips (my last 3 trips have been around 3000k's return each trip) and I don't what to get stuck on the side of the road or somewhere a long way from home.    MUSKY if I am going to 12v I will go the whole hog and put my hand in my pocket for an Alton alternator and a quality gel 12v battery and change over to neg earth so I can fit heated grips (I'm gittin old mate) Does anyone sell the Altons in Australia? BTW with a 35w halagon bulb in the headlight and the DVR2 the lights are O.K. doing legal speeds in the night. (I know you like to go fast and would need 12v lights ha ha) As I said in my post does anyone have any experience with the 6 volt Boyer unit?
Title: Re: tapered drive shaft loose on K2F armature
Post by: bsa-bill on 03.10. 2013 11:06
my main concern about going electronic is reliability

not having done anything like your mileage I couldn't comment re electronic reliability but there are no points to go wrong and few moving parts really, however I think the Alton option is one where reliability could be up for comment, I know there were issues with some of them, best for members here who have them to comment, maybe just a few failures - don't know but it put me off going down that route some while back.

Those batteries should be available in OZ, there not specifically motorcycle batteries, apparently spiral configuration inside and I "think" Gel.