The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Sluggo on 01.12. 2017 08:36

Title: A10-A7 alternator models and conversions.
Post by: Sluggo on 01.12. 2017 08:36
in light of discussion, Thought i might create a thread dedicated exclusively to alternator model preunit BSA Twins for both factory models with alternators as well as customs and modifications.
Try to keep on topic (A challenge for me so pot=kettle) but i would like to see basically pictures, diagrams, tech bulletins and service data and any posts relative to educating owners about this

But this is the engines side, I suppose mods might put this off into Ele-ktrc-ical.  But what I am hoping is some pictures, specs and details for alternator model cranks and how to spot them as well as other bits.
<OR>  What parts are more suited to this doing your own mods.

Here is a start,, pictures from a recent UK posting on FeeBay.
Link is only good for so long, but here it is. 
See: https://www.ebay.co.uk/itm/BSA-A10-ENGINE-Gearbox/222736481908?_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D49481%26meid%3D7ca7021f489f458da3398600d0b6a01e%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D192365036117&_trksid=p2047675.c100009.m1982
Currently 900 pounds with 4 days to go.

Title: Re: A10-A7 alternator models and conversions.
Post by: JulianS on 01.12. 2017 09:29
The A10 alternator crank came in small journal and CA10 cases until 1960 when it gained a large journal crank and engine number prefix DA10A. There were about 400 DA10A engines made.

The visual difference in cranks is the plain part of the drive side shaft to take the rotor and key.
Title: Re: A10-A7 alternator models and conversions.
Post by: edboy on 01.12. 2017 11:40
hi julian,
i have a 500cc alternator crank engine, small journal. were the a7 versions police bikes or ministry bikes? any photos of a7 police bikes?
Title: Re: A10-A7 alternator models and conversions.
Post by: JulianS on 01.12. 2017 14:17
Sorry got no information on the alternator A7.
Title: Re: A10-A7 alternator models and conversions.
Post by: groily on 01.12. 2017 18:15
I've often idly wondered how hard it would be to mod a simplex primary A to take an alternator  . . . more than a couple of people must have done it I suppose?
The outer chaincase question is one thing that could be tricky, but presumably the mounts for the stator wouldn't be so hard to figure (nor the need for a cush-drive clutch, as they can be had easily enough). But what about the crank end?
One of the things that AMC did (I have a long-term affair with AMC twins  . . . yup, I know, but I shan't apologise 'cos they're excellent too  . . .) was make a factory extension that converted dynamo cranks (for non s/abs later models with rubber clutches) to alternator, using a neatly made screw-in shaft. A mod that is still available. But their stators were held in the outer primary, like many another machine - which is basically pretty horrible, even with good dowelling on the chaincase.
The Beesa option, if the pix from Sluggo are typical, shows the stator on studs into the drive side case, which is much more elegant even if one overlooks the apparent stack of nuts packing things out. Stator on the crankcase and a chaincase outer with a detachable panel to allow direct measurement/tweaking of the clearance between rotor and stator  . . . would be nice.
Not about to try to do it, as I'm not unhappy with the dynamo I have got, but  it keeps entering my head that a neat conversion package is waiting to be put together. Mag and alternator was often regarded as a 'plus' back in the day, and made, eg, some of the Ton Ten Triumphs a more attractive proposition for some people than the dynamo options. It's certainly a decent and dead reliable mix on my P11 and 650SS Norton  . . . more non-apologies  . . .
Title: Re: A10-A7 alternator models and conversions.
Post by: JulianS on 01.12. 2017 18:28
I dont think the bike featured above is an original factory alternator job - the A10 alternator was mounted on the outer primary chaincase which had a large chromed access to set the clearance. I once had such a chaincase and was considering an alternator conversion. The primary case on the featured bike looks like alternator B31 or 33 type.

The below photo shows an alternator A10 seen at the BSAOC open day in May this year.
Title: Re: A10-A7 alternator models and conversions.
Post by: chaterlea25 on 01.12. 2017 18:37
Hi All,
Julian beat me to it
Yes, modified B series cases, The allen screw holding on the rotor also points to home made setup  *????*
I wonder if its a modified standard crank?
The triplex primary drive and clutch may be A65 or similar ?

John
Title: Re: A10-A7 alternator models and conversions.
Post by: duTch on 01.12. 2017 19:57

 
Quote
....The triplex primary drive and clutch may be A65 or similar ?

 I was looking at that yesterday and decided my eyes are gone weird, as I can only see two rows of teeth on the clutch... *eek*

 I considered doing an alternator conversion on my Plunger FR, but relegated it to the to hard basket for now so i can just ride it, even though  I acquired a crank (which was probably an A65 one) but swapped out for something,  maybe a tank... good idea in concept though; I'll follow this one.
Title: Re: A10-A7 alternator models and conversions.
Post by: edboy on 02.12. 2017 03:02
of course, the a65 uses a different drive side bearing so will need to be built up to 30mm if i remember correctly. not such an easy conversion.
Title: Re: A10-A7 alternator models and conversions.
Post by: chaterlea25 on 02.12. 2017 12:40
Hi ALl,
I have sent the ebay seller a message outlining the inaccuracies of the description of advertised
engine / primary and gearbox
I wonder if they will respond?

John