Author Topic: alternator chaincases  (Read 2738 times)

Offline bonny

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alternator chaincases
« on: 06.11. 2010 14:53 »
i picked up these alternator chaincases for 40 euros today at an auto jumble , there seemed to be at least 3 sets of these for sale on various stalls , this set were the cleanest and least butchered, i know they are for b-series bikes  , for 40 bills i took a chance on them , can they be fitted to an a10 ? can a rotor be fitted to the end of the crankshaft ? 

Offline brackenfel

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Re: alternator chaincases
« Reply #1 on: 06.11. 2010 16:22 »
Hi Bonny,
Those as you say are from a late ('58 on I think) B31 / B33 ..

A while ago I almost bought (sight unseen) an alternator A10 with a few non-standard bits fitted.. In the end I chickened out as it was a bit too close to the price of a standard unmolested A10 ... He was a nice genuine bloke, I often wondered if I should have had it, just for the rarity value..

Anyway, I've found a couple of pics he sent me ( the alternator didn't work - hence it wasn't fitted - see pic) . It also had a dynamo, but that wasn't working either!
I recall him saying that the crank was special for this model & if you look at the photo the shaft does look pretty long - I'll leave it to the experts out there to decide!!

Hope these help or are of interest. I include a pic of the engine to show the A10 primary side..

1961 A10 650 Golden Flash - Blue
1954 BSA B33
Velocette Viper
Laverda 750 SF1
Kawasaki W650
Buell XB9S
Ariel 350NH & Matchless G3LS in bits...

Offline bonny

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Re: alternator chaincases
« Reply #2 on: 06.11. 2010 17:36 »
thanks for taking the time to post the pictures brackenfel , i can see what you mean about the crankshaft , but is there the face cam cush drive behind the sprocket as on normal a10's ?  i just wonder if even bsa with all its industrial might would bother to make an entirely new crank for very few bikes . i'll search the web and see what the answer might be.

Offline Beezageezauk

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Re: alternator chaincases
« Reply #3 on: 06.11. 2010 18:49 »
The Alternator A10 (Police) models didn't have the conventional cush drive as fitted to the normal A10's.  BSA fitted the Triumph type 4 spring clutch to these which had hard rubber inserts set in the middle of the clutch.  The cushioning was done by these rubber blocks.

The 4 spring clutch fitted to the A10 models with the conventional cush drive was very similar but didn't have the centre spider or the cush rubbers.


Offline Flatboy 1950

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Re: alternator chaincases
« Reply #4 on: 06.11. 2010 19:01 »
The A10 cases have a larger aperture in the inner case than the singles , where it bolts to the crankcase. Single & twin inner mounts are different.
Cush drive is eliminated & crank is longer. But A10 Alt cases will fit std. A10.


Offline wilko

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Re: alternator chaincases
« Reply #5 on: 06.11. 2010 21:36 »
Perhaps with a lathe and some ingenuity you could turn up an extension shaft that screwed on to the exhisting thread to accomadate the rotor? Probably end up being too long?

Offline LJ.

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Re: alternator chaincases
« Reply #6 on: 07.11. 2010 10:48 »
Interesting engine number 'DA10 A 424' Do we know how many of these Alternator models were produced? And did BSA produce a Super Rocket alternator model...?
Ride Safely Lads! LJ.
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline chaterlea25

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Re: alternator chaincases
« Reply #7 on: 07.11. 2010 21:56 »
Hi Bonny,
Yes we did meet and have a brief chat Yesterday!!
I dont know if there was a similar setup to the B33 made for the A10 , ie, with the alternator mounted on the inner primary, not the outer case as in the picture???
Mounting it on the inner is a much better proposition as its much easier to centeralise the stator to the rotor
 Good luckwith the project
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline BSA_54A10

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Re: alternator chaincases
« Reply #8 on: 07.11. 2010 23:26 »
No the only alternator model has the stator mounted on the outer cover.
If you look at it there is no where to mount the stator securely without making a substantial modification to the chain case inner and probably to the crankcase as well.
The A10 was in the process of being replaced so making up new patterns for the crankcase would not be on the agenda
Bike Beesa