The BSA A7-A10 Forum

Bikes, Pictures, Stories & more => Chat, Offtopic, Meetings & Everything Else => Topic started by: cyclobutch on 06.07. 2015 16:25

Title: A10 Sunbeam
Post by: cyclobutch on 06.07. 2015 16:25
I was at the SoF (Sunbeam) rally in Derbyshire at the weekend. Mostly S7 and S8 motorcycles in various states of use as you would expect. One of them though had been through a conversion to A10 power. I think I might have seen pics of this one before but never in the flesh. Effectively the engine was turned sideways so that the crank output ran into the Sunbeam bell housing before driving through what appeared to all be std Sunbeam transmission to the rear wheel. Given the reputation that has for a certain level of frailty you can only wonder how it copes with the A10 output. The motor was all iron and with thin flange barrels so is presumably running in fairly soft tune – and I did have to wonder how the cooling worked out for the now rear cylinder. Timing chest faced forward of course, which did look decidedly odd. But all in, quite a feat of engineering of course.

I took a whole bunch of pics and I’ll try and work out how to post some.   
Title: Re: A10 Sunbeam
Post by: chaterlea25 on 06.07. 2015 17:13
Hi cyclo,
The Sunbeam transmission must be stronger than the credit its given ??
Theres a very decrepit (rat) Sunbeam running in Ireland with a 1200 (?) VW engine *conf2*
The conversion had  been done a long time ago, and I suppose was just abandoned eventually
It was found years later and returned to the road (as is)

Cheers
John
Title: Re: A10 Sunbeam
Post by: cyclobutch on 06.07. 2015 21:24
Trying ... to post ... pics ....
Title: Re: A10 Sunbeam
Post by: cyclobutch on 06.07. 2015 21:27
Hmmmm, had to down size quite a chunk from what was suggested. Hopefully here are three more:
Title: Re: A10 Sunbeam
Post by: chaterlea25 on 06.07. 2015 21:55
Hi All,
Hmmmm *ex* *ex*
Something very odd about the way the dynamo/garden tractor alternator is sitting (Not??)  *eek* *eek*

John
Title: Re: A10 Sunbeam
Post by: Greybeard on 06.07. 2015 22:13
The engineering looks very good to me.
Title: Re: A10 Sunbeam
Post by: chaterlea25 on 06.07. 2015 23:38
Hi
Greybeard,
look and you will see a tapering gap between the dynamo housing and the crankcase cradle *conf2*
To align the drive the dynamo body needs to sit into the cradle properly

Cheers
John
Title: Re: A10 Sunbeam
Post by: duTch on 07.07. 2015 03:24

 I'll stick my neck out and suggest that there is a short bearing housing where the genny usually sits, with some kind of offset interim 'flex-drive' between there and an alternator against the bell housing, the interim drive having a tin cover over it.
Title: Re: A10 Sunbeam
Post by: RichardL on 07.07. 2015 04:40
Well, John certainly has the eye for "garden tractor alternators". I never would have known that, then, searching Google images for that exact phrase brings up that exact piece. Then, I was going to question Dutch's flex drive, but there needs to be some way to adjust chain/belt tension while the alternator stays fixed in place, so flex drive makes sense. Dutch's bearing housing appears to be used as the former for the tin cover, held in shape by the three allen screws. I think the tin cover is mostly for aesthetics, so the fact that it doesn't sit in or align with the cradle wouldn't matter much. What I really don't understand (but will become obvious to me as soon as I'm told) is: why not just use an original dynamo?

All of the above aside, when I heard about this bike, I was expecting some bodgy thing but, as Greybeard said, the engineering looks very good. Really, to me it's pretty amazing.

Richard L.
Title: Re: A10 Sunbeam
Post by: duTch on 07.07. 2015 05:38

 Actually, when I say flex drive, I really meant flex coupling(s) one each end like a rudimentary universal joint like on a steering shaft or similar drive shaft... did that in a hurry as I still am (again)
Title: Re: A10 Sunbeam
Post by: Klaus on 07.07. 2015 07:34
my opinion is the alternator is an alton right in place, driven with a belt or chain. the dyno is parallel with the barrel, so l gues it is an optical illusion. altons are much shorter as genny dynos,so there is enought space for an electrikstart at the oposite.
the bike is clever build, and it make no sense to use a flexi drive.

sorry for my write smal, l breake my collar bone by racing with the a10 , slipping the frontweel, last sunday *roll*

only the left footrest is a twisted and a soft tuch on the fairing.

klaus
Title: Re: A10 Sunbeam
Post by: Greybeard on 07.07. 2015 08:39
...I breake my collar bone by racing with the a10 , slipping the frontweel, last sunday...

 *sad2*
Title: Re: A10 Sunbeam
Post by: tombeau on 07.07. 2015 09:16
Impressive.
Wouldn't want to have to remove the timing side cover though.
Title: Re: A10 Sunbeam
Post by: muskrat on 07.07. 2015 11:37
Wonder what the extra plate between the timing covers is for?
Cheers
Title: Re: A10 Sunbeam
Post by: Topdad on 07.07. 2015 12:17
A bit of additional clearance for the genie drive ??
Title: Re: A10 Sunbeam
Post by: a10gf on 07.07. 2015 13:05
A crazy idea that became reality *smile*, am appreciating all this excellent workmanship. Thanks for the photos.
Title: Re: A10 Sunbeam
Post by: shuswapkev on 07.07. 2015 13:13

  like to install that alternator on my A10...
Title: Re: A10 Sunbeam
Post by: chaterlea25 on 07.07. 2015 13:25
Hi All,
Quote
Wonder what the extra plate between the timing covers is for
This appears to be for the front engine mount, the engine /gbox are hung on rubber mounts, you can see the snubber rubbers pointing to the sides of the cases

On the garden tractor genny, the alloy plate houses the bearing(s) and stator, the anodised "cover" is over the magnets and spins, the front of the cover forms half the V pulley with an opposing washer forming the other side

At one time I pursued  the idea of using one of these on an A10 and obtained one for experiment
Like early Alltons they suffer from magnetic pulse at low revs and I did not think this would do any good to the timing gears or dynamo drive
My next experiment was going to be to introduce a centrifugal clutch into the drive so as it would only "work" above a set lower limit
Another line of experimentation that was never concluded *pull hair out*

Cheers
John
Title: Re: A10 Sunbeam
Post by: Klaus on 07.07. 2015 13:42

My next experiment was going to be to introduce a centrifugal clutch into the drive so as it would only "work" above a set lower limit
Another line of experimentation that was never concluded *pull hair out*

Cheers
John

the chainsaw solution *good3*
Title: Re: A10 Sunbeam
Post by: chaterlea25 on 07.07. 2015 17:06
Hi All,
Klaus,
Yes, or one from a weed whacker
Theres a guy in USA/Canada who makes up generators for Vincents using similar components
http://www.thevincent.com/McDouglator.html

Regards
John
Title: Re: A10 Sunbeam
Post by: nimrod650 on 17.07. 2015 19:53
I was at the SoF (Sunbeam) rally in Derbyshire at the weekend. Mostly S7 and S8 motorcycles in various states of use as you would expect. One of them though had been through a conversion to A10 power. I think I might have seen pics of this one before but never in the flesh. Effectively the engine was turned sideways so that the crank output ran into the Sunbeam bell housing before driving through what appeared to all be std Sunbeam transmission to the rear wheel. Given the reputation that has for a certain level of frailty you can only wonder how it copes with the A10 output. The motor was all iron and with thin flange barrels so is presumably running in fairly soft tune – and I did have to wonder how the cooling worked out for the now rear cylinder. Timing chest faced forward of course, which did look decidedly odd. But all in, quite a feat of engineering of course.

I took a whole bunch of pics and I’ll try and work out how to post some.
do any photos show reg n0 been looking for my old s7 oua 79
Title: Re: A10 Sunbeam
Post by: cyclobutch on 19.07. 2015 20:43
I'm a member of the club, so I can check directly as to whether that is a 'known' bike. I'll report back in due course ...
Title: Re: A10 Sunbeam
Post by: cyclobutch on 20.07. 2015 09:43
Response from the SoF reads:

"The bike is in the 1978 register.
 It was owned by R Brannan of Cumbria.
 The 1978 register listed all Sunbeams owned by SOF members and to the best of my knowledge there has not been an update since."

There is a guy at the branch meetings who keeps a log of all the Sunbeams he's ever come across, so I'll also check with him next time out.

  B
Title: Re: A10 Sunbeam
Post by: nimrod650 on 20.07. 2015 18:32
many thanks for all your efforts i passed my test on the bike in 1961 age 16 first time