B.T.H PBM1 Mag-Dyno (Early Series ‘A’ Singles)

Bill Thomas

Bill Thomas

Well Known and Active Forum User
VOC Member
delboy said:
Hi Bill,
twas all in MPH some time back from Glenn Shriver. Also to be found in the "A" book; "Back to A"
A modern made self contained Magdyno made by Powerdynamo GmbH which can be ordered with the 35mmm shaft height.
Cheers, Delboy.
Click to expand...
Many Thanks Dell.
 
Rob H

Rob H

Well Known and Active Forum User
VOC Member
vin998 said:
Rob

This type of BTH unit was used on early series A singles from 1935 & early 36 but then the factory must have found a few in stores as they were used on a batch of bikes in early 1937 of which mine is one. They were also used on some of the pre A bikes ie, Pythons and maybe Model J.

It looks correct in the photos as in the advance cable takeoff on the points area is the correct side for slackwire advance for Vincent rotation direction. I note that there is only one pickup which is on the correct side for a Vincent, but the other side should have a blanking plate over the redundant pickup hole. So one thing you can check is remove the points cover and check is the cam a single lobe or does it have two lobes? If two then it is most probably off a Scott as the early 1930's Scotts used these as well. If it is off a Scott then because the Scott was 2 stroke then the internal bevel gears for the dynamo drive will be the wrong gearing and if fitted to a Vincent the dynamo will rotate at 1/2 speed which means more revs required to generate the massive 24 watts of 6V electricity.

Has the unit been restored by a reputiable person as if not then it could cost a LOT of money to restore / repair due to difficult to source spares. So the value all depends on if it needs a rewind / rebuild.

Simon
Click to expand...

Was told cam has a single lobe, he has had the unit for over 30 year so is guessing it would need a refurb/test
 
Marcus Bowden

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
I have an identical unit on my "A" and Bill Brown of Bright Spark did mine the permanent magnet generator was kicking out 19V so have put 24v to 12v regulator in the circuit if that doesn't work then try 24v to 6v. I think it looks a very neet mag/dyno unit.
 
Marcus Bowden

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
No Vincent you can't buy it but you could give my twin "A" a good run as it's sat idle since my solo ride around NZ in 2018.
 
Vincent Brake

Vincent Brake

Well Known and Active Forum User
VOC Member
Its available.
Bit want to go for a real BTH.
Its a very special unit.
I like it a lot.
Ive got an empty one.

But like i full one.....

And get that electronic ignition out.

Cheers

But Marcus.
If you don't ride it, just flog A2 two me.
..
 
G

Georgehrd

Forum User
Non-VOC Member
Hi I know this is a old thread but I am looking for a advance retard cable for one of these does anybody know where I could source one ? Thanks
 
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