E: Engine Twin Dynamo Pinion Retaining Nut

paw99

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VOC Member
Dynamo drive lock washer should be PD23/1 NOT 508 and E50/4 pinion shim ET173/1 should be deleted.(too large a hole)
Can I ask another related question, please? My dynamo drive pinion nut has only about two threads to hold on to at end of armature, even before I add the locking washer, this worries me; Can someone please advise dimensions of PD16 dynamo sprocket boss, as that's the most likely component to take up the space.
The one I have measures 0.315" across the main part, and 0.473" overall (there is a shallow protruding ring on the dynamo side and a deeper protruding ring on the sprocket side).
Regards
Peter Killow
 

b'knighted

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Now moved to new thread - many thanks

Hi Peter,
The old thread was about the gear drive in the Comet timing chest. Have you got a Comet now or are you asking about the chain driven dynamo drive on your twin?
 
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paw99

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VOC Member
Hi Peter,
This thread is about the gear drive in the Comet timing chest. Have you got a Comet now or are you asking about the chain driven drive on your twin?
Sorry Ian, my inexperienced mistake - yes the twin dynamo drive, not timing at all; where should I post it?
I was going to ring you to ask, but can't find your number!
Do you have my email address for a chat?
Cheers
 

timetraveller

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VOC Member
Peter, something is wrong and I suggest you do not use the bike until it is sorted out. If that nut comes off the dynamo drive and goes through the primary chain it can break the chain and/or break a piece out of the front of the crank case and more. Two threads is not enough. Also your description of the dynamo drive sprocket does not sound right. There should not be a raised portion on either side of the central hole. The sprocket teeth themselves should run in the central line of the chain. Does yours do that? There are different drive shafts on different dynamos. Some are tapered and some are parallel. Do you have all the correct parts to mesh together?
 

paw99

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VOC Member
Peter, something is wrong and I suggest you do not use the bike until it is sorted out. If that nut comes off the dynamo drive and goes through the primary chain it can break the chain and/or break a piece out of the front of the crank case and more. Two threads is not enough. Also your description of the dynamo drive sprocket does not sound right. There should not be a raised portion on either side of the central hole. The sprocket teeth themselves should run in the central line of the chain. Does yours do that? There are different drive shafts on different dynamos. Some are tapered and some are parallel. Do you have all the correct parts to mesh together?
Hi Timetraveller,and thanks for reply.
I apologise to all for being on wrong thread - I searched for Dynamo Drive, and this one came up.
Should Twin Dynamo be somewhere else?
My situation is: I fully appreciate the damage that loose metal in primary chaincase would cause, hence my concern.
I have "C" Rapide, and the dynamo drive is as per handbook, tapered drive from armature, through dynamo drive boss, oil thrower ring, drive sprocket, drive plate.
There is only about 1/8 " of thread showing when these are in position.
My question is why, and I wonder if the PD16 drive boss (with tapered hole) may be too thick.
So I measured it, and need dimensions of a known correct PD16 to compare.
I believe the armature thread is correct length, as I have two the same.
Dynamo is Miller, the long 3" one.
The raised portions i referred to are not on the sprocket, but are on the drive boss.
In hope of a safe solution
Peter
 

timetraveller

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VOC Member
Peter, I do not have a PD16 so cannot help with the thickness of that but two questions might help. Is the dynamo right up against the back of the crank case casting and is the sprocket in the centre of the chain. If the latter is correct but there is a gap between the casting and the dynamo body then perhaps there is something wrong with the PD16. You also refer to the dynamo as the 'long 3" one'. All the Miller dynamos for Vincents which I have seen are about an inch shorter than the later Lucas dynamos. 5" as opposed to 6" from memory but someone will correct me if that is wrong.
 

paw99

Well Known and Active Forum User
VOC Member
Peter, I do not have a PD16 so cannot help with the thickness of that but two questions might help. Is the dynamo right up against the back of the crank case casting and is the sprocket in the centre of the chain. If the latter is correct but there is a gap between the casting and the dynamo body then perhaps there is something wrong with the PD16. You also refer to the dynamo as the 'long 3" one'. All the Miller dynamos for Vincents which I have seen are about an inch shorter than the later Lucas dynamos. 5" as opposed to 6" from memory but someone will correct me if that is wrong.
Yes, I take your point about alignment with chain; but before that, I need to have the sprocket securely attached to the dynamo. The alignment may be affected by the presence or absence of a felt washer between the dynamo and chaincase - do you know if there should be one?
I think my next step is to ask Bill Parr (Technical Officer) or VOC spares company .
Thanks for your help
 

robin

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VOC Member
Peter,
The correct nut to use is ET154. This screws up inside the drive pinion.
Robin.
 

paw99

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VOC Member
Peter,
The correct nut to use is ET154. This screws up inside the drive pinion.
Robin.
Many thanks Robin, that seems to answer my question well.
But very different to what the various Vincent literature would have me believe!
(Or I am reading the spares list wrongly).
Thanks
Peter
 
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