dynamo drive sealing

ogrilp400

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Ah it comes back to me slowly now. Yes there was a felt seal in there but as Len says it did little. I remember squeezing an O ring in there that worked better but yes, the best result was to use a sealed bearing. Even with minimal oil in the PD case it still dribbled a bit. I you want to see just how much oil gets thrown up into the generator gear cavity, just start the bike with the generator drive cover off. All the oil in the primary chain case will be out in about .2 of a second.

Phelps
 

vince998

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A comment if I may concerning sealing the dynamo against the back of the sprocket housing. Oil loss from here is usually due to excess oil in the primary chaincase. It's well known that most Twins have a tendancy for oil to pass through the drive-side main bearings necessitating the need to drain off the surplus via the level screw.If you seal the dynamo in the way some have described you will prevent the primary chaincase from breathing so any pressure build up will be forced into the dynamo. (Or into the gearbox, won't it Hugo Myatt?!) The felt ring in a Miller dyno won't stop much, far better to use sealed armature bearings which are readily available from bearing stockists.

I can confirm lens statement to breathing through the dynamo.
I fit the E3L to my D, line up and secure. I then remove the drive sprocket and drive boss (keyed to the armature shaft) and seal the dynamo to primary mating surface from the inside with silicon. (I’ve tried the bead of silicon on the mating surfaces trick a couple of times, but I end up with silicon everywhere and it still leaks afterwards!!)

The last time I inspected the dynamo, it looked as though it had laid on the sea bed for 10 years! Inside was full of rust, and the bandage wrapping the coil had almost totally disintegrated.
The primary is definitely breathing through the dynamo, and although I have no problems with oil in the dynamo, the air being transported is carrying a lot of condensation (I’ve ridden 200 miles in winter before now, and on looking into the primary to adjust the chain, have found the oil to be milky brown (emulsion?), so condensation is a definitely problem.

Theoretically, if you could seal the primary effectively (dynamo, gearbox cover plate & detent housing, kick-start shaft tunnel etc) then the pressure in the primary would stay constant.
If no more gasses are travelling through the bearings, no more oil would be transported through the bearings and your primary oil level would stay relatively constant.

These are all unfortunately answers to the symptoms and not a solution for the cause.
This would be primary mainshaft seal or sealed bearing.

I’m looking at fitting a sealed bearing at the moment, but have yet to find a way of removing it from the mainshaft/housing without splitting the cases.
Anybody managed this before?
 

lindie

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apologies re the aforementioned link.

have tried it since and realize its after a password. sorry.

images to follow.

DSCF0416.jpg


DSCF0418.jpg


DSCF0461.jpg


DSCF0427.jpg
 

lindie

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Ah it comes back to me slowly now. Yes there was a felt seal in there but as Len says it did little. I remember squeezing an O ring in there that worked better but yes, the best result was to use a sealed bearing. Even with minimal oil in the PD case it still dribbled a bit. I you want to see just how much oil gets thrown up into the generator gear cavity, just start the bike with the generator drive cover off. All the oil in the primary chain case will be out in about .2 of a second.

Phelps

will put the felt in as a preliminary as theres nought there at present.

quote_icon.png
Originally Posted by Len Matthews
Oil loss from here is usually due to excess oil in the primary chaincase. It's well known that most Twins have a tendancy for oil to pass through the drive-side main bearings necessitating the need to drain off the surplus via the level screw. "

will recheck the level as too much is a problem and it'll get topped up from the engine by the sound of it so any it leaks will be replenished. kind of pouring water from one bucket into another really isn't it.


vince998 "
Theoretically, if you could seal the primary effectively (dynamo, gearbox cover plate & detent housing, kick-start shaft tunnel etc) then the pressure in the primary would stay constant."

would be nice but the way it is now seems less breathing through the dynamo as blasting into. can't blame it really as with missing components odd crap is bound to occur.

thanks everyone for the suggestions thus far. glen.
 

Len Matthews

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These pictures puzzle me. It looks as though this dynamo is a mixture of Miller and Lucas components.The Miller certainly does not have a Bakerlite end cap so is it a Liller or a Mucas?
 

lindie

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puzzles me too. for instance, are the armatures between miller and lucas close enough in length to let this have been done? and are the field coil bolt spacings and clearances to the armature/coil similair enough that it could have worked? i've yet to have try and motor it so its an unknown at present.

i'm guessing you've not seen this before then either?

from the other post:

features of note are as follows.

casting numbers on the brush holder end 200717 above the letters F.R

said casting has nuts in hollows that meet up with the through bolts, and from photo's also the lucas type brush earth screw position.

only appears to have two wires exiting the field coil.

type d6 and a clockwise arrow on the drive end housing.

the plastic cap is a perfect fit on the brush holder end.

the armature has a keyway cut into it.

it also has a rough ground looking taper that takes a two pin type drive collar.

the coil housing has 82 stamped beside the number H7882 on the drive housing but no other stampings.

i've suspected for a while that it was made up of a lucas armature modded to take the miller drive method in a miller drive plate with the other end and components from a lucas. the coil housing may be miller too and possibly a lucas coil?

your mention that the two brands used the same bearing put me into the mood to strip it down again for photo's. has anyone ever seen this done before please?
 
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Hugo Myatt

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Chaincase oil

Len is right. I famously sealed every possible escape route for oil in my Rapide's chaincase and ended up with the oil level rising dramatically in the gearbox. The chaincase needs to breath and it does so through the dynamo drive. If you examine the Comet there is an enormous hole behind the clutch to allow the gearbox to swing for primary chain adjustment. However it doesn't leak, at least mine don't. On twins with Miller dynamos there is a dynamo locating washer (of varying thicknesses PD19, PD19/1 or PD19/2) between the dynamo bearing plate and the dynamo sprocket boss (PD16) in order to centralise the sprocket in the primary chain. This fits in the tapered recess at the back of the chaincase and reduces the size of the hole somewhat. Fitting a Lucas dynamo to a series B or C requires a tapered plug (once available as a spare) that does the same job but often needs reducing in thickness as no two chaincases or dynamos are the same.
 
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lindie

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will see how the felt goes on sunday i believe. i'm hopefully heading out to fit new carb rubbers to dads suzuki and should be able to get at the dynamo while i'm there. must take a check of how much and often the level in the chaincase rises and see if the engine level is dropping from burning or just dumping through the main bearings. thanks for the hints, glen.
 
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