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Request for advice - Miller dynamo problems

BlackLightning998

Well Known and Active Website User
VOC Member
Evening all,

Doesn't it always happen this way - getting the bike ready for Ace Cafe this Sunday (Black Shadow day) I knew I had had a problem on the dynamo side - not charging last time I ran the bike - anyway I took the end cover off to find the commutator has "eaten" itself with once copper segment disappeared completely and some serious chunks missing from the carbon brushes as a result.

I was advised to speak to Stuart Towner and sure enough he will be able to sort the dynamo for me - hurray, however the question for the Forum this evening is about running the bike this weekend.

I've got a 14AH battery - so fully charged there will be no problem riding the bike in daylight to and from the Ace - even though she's on electronic ignition it pulls next to nothing from the battery.

My question for the Forum is about leaving the bike safe and rideable for the trip. I don't want to leave the dynamo running as is, if something else breaks down and the dynamo seizes there could be bigger problems!! Removing the dynamo from the bike would leave the bike not oiltight - so seems sensible to leave it in place if I can and remove/disconnect the drive.

I've opened up the primary inspection cover, removed the assembly as follows on drawing M014 - nut (198), (dynamo lock washer PD23 is missing), dynamo drive plate (PD17AS), dynamo sprocket (PD15/1), dynamo oil thrower (PD28) and so only dynamo sprocket boss PD16 is left on the shaft.

Question - am I safe to button up again and run the bike with PD16 left on the shaft with no lock nut? Or should I use nut 198 to tighten up on the end of the shaft, although there doesn't appear to be any way of getting some purchase on the nut whilst holding and preventing the dynamo armature shaft from spinning.

Or should PD16 come off - if so, any bright ideas of how to pull it off?

If that's done, does that mean everything is off that needs to come off the primary drive side and I can simply replace the inspection cover and happily ride the bike?

Thanks all.

Stuart
 

timetraveller

Well Known and Active Website User
VOC Member
Years ago when I used to sprint in the production class I would take off the dynamo sprocket etc to reduce the power taken by the dynamo. Everything was taken off but the PD16 left in place. It never came loose so go ahead and enjoy the day. :)
 

johncrispin

Well Known and Active Website User
VOC Member
Dyno

Stu,
No harm in leaving the (bare) end of the armature shaft. The whole lot is Ok in situ, it is after all clamped in. I am going to try to make it up on Sunday, regrettably not on the Shadow, but I have a spare 12v Miller ( my spare) if you want to use it while STU T. fixes yours.
 

BlackLightning998

Well Known and Active Website User
VOC Member
Many thanks John...

Hi John,

Sounds like the PD16 can stay in place on the shaft for the run on Sunday - that's good news and I'll button it up again in the morning.

I think I can manage for the 3 weeks that Stuart says he needs - I intend doing the Bill Hancock Rally in York on 7 June so should just make it all back together for that. If I get stuck perhaps I could give you a call and take up your offer - very kind of you indeed.

What's driving my calculation is that the bike has a 14AH battery fitted and the ameter shows discharge at less than 0.5A when running so the electronic ignition system is clearly not taking much. On that basis, so long as I am riding in daylight, I should be OK for my runs out and about.

I've got the famous AA card if I get stuck.

Fingers crossed Stuart T. can get me all back together again even sooner.

Interestingly Stuart suspected that perhaps with headlight on the bike may be drawing too much as the dynamo is rated at 50W. I can't find a marking on the bulb but from it seems to only draw 2 to 2.5A when switched onto main beam. It's not the first time Stuart says he has seen the commutator cry "enough".

Cheers John, and thanks again so much, really appreciated.

Stuart
 

petermb998

Well Known and Active Website User
VOC Member
Hi Stuart
Don't forget the small amount of current you will use for your brake light.
If you have a spare battery and some were to fix it safely i would consider taking one with you. fully charged of course.
Hope to see you at the riders Rally.
peter
 

Len Matthews

Well Known and Active Website User
VOC Member
PD16 left on the shaft? Definately not. I wrecked the primary drive and damaged the crankcase of my outfit when competing at Cadwell. Like Norman, I decided that I didn't want the dynamo whirring round whilst out on the circuit so I removed the sprocket and oil thrower but omitted to put the retaining nut back on. After two laps of practice PD16 broke loose from it's taper and got carried along the top run of the chain and burst out of front of the crankcase. The chain was reduced to fragments and the clutch sprocket was in three pieces plus damage to crankcase and cover. End of racing that day!:(
 

timetraveller

Well Known and Active Website User
VOC Member
Following Len's comments I thought I would go out to my workshop where my old sprint engine, complete with Miller dynamo and PD16 lurks. No way I could get the PD16 off by hand but as soon as I put a puller on it, it came loose. It has been sitting there for more than 40 years since I sprinted and for the several years whenI was sprinting. I must have been lucky so listen to Len and see if you can get a small puller in there and take off the PD16 or somehow wedge the dynamo shaft and get a nylock nut on there. A question. Why would anyone want to continue to use a Miller dynamo? Is this a question of originality? They were unreliable 50 years ago and almost everyone changed over to Lucas regulators and then to Lucas dynamos (series'D's). With a total potential power output of 50 W they are hardly the thing to be using in modern traffic. Many a night I used to have to ride home without lights, only switching them on when other vehicles appeared. I remember one night passing a whole bunch of late night, unlit party returnees on a quiet country road who must have thought that they were about to be devoured by an invisible roaring, clattering demon as I hurtled past. Modern traffic conditions are not condusive to such youthful indiscretions!! :cool:
 

BlackLightning998

Well Known and Active Website User
VOC Member
Hi Stuart
Don't forget the small amount of current you will use for your brake light.
If you have a spare battery and some were to fix it safely i would consider taking one with you. fully charged of course.
Hope to see you at the riders Rally.
peter
Brakes, what are those - aren't they something that those modern, new fangled machines have to stop you!!

Seriously, cheers Peter. I'll now put a 3/8ths BSF nut on the end of the shaft with a little medium locktite if ||I can find a way of stopping the shaft spinning, charge the battery full and head off to enjoy myself with an AA card in my pocket!!

See you in York one way or another...

Stuart
 

BlackLightning998

Well Known and Active Website User
VOC Member
Thanks Len - and now for the next step.......

Len, thanks for the advice.

PD16 is on and the nut is now fully home with some "frequent" locktite, battery's on charge so all being well in a couple of hours I will take it for a spin.

Thanks to Bruce for sending details of the "little puller".

So the next question for the Forum is - how do you take the dynamo off if the PD16 collar is on a taper fit.

I'd have thought I slacken off the mounting cradle bolts and simply pull it/slide it towards the gearbox side - but I am guessing it is not that straightforward?

I would think that even the gentlest of tap on the end of the armature shaft will be exactly the wrong this to do and cause real damage given the tolerances of the arnature spinning in the housing.

I'm sure many members will have done this job many times - here I am once again as a spanner wielding novice not wishing to damage anything, later on I'll find time to read the books - but advice eagerly sought and gratefully received.

Thanks to all who've replied so far.

Cheers

Stuart

PS - Really looking forward to the Shadow Anniversary Event at the Ace Cafe tomorrow - weather is looking hot and sunny like last year - watch the Forum for some new pictures tomorrow evening.
 
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