Thunderbird 6T Alternator Connections

[VintageBike]

Guys,
am lucky enough to have acquired a 1954 6T Thunderbird in unrestored and totally original condition.  Hopefully only needs a bit of fettling to get it on the road - but I need some help.  After taking the primary chaincase off to check condition, most of the soldered connections from the alternator have broken where they join the wiring harness.  

Q1. - How on earth do I work out which wires from the stator go to which cable?  Can anyone advise?

Thanks

Nigel.

[L.A.B.]

Nigel,

Do you mean the wires have broken directly at the stator?

What model stator is it?

If it is an original I would expect it could be a non-encapsulated RM14 type?

What (loose) wire colours have you got going to the stator from the harness?    

[VintageBike]

Yep I believe it is an RM14.  Certainly non-encapsulated.  I have a few of the staor wires still connected to the harness, but I have 3 (as i recall) that have become disconnected.  One has broken quite close to the coil so will need extending slightly in order to reach the harness (can you buy that insulated wire?).

The harness I have has green, white and black cables extended to the stator.  The cover is currently back on, so I can't recall the current (excuse the pun!) connections.

Nigel.

[L.A.B.]

The harness I have has green, white and black cables extended to the stator.

I would have expected to find light green, dark green and green/yellow wires coming from the stator, and continue into the wiring harness (as there should be three bullet connectors somewhere between the stator and the harness?).  

[VintageBike]

I'll pop the cover off in a bit and just check what I have....!

Nigel.

[VintageBike]

Current wiring is:
Black disappears into headlamp sheel - appears to go to ignition switch
Green follows an identical path to ign switch?
White to rectifier.

Of the six stator coils:
1, 2 & 3 not connected,
4 connected to green
5 connected to white
6 connected to green

What may be confusing the issue here also is that the bike is an imbetween model and still has magneto ignition (from 53 spec) but with an alternator.  

[VintageBike]

An update...had another dig, and it seems that I may have misread the wiring:
Current wiring is:
Black disappears into headlamp sheel - appears to go to lighting switch (no ignition switch on a mag! )
White to rectifier.
Green to a terminal not currently connected to anything, but could easily have become disconnected from rectifier.  Further cable from this terminal goes to light switch.

I have found a wiring diagram from a later T110 which is based on the same combination of Mag and alternator and this seems to fit i.e. two wires from alternator to rectifier and one to light switch.

Assuming this to be right, does anyone know how the wires from the coils would be connected to these three?

  

Nigel.

[L.A.B.]

Nigel,

I must admit I'm having problems understanding what you are describing?

As I understood it you had three of the internal (non-encapsulated) stator wires loose (the ones that link the various coils together that join up before the wires leave the stator body?

Then there should be a short length of sleeving from the stator containing *three* wires with connectors which connect to the wiring harness? Which on an RM14 could be coloured light green, dark green and green/yellow?

But you said:

I have a few of the staor wires still connected to the harness, but I have 3 (as i recall) that have become disconnected.

Are you saying that you actually have six wires coming from the stator?

Are you describing the stator output wires as 'harness' wires?

I would certainly expect two (of the three) stator wires to go to the rectifier and the other to the lighting switch.

Perhaps if you could describe the setup in a little more detail please?      

[VintageBike]

Les,

here is a picture - hopefully may help!

Obviously the sleeved cable has ben replaced at some point with a different colour scheme.
Yes, there are three wires "hanging" from three of the coils.

http://www.vintagebike.co.uk/YaBBAttach/alternator.jpg

Does this help?

Cheers

Nigel.

[L.A.B.]

Thanks Nigel, that confirms what I thought the problem was.

Unfortunately as I don't have an RM14 handy I can't really be of any help, although someone else here might?

If not, then I would think Al Osborn would be able to help?:
http://www.aoservices.co.uk/index.htm

[VintageBike]

Les,

thanks for the contact.  I'll be in touch with him today and will let you know the answer (just in case you are ever as ham-fisted as I was!)

Cheers

Nigel

[VintageBike]

Les,

for your info, the following should be:

1. The low output connection (normally green/black, but white in my case) should have a connection to the stator

2. The high output connection (normally green/yellow, but black in my case) should have two connections to the stator.

3. The common output connection (normally green/white but green in my case) should have three connections to the stator.

So its simply a case of connecting one of the floating stator wires to the green cable!

That is the easy part!  The hard part is that there is no way of telling which stator wire!

Even Al Osborn (a superb recommendation by the way) wouldn't be able to tell other than by guesswork.  An incorrect guess will result in reduced output.

So, it's a question of how lucky I feel!

Thanks for all your help - I've certainly learned something here.
Nigel.

[L.A.B.]

Thanks Nigel, and I do have the Lucas stator wiring layout diagrams, although unfortunately it doesn't show which of the coils is which!

Possibly you can tell from the wire gauge of the windings and the spacing of the rotor magnets which coils need connecting together?

And I am glad that Al Osborn was able to give you some assistance, although the wiring colours you mentioned apply to the later alternators!
Originally the wire colours used for the single phase three wire alternators would have been: light green, mid green and dark green (certainly for RM13) by RM14 this had been changed to light green, dark green and green/yellow.

Later the colours changed to green/white, green/yellow and green/black, and later still, the green/white (green with white tracer) was changed to white/green (white with a green tracer).

It is also worth noting that the wires are configured differently on these early systems according to whether they were used for battery/coil, capacitor or non-ignition (magneto) systems.

The mag/alternator versions only using two coils for charging, the other four were used for the lighting circuit. This information coming from the Lucas Service Manual of the period.

Although of course the complete system could be upgraded and fitted with proper voltage control, and if the original rectifier is still fitted then I would seriously consider replacing it.    

[VintageBike]

Les,

do you happen to have the Lucas info in a soft copy that you could email?  Sounds like a VERY useful doc.
No problems if it is too much work.
Cheers
Nigel.