Various Electrical and headlamp shell questions

Information relating to the Matchless G12 or AJS Model 31 650cc twin
Spock
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Joined: Wed Dec 21, 2016 12:07 am
Location: Inverness

Various Electrical and headlamp shell questions

Post by Spock »

I am rewiring my 59 G12 and while repairing and replacing parts of the bike have come across a few issues that are a bit unclear.

Headlamp shell - someone in the past had drilled out the captive mounting bolts. I have bought the chromed bolts that screw into the shell but need the nut size so I can reweld new ones into the shell to replace the drilled ones. Also the mounting bracket holes seem to be very large, the mounting bolts are simply going to be floating around in these. Is there a spacer of washer needed for these of has someone drilled these out too?

Alternator - my alternator does not have the standard colours but I have found similar from a bantam, orange, green and yellow. Trying to work out whether it is simply the wrong alternator or whether someone has changed the colours, any ideas on whether this colour scheme is known on any normal alternator?

Brake cable routing - my front brake cable doesn't go through the holes in the handlebar bracket or between the forks like the speedo cable, looking at it it seems to me it would be slightly too long to do so without some bends, is this normal or would, as I suspect, have the wrong cable probably fitted which is slightly too long?

Any advice appreciated
Mick D
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Re: Various Electrical and headlamp shell questions

Post by Mick D »

Hi

I'm not aware of any 'adaptor' washer for the headlamp mounting bolts, the bolts are 1/4" x 26 TPI BSC from memory, (may possibly be 5/16" but easy enough to check with a ruler - still 26 TPI). Sounds as if someone has drilled out you mounting brackets - easy enough to fix if you have access to welding / brazing equipment.

Can't help with the alternator question other than to suggest checking the part number online - stacks of Lucas data available.

My front brake cable does not route through the lower yoke but does go through the upper - I used a cable supplied as per the parts manual number and the fit looks spot on.

Regards Mick
Spock
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Joined: Wed Dec 21, 2016 12:07 am
Location: Inverness

Re: Various Electrical and headlamp shell questions

Post by Spock »

The holes I am meaning are arrowed, the nuts within the headlamp shell will be easy to fix by welding in two new nuts of the correct size.
The holes in the brackets arrowed are about twice the diameter of the new bolts though and were much bigger than the nuts and bolts originally in there, and the new ones. Can't see why they would have been drilled out so large, hence me wondering if I am missing some sort of spacer?

The brake cable route on the bike is arrowed, I assume it should go through both upper and lower yokes instead? as can be seen if I do route it this way it will be too long, particuularly once the bike forks are compressed. I assume the cable is incorrect.
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dave16mct
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Re: Various Electrical and headlamp shell questions

Post by dave16mct »

Sounds like you've got '55-57 headlamp brackets for sidelights. These had bigger holes without an inner thread because the sidelight's nut held it on the inside. You could make a thin sleeve to go between but you'd be better to swap for the correct brackets. From memory the colours were green/light green and white/dark green and white, or something like that. I'd convert to 12volts if I were you, so much easier!
Dave
Mick D
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Re: Various Electrical and headlamp shell questions

Post by Mick D »

Hi

Sorry - I've just been out and checked, (age has obviously got the better of me), the cable passes through the lower yoke as well - not sure this is as it came out of the factory but it looks 'right' to me.

Regards Mick
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Rob Harknett
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Re: Various Electrical and headlamp shell questions

Post by Rob Harknett »

Someone may had fitted torpedo sidelights in the past.
Spock
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Joined: Wed Dec 21, 2016 12:07 am
Location: Inverness

Re: Various Electrical and headlamp shell questions

Post by Spock »

Not familiar with torpedo lamps but can guess. The hassel of changing them for something you won't see once assembled means that spacers are probably the way forward here.
I am currently converting the bike to 12v Neg wiring, hence the current work.
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Rob Harknett
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Re: Various Electrical and headlamp shell questions

Post by Rob Harknett »

It could also be possible the parts are from an early model that did have the torpedo sidelights.
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Duncan
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Re: Various Electrical and headlamp shell questions

Post by Duncan »

I do not run my brake cable through any of the holes as I find it reduces its effectiveness as the forks compress and the cable bends, just find a straight run where the cable has room to move. Not all top yokes have the cable holes, I assume these were the later ones, can any one categorically confirm?
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Rob Harknett
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Re: Various Electrical and headlamp shell questions

Post by Rob Harknett »

Good point about not running through holes. They can limit steering lock. When you tried the cable length, in the lever with the bars fitted etc. Did you turn the steering, fully both ways, which the cable length must allow to do so..
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