Thread: Lucas Motorcycle tail light

If memory serves - the little brass disc should be soldered to the wire and makes contact with the end of the lamp (bulb). The spring, threaded onto the wire under the brass disc, is compressed when the lamp is is pushed into place and keeps the disc in contact with the lamp
Return is back to the frame via the lamp bayonet fitting.
(used to ride a 1942 Matchless G3L)
Mark

The ground I think runs through the body of the light as you said Mark. One wire attaches to the spring and the other to the brass plate, that is it????

I thought there should be something soldered to the brass but there is no sign of any solder. Maybe with age it has just cracked off and vibrated out.

How does high & low beam work (tail & stop) ?

I know nothing about wiring & electrics.

Ah, Lucas, Prince of Darkness.

I used to have a Triumph car. The (lucas) fusebox used those glass tube fuses, but not in the common 3AG size, but an almost identical (but seemingly 2mm shorter) size called 3EN. They were not interchangeable. No-one had heard of the 3EN size, either, but that's what was stamped on the fuse cap. I got good at putting new fuse wire into blown fuses and soldering it to the endcaps. Then I got a dremel and got good at grinding down the length of the 3AG fuse glass.

If your light fitting is stop & tail, there should be two (coloured) wires coming into the unit , one from lighting circuit & one from the brake light switch & they will connect to the two terminals on the base of the lamp (bulb).


If you have only one wire coming in then you just have a tail unit & ground is through the lamp (bulb) holder.
If you have two wires into the unit & one of them is black that is probably ground and you just have a tail lamp unit.


The attached pic shows an old Lucas tail only unit with black ground wire.
IMGP3224.jpg

Mark

Originally Posted by Old-Biker-UK

If your light fitting is stop & tail, there should be two (coloured) wires coming into the unit , one from lighting circuit & one from the brake light switch & they will connect to the two terminals on the base of the lamp (bulb).


If you have only one wire coming in then you just have a tail unit & ground is through the lamp (bulb) holder.
If you have two wires into the unit & one of them is black that is probably ground and you just have a tail lamp unit.


The attached pic shows an old Lucas tail only unit with black ground wire.
IMGP3224.jpg

Mark

Mine's quite different to that. the little brass (or maybe not) disk goes between the spring and the globe.

TaDaaah1.jpgTaDaaah2.jpgTaDaaah3.jpg

Hi Mate. I just had a look thru my jar of 50+yr old terminals with no luck. They used a brake rivet type dovee with the wire either crimped or soldered in as contacts for the bulb,I have seen the wires pushed thru the fibre washer with a neat dob of solder on the ends large enough not to pull back thru, they should be available somewhere as vintage cars would use the same. As a quick fix you could find brake rivets or I would use pop rivets with the pin knocked out and then crimp the wires in, you might have to drill the rivet out to get the wire in to be crimped. Your fibre base washer is in good nic, next check the bulb pins they should be straight inline with each other but could be staggered make sure the bulb holder is the same, your two wires are power for stop and one for tail with the earth thru the frame or ideally with it's own wire from a common earth to the light frame, your spring should be a good fit in the bulb holder not sloppy as it could earth out on the terminals. With your bulb the heaviest filament is the stoplight you should be able to swap the two power wires near the light if you get the wires #### about and the rivets should be a neat fit in the washer and not too long so they don't earth out when the bulb is installed. I have tried to Upload a drawing with no luck if you PM me your Email or Fax I will send it. Sorry about the one sentence the computer is chucking a wobbley again. Hope this helps.

Originally Posted by DSEL74

Mine's quite different to that. the little brass (or maybe not) disk goes between the spring and the globe.

TaDaaah1.jpgTaDaaah2.jpgTaDaaah3.jpg

Now that I've seen what you have, I can repair the wiring on that socket for you, whereabouts in Melbourne are you?

Originally Posted by DJ's Timber

Now that I've seen what you have, I can repair the wiring on that socket for you, whereabouts in Melbourne are you?

East Doncaster… But happy to Put the lens back on and ride light less to you.

Originally Posted by DSEL74

East Doncaster… But happy to Put the lens back on and ride light less to you.

PM me your address and mobile, I'll be in North Ringwood over the next few days doing log recovery and my folks live in Mitcham, so I won't be going out of my way to pick it up.

Looks like Whitey & DJ have sorted it for you.
Ride safe & remember it's rubber side down & shiny side up.......

Mark

Phew! Computers are the "Devil's work" finally uploaded on Chrome

Originally Posted by whitey56

Phew! Computers are the "Devil's work" finally uploaded on Chrome

Ok that diagram makes sense except where and how did the extra parts disappear???? Parts fall off my bike all the time blue loctite is no match for the vibrations of the bike, but in this case the housing and lens were sealed and the light had been functioning previously...

Looking at your photo's someone has done a bodge where they pushed the wires thru the washer then splayed the bare ends over, you can even see a witness mark on the fibre washer from the bulb contacts. In the sixties you could buy a small brass split washer which would fit on before splaying the wire which you could add a dob of solder or leave as is. Going buy the size of the holes in your washer there would have been some sort of rivets. All this bring back memories of when I was a apprentice mechanic at a transport firm and all I seen to do was sweep floors and fix lights.