L.A.B. wrote:

britbike220 wrote:The third wire on the original looks to be a ground only, but I don't get how I am suppose to get a brake tail combo with two wires? Help anyone?

I think the early bulb holders only ground through the actual tail lamp unit itself, and the later tail lamps have "proper" ground wire, check how the two tail lamp wires connect to the bulb holder, as the tail lamp assembly should still have a double filament bulb holder with two insulated bulb contacts?

I suggest you run an additional ground from the tail lamp assembly back to the harness or other ground point?

Yes, early ones ground through the tail lamp.

You would think for the money vendors charge they'd supply the right wiring and the part would somewhat fit without modification, but welcome to pattern parts from china. I'll try running a ground from the lamp housing to the harness like the original.

I supplied an extra wire and it works now, thanks guys. Hopefully I'll have it on today.

britbike220 wrote:You would think for the money vendors charge they'd supply the right wiring

They did,- didn't they?

If your early style tail lamp has no ground wire-then it's got the right wiring!

L.A.B. wrote:

britbike220 wrote:You would think for the money vendors charge they'd supply the right wiring

They did,- didn't they?

If your early style tail lamp has no ground wire-then it's got the right wiring!

If he has an aftermarket tail light (like I did) then the wires are black and red.

But that is acceptable as that tail light fit many bikes, not all of them using the Commando color scheme.

Dave I think I have the same black/red wired housing you have, but I had to add a third wire grounded to the lamp housing as LAB described? At any rate it works with the extra wire and I have everything made so I hope to have it on today. I really don't think the cheap thin plate bracket is going to last long with vibration.

I didn't want to drill my rear fender either, but definately wanted a Lucas 679 taillight on my '74 MkIIA. I removed the original tail light and mounted the 679 backing plate on my original DOT mandated way oversize taillight bracket where it looked right to me, I scribed around the top of the 679 backing plate, then I cut off the top of the original mounting bracket to match the shape of the new tail light. I filed and sanded it smooth and repainted it. Then I installed the fiberglass fairing on the bracket and cut it back so it was as close to the size and shape of the 679 as I could get it. I then used styrofoam to fill in the small gaps between the cut off part of the fairing and the recut bracket and sculpted the foam to contour everything together into the 679 shape. The foam just served as a mold pattern, and I sanded it smooth and layed up 3 layers of fiberglass and epoxy over the foam and the remains of the original fairing. After it set up I removed the foam from the under side of the fairing, sanded and smoothed up the new 'glass and primed and painted it. The bracket bolts right up to the fender just as it did originally, holds the much more pleasing to the eye Lucas 679, looks like a factory piece, and if I ever want that big wart of an original tail light back on, all I need is a stock '74 bracket and fairing. Of course if I had known of the CNW or Old Britts brackets I could have saved a bunch of time.......

flyboy49 wrote:I didn't want to drill my rear fender either, but definately wanted a Lucas 679 taillight on my '74 MkIIA. I removed the original tail light and mounted the 679 backing plate on my original DOT mandated way oversize taillight bracket where it looked right to me, I scribed around the top of the 679 backing plate, then I cut off the top of the original mounting bracket to match the shape of the new tail light. I filed and sanded it smooth and repainted it. Then I installed the fiberglass fairing on the bracket and cut it back so it was as close to the size and shape of the 679 as I could get it. I then used styrofoam to fill in the small gaps between the cut off part of the fairing and the recut bracket and sculpted the foam to contour everything together into the 679 shape. The foam just served as a mold pattern, and I sanded it smooth and layed up 3 layers of fiberglass and epoxy over the foam and the remains of the original fairing. After it set up I removed the foam from the under side of the fairing, sanded and smoothed up the new 'glass and primed and painted it. The bracket bolts right up to the fender just as it did originally, holds the much more pleasing to the eye Lucas 679, looks like a factory piece, and if I ever want that big wart of an original tail light back on, all I need is a stock '74 bracket and fairing. Of course if I had known of the CNW or Old Britts brackets I could have saved a bunch of time.......

Um, pics?

Well I got it done looks good except it appears to dip down a bit, not bad, but I notice it. In my mind it should come off the fender straight out w/o a dip. If the holes were drilled different I think it would look better, but I guess when converting something there can always be something a bit out of whack. I ended up making two extra brackets for the plate to mount to the narrow plat bracket provided. It started storming so I couldn't take a picture. I'll try and post one Saturday. Guys I thank you for all of the input.

The finished product on my beater

http://good-times.webshots.com/photo/2640884610097461507nAwrfU

britbike220 wrote:The finished product on my beater

http://good-times.webshots.com/photo/2640884610097461507nAwrfU

Not bad.

It is used very regularly and needs a lot of cosmetic attention. Actually have to redo the swing arm which I have never done and am not looking forward to. I bought Heinz K's brackets two years ago and just didn't have the ambition to take the old girl apart, but I am to a point where it needs to be done. Anyway Thanks Dave

Wow that lasted just a few days over a month. I would not recommend buying an aftermarket early tail light and retro fit to an 850 from......never mind it's been hashed over already. Any way the thing broke from vibration and is now a candidate for the vendor wall of shame. Looking at the design, I can' believe anyone would think this is a sound way to put a part together. A shallow nut embedded in fiberglass as a mounting point with stress and pressure. It will either pull out, vibrate loose or both. I am going to try and cut a slot put a bolt in the mounting hole with a washer and then jb weld it in. That is the same type of concept they used for the 850 tail lights. the 850 lights are butt ugly, but fairly sound. All may not be lost yet.