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Lucas tail light + signal relocate DIY

22K views 28 replies 18 participants last post by  rodhotter 
#1 · (Edited)
Well, I searched and searched, and finally just pieced together what I could in order to do this job. It didn't take long to realize I was on my own for a lot of this. It seems almost weekly I see posts on the Lucas tail light, people wondering how to do it. (I was one of them) So I thought I'd post a little help. I know this is easy for a lot of you experienced guys. But many of us out there have trouble doing some stuff on our bikes when we don't receive, at least, a little bit of coaching.

I hope I'm not repeating a how-to on the Lucas light. If I am, sorry guys, move on.

I also noticed that most want to relocate their tail lights when they do this. I thought I'd maybe give people something to think about if they don't want to spend the $10 to $20 for the brackets. Of course, this isn't the only way to do this.

If anyone has better ideas, please post them here. Hopefully this will help future would-be fabricaters.

Part I: Lucas Tail Light



As you can see, the base of the light doesn't really match the curve of the stock fender. Depending on where you place it on the fender, this gap may even be visible with the rather thick base gasket in place. So I did a little taping on my light, and got the tools I needed (air grinder with sanding disk, air saw (for signal brackets) and vice grips (also for brackets)). Using masking tape, I marked where I needed to sand to:



The sanding left a very sharp edge, so a disc sander with 180 nicely broke the edge, preventing the light cutting through the gasket in time. I wanted my light a little higher on the fender so that the top of the light is level. If I had used the pre-existing holes in the fender, my light would have been pointing at the ground. So after much positioning and visually testing, I decided on a placement which yielded these holes (the 3 smallest holes are the ones I drilled):



Using the pre-existing top hole to feed my electrical wires through, I fitted and attached the light. For the electrical, I just used electrical connectors that can be found anywhere (the male/female type). Having already removed the lights and harness from the fender, I clipped the ends off (leaving them with the stock lights in case I ever needed to put them back or sell them) and attached the new ends. As for the ground for the tail light, notice the eyelet I attached on the harness. This is because NEITHER of the 2 wires on the tail light are a ground. The light itself is its own ground. But just attaching it won't work because the fender is not grounded to the frame well (or doesn't seem to be after much inspecting). That eyelet should be attached to 1 of the 3 bolts holding down the light. This will ground the light.

A previous post by Forchetto gave me the insight of how to differentiate the running/position/marker light wire from the actual brake light wire. Touch the base of the light (the ground) to the negative terminal of your battery. Touch each wire, one at a time, to the positive terminal. You'll see very easily. In this case, the black wire is the brake, the red is the position light. On the harness, blue is brake, red is position.

Here is the link to his post:

http://www.triumphrat.net/twins-talk/195774-wiring-new-indicators-and-lucas-tail-light.html

Now, there are several ways to wire for the signals. We'll get to that later. But as for the tail light, this is the finished product underneath:




Part II: Signals

I really like the placement of the signals at the rear shock mount point, but... With my lowered bike, and keeping the back fender, I feared that with the lower profile of the lights, cars behind me would not see them if they were at any angle other than straight behind. So I opted to place them at the rear of the seat. (Not to mention they look pretty slick there, too)

I saw many brackets in many different places. I used book shelf brackets I found in a local home improvement store. Then, after removing the seat, decided to use 2 of the 4 pre-existing holes (I think used for grab rails? Not sure) So I just marked the brackets, placement of the attachment holes on top and on the side for the light mount. I drilled the holes with a unibit (some call them step bit) Cut them down and sanded the edges smooth and the visible face to accept better the paint:



Painted them up, and here we go



Ok the wiring. There are several ways to do this. I'm a person who will do 3 times the work to maintain originality, so I didn't want to cut up the wires of my harness. So I split the sheathing and ran the 4 signal wires back from halfway down the fender, then wrapped the sheathing back and taped it up like mad with electrical tape:



Had I to do it again, I would have probably just cut away the sheathing close to the connector, isolated the 4 wires, clipped them there, attached the connectors there and just left the 4 dead wires hanging at the back. But this is my first time, so I guess I'll allow myself one misjudge.

For those of you who don't have your manual, on my '06 Bonnie, the left rear signal hot is orange and right rear hot is brown. Blacks are grounds. I'm not certain of which years these colors were used. The manual has that info. If anyone needs help and has no manual, I'll be glad to help.

One more thing: The stock light comes with zinc-plated screws. If you will EVER drive your bike in the rain, please spend a little extra and get some stainless bolts/washers/nuts. I opted for the hex-keyed. I think they just look cleaner. If you're here in Jacksonville, I highly recommend "Threaded Fasteners Inc" A .70-.80 cent stainless bolt in Ace Hardware costs me around .08-.12 cents at TFI. Awesome guys. Super helpful, not only on prices but on application information. Very knowledgeable.



And so this is the finished product. Hope this helps any future fabricaters/electricians. I got this light from Bella Corse and I really like it. It's much sturdier than the stock plastic one.

Be nice guys with any criticism. I do appreciate it, though, when it's constructive. Any additional help or info will be appreciated, I'm sure, by future readers.



 
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#4 ·
Wow thanks so much guys! It seems almost every time I do something, THEN I see something or talk to someone that helps me realize that there are better ways to do it. This one had me stressed for a few days before I started. I really appreciate this forum though, especially all the posts by Forchetto. They helped me a lot. Thanks again
 
#5 · (Edited)
Thanks for writing this up. The pictures and description is very helpful.

This is on my list of one of the first mods when I get my bike. I HATE the shameful stock lights and this will be the thread I turn to when I do this.

One note. If could add the link to Forchetto's thread (where you mention it) in your tutorial it would make it easier for folks to reference it.

Thanks again.

Cheers.
Brian

PS... what length shocks are you running in the photos above?
 
#6 ·
Thanks. Point noted. The link is now there. Shocks? 300mm. I love them but might be going up to a 310. I'm kinda scared of the kickstand bracket scraping. I still have to lower the front so I'm about to, at least, try to sell them on the classifieds. I think maybe a Speedmaster might be better suited for these.
 
#7 ·
Sweet look Kreem, and a great step by step write up. It'll be a fine addition in the search function for others. My Lucas rig up is similar but very different. I hadn't even thought of those attachment points under the seat. I made two small right angle brackets, then bolted one side to the Lucas tail light using the two bolts that hold the Lucas interior reflector in place. The other side of the bracket then bolts the stocker turn signals in place, right and left.
I know everyone hates the stock signals, but I had them and as usual in a hurry.
That T100 has really inspired you! Congrats on a fine job!
 
#8 ·
Haha thanks. Yeah, Triumphs have always appealed to me, but the new Bonnies have so many after-market parts, it's a tinkerer's paradise. Now I'm brainstorming ways to make it mine. I'm about to paint the fenders and am considering some coatings on the covers in the engine area. Also looking into powdercoating my rims, but I'm afraid to know the cost (de-chroming first, lacing the spokes, etc.) But it's fun anyways.

I'm not quite clear on your light setup. Post a pic? Might be something for another person to consider...

Ride safe
ksT100 :cool:
 
#9 · (Edited)
Great post! Great pics! I have a Lucas rear light & a mudguard from a 2006 Bonnie in the garage and I've been meaning to chop it down and make a shortie-lucas rear end for my Thruxton - your post may be what I've been needing in way of a kick start!
 
#15 · (Edited)
Yes, I just bought some 310mm shocks (10mm longer). On the other side, I had them set on the softest setting. When I twisted up the preload it seemed to have helped a lot. Thanks.

Hey about to do this myself but with the catye/oval one.

Don't you think these wires should be better protected?
That couldn't hurt. The section of I shielded wire is actually very short. I don't worry nearly as much about the wires showing as I did they're passing through the metal fender. For the moment I have a little electrical tape around the edge of the hole until I can think of a way to fabricate a grommet.

I do plan to get the extra wire to tuck in behind the light, though. I didn't mention that I had to also do some cutting on the light base gasket to accommodate the angles of the screws and the wiring. The pic was for the sake of the write-up. Of course, this post was only to provide suggestions/ideas for those who don't know where to start (like me). It would be great if someone has a better suggestion and posted it here with pics. Hopefully one day we'll have a complete, definitive way to do install it so there's not all the confusion that has existed for so long. Thanks for the suggestion
 
#21 ·
Thanks for the compliments, guys. Very kind of all of you. I'm really glad if this thread can help in any way.

Ed, that's a VERY good piece of advice. There are a few things I would have done differently, and that's one of them. Like I posted in the main article, I probably also wouldn't have doubled-back on the harness, I would have bypassed it (for the wiring of the signals). Regardless, it would have been wise to stagger the splices. I still plan on redoing a few things there at the back end, but with all my other projects, I haven't been in the mood. Probably next week I'll clean it up a little more on the under side. I have to black out the signals, so that'll be a good time.

Thanks again, all!
 
#22 ·
nice install! i just trial fitted my bellacorse oval lucas light, very poor IMO! i know nothing can be done for the lower offset other than a nice setup like Maund's which is more costly but fits perfectly for those without the desire or ability to REFIT a NEW part that should fit correctly no GRINDING IMO!!
 
#23 ·
i just received the maund setup, VERY NICE, he cuts down the light for a perfect fit to his own base for a perfect fit using the original holes and filling the lower offset, even though thats mostly covered by the number plate. i may give it a go to match the oval tail light i prefer. using weatherproof connectors that have hear shrink on them works great for a good seal, lots of slop under the rear mudguard for sure
 
#24 · (Edited)
Hi just wanted to share this alternative to the rubber thing that comes with the lucas tail light:



Ø1cm black wire with the smaller wires inside removed. It looks perfect and compensates for the difference in curvature between the mudguard and the taillight :)
 
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