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Discussion Starter · #1 ·
Has anyone split the two bulbs into turn signals? So they run dual purpose.
Similar to newer LED turn signals.
what would be the “how to”?
 

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Use the brake light bulb for both brake and turn signal, the tail light will still be fuctional. However it would be best if the running light on that side turned off when one side was flashing so that an on off pattern was established rather than a bright dim pattern.

Personally not something that I would recommend. I want those following me to know very clearly what I intend to do. Separate widely spaced turn signals achieve this goal.

I suspect this is a case of form over function. I never notice the esthetics of my bike when I'm riding and that is what I want to do with mine. To each their own.
 

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Discussion Starter · #4 ·
Would still keep turn signals, if I changed them they would be for a dual set also.

Got the idea while following a Harley that had this set up. Was the most visible thing I’ve seen on a bike.

1980’s technology vs. 2020’s
 

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Discussion Starter · #5 · (Edited)
OG taillight would remain. Instead of it only getting brighter when brake is applied, a on/off to one half of the tail light would happen when turn signal is on.


ANKIA 40-LED 40W Motorcycle Tail Light Integrated Running Lamp Brake&Turn Signal Light with License Plate Bracket for Harly Motorcycle Street Bike Cruiser Chopper (Black) Amazon.com: ANKIA 40-LED 40W Motorcycle Tail Light Integrated Running Lamp Brake&Turn Signal Light with License Plate Bracket for Harly Motorcycle Street Bike Cruiser Chopper (Black): Automotive
 

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OG taillight would remain. Instead of it only getting brighter when brake is applied, a on/off to one half of the tail light would happen when turn signal is on.
For this to work it would need to be the brake light which flashed. If it was the tail light which flashed that wouldn't be very visible with the brake light on steady, The flashing of the brake light would be more visible if the tail light on that side was extinguished while signalling a turn. I think that this could be accomplished using a couple of relays.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I've considered replacing the ugly Custom taillight with a pair of lights on the sides. Using front signal assemblies with red lenses could give the same tail light/brake light functions. Placement would need to be carefully considered.
 

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Discussion Starter · #8 ·
I've considered replacing the ugly Custom taillight with a pair of lights on the sides. Using front signal assemblies with red lenses could give the same tail light/brake light functions. Placement would need to be carefully considered.
Check out the ones from Speed Moto I linked above.
 

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I don't like the one-piece ANKIA unit, but the pair from Speed Moto is OK.
For the build I'm considering, I liket the look of period parts, so I'd want to use the stock signals. I think there are red lenses available in the aftermarket.
 

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Discussion Starter · #10 ·
I don't like the one-piece ANKIA unit, but the pair from Speed Moto is OK.
For the build I'm considering, I liket the look of period parts, so I'd want to use the stock signals. I think there are red lenses available in the aftermarket.
I like the stock parts too, that’s kinda why I was asking if there was a way to integrate the dual purpose of the newer tech into the original parts.
I was hoping it was just adding extra wires and not relays.
 

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Relays are no harder to add than extra wires.
 

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Watch out with putting relays into the brake lights, they aren't fast enough and every moment counts when it comes to warning people behind you of your intents. I'd want to rig it up with a couple transistors instead as the delay would be minimal. Or rig it so the relays are on normally, so the brake light works at normal reaction time, but the relay can cut one side off in sync with the flasher. IIRC some study was done and they found the cars with LEDs which light up faster than traditional bulbs statistically were rear ended less often, so the speed of the light turning on is already slower than optimal.
Here is an example of a relay that may work well for this, it has both normally open and normally closed outputs and costs a couple dollars. Definitely a bit overkill in terms of amperage tho... https://www.mouser.com/datasheet/2/315/Panasonic_05172021_Relay_Automotive__TE_Series_-2326578.pdf
Found a decent writeup on relay designs here http://autoshop101.com/forms/hweb2.pdf
 

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In the UK the L and R indicators must be at least 240 mm apart (I think, or something like that) to be road legal on a motorcycle. I guess putting the indicators in the rear light housing would not achieve this, would it? Aren’t there similar rules in the USA?
 

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Discussion Starter · #15 ·
In the UK the L and R indicators must be at least 240 mm apart (I think, or something like that) to be road legal on a motorcycle. I guess putting the indicators in the rear light housing would not achieve this, would it? Aren’t there similar rules in the USA?
Good point. It would not be legal for turn signal only. 4” is what I found.
I would want to apply this idea in addition to turn signals though.
Essentially adding a turn to one side and a brake light to the other.
 

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I would want to apply this idea in addition to turn signals though.

Ah, ok, well I’d put my money and effort into some nice neat little bright LED indicators and not try and incorporate into rear lights. But each to their own.
 

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Discussion Starter · #17 ·
Watch out with putting relays into the brake lights, they aren't fast enough and every moment counts when it comes to warning people behind you of your intents. I'd want to rig it up with a couple transistors instead as the delay would be minimal. Or rig it so the relays are on normally, so the brake light works at normal reaction time, but the relay can cut one side off in sync with the flasher. IIRC some study was done and they found the cars with LEDs which light up faster than traditional bulbs statistically were rear ended less often, so the speed of the light turning on is already slower than optimal.
Here is an example of a relay that may work well for this, it has both normally open and normally closed outputs and costs a couple dollars. Definitely a bit overkill in terms of amperage tho... https://www.mouser.com/datasheet/2/315/Panasonic_05172021_Relay_Automotive__TE_Series_-2326578.pdf
Found a decent writeup on relay designs here http://autoshop101.com/forms/hweb2.pdf
What transistors would be needed?
 

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What transistors would be needed?
Depends on how you run it but a couple mosfets as are probably the way to go - main consideration is that they have the ability to dissipate the power requirement of the bulb. You'll want to run them in "switch mode" as if they weren't linear devices. Here is a quick tutorial on it but I recommend both learning more about these things and building some test systems before bolting anything to a bike, since the brake lights are sort of critical for safety. https://www.electronics-tutorials.ws/transistor/tran_7.html
 

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The easiest way would be to use a trailer light adapter that is made for connecting trailer lights that use the same filament for tail and brake lights to a car that uses separate bulbs for tail & brake lights.

BUT it wouldn't be legal. US DOT and Transport Canada regulations require a 4"/100mm distance between a turn signal and any other light that is on when the signal is flashing. This is a good regulation because if a signal is close to another light it is hard to tell if it is flashing.

I have to agree that changing to signals that are more visible would be a better use of your time/money/effort.
 

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Get one of the wiring adapters that allow single-light trailers to function properly behind car/truck with separate brake and turn signal bulbs. Splice it in. Have fun riding!
 
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