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View Full Version : Riddle me this (LED 1157 bulb)



KT
08-26-2009, 7:51 PM
Alright here is a good one....

My bike has a sparto tail light with a 1157 bulb ..Well my bike shakes and rattles at the rear fender (fender is tight and you can pick the bike up by it) it just vibrates violently cause of the triumph thumping ...Anyways I stop off at the auto store grab 2 LED 1157 bulbs thinking ok here we go problem solved .....

Nope and here is were it is interesting ...Stick the bulb in nothing ..Take the bulb over stick it in the 76 cb 750 lights right up ...grab a regular 1157 stick it in the triumph lights right up ...

Biggest difference is the honda has 3 wires on the tail light and the triumph has 2 and the triumph is +ground .... So I tried grounding the tail light on the triumph with a 3rd wire nada nothing

So does anyone know WTH is the difference in a LED 1157 and a regular one?
My bike is wired exactly like this except I have it + ground and 2 6v coils instead of a dual..

http://raskcycle.com/techtip/webdoc16a.html

eightthirtysixcc
08-26-2009, 8:23 PM
Try putting a resistor in line, that should fix it (8 ohm). Or just go buy a dual sport tail light bulb. They put an extra brace on the filiment to keep it from braking. Thats what I use on all my bikes. They are meant for hard core off road use so they hold up impeccably on the street.

Go to Honda and get a bulb for an XL500

L7Josh
08-26-2009, 8:48 PM
i agree its probably a resistor issue

choncho
08-26-2009, 9:53 PM
you need special bulb for positive ground. power can only flow + to - in a diode.check out this site.[URL="http://www.norbsa02.freeuk.com/goffyleds.htm"]

eightthirtysixcc
08-26-2009, 10:34 PM
Ah, missed the bit about positive ground... Never had any experience with that type of system.

JL
08-27-2009, 12:24 AM
you need special bulb for positive ground. power can only flow + to - in a diode.check out this site.[URL="http://www.norbsa02.freeuk.com/goffyleds.htm"]

Yep, LEDs are diodes which only work in one direction.
If you isolate your bulb holder from your bike's frame you can wire it however you like, allowing you to use regular LED bulbs.

billyd
08-27-2009, 1:14 PM
Here's the easiest way to do it:
http://i219.photobucket.com/albums/cc105/rc51billy/triumph%20build/LEDwiringdiagram.jpg
Basically just trick the LED by isolating the light housing so it's not grounded and reverse the wiring to positive ground. Worked like a charm for my Triumph.

rus
08-27-2009, 10:41 PM
there's no way those wires are gonna be long enough, that diagram is faulty.

billyd
08-30-2009, 11:46 AM
there's no way those wires are gonna be long enough, that diagram is faulty.

Uhhh, you're kidding right?

If you're not kidding, then you're wrong. I've used this diagram on a couple of Triumphs to run LED lights with no problems.

NHMike
08-30-2009, 4:08 PM
Uhhh, you're kidding right?

If you're not kidding, then you're wrong. I've used this diagram on a couple of Triumphs to run LED lights with no problems.

Yeah, unless the iginition and EVERYTHING ELSE is mounted to the rear fender then those wires are WAAAAY too short, hahahahaha

rus
08-30-2009, 4:13 PM
dude, it was a joke.

Gepetto
08-30-2009, 4:56 PM
L.E.D.s don't like pos. ground.

KT
08-30-2009, 5:14 PM
Thanks ..I rewired the bike - Ground ...found out the disc in the light was'nt indexing right with the bulb and lighting both lines ...So I had to take apart another light and use that socket but all is good now Thanks again ....

billyd
08-30-2009, 5:23 PM
dude, it was a joke.


Yeah, I kind of figured that the part about the wires being too short was a joke, but wasn't sure about the diagram being faulty part. ;)

BubbaKahuna
08-31-2009, 10:26 AM
Just for future reference, many LEDs not only don't like positive ground, but will instantly fry if you power them up that way. You got lucky if you pushed positive ground into an LED array and it still works.

It would be easy for light makers to make a positive ground version, butapparently they don't see enough of a market (at least in the US) to bother making them.

Cheers,
- JJ

Beaner
09-01-2009, 8:03 PM
A diode is like a check valve. Lets power flow across one direction but chokes it off the other direction.

The thing you also have to remember is that + and - is that Voltage flows from + to - but actual electrons flow the opposite way. so on a Triumph or + ground system is that voltage flows from the battery to the frame and the wires actually carry the current from the negative terminal to the load and into the frame back to the battery. A regular incandesent light could care less how it gets its power.

KT
09-01-2009, 9:34 PM
Roger that ...I shoulda thought about it alittle harder burn out I guess =P ... I went from metal worker welder to computers as a occupation bad ironworking accident seen to that.... I have converted pc case with all kinds of LED lights and mods ...just wasn't thinking ...put one mark in the duh category ....Thanks for straighten me out though ..I need it sometimes =)

Easy
09-01-2009, 9:46 PM
ahahaaa(snort)hahaha this post is gooood.

s650t
09-14-2009, 5:59 PM
I figured I'd keep the LED questions together...

I have an old taillight with an 1158 bulb. Does anyone know of a LED replacement?

I'm assuming that LEDs have a "running light" that's always on, emulating a dual filament bulb?

If I need to, I don't mind gutting the taillight and gluing in a cluster of LEDs if that's a better solution.

KT
09-14-2009, 6:17 PM
I figured I'd keep the LED questions together...

I have an old taillight with an 1158 bulb. Does anyone know of a LED replacement?

I'm assuming that LEDs have a "running light" that's always on, emulating a dual filament bulb?

If I need to, I don't mind gutting the taillight and gluing in a cluster of LEDs if that's a better solution.

I am pretty sure a 1157 and 1158 are damn near same bulb ...mine is a 1157 but it has running light plus brake light so it has two brightness levels ....Just go down to your local autozone or whatever ya got and go look at bulbs they will have them I would almost guarentee it....

L7Josh
09-14-2009, 6:43 PM
i think the only difference is a 1157 is single contact and the 1158 has two im guessing but im sure it isnt too far off

KT
09-14-2009, 8:02 PM
yea if i still had the cardboard they came on I would read it I think it actually said it replaced 1157,1158

JoeNots
09-15-2009, 12:09 PM
perfect thread for me right now. my friend just told me he can't see my tail light at night if i get too far ahead of him. i need a brighter light & i think the LED will be just i need. thanks