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Old 08-01-2004, 11:38 AM
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TopCatGr58 TopCatGr58 is offline
Join Date: Jul 2002
Location: Portsmouth, Va.
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L.E.D. Brake Light Mod

"Much less power drain, reliable, and very visible!"

by T.C."TopCat" Gresham , posted 11-16-03

Well, during the '03 Ga. Rally after riding behind "Harley" Dave and his new Yamaha FZR-1? with his LED brake lights and clear tail lens, and also reading about other XSives having trouble with dimming headlights when applying brakes, I decided to persue the LED brake light conversion for my 81Special. I had seen this link:LED tail light mod, 4" round about using a 4" round LED truck light assembly, but I thought that would be a more suitable fix for the Standards that have the smaller tail lights. With my Special and it's larger/wider tail light, I wanted to find some LED's that would better fill up the tail light lens.

Well, after doing some web surfing, and measuring of the tail light lens, I found that the OVAL shaped 6" long lights would fit perfectly, and I found some at the following web site: SuperBright LED web site . Their prices were quite reasonable($24.95), and they had a good selection of both the OVAL lights, as well as the smaller ROUND amber ones I used for my turn signals....see other tech tip for LED turn signal mod!

I run two sets of tail lights, one in the normal place behind the seat, and a second one up high on my backrest, like the high mounted ones on cars. I ordered 2 of the 6" oval light sets at $25.00 each plus shipping. After receiving them, I first took off the upper tail light lens, and removed the bulbs, and did some tests with the new LED lights, to see how bright they were compared to the OEM lights. I compared both running tail lights, and brake lights. I also compared many combinations of the cover lenses because they come sealed in a red colored lens, but the LED's are already RED in color. I cut off the cover lens from the LED's, and then temporarily mounted them in the tail light, then put the XS11 brake light cover lens on. The below image doesn't look as bright for the upper light which is the LED, because it's sitting right up against the inside of the tail light lens. When it's mounted properly against the back of the fixture, the diffusor works well to expand the light to fill up the entire rear light area!

I also noted that the OEM Special tail light lens has a clear diffusor inside the RED cover lens....hmmm!? Have Dremmel, did some 'plastic' surgery. IMHO, using the LED's without their red cover, and cutting out a large section of the red cover lens of the tail light lens provides the best visibility from these LED's, and after putting a thin clear plastic cover over the resulting 2" x 5" hole in the tail lens, I think it looks pretty decent. However, for those of you that want to keep your bike looking as stock as possible, just removing the red lens from the LED is good enough. The tail lights still look quite bright, and the diffusor helps to spread the light across the back of the tail lens so that it can be seen from a wide angle, not just from directly behind!!!!

"Doing the MOD"
The model # for the 6" Oval Stop/Turn/Tail light is 5540 R ; without flange, 61 pcs L.E.D. It comes with a 6" long 3 strand wire(ground/tail/brake) and plug so no pigtail or rubber grommet is required, just cut off the plug to hard wire it in! Get your Dremmel with a thick cut off disc/wheel, and use it to cut the red lens off at the base, just be careful not to hit the LED's or the resistors.

Next, measure and mark about a 1/4" from the base, and then cut the base off as well. The wires are hot glued into the base plate, using the Dremmel, you can cut the base right next to the wires to pull them free, or you can just cut them and splice them back together. The wires are color coded "wrong", white=ground; black=tail light; red=brake light!!

Next, cut a wedge off of each end of the light to allow room for the tail light lens mounting screws to fit around it.

Then pull the old bulbs(1157) out of the sockets. I then soldered the white wire to one of the tangs on one of the sockets for the ground. There are two holes in the back of the tail light bracket, after you loosen the mounting bolts, you can then slip the red and black wires through these holes.

Next position the LED against the mount over the bulb protrusion and get your trusty Hot Glue Gun and secure it with that!! Then connect the tail light wires splicing them into the required ones. Now replace the tail light lens cover and your done if that's as far as you want to go.

I used the Dremmel and cut a nice rectangle in the tail light lens at least a 1/4" inside the mounting screw holes, and looking closely at the tail light lens, you can see the diffusor lines in the red lens, I cut along the 3rd line from the middle above and below the position of the screw holes.

The clear diffusor sits 1/4" away from the tail light lens, so you don't have to worry about hitting it too easily with the Dremmel disc while cutting.

Next, I used the Hot Glue Gun, and ran a bead along the inside of the clear lens/red lens junction all around the inside, except right around the screw holes, to reinforce the mounting.

Then I got some thin plastic sheeting from Walmart from a picture stand for under $2.00.

I measured out and cut out a rectangle shape that would overlap the hole by 1/4" all around. Next, I used a blow dryer to heat up the plastic to bend it slightly to conform to the slight curve of the tail light lens. Then I applied a nice bead of clear silicone sealant around the edge, and stuck the clear cover over the hole to further seal the tail light lens from dust, water, etc.! Then, after it had cured, I mounted the lens onto the brake light!

The next few shots are to show the cutout lenses and their brightness with running lights and brake lights!

In this picture, they look dim, but it's difficult to capture the true appearance, either the camera makes them look dimmer than what you see with the human eye, or they look much brighter!?
First, tail lights, this view looks dimmer than actual!

Tail lights from angle, to show they are visible from an angle.

This next image is brighter than should be, top is cutout LED tail lights, bottom is OEM cover with 1157 lights to try to show comparison of brightness...look similar don't they?!

Next is brakes on showing both sets of LED's with cutaway lenses.

Same as above, but from angle to show visibility from angle.

In summation, I was running 4(four) 1157 bulbs. Running lights drew total 3 amps. Brakes drew total of 9 amps, and that got added to the 3 amps running lights at same time when applying brakes. Then add 2(two) 1156 turn signals at 4.5 amps per side if I was signaling a turn while stopped for a total surge draw of 16.5 amps!

With LED's for brakes and turn signals: 0.06 amps total running lights; 0.60 amps total brake lights; and 0.06 amps total turn signal surge for grand total of 0.72 amps, a power savings of ~15.78 amps!
You could run 2(two) 80 watt halogen headlamps with that much power!!! It's no wonder our headlights dim!! Okay, hope you have found this useful. Enjoy.
T. C. Gresham
81SH "Godzilla" . . .1179cc super-rat.
79SF "The Teacher" . . .basket case!
History shows again and again,
How nature points out the folly of men!

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