Author Topic: 1964 GM PD4106 Tail and brake lights  (Read 6010 times)

Offline Iceni John

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Re: 1964 GM PD4106 Tail and brake lights
« Reply #15 on: June 27, 2014, 08:02:38 AM »
Wasn't Odyssey Sean talking about HID retrofits of headlights, not LEDs?   Putting an HID capsule in a reflector designed for incandescent lamps is A Very Bad Idea, but LEDs are a different matter altogether.   As long as the LEDs don't produce more scatter or glare than the original lamps, what's not to like?

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Offline Jeremy

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Re: 1964 GM PD4106 Tail and brake lights
« Reply #16 on: June 27, 2014, 09:59:43 AM »
I'm not sure there is such a thing as a direct-replacement HID bulb because they require the electrical supply to be upgraded too, and come complete with their own wiring harnesses and ballasts.

I was operating from memory before but just tried putting "sean led bulb" into the search box at the top of the page, and immediately found not just one but several previous threads where Sean talked about the illegality of the LED bulbs. As I said before, the "What's not to like" is simply that the reflectors are designed around a single point source of light which the common Christmas-tree type of LED bulbs can't replicate - if you have a light source (actually multiple light sources) which aren't at the focal point of the refector, the beam pattern will obviously suffer. High School physics, as someone said

But that isn't to say that the latest high-wattage LEDs similar to the sort now used in headlights couldn't overcome the problem by providing a true single point source of light at least as powerful as an incandescent filament

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Offline shelled

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Re: 1964 GM PD4106 Tail and brake lights
« Reply #17 on: June 28, 2014, 12:08:40 AM »

My point about incandescent bulbs is that, while for simplicity's sake you talk about them as being a point source, in actual fact this is absolutely untrue.

The light source in an incandescent bulb is a tungsten alloy wire more or less 3/8 inch (close enough to 1 cm.) long depending on the wattage which, due to manufacturing techniques/tolerances, is mounted at some varying length and distance from the theoretical focal point of the reflector.

This is a good reason why Sean punted to the regulatory case against LED replacement "bulbs.". Ow that DOT approved versions are available the old argument has no basis.

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Offline Cosmo

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Re: 1964 GM PD4106 Tail and brake lights
« Reply #18 on: July 01, 2014, 07:46:02 PM »
Thanks Will, looks like I will give those lights a try. Th e y look like exactly what I'm looking for.
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