Farrar's car blog

[Farrar]

I would STRONGLY advise against that. That diffuser also acts as a DOT spec reflector, required on the car. CD's will not work as needed in all safety situations. I personally think its an excellent part of the taillight system. The only mod anybody should make on the taillights would be to make the running light a combo-brake light. Which it appears is all you plan on changing now.

Why on earth would I use a CD? They have light diffusers where I work on all the fluorescent tubes; I can cut a sheet of the same material to fit the middle housing.

With the effort it seems your planning to put into this, I dont see why you dont just get a set of new taillight boards?

Planning in my case is not much effort; I simply take out a pen and paper and start drawing stuff. The reason I plan on using a Weatherpak connector is because I don't like the stock edge-clip connector.

Farrar

[dmc6960]

Why on earth would I use a CD? They have light diffusers where I work on all the fluorescent tubes; I can cut a sheet of the same material to fit the middle housing.

Because Bill used CD's.

Do your diffusers from work have a DOT certified reflector in them? Its difficult to diffuse, transfer light, AND reflect light. Our taillights do it, but I rarely see other cars today with their DOT required rear red reflectors running double duty with the lighted parts.

[Farrar]

Because Bill used CD's.

Do your diffusers from work have a DOT certified reflector in them? Its difficult to diffuse, transfer light, AND reflect light. Our taillights do it, but I rarely see other cars today with their DOT required rear red reflectors running double duty with the lighted parts.

Ah, so I think I see what you're getting at -- both a diffuser close to the lens and a reflector behind the bulbs would be necessary. Interesting.

I had forgotten that Bill used CDs, it was so long ago when last I looked at photos of his setup.

What do you mean by "running double duty with the lighted parts"?

Farrar

[dmc6960]

See this picture of a Mustang tail light...


You'll see the primary running/brake/turn signal lights on the top 3/4. On the bottom right 1/4, you'll see the reverse. And on the middle/left bottom 1/4, you'll see the required DOT red rear reflector. The reflector portion does not light up with the running/brake/turn signal. This type of setup is what I typically see on most cars. Our cars are fairly unique in which the running light segment also has the DOT reflector in it. Thats what I mean by double-duty.

BTW, putting a diffuser in front, and a reflector behind the bulb would be no good. The reflector is for OUTSIDE light, not the taillight. The idea is an oncoming car would see the illuminated reflectors and know about your car if it were completely dark.

[Farrar]

The reflector is for OUTSIDE light, not the taillight. The idea is an oncoming car would see the illuminated reflectors and know about your car if it were completely dark.

OK, I think I understand now -- so it's a requirement that there be reflectors, like those safety strips on construction vehicles, and it's OK to shine light through them as long as they do their job, but it isn't necessary.

So would it be illegal to simply have all three red bulbs as 1157s without removing the diffuser/reflector? I know it wouldn't match in intensity but that's not my main concern.

Farrar

[dmc6960]

So would it be illegal to simply have all three red bulbs as 1157s without removing the diffuser/reflector? I know it wouldn't match in intensity but that's not my main concern.

No it would not as long as there isn't a significant difference in visual appearance. There are specifications min/max brightness of both a running light and a brake light. I dont know specifically what they are though. In general, it would be illegal to have the bright filament of a 1157 on as your running light. So as long as you have them all dim for running/park, and bright for brake you should be fine. If I were doing this myself I would only add bright brake function to the running light. I would personally not add dim running function to the brake lights.

[Farrar]

If I were doing this myself I would only add bright brake function to the running light.

Well, that's easy enough. Are you going to?

Farrar

[dmc6960]

Well, that's easy enough. Are you going to?

Perhaps as an experiment sometime next year, but likely not this year. I need a replacement taillight assembly for the passenger side (amber is moderately faded), and both taillight boards are marginal at best (original boards with poor soldering repairs). So fixing up the taillights is on my list of things to do before next DCS.

[dmc6960]

Here is the full text, minus the images, for the federal DOT regulations regarding external lighting and reflection...

http://fmvss108.tripod.com/fmvss108text.htm

Standard No. 108: Lamps, Reflective Devices, and Associated Equipment
Scope and Purpose:
This standard specifies requirements for required original and replacement lamps, reflective devices, and associated equipment and their installation. The purpose is to reduce traffic crashes, deaths and injuries resulting from crashes by providing adequate illumination of the roadway, and enhancing the conspicuity of motor vehicles on the public roads so that their presence is perceived and their signals understood, both in daylight and in darkness or other conditions of reduced visibility.

Application:
Passenger cars, multipurpose passenger vehicles, trucks, buses, trailers, (except pole trailers and trailer converter dollies), and motorcycles

[content22207]

Feds are of the opinion that I should be running catalytic converters. Feds are of the opinion that I should not be running a carburetor. I am not about to go running in fear from the specter of Federal boogymen.

My car passed a North Carolina safety inspection. According to a state licensed safety examiner, it met all legal requirements to drive on public roads.

All I know is: my tail lights do not look as ridiculous as a stock DeLorean with only one anemic tail light illuminated in a sea of red lens.

Any DeLorean owner following behind me, who thinks I am driving 80 MPH with my foot on the brake, is crazy.

BTW: I did not use CD's in Position 3. I tried that already -- they don't work. My 3rd positions have proper reflectors, just like positions 2 and 4 (I made concave rears, then lined the entire housing with chrome tape).

Bill Robertson
#5939