Dan, I don't mind you pulling rank, I just wanted to see some form of confirmation. Thanks for the information on the brake lights, and I humbly admit my wrongness

Yeah, and it's Shivadart, don't know why it said guest I did sign in.

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My car may be slow to sixty, but at least it's been reliably slow to sixty for more than thirty years.

Well shee-yoot, I hope I didn't come across too strident and bossy!

Dan, i was just replacing my headlight switch today (and speedometer) and I found this old link. I have always wanted brighter bulbs and the green halogens would look great with my green interior. I jumped on candlepower.com but could not find the specific bulbs. Do you have a part number?

<<Stock bulbs are dim. You have to be careful about which bulbs you run, because it's easy to melt the blue plastic diffusers. If, however, you *remove* the blue plastic diffusers (just snap 'em off) your options grow. A lot. You can use a new 6w Krypton-Xenon filled bulb or a 5W halogen that's a direct swap for the originals, together with the new-type blue, amber or green silicone bulb sleeve that fits right on the bulb and will NOT melt. Or you can use a bulb called WY5W which is an amber bulb that will make the gauges light up orange instead of greenish. All these options will give you a great deal more light. >>

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God took you away, then brought you back to me.

On your '75, you need the wedge-type bulbs, so you'd want to count-up how many you need, order that many P3652 bulbs and that many green silicone sleeves (if you must...truthfully, there's no reason to have the green/blue diffusers on there.)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Or just color them with a green magic marker. Works great. I did the bulb in my tach this way and it works great.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

I cobbled up an LED replacement for one of the dash lights (#168?) with a bit of old modem, a few hundred home resistor, and a ultra-bright red LED that worked OK, but you had to plug it in w/ the right polarity.

I then saw Autozone sells a much nicer 4-LED replacement w/ rectifier and current limit built in; I think it was 2 for $10. I bought a pair, but haven't tried them yet.

These sometimes work passably well in indicator lights, but it depends on the angle and distance of the bulb holder relative to the indicator light lens. I have a blue one that works fine in my truck's high beam telltale, and a red one that works poorly in my truck's "BRAKE" telltale. The red LED actually puts out more light; the difference is distance/angle.

And, they don't work in indicator lights that have current flowing through them in either direction depending on situation (so, for example, they do not work in single green turn signal telltale lights, because current flows through such lights in one direction when you signal for a left, and in the other when you signal for a right.)

These "LED bulbs" do not work very well for dashboard illumination purposes, and they are abjectly dangerous to use in signalling applications outside the car (brake lights, turn signals, etc.)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan,
I have seen a new LED retro-fit kit from Hi-Tech in the latest MCG's new product section. This appear to have been designed specific to the models (ie, e-body 72-74, b-body 68-70 etc.). Have you had a chance to check any of these out, are they worth while? The review from MCG seemed pretty high on the increased brightness of these since they position the LED across the entire lense.

Brian

Bulb-type brake (etc.) lamps really need to use bulbs. The model-specific LED "retrofits" are certainly less godawful than the so-called "LED bulbs" (1" wafer of LEDs on a bulb base), but they still mostly aren't a good idea. The performance of all exterior signalling functions (brake, tail, front and rear turn, parking, back-up, sidemarker, etc.) is regulated in great detail. It's not just a question of how bright they have to be!

There are specifications for minimum and maximum intensity, for each different function, through a large range of horizontal and vertical angles. That's to make sure that not only can the guy directly behind you see and recognise your brake lamps as brake lamps when he's sitting at about the same height as you, but so can the guy in the next lane over to the left, sitting down low in his Corvette...and so can the guy in the next lane over to the right, sitting way up high in his semi truck...and so can the guy on the on-ramp in his SUV. There are also specifications for the minimum intensity ratio, again through a large range of H and V angles, between functions that share a lit compartment (brake/tail, for instance, or park/turn). That's so that your taillamps can't be mistaken for brake lamps, or your brake lamps for taillamps. There are specifications for minimum projected active illuminated surface area, to make sure that the lamps, when lit, are "big" enough to do a reliable job of grabbing attention and quickly and accurately conveying the intended message.

When you use a bulb in a bulb-type lamp, the entire reflector is illuminated when the bulb comes on. Now, leaving aside the photometric requirements (intensity through various angles, bright/dim ratio), take a look at these two Hi-Tech "conversions" and think about that last requirement I mentioned (active illuminated area):





H'mmm...now, without some very fancy measuring and calculating, I can't determine if these LED "conversions" will reduce the active illuminated area below the legal minimum, but it will certainly reduce it. Safety...?

As far as intensities and intensity ratios, the only way to test this is with a goniophotometer, which is just as specialised a piece of equipment as the name suggests. It's a machine that measures the amounts of light being emitted by a device, over a range of angles relative to the axis of the device. It produces a plot of the intensity that looks like this (this one's for a low beam headlamp), and from that plot and the raw data, it can be determined whether the device meets all the requirements. I do have a lot of respect for Rick Ehrenberg at Mopar Action, but snapping a picture or filming a video of taillights and saying "Gee, wow, lookit how bright they are!" just plain doesn't cut it. Neither the human eye nor a camera is an appropriate or valid measuring device for assessing the safety performance of vehicle lighting devices.

There is an additional issue with LEDs that is not at all addressed with these "conversions": Heat. Everyone knows LEDs produce hardly any heat, right? Wrong! LEDs are commonly considered to be low-heat devices due to the public's familiarity with small, low-output LEDs used for electronic control panels and other applications requiring only modest amounts of light. However, LEDs actually produce a significant amount of heat per unit of light output. Rather than being emitted together with the light as is the case with conventional light bulbs, an LED's heat is produced at the rear of the emitters. The difficulty is that LEDs' light output is extremely variable depending on temperature, with many types producing at 30° C (85° F) only 60% of the rated light output they produce at an emitter junction temperature 16° C (60° F). Take one hot day...add one traffic jam with extended brake light "on" time...and it is extremely likely that these LED "retrofits"' output will drop to such a degree that the lamp assembly will no longer produce minimally adequate safety performance.
The opposite case is also true: Many types of LEDs produce at -12° C (10° F) up to 160% of their 16° C (60° F) rated output. Take one cold night, add LED "retrofits"...and the lamps could easily fall outside of the intensity and intensity-ratio requirements.

All of these factors can be managed, otherwise we wouldn't see LEDs showing up as original equipment on some cars (and the almost complete adoption of LEDs in the standard-size lighting devices used by heavy trucks and buses). Thing is, all of those devices are engineered and tested from the start as LED devices. They are not bulb-type devices with LEDs "retrofitted" into them. They contain intricate control circuitry that compensates for output change with temperature, and advanced heat sinks that minimize heat buildup behind the emitters (with resultant output drop). They contain optics specifically designed to collect and distribute the light from LED emitters, which bulb-type lamps do not. All of that engineering and testing is missing from these LED "retrofit" kits.

It is possible that some of Hi-Tech's "retrofits" may result in safe, legally-compliant lamps. But none of the relevant information is present on their website, and their response to my inquiries was not confidence inspiring ("They're bright enough. They're really bright. Don't worry about it.") In order to know for sure, each retrofit kit would have to be tested in the lamp for which it is marketed. My experience in such matters tells me there would be a large number of failures.

Most complaints of too-dim brake lights can be resolved by paying attention to the lamps and their power source: Good, loss-free wiring on the feed and ground side, a reflector that's been cleaned and resprayed with "Chrome" spray paint from the hardware store (yes, that's really all it takes) and a lens in good condition that's been scrubbed with hot water and liquid dish detergent. Brighter bulbs can be installed to increase the lamp intensity without screwing up the ratios or viewing angles. And if ya gotta, just gotta have LED lights, that's certainly possible in many cases: Start with a standard-size truck/bus LED lamp assembly and install it complete, rightside up and straight upright, into the car's original taillamps. (An earlier issue of Mopar Action suggested cracking open a truck/bus unit, removing the circuit board containing the LEDs and using just that. NO, you lose the necessary LED optics!)

There are a few cases in which a few cars, mostly pre-1968, may have original brake lamps that are too dim even when in perfect condition and fed properly, and a truck/bus LED assembly can't be hidden inside because of physical fit issues. In that case, it can become worth looking at LED retrofits...but really only as a desperation last-ditch effort of this type.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Do you have to take shots for that?

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

So in essence, the Hitech $180.00 conversion kits ( I didnt even check prices before reading Dan's post) is a possibly not so good. Man i need to come up with something that might not work all that great that I can sell for way to much money.

Brian

Well, yeah, but you said it in only one sentence.
Man, tell me about it! *grumble grumble blue headlight bulbs grumble*

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks SlantSixDan - your are quite right about the viewing angle for LEDs; they would generally make for poor running lights and dash illumination lights.

However, these ones from Autozone should work in indicator applications where the current flows both ways, as they seem to have a rectifier built into them - they seem to be designed so they can be plugged in either way. However, I've not actually tested them yet.

I had to use a LED in place of a bulb to prevent overheating the indicator legend I'd fabricated for it (see http://www.tidewatermoparclub.com/TECH/yeehaw4.pdf). Laser printed transparencies don't seem to take heat well.

I have also used an amber LEDs for the top-of-the-hood mounted turn signals in the TMC '71 Satellite
(http://www.tidewatermoparclub.com/2000car.html) very successfully. I roughened the face of the LED and epoxied it to a piece of (lightly sanded to diffuse the light) Lexan and then used trial & error w/ resistors to get the intensity correct. When it was done and held up alongside the factory lights it seemed a very good match w.r.t intensity over the whole viewing range (which wasn't all that wide).