great thread!
what would the cost of certification add to each unit?
Not very much, in the context of all the R&D, tooling, and production costs of a product such as this. A full compliance workup from a lab like Calcoast would probably cost less than $1000, and then the manufacturer's got airtight proof his product conforms; all he'd ever have to do is produce that paperwork and demonstrate that his regular-production lamps perform the same as the ones he sent in for compliance testing and he's met his legal burden; then no liability can be hung around his neck for property damage, injury, or death resulting from a crash. Talk about cheap insurance, and it'd probably pay for itself in increased marketability of the product, too: "Our lamps are fully DOT-certified and we can prove it".
All products for vehicles from 1967 and back can then use any lighting devices they want?
Not quite. For one thing, many components that fit '67 and earlier vehicles also fit '68 and later vehicles, and the law is that any regulated item of vehicle equipment must comply with the regulations if it is
physically capable of being installed on a regulated vehicle. There is no provision in the law for exemption phrases and usage conditions like "For Off-Road Use Only" or "For Pre-1967 Cars Only". Some vendors, importers, and manufacturers apply labels to that effect on their products, in the mistaken belief it shields them from legal and civil liability. It does not.
Moreover, some US states and Canadian provinces have their own vehicle equipment codes which contain design, performance, and/or compliance requirements for vehicle lights.
Finally, even if you can figure out a way to zig and zag and duck and dodge your way around the various laws ("Let's see here...my car's a '66, so no Federal requirements, and if I read my state code a particular way that could be considered reasonable, there's no state law against this what I want to put in my car's lights, so I'm gonna do it!"), it's unwise to do so unless you are absolutely (and objectively) sure the lighting devices or modifications you're going to put on your car will give (objective) safety performance at least equal to the original equipment. This really can't be determined by observation because a lot of the aspects of safety performance aren't obvious. You may think your modification is going to improve the performance of the system, and in some respects it might, but in other respects it might well do the opposite. That's why manufacturer certification is important and required. All vehicles come with lighting systems that perform in accord with the requirements. These are based on the idea of standardized signaling so that everyone on the road can immediately determine what the vehicles around him are "saying", without having to stop and think about it. There's a fair amount of flexibility built into the regulations -- some functions like front parking lamps and rear turn signals give a choice of two colors, and there's a range of allowable intensity throughout the regulated visibility angles, for example -- but the limits of that flexibility are established to provide immediately and unambiguously clear messages. It's probably not a problem if someone has to take a second or two to figure out your message on a rural road with only three cars on it and a speed of 30 mph. It's quite another matter at 70 mph on the interstate in heavy traffic.
And then (yes, this really is a lot more complicated than it seems on the surface!) there's the question of mounting. What if you put a standard truck/bus 2" x 6" oblong LED brake/tail/turn light behind the vertical lens of your '66 Valiant, or a standard 4" round unit behind the round lens of your '64 Dart? As long as it's not obstructed and as long as it's mounted facing straight rearward -- not angled up, down, left, or right -- then it'll be fine. Those units, as long as you buy a reputable major brand, are all appropriately tested and certified. But if the LED unit is tilted, even just a little bit, then the light distribution will be wrong; there will be safety-crucial angles from which your brake lights won't be properly visible. Maybe it'll mean the guy in the Honda Civic in the next lane, or maybe it'll be the guy behind you in the tanker semi who doesn't properly see your brake lights as a result. Luck's not worth relying on; vehicle safety lights really need to work
all the way correctly.
