"I like the led idea, especially to replace the double filament bulb, which I suspect melts the tail light during long periods of braking."

It is one of those "silly engineer" myths that the bulb is melting the tail lamp's plastic. People are quick to blame the design, rather than its implementation.

If the brake lamps were the cause of the melting, they would have been melting in the first few warranty years back in '79, but the heat is actually generated by the lousy oxidized connections - bulb to holder, holder to flex circuit - caused by moisture ingress from leaky welds in the tail light's housing.

When you replace those pricey flex boards, you fail to address the problem if the plastic has already deformed, reducing the contact force at the bulb holders and harness connector. That spring force is what deforms the plastic as the heat softens it. That force is what keeps contact resistance at a minimum. So the new boards quickly become like the old ones.





Once you wire around those bulb holder and harness connectors, you've fixed the heat problem permanently.



And if you solder to the bulb holders, you still have easy access to bulb replacement -- and you will need to replace bulbs, because those leaky lens welds will fill them with water, and the eighth-inch drain holes you drilled will wind up being clogged by debris.

Sure LEDs will reduce the heat, not only in the generation of light, but in reduction of the current (I) in the high-resistance contacts (R) by I-squared-R losses. Then you have to sort out the bulb failure warning consequences, which in the aftermarket industry have been addressed by load resistors, completely negating the efficiency and current reduction benefits of the conversion.

So not only do you wind up wasting time, but also some pocket change. However, the process and the learning that accompanies it is what makes a hobby attractive.


--
Art Benstein near Baltimore

When the smog lifts in Los Angeles, U. C. L. A.