round logo
Nat'l POC logo


Revisiting LED Auto Lights

by Phil Lapin / CPPC Tech Committee and President

In August 2018 I wrote an article about LED lights for our vintage cars.  Since that article, there are new additions to what are available in LED lights, including one style I have taken great advantage of.  I have also learned that not all LED bulbs work well as direct replacement for filament type bulbs. 

For reference purposes, you may want to visit to see what is available as of 2020. Look under “Products”-“Automotive”- then filter to “6 volt”.

FestoonFirst, let me address the issue of swapping out LEDs for filament lights. All of the bulbs I purchased were of good quality – so I am not being critical of the actual products.  What messes up some swapping is the specific design of LED bulbs.  Single LEDs radiate light outward in one direction only – typically under 120 degrees.  It is the nature of the device. Many of the replacements have an array of LEDs mounted radially around a solid central “core”.  In this way, they can radiate light in all directions. The problem is that if you look at only one side of the lamp, only a portion of the LEDs with shine on you. The rated output is only partially available, reducing the light value.  If you use these types of bulbs in a mounting that has a very efficient reflector, you may get somewhat near the rated output. If, however, you stick them into the instrument cluster backside, they don’t have the advantage of a great reflector, so they appear very dim.  I found this to be a major issue in several applications on my car.  I ended up reverting to filament bulbs in these situations. There may also be an issue of clearance in some tight fitting enclosures.

Another variation on LED bulb has a “cluster” of LEDs pointing directly away from the metal base.  These work well for taillights, brake lights and such, as ALL of the output is focused in one direction – similar to a flashlight beam.  They still will not look the same as a filament bulb from behind the glass lens, but they will be bright.

Overall, you must consider the design of the lamp housing and location before choosing a particular LED lamp. That can be difficult when looking at a picture, but just keep in mind how LEDs radiate light.

There is another style of LED lamp that I discovered, and now have used several of on my car.  It is a “festoon” bulb (similar in design to older glass fuses).  Both the bulbs and the mounting bases are available through the site. These also produce a very directional beam of light – but it can be rotated in the mounting socket. The backs have an integral heat sink. I have used these for my rear dome light, interior side lights I fabricated, as well as one under the dash.  I plan on using others under the hood and in the trunk.  It is easy to mount the bases for them. In the picture, I have made up a metal mounting to lower the profile of the bulb, which has worked out well. Have fun with them!

Click here to see a bigger picture.