Jump to content

890 front signal bulb- question for GM is why?


Guest jimmyk

Recommended Posts

So, why DID GM chose to use a halogen, expensive 890 bulb for the front signals? 2057NA's were inexpensive, common and would not have required the amber globe in the lamp housing. And would not have needed the resistors since they are dual filament.

Link to comment
Share on other sites

Hard to read the minds from almost 30 years ago. The 2057NA had two problems, matching the 194A output and size. The front lens array is pretty slender and the socket for a 2057 is relatively large. GM wanted to have that front array display a uniform brightness in Park mode but at the same time they had to meet federal requirements for turn signal brightness. Granted the 2057NA could meet the later, but I don't think it would have matched the lower level outputs of the 194A bulbs. Cadillac (the ones who actually did most of the design work on the Reatta) seemed very concerned about uniformity of illumination as they went with 2057s across the entire tail light even though only the outer 3 per side actually implemented the higher output circuit, so that same concern is likely why they designed the front array as they did. Again, I don't think there would have been physical room for 2057 bulbs as they require not only a much larger socket but also more room for heat dissipation.

Link to comment
Share on other sites

Dug out the actual lumen output of the 194A and the 2057NA bulbs. The 2057NA has a low filament output of 24 lumens while the 194A outputs 19 lumens. That is not a HUGE difference, but it puts the 2057NA about 25% brighter than the 194A and that is in the range where the human eye can detect the difference. This plus the significantly larger socket size of the 2057 series are likely the base reasons for the choice of the more complex and expensive 890 route that was chosen.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...