12 volt prefocus bulbs

[Harry Moon]

When I first got my C15a Wire 5 I had a heck of a time getting the headlights to work
All the circuits worked and I tested the2331 bulbs but no way would they work when installed. I put sealed beams in instead for the winter and back to the bridge plate and blackout light in summer.
I then, (I'm slow on some things) discovered that the contact points are out 90 degrees. So I had some success heating up the flange and rotating it 90 degrees but that was of limited success.
recently in researching a guy who will make halogen bulbs to fit these things I found out that the 12 volt bulbs are 90 degrees to the 6 volt bulbs. trouble is nobody could find me any at parts stores. By chance I found out that those cheap Chinese scooters that are imported use a 12 volt prefocus bulb of the correct orientation. The part # is 6245Y. I bought 2 on eBay and they snapped in place and work.
Looking through the parts manuals I think my truck probably was originally a 12 volt and not a 6 volt, lots of different headlight bucket assembly's.
Mine was built July 44 and the headlight bucket was the original ones with the wire wrapped loom
All I did was change the Voltage regulator to 12 volt and the bulbs. Now I think I might dig up the original gas gauge that never seemed to work on 6 volt and see if it works properly now. any body else ever notice the difference in the orientation of the contact points in their headlight sockets?

[Phil Waterman]

Hi Harry

Just this afternoon I replaced the 6 volt Halogen bulbs with some of the old prefocus blubs which I had done just what you describe of re-soldering the base and rotating them. Some of the bulbs also have the ring the wrong distance to the base which is corrected the same way.

But back to the 6 volt halogen bulbs, while they are a lot brighter than a standard Prefocus bulb and with a good reflector nearly as bright as a seal beam they have in my experience a short lived. I drive with my headlights on all the time (no mater what I'm driving) and the 6 volt halogens last about half as long as a 6 volt seal beam. Put the halogen in two trucks at the same time and the low beams of both failed this spring.

Photos below are some test that I did when I first installed the Halogen bulbs. 1st picture Halogen Left standard 2331 Prefocus right both LOW beam. 2nd is Halogen Left standard 2331 Prefocus right both HI. Type of mount is the 3rd picture

Halogen is brighter and tighter but shorter lived.

Cheers Phil

PS- All three of my trucks have 6 volt systems which have not given me any reason to change over to 12 volt having said that, all three trucks carry 12volt batteries as well to power radios and accessories . When I put the 261 engine in my C60S I was concerned about starting so I installed a marine battery switch will allow me to shift just the starter over to the 12 volt in an emergency to start. Think I've used the 12 volt for starting maybe twice.

[Harry Moon]

It could be Phil that your trucks light fixtures were on a 12 volt truck, if original maybe your truck(s) was originally 12 volt? Try those 12 volt bulbs, no re soldering of 2331's

[Phil Waterman]

Hi Harry

I got my blackout headlights years ago, don't even remember where. They are visual match to those shown on the 1945 production HUPs and to what is shown in the late Driver Handbooks.

As to bulb numbers I will have to look to see if I am using the same number your are. Which could explain the difference in the base.

Cheers Phil

[Lynn Eades]

So back then, to change over from left hand drive to right hand drive, you would have installed a left dipping or right dipping bulb.
Is this anything to do with the problem?

[motto]

I've always believed that l/h or r/h dipping is determined by the lens pattern and that the bulb remains the same as does the reflector.

Somebody will know for sure.

David