Packard Forum Index » V-8 (1955-56)

Has anyone disassembled one of these? It needs a new wire.

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You may be able to repair it. I know mine is pre-war but I expect the process is the same.
You should be able to get the assembly apart by getting the insulator disc to clear the bore of the housing. Then push the wire and the soldered endcap free of the assembly


Carefully heat the tip and remove the cap from the wire. You may find using a wire brush helps clean it up and allows the heat to flow to the solder bulb better.
While the cap is off polish up the bore of the housing to ensure a good grounding surface for the bulbs outer shank.
Dispose of the old wire and reassemble the insulator cap and spring and housing onto the new wire and place the cap on it. Again, you may have to run a drill bit into the caps bore to ensure a nice snug fit on the wire's stripped end. (Try and strip the wire just enough to have the wire's end match the caps top surface.
Solder the cap on leaving a dome of solder to act as a contact pad for the lamp.


Push everything back into the housing and celebrate with the beverage of your choice!


Have fun!
Bob J.

Getting the cap off is the hard part. Heat may help expand it if you can keep the heat mostly confined to the cap so it expands more than the can. Once it loosens a tiny bit then gentle taps with a light hammer and punch all around the edges might persuade it off. Older Mercury switches had a glass capsule containing the mercury and contacts inside the can but if it is off your 55 it probably has a steel ball inside.

If the mercury type and it has deposited some kind of oxidation on the contacts there is not much that can be done to fix those. Steel balls rust and others say a good cleaning by vigorous shaking to knock the rust off usually works for awhile. Not had one of those apart to know if the ball is just loose in the chamber or it they have a capsule as well.

Here are photos Jeff took of a 48-50 mercury type. I think the electrical part is essentially the same in the later models with the main difference being that the earlier unit has the round housing for mounting to the lid and a cover over the bulb while later cars just used the screws thru the tab leaving the bulb exposed.




My 47 had the mercury type and I was able to fabricate a plate to mount and mostly hide an external burglar alarm mercury tilt switch to take the place of the non conducting capsule. Made a plastic spacer to replace the insulator tube and take up the space the capsule formerly occupied. Also used that to move and hold the wire contact directly to where the bulb end contact could touch it. You could probably use the same method and switch on later units but would need to find a different place or way to hide the switch.

Thanks everyone. I will hit it with a bit of heat one of these days. Needs to go in the de rust bath as well.

Old analog thermostats have mercury switches in them too, I always steal all the parts out of stuff when I update for weird stuff like this in the parts bin.
Bob J.

I got an NOS one from Max Merritt. Don't remember what I paid for it, was a while ago.

Nice. Fortunately don't really NEED another. Just would like to repair this one at some point if I can. Some customers have damaged ones as well.

I still have one of the glass mercury switch capsules from a 1940 glove box light. Other than there being mercury in it, the technology was basically fail-safe.