I just had my 1927 Model T repainted and am having trouble getting the headlights to work. I assume it is a grounding problem
Does the headlight bucket get grounded through the bolt to the headlight bar?
Also does the bolts holding the bar to the fender require grounding (rubber pad installed)
I know the headlights were removed for painting. I do not want to ruin any paint while trying to ground
It grounds thru the mounting bolts/brackets, the bolts that mount the bar to fenders then thru the fender irons to frame. You will need to clean off some paint in all those areas to get a good ground. Can't ground thru paint! At least clean the paint out of the holes to help and lock washers should dig in some and help ground.
Take an ohmmeter and check ground from socket to bolt which holds headlight to bar. You should have nearly zero ohms. Then check from the hole in the bar to the fender bracket. If both lights do not work, I would suspect the problem is in the connection between the bar and the bracket. Next check from the bracket to the frame. If the starter will work, your frame is grounded and you shouldn't need to go any farther in your check. Be sure the head of the fender bolts at the underside and the bar make a good contact and also the nuts and lockwashers at the bracket.
To get a good ground I will strip short sections of copper stranded wire. I place the strands between mounting pieces. It will bite just enough to provide a good ground. Since it is copper, it doesn't rust either.
You may have problems with grounding where the bulb holder moves in and out for focussing. It either has to ground through the adjuster or via the fixed tube in which the holder slides. Neither is very good.
I soldered a wire from the holder itself to the lamp body.
A quick easy test to be sure it is a ground problem is to turn the light on, then with a volt meter connected to a known good ground like the engine block, frame etc., touch the other probe to the ground, or outer part of the light socket. If you get a voltage reading, it means that the ground is poor! The higher the voltage, the worse the ground is! Ideal would be no voltage reading at all.
Can you use the same wire to ground the valves that you use to ground your headlights ?
You guys are nuts. The car was assembled by Ford with bare metal to bare metal. It survived the past 90 years and did not rust, because those bare metal spots did not have any oxygen or moisture on them, thus no corrosion.
For goodness sakes scrape off the paint in the areas necessary and move on to a legitimate problem. You are making problems for yourself and future owners by adding unnecessary wires.
6 volts will not pass through paint.
6 volts will pass through bare metal.
Connections should be shiny and tight.
Paint is highly over rated.
Get out your knife and start scraping.
Make things work, not look pretty.
Thanks for the advice
I will begin scraping paint to get good grounding
I have a British car that I will not mention here, other than to say that it has dual connections on the headlight bulbs, DC bayonet type. Single filament bulbs. It has two wires and they both run back to the fuse box, where there is an "earthing strip". This is not unlike how a house is wired. Yes, there are more wires in the system, but it is a good way to do it when the body is made of wood and grounding is not certain. My model T has no trouble with its single wire system. "the all steel Model T"