Jump to content

Headlights terribly dim - where to start?


John_Mc

Recommended Posts

Hello, I've searched the archives but can't find an answer. My 37 Z has very dim headlights and I'm not sure where to start. I'm not expecting them to match today's standards but right now it’s like having two candles out front.

Start by checking grounds? OK where are they? Oh, and I will NOT consider a 12 V system or LED or Halogens, rather keep what I have.

Link to comment
Share on other sites

The sockets need to be clean and shiny. They are grounded to the buckets, clean there. The buckets are grounded to the body (Clean there) which is grounded to the frame. The battery ground must be clean and affixed solidly to bare metal at the frame and tight to a clean and shiny battery post. Proper gauge wire to the headlights is also important. New bulbs can be brighter than used ones also

Link to comment
Share on other sites

Very well done article. I will start with eliminating any corrosion and go from there. As stated earlier, modernizing would of course solve the problem but I don't mind the "yellowish" old style of light on this 80 year old car but right now I can't really see much at night.

Link to comment
Share on other sites

Obvious clean connections, lenses and shiny reflectors...no brainer..

now, with a volt meter see what your generator is putting out at 1500-2000 rpm...

this car has a cutout, not a voltage regulator, it is either charging or car is off..the charging rate

is adjusted by moving the 3rd brush..if you increase voltage, you must operate those lights or radio

or risk boiling your battery..To brighten lights, increase volts..I have set my voltage regulator style car to charge

at about 7.4, lights ..You can have your cut out rebuilt with modern circuitry that operates as a regulator..

These lights are not very bright period. Time for some trippe lights or you ought to consider halogen 6 volt bulbs

in your factory buckets, no one will know, and you might actually see at night..

Edited by Mssr. Bwatoe (see edit history)
Link to comment
Share on other sites

John, you are probably not delivering sufficient voltage to the bulbs. The bulbs require at least 6 volts to obtain normal brightness. Your battery should deliver about 6.3 Volts when the generator is not charging.

If you have a foot dimmer switch, I would start by operating it about 50 times. If that doesn't fix the problem, then do a voltage drop test. This will pinpoint the area of high resistance, and will reduce the time to repair that problem.

Connect the COM (black) lead of your voltmeter to the NEG terminal of the battery and the other lead to the wire going into the headlight. Turn on the lights. If everything is alright, your meter will read 0.2 Volts. If you have a reading higher than 0.3 volts, move your red lead back to the dimmer switch input.

A good light switch will show 0.1-0.2 volt on your meter. Any reading higher than that and you should disassemble the light switch, clean and lube it with Tuner cleaner from radio Shack and a little Vaseline. The same can be done to the dimmer switch. If you need help with this, I can probably come up there some afternoon, when the snow clears.

You can also check your ground circuit that sane way. Connect the Red lead of the meter to the POS terminal of the battery and then probe the headlight mounting with the black lead. Turn the lights on. You should have a reading between 0.0 and 0.1 Volts. The ground for the headlights is through socket to the bucket, to the fender, to the body, to the frame, and through the ground strap. The ground strap should be a 6 volt strap, just like the battery cables should be 6 volt cables.

When you are sure that you have the correct voltage to the bulbs, I would install new ones. Bulbs get dimmer as they age and you do not know how old these bulbs are. I would also modify a flashlight reflector to fit in the tail light housing behind the bulb. This will double the light that reaches the lens.

Halogen bulbs require much more current than the stock wiring can handle. If you are going to them, you should consider bringing a 12 gauge wire from the battery connection on the starter switch to a relay panel on the left front fender. Use the current wiring to pick the relay(s) and feed the lights with the 12 gauge wire, through the relay points.

Edited by 19tom40
add text (see edit history)
Link to comment
Share on other sites

19tom40, Are you sure about those voltage readings? I would think that you should see somewhere near battery voltage, give or take a few tenths of a volt for wiring resistance, at the headlight base.

Edit: I messed up. I now realize you are using the neg. post on the battery. You are measuring the voltage drop in the wiring system to the lights. Sorry.

Edited by Beltfed (see edit history)
Link to comment
Share on other sites

Thank you Tom. I think I've found my problem - the dimmer switch. When I push on it the lights go basically out and then come back. I will do as you suggest and "clean" the contacts by pushing on the button 50 times or so and if that does not work I will remove the swith and either clean it or replace it as I'm pretty sure these were a standard itme for decades. And yes Tom, love to have you up here. I would apprecate you running the electrical test together. I'll keep you posted. I did remove the headlght bulbs and didn't really see any corosion and after reassembly found no difference.

Link to comment
Share on other sites

Beltfed,

A voltage drop measurement is much more accurate than a resistance measurement for low voltage systems. The resistance can change slightly when current is flowing and the connections heat up. It only takes a small amount of resistance to drop the voltage enough to make lights dim or a starter crank slowly. A direct voltage reading is not as accurate either. You will have to use a higher scale on the meter and it can be difficult to tell whether you have lost 0.1 or 0.4 Volts.

John,

The dimmer switches are notorious for developing resistance. They are seldom used on the collector cars and corrode due to the lubricant deteriorating and allowing moist air to come in contact with the contacts. If there is some lubricant left in your switch, operating it will distribute the lube and clean the contacts.

I believe that the 37 dimmer switch has soldered connections, the replacement switches all have screw connections.

Link to comment
Share on other sites

I agree 19tom40. As many years as I've been turning wrenches I still have to remember that our Zephyr's are positive ground. That makes some sense since electron flow is from the negitive battery terminal to the positive. My electrically challenged car buddies have trouble understanding that the spark at the plugs jumps from the ground to the electrode on negitive grounded cars.

I'll ask you an interesting question since you know your way around electrical systems. Why did auto makers adopt the negitive ground concept? I don't think I've ever seen the answer if their is one.

Link to comment
Share on other sites

My headlight issue is now fixed. Tom you were right. I remover the dimmer switch and it was a mess, taped splices, frayed wires, terrible corrosion. I removed the switch, cut out the splices, checked continuity and then put it all back together properly soldering all connections. The dimmer switch works like brand new and both low no high beams are much improved. Thanks to all. Another satisfying project completed.

After unwrapping 6 layers of electrical tape, this is what I found. Lucky I didn't burn the whole car up!!

post-51224-143142958905_thumb.jpg

Edited by John_Mc (see edit history)
Link to comment
Share on other sites

John, you are goiig to thave that Zephyr in like new condition for the summer driving season.

Beltfed, Here is a link to an article on why POS ground was used and why the change to NEG ground was made. It was written for Jaguars, so there is the reference to the leaky wires that Lucas electric systems had. I don't know that I agree with the reasoning as transistors were not in use in many applications in 1955 when Ford changed the 56 to 12 volts, NEG ground. I suspect that it had to do more with standardization due to military uses.

http://lajagclub.com/the-argument-for-positive-ground/

Edited by 19tom40
spelling (see edit history)
Link to comment
Share on other sites

Well Tom, I sure hope so. Two last things and to review the tolal brake system and then drop the oil pan and look into the engin knock and fixing the oil float. More on that later. Did you see the rat's nest of that dimmer switch???

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...