Topic: Tail & Brake Light:


fortyford    -- 05-29-2016 @ 10:55 AM
  For some reason one of my tail light and brake lights is just a tad brighter than the other?I have tried different bulbs switched the lens and done all I know to do to correct!I even ordered two new lens from DC so they would be the same and I did not like these lens because they seemed dark and did not have the glow that my old ones do.Can I check with a meter to see where I am at?I am about to the point to just get to brand new assemblies and start from there.I am figuring there is a ground problem somewhere?

This message was edited by fortyford on 5-29-16 @ 11:01 AM


kubes40    -- 05-29-2016 @ 1:14 PM
  Nearly ALWAYS, if one is dimmer than the other, there is a ground issue with the dimmer of the two.
You must be certain there is a good ground between the tail lamp housing and fender. Also, between the fender (body) and frame.
On occasion, I have found a poor connection, usually simple corrosion, at the butt connectors. You may want to check those out as well.
When I fully restore a car, I solder the butt connections prior to slipping the rubber sleeve over the butt. I also solder a ground wire directly to the socket of each lamp and route that "extra" wire through the conduit, attaching it to a clean ground that is well hidden.
Hope this helps,
Mike Kubarth






fortyford    -- 05-29-2016 @ 3:47 PM
  Thanks, Mike.Where do you get your lens from?Do you have any NOS?I wonder how good made the new assemblies are?


kubes40    -- 05-29-2016 @ 6:21 PM
  I have a bunch of NOS.

I have seen the repop tail lamp buckets and am not too impressed. Overall, they are not bad as far as shape and from what I hear, fit. . However, the few I have seen close up had the socket so loosely riveted, they would surely have to be redone to make an adequate ground.


TomO    -- 05-30-2016 @ 7:56 AM
  Different lenses probably will not make much of a difference. Clean the sockets of both bulbs with brass wool. Make sure that they are riveted solidly to the housing. If there is corrosion around the rivets, you probably are better off soldering a short wire from the socket to the housing.

You can also use "bulb grease", sold at Ace and other auto supply companies, on your bulbs and on the bullet connectors to help keep corrosion from creating resistance.

To use a meter to check circuit resistance (better known as "voltage drop" :

Hot side

Connect your meter com or black lead to the NEG post of the battery and the +or red lead to the point closes to the load or in your case the light bulb. Turn on the lights or activate the brake switch and read the meter on the voltage range.

For the tail and brake lights, you should read 0.3 or less. The brake light will give a slightly higher reading.

Grounded side

Connect the + or red lead to the POS battery post and touch the black or COM lead to the bulb housing. The meter should read 0.1 or lower.

The readings will be the voltage drop in the circuit. (if you have 6 volts at the battery and a 0.5 reading during the voltage drop test, your light bulb is seeing 5.5 volts).

Placing a flashlight reflector behind the bulb, will reflect more of the bulb's light through the lens.

Tom

This message was edited by TomO on 5-30-16 @ 7:58 AM


len47merc    -- 05-30-2016 @ 8:27 PM
  I have to agree that the vast bulk of brightness variances side-to-side are ground related and taking the steps Mike & Tom recommend will solve the majority, if not all, of your issue.

Rare for me here, in fact possibly the first time ever - I have to disagree with Tom only with respect to different lenses not making much of a difference. When I obtained my '47 Merc the driver's side rear lens was cracked. After a long eBay and swap meet search I found a used replacement, and, after following their advice repeated above and ensuring, without the lenses, that readings, reflector surfaces and brightness' were crisp and consistent (significant and obvious variances existed previously without the lenses), I reinstalled the original and replacement lenses only to find a new, different and still unacceptable to me difference in hue and intensity existed side-to-side. After extensive research I found: 1) Two suppliers of the lenses were used for '46-'48, with different center and cross-hatch patterns employed by each and 2) Lot-to-lot variances in color depth existed over time within each suppliers' lenses. With the same supplier's lens I found I can have a dark ruby red with a NOS lens on one side and a lighter red with a very slight 'aged' yellowish-orange tinge on the original. When using different suppliers' lenses similar and other variances exist. Piecing together the cracked original with super glue and reinstalling it the taillights and brake lights are identical in hue and intensity (and also very visible during bright daylight with the original 6V pos ground system). I am still looking for a good matched pair (note it is hard to tell without having them on the car - at night - whether they are going to be consistent or not) .

This said, repops from DC should be assumed to be relatively consistent and should produce adequate hue and intensity consistency, so your prob will likely be resolved through following Mike & Tom's advice. My tail and brake lights, without the lenses, showed a significant difference in brightness before following their procedures and after I could tell no side-to-side difference without the lenses, only that they were both much brighter. Just keep the above in mind when using NOS and used lenses that variances can and do exist - perhaps not on '40's (Mike - ?), but certainly experienced by me on later years.

Steve

This message was edited by len47merc on 5-30-16 @ 8:39 PM


fortyford    -- 06-03-2016 @ 2:27 PM
  Kube,do you have any NOS 40 tail light lenses?


kubes40    -- 06-03-2016 @ 3:05 PM
  Sure do.


fortyford    -- 06-03-2016 @ 8:03 PM
  The two wires leading to the tail light-is one tail light and the other brake light?Does it make a difference which way the wires are plugged in to the harness?


kubes40    -- 06-04-2016 @ 6:04 AM
  It does make a difference as the two filaments within each bulb are not the same size. If you take the lens off, you'll easily see which filament on each bulb is lit when power is applied.


TomO    -- 06-04-2016 @ 7:06 AM
  If you can still see the color code, the green wire goes to the stop lights and the black wire goes to the tail light. The stop light filament is much brighter than the stop light filament.

You may be able to see the color code inside of the tail light housing or by pushing back the cloth conduit.

Tom


fortyford    -- 06-04-2016 @ 2:37 PM
  Kube,I sent you a PM.


fortyford    -- 06-04-2016 @ 5:56 PM
  Kube,I sent you another PM.


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