Lighting

Before Dual Filament Headlights

Thursday, April 11th, 2013


During the early years of automotive history, the invention of the dual filament light bulb had not emerged.  Therefore, there was no high and low beam headlight bulb on cars and trucks.  Only one beam existed for night driving.

This created a problem with the headlight beam from an on-coming vehicle on the narrow roads in town and country driving.  It was not until the late 1920’s that the two filament headlight bulbs came from the factory on new vehicles.

The attached photos show a great example of American Ingenuity sold in some vehicle parts stores during the 1920’s.  It is an electrical rheostat that allowed the driver to lessen the amount of light from the headlight.  This accessory was mounted on the steering column.  By moving the long lever with a finger, the driver could regulate bulb lighting.  How ingenious!  This very attractive assembly was recently found in an old trunk.   The unit is nickel plated as chrome was not yet available during these early years.  It is a very high quality part.

The price was $7.50, very expensive considering most workers made less than $1.00 per hour.   The sales company is shown to be the Universal Distributing Company of Tulsa, Oklahoma.

No doubt, the sales were limited due to the price but also because of a human trait.  Yes, the vehicle owner could lessen his light on the road but chances are good, the on-coming vehicle did not have one of these inventions.  The person that had spent the money on this accessory still received just as much light in his eyes from on-coming vehicles while he suddenly had less lighting from his vehicle!

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Change-over to Sealed Beam Headlights

Friday, March 1st, 2013


In 1939 US auto and truck manufacturers realized the following year would be the introduction of the revolutionary new sealed beam headlight bulbs.  These first seal beams were very unique by the newer standards 15 years later that most of us are acquainted with.  This early sealed beam assembly was much like the later design except it had a much smaller 2 filament light bulb inside.  Yes, the inside reflective plating was sealed inside with a glass fluted large lens that was now part of the total assembly.  This reflective coating was sealed from outside air and oxidizing did not occur.  There was no loss of shine with age.  It was one of the best improvements in safety since the introduction of bulb headlights.

A very interesting characteristic of these first seal beams:  A small hole from a flying rock did not burn out the unit.  The argon gas that protected the glowing filaments from quick burn-out was still inside the small internal bulb.

Seal beam bulbs introduced in the early 1950’s were different.  They were one large argon filled assembly.  When cracked by a flying rock, they instantly burned out.  Imagine the number of new designed seam beam bulbs that were lost by vehicles driving at high speeds on gravel roads behind other vehicles!  There must have been a run on the old style obsolete units in rural areas.

The 12 volt sealed beams were not made with the early design “small bulb in the assembly” design.

For most car and truck manufacturers it was too late to do a major redesign of the headlight assemblies for the 1940 year.  Chevrolet and GMC trucks reshaped the metal edge on the 1939 bucket so the new seal beam bulbs fit perfectly.  For those not having a detailed eye for auto and truck changes, it would probably never be noticed.

For those buying a new 1940 vehicle after driving with the old style reflector bulb design, it would be the most significant change in years.  The gradual diming of their lights over the years as the silver reflector tarnished was now history.  Yes, the owner could have removed the glass lens from his older vehicle, polished the silver plate, and reassemble; however it would be like today; most drivers would not take the effort.

Attached are photos of the earlier 1937-39 headlight and the new 1940 with the redesigned seal beam.  The visible part of the buckets is identical including the chrome rings.  It’s only the hidden seal beam edge that is different.

 


1940 Sealbeam bucket
1939 and older headlight-reflector bucket

1940 Sealbeam Headlight
1939 and older Headlight

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1936-46 GMC Taillights

Monday, July 2nd, 2012


1936-46 GMC Taillights

Though things were shared between GMC and Chevrolet trucks, General Motors made sure many items remained very different. The GMC truck dealers preferred very few things to be similar to Chevrolet. Their customers needed to see an almost stand-alone truck with the higher price they were paying.

One very obvious difference is the change in taillights. There is no comparison. The massive GMC stamped steel one piece bracket combined with a redesigned 4 inch taillight makes the pair a “one of a kind”.

Finding any of these parts during a total 1936-46 GMC pickup restoration has become almost impossible. It is said a shop is attempting to remake the bracket, however, if that happens the taillight will be almost as big of a project to get. The light is not being reproduced.

Hint: This taillight was also used on the center of a Chevrolet station wagon tailgates from 1949 through 1952.

1936-46 GMC Taillights 1936-46 GMC Taillights

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1941-1946 Park light and Headlight Assemblies

Monday, June 20th, 2011


At the beginning of the 1941 Chevrolet and GMC truck body style, the parking light assembly was placed on top of the headlight bucket.  This was the first time both were placed on the fender as a pair.  All worked well together.  To save tooling costs, GM chose to add a pre-existing assembly from the year before on the 1940 Pontiac car.  No changes were made from this Pontiac park light assembly except its long sheet metal top was now painted and not chromed.

Overseas during World War II, when civilian front fenders were used on GM military trucks (instead of the more famous flat fender ‘army truck’ style) General Motors created a parking light that emitted a small strip of light to be seen at a shorter distance.

Beginning in 1942 and continuing through mid 1947 (when this body design was discontinued), GM used a much less expensive park light housing on civilian trucks.  A one piece stamped metal cover was attached to the headlight bucket for a fraction of the cost as in 1941.  This also used a smaller less expensive glass lens.

Therefore during this 6 ½ year truck production (1941-Mid 1947) the same headlight buckets were on Chevrolet and GMC trucks.  The difference was their hole punching which adapted to changes in parking light assemblies.

1942-45 Military

1942-45 Military

NOTE:   THE 1941 PHOTO WILL FOLLOW SOON

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Early Park Light Assemblies

Thursday, February 11th, 2010

The introduction of factory sealed beam headlights came to the automotive industry in 1940. It was then necessary to create park light assemblies. (They could no longer be incorporated in the bulb and reflector style headlight as before).

To some, the first 1940 GM assemblies were simply “add-ons”, maybe a quick design due to the fast industry acceptance of the new sealed beam system. They sat on the front fender away from the headlights and were the same on Chevrolet and GMC trucks as well as Chevrolet cars. Right and left are identical.

By 1941 GM engineers had developed park light assemblies to flow more with the body lines. Most every GM vehicle had a newly designed unit. The exception was the Chevrolet and GMC trucks. Whether to save money or there was not time, GM’s 1941 commercial vehicles were given the same park light assembly as used on the Pontiac car the year before. These 1940 Pontiac assemblies secured very nicely to the top of the long truck headlight bucket in 1941 and provided the more modern look.

By 1942 GM trucks were finally given their own park light assemblies. They were similar to the 1940 Pontiac design but were more basic. What had required four die cast pieces with the early Pontiac style now could be accomplished with one stamped sheet metal cover. This of course, required a subtle change in their glass lenses. This 1942 design was continued through 1946.

Early Park Light Assemblies

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1934-1946 GMC Tail Lights

Thursday, February 11th, 2010

Early GMC Tail Light

Though items were shared between GMC and Chevrolet trucks between 1936 and 1946, General Motors made sure many parts remained very different.  The GMC dealers preferred very few things to be similar to Chevrolet.  Their customers needed to see an almost stand-alone truck with the higher price they were paying.

One very obvious difference is the change in tail lights.  There is no comparison.  The massive GMC stamped one piece steel bracket combined with a redesigned 5-inch tail light makes the pair a “one-of-a-kind”.  They do not interchange with Chevrolet during those year.

It was not until the new body style in mid 1947 that the two brands shared tail lights. When the larger GMC’s 5-inch light was discontinued on trucks in 1947, Chevrolet introduced it on their 1949 through 1952 station wagons and early GMC buses. It was placed in the center of the gate and was the only factory light on the vehicle.

Even though 1936-1946 taillight was used for so many years, it is becoming very difficult to find. Most GMC pickup restorers use the reproduced Chevrolet rectangular design and only a few GMC perfectionists are aware that there is a difference.

A shop in the US is attempting to remake this bracket; however, if this happens the tail light will be almost as big of a project to find.  It is not being reproduced.

The photo below shows the real GMC tail light and bracket of the early years 1936-46 GMC.

1934-1946 GMC Tail Lights 1934-1946 GMC Tail Lights

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6 Volt Bulbs

Thursday, February 11th, 2010

Two major changes occurred in 6 volt General Motors sealed beam bulbs since they were first installed on vehicle assembly lines in 1940. The perfectionist restoring his truck to exact original specifications must have the correct sealed beams for his year. In very competitive judging, it’s these details that can make a difference. No doubt, replacement bulbs from a GM dealership with slow sales could sometimes be placed on newer vehicles a few years after the units were discontinued, however this article is based on bulbs you would have bought new from the factory during that particular year.

1940 through about 1946 – These sealed beams had a double filament small bulb built inside. The large glass reflector in the back was sealed from the elements.  It stayed bright until the bulb burned out.  It was not like earlier open reflectors that could tarnish with age.  The assembly comes with a metal black back attached. If the outer glass gets a rock hole, the light continues to work well. The filament is still encased in the smaller argon gas filled glass bulb (see photo).

6 volt bulb

1940 through about 1946 (above)

About 1946 through 1955 (below)

The first sealed beam bulb, as we know it, was introduced after the end of World War II. Between the reflector and the outer glass covering is the open unprotected filament (no small internal bulb). The total interior is filled with argon gas to protect the filament from air which causes instant burn out. When a rock places a small hole in the glass the filament is ruined.

The big visible difference in this first real sealed beam bulb and today is there was no aiming bumps on the outside as in later years. The dealer aiming equipment had not been invented.

1955 and Newer 6 volt bulb

1955 and Newer 6 volt bulb

1955 and newer…(above)

Beginning in 1955 the 6 and 12 volt sealed beams have three glass aiming bumps molded in the edges of the lens. The bumps were needed by new light aiming equipment provided to GM dealerships. All of these GM bulbs with aiming bumps have the letters T-3 molded in the center of the glass lens. Most will also have the word Guide at the top of the lens.

Note: These modern bumps will interfere with properly attaching the chrome bezels on a 1940 headlight bucket as well as a 1937-1939 bulb light that has been converted to sealed beams. The bezels were not designed for the bulb still 15 years in the future. The 1940 GM vehicle owners will have a long hunt to find sealed beam bulbs without the three bumps.

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4 Speed Back Up Light Switch

Thursday, February 11th, 2010

Four Speed Backup Light Switch – They Did Exist!

4 Speed Back Up Light Switch

The first design of the 4-speed synchronized truck transmission, introduced in 1948, was used through about 1965. About mid series, when the dealer installed backup light increased in popularity, a special switch was attached to the base of the floor shift lever. This was the only location possible as there is no external linkage on a 4-speed.

No doubt regular floor contact with shoes and boots shortened the life of this small electrical switch.

Buy Parts for 1934 to 1946 Trucks

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