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Posts Tagged ‘lighting’

Dim Lights

Thursday, February 11th, 2010

When you notice your head, tail and dash lights are often dim, sometimes even flicker on a rough road, check your cab to frame ground cable

Because the 1967-1972 cab and radiator supports are seperated from the frame by rubber mounts. GM used a small mount woven wire ground strap that by-passes one cab mount. This insures electrical flow even if the cab mount bolts become rusted and electrical current can not flow properly.

You must be under the cab to see this by-pass cable. Yes, GM planned for the trucks later years when rusty mounting hardware caused the lights to dim

dim lights ground strap

1969-1972 Head Light Bezel

Thursday, February 11th, 2010

Contrary to what almost all Chevrolet truck parts dealers list in their catalogs, the 1969-1972 headlight bezels were not alike. Though today all are reproduced in bright-anodized aluminum. This is actually only correct for 1971-1972.

The 1969-1970 bezels were black stamped steel even on the most deluxe models. This color is necessary to blend with the two horizontal black lines in the center grill bar.

If you don’t have the correct stamped steel bezels for your 1969-1970 Chevrolet, paint the 1971-1972 aluminum copies in satin black to match the grill stripes.

1969 headlight bezel 1

1969-1970 on Left | 1971-1972 on Right (above)

1969 headlight bezel 2 1969 headlight bezel 3

1967-1972 Cargo Light

Thursday, February 11th, 2010

The cargo light above the rear window on the 1969-72 GM cab was a factory option and is mostly seen on the more deluxe trucks. This light is controlled from a switch beside the interior dome light and is wired so it will not operate while the truck is in the forward gear. This prevents the bright 21 cp bulb from being on while the truck is on the road which would create road glare to following traffic.

To save GM production costs, the clear rectangular lens in this cargo light housing is the same as a 1969 Camaro right side parking light lens.

Suburban Back Up Lights

Thursday, February 11th, 2010

For those on a quest for near unobtainable GM options, this one will provide years of searching. During the mid 1950’s, backup lights began to show growing popularity and were occasionally seen on pickup trucks near each rear fender.

The limited production 1955-56 Suburban was no exception but the location for its backup light was unusual. Their single center tailgate running light was given this attachment on its right side. The foot on this small backup light was curved to secure just right to the round tail light housing. The photo below shows this option as it was installed by GM.

Activating the light on a factory column shift three speed or Hydramatic was relatively easy. The switch attaches to the shift linkage levers on the steering column.

The 4-speed transmission backup light switch must be totally different as there is no external linkage. This photo is of this very unusual switch attached to the base of the floor shift lever.

suburban back up light 1

suburban back up light 2

suburban back up light 3

Step Side Tail Lights

Thursday, February 11th, 2010

step side tail lights

The differences between these two series of tail lights is an excellent example of lowering costs during production. To keep competitive, manufacturers will always consider making products of equivalent quality, but at lower prices.

In 1960-1966, GM, as well as several aftermarket companies, used a redesigned tail light lens and eliminated the need for the earlier metal bezel. The new plastic lens wrapped around the front edge of the same metal housing making it one piece. This new lens was created so it could also replace the previous 1955-1959 lens and bezel combination. Therefore, as supplies of 1955-1959 lenses were used up, dealership parts departments would offer the later style lens as a stepside replacement. This made the original 1955-1959 taillight the 1960-1966 type.

The black housing and wiring are the same from 1955 through 1966.

Ignition Cylinder Light

Thursday, February 11th, 2010

ignition cylinder light

The 1955-59 Chevrolet and GMC originally came with a non-metal shield to direct light into the ignition switch to the key slot. This shield is almost always missing after fifty years. Most shrink after twenty years and fall from the switch. The accompanying photos show this snap-in shield in place. Even the die cast opening is notched on all switches to hold this non-metal plate. The illumination from the snap-in light bulb socket directs the illumination through the small lower opening, then to a hole in the switch, and finally to the key slot in the ignition cylinder. When the driver enters a 1955-1959 GM truck at night, he pulls the headlight switch and the illuminated key slot shows where to place the key.

1966 Stepside Back Up Lights

Thursday, February 11th, 2010

The rear stepside fenders on the 1955 through 1966 are usually considered the same. The reproductions on both metal and fiberglass are listed in catalogs and related advertisements as being identical on the right and identical on the left.

Not true if you are a perfectionist! In 1966 Federal automotive regulation required all cars and light trucks to have back-up lights. Thus, GM modified this fender with a stamped indention to better fit the required back-up light assembly.

1966 stepside back up light

1960-1966 Back Up Lights

Thursday, February 11th, 2010

To keep vehicles base price low, GM made many items dealer accessories. If the buyer required extras, the dealer was the installer. This created less complications on the assembly line and added more income for dealerships.

One of these extras was back-up lights on the 1960-1966 Fleetside pickup. After 35 years they have become very rare due to their location below the taillight assembly. They were always subjected to water and salt. Corrosion of the chrome outer die cast bezel is a normal result of trucks used regularly.

The adjacent photos show the light assembly before installation plus their correct location on the pickup box.

1960 1969 back up lights 1

1960 1969 back up lights 2

1960 1969 back up lights 3

1960 1969 back up lights 4

1960 1969 back up lights 5

Panel Truck Tail Light

Thursday, February 11th, 2010

With the introduction of the Advance Design panel truck in mid 1947, it was soon evident that a serious safety hazard existed with a few companies, some night deliveries required the rear double doors to be open. This prevented the taillight from being seen! No doubt this caused some accidents particularly with a fast vehicle coming from behind, with dim older bulb headlights.

The General Motors Product Service Bulletin (issued regularly to dealers) dated May 31, 1948 relates to this condition. Though it is dated over a year after initial panel truck production, it warns dealers and offers an alternative to lessen this unsafe condition.

The following is a copy of the suggested GM modification to correct the problem. As this particular product service bulletin was issued in Canada for their Canadian dealerships, it is not known if the announcement was also made to dealers in the USA .

It may be of interest that this extra light #916877 also used the same number in the Chevrolet Master Parts Catalog as the left 1939 car taillight assembly. (It appears GM used no extra tooling to create this new panel truck extra.) Note: They even requested the dealer to solder the water drain hole in this car light and re-drill because of its different mounting position.

The following is taken from the May 31st, 1948 Product Service Bulletin.

Rear Signal Lamp Released – All Panel Trucks

Some requests have been received for a signal lamp, which would be visible on Panel trucks when the rear doors are open at night. This type of lamp, which will operate in conjunction with the tail lamp, can be mounted on the roof panel, as shown in Fig. 77. The material necessary to make this installation is shown in Fig. 78.

panel truck tail light 1

Fig. 77 (above)

panel truck tail light 2

Fig. 78 (above)

panel truck tail light 3

panel truck tail light 4

Fig. 79 (above)

Of the material listed in the chart, the insulated wire, the metal plate, and the two rubber washers are to be made up locally. The dimensions for the metal plate are shown in Fig. 79 and the dimensions for the rubber washers are given in fig. 80. Assemble the bayonet connection to one end of the insulated wire and the eye terminal to the opposite end. A drain hole will be found in the side of the lamp rim. this should be plugged with solder and the same size hole drilled in the bottom of the rim for drainage.

panel truck tail light 6

Fig. 80 (above)

The installation procedure is as follows.

1. Center the metal plate, Fig. 79, nine inches from the rear drip molding over the center of the rear doors.

2. Using the plate as a template, drill two 7/32″ holes and one 3/4″ hole in the roof panel.

3. Drill a 7/16″ hole in the roof left side rail, “A” Fig. 81, and another 7/16″ hole “B” in the lower side panel behind the left rear door.

4. Place the two rubber washers over the studs in the lamp and the rubber grommet around the wiring. Assemble the metal plate on the inside of the roof panel and install the lamp using the attaching stock supplied.

5. Connect the 6 ft. of insulated wire to the plain wire in the lamp by means of the bayonet connection. Note: A two filament bulb is used in the lamp. One 3 C.P. and the other 32 C.P. The plain wire connects the 3 C.P. filament. Cut of the other wire.

6. Thread the insulated wire through the holes drilled at “A” and “B” Fig. 81. Install one of the wiring clips under one of the screws in the rear door upper striker plate “D” and the other clip under the screw at the rear of the belt strainer “C”. Compress the clips so that they fit snugly around the wire.

7. Connect the wire to the tail lamp switch “E” at the same terminal as the black tracer wire.

panel truck tail light 5

Fig. 81 (above)

1951 Tail Light Bracket

Thursday, February 11th, 2010

Beginning in 1951, the rear bumper became an option on both Chevrolet and GMC pickups. This required a change in the standard left tail light bracket. The tail light assembly was now unprotected without the bumper. GM created a new bracket design that brought the tail light slightly ahead of the rear edge of the stake pocket.

In this way the tail light was not hit when the pickup backed against a loading dock. Of course, when the truck came with the now optional rear bumper, the tail light bracket remained as earlier years.

The non rear bumper tail light bracket is not being reproduced. For the perfectionist, it will require some hunting to uncover one of these rare assemblies. Most restorers want the optional rear bumper and thus there is little demand for this forgotten bracket.

1951 tail light bracket 1

1947-1950 (above)

1951 tail light bracket 2

1951-1953 (above)

1951 tail light bracket 3

1947-1950 (above)

1951 tail light bracket 4

1951-1953 (above)

1951 tail light bracket 5

1947-1950 (above)

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

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 during the early years the GMC preferred very few things to be similar to Chevrolet.  Their customers needed to see an almost stand-alone truck with the higher price of the GMC.

One very obvious difference is the change in tail lights.  There is no comparison to Chevrolet.  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.

Hint: This tail light also was used on Chevrolet, Buick Oldsmobile Station Wagon tail gates from about 1949 through 1952.  Therefore you will see more lights than GMC brackets at swap meets.  See Photos

1934-1946 GMC Tail Lights 1934-1946 GMC Tail Lights 1950 chevy taillight 1951 old taillight

Park Light Lens, Amber or Clear

Thursday, February 11th, 2010

When viewing older GM cars and trucks we see both colors of park light lenses. There seems to be no consistency that gives us the proof of what is actually correct, however, it is easy as remembering a year.

Beginning in 1963, federal regulations required park lights to show an amber color. Today, companies reproducing original clear lenses find it easy to run more in the same die using an amber additive. Therefore, in GM trucks most 1954-62 clear lenses now can be found marketed with an equivalent amber style.

One exception is the 1969-1970 Chevrolet truck. Originally it came new with clear lens but behind them are amber park light bulbs giving the required color appearance when illuminated.

6 Volt (Not Actually) Sealed Beam Bulbs

Thursday, February 11th, 2010

Two major changes occurred in 6 volt General Motors sealed beam bulbs (are actually not sealed beams) since they were first installed on vehicle assembly lines in 1940. The perfectionist restoring his truck to exact original specifications must have the correct headlights 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 1955 – These headlights had a double filament small bulb built inside. The large glass reflector in the back was sealed from the elements.  It stayed bright even after the inside bulb burned out.  It was not like earlier open reflectors that could tarnish with age due to the silver plating.  The assembly comes with a metal black back attached for support. 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 assembly (see photo).

6 volt bulb

1940 through about 1946 (above)

About 1955 and Newer (below)

The first truly  sealed beam bulb, as we know it, was introduced about 1955.  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 there is instant burn-out

One of the big visible differences in this first series sealed beam bulb and today is there are the three aiming bumps on the outside in about 1955. The bumps were necessary when using the new dealer aiming equipment.

1955 and Newer 6 volt bulb

1955 and Newer (above)

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

Note: These modern bumps will interfere with properly attaching the chrome factory bezel on a 1940 headlight bucket as well if 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.

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.