The “Real” 1947-52 Brush and Contact

Wednesday, March 4th, 2015

Six volt horn without a factory relay doesn’t sound? If you use the original 6 volt system, you “cannot” use the gray plastic incased brush and contact that also slips into the steering wheel hub on the 1947-52 First series Chevrolet/GMC Trucks. This is made only for the 12 volt second series 1955-1966 trucks. (Or can be used with 1947-55 with a 12 volt system)

Unfortunately for the 6 volt people this incased brush and contact also fits the 1947-55 steering wheel. It burns out instantly when their horn button is pressed if you have on original 6 volt system! With a complaint to their supplier, the owner may receive a replacement but it is ruined just as fast. NOW both buyer and seller are lost!

ANSWER: The 6 volt brush and contact has a heavy woven wire inside that carries the extra electric flow needed for the original system. It is not incased in plastic as is necessary to protect the single fine gauge internal wire of the 12 unit. The 6 volt brush and contact fits into a non-metal black cylinder which is separately pressed into the steering wheel hub. This cylinder should be found in the hub even without the brush and contact. They are two separate parts. See Photo.

BEWARE: If your supplier tells you the horn brush and contact is the same on 6 and 12 volts during 1947-55 he is a “lost ball in high weeds”. Don’t buy it if you have a 6 volt system!!

The correct replacement is now available from Jim Carter Truck Parts and a few other full stocking dealers. Pricing about $7.50 to $9.50. Our part # EL520.

Non-Metal Cylinder

1947-55 NOTE: Heavy Copper Internal Cable 6 Volt

1955-66 Fine Gauge Wire Incased, for protection 12 Volt(only)

The 20 Year Chevrolet Horn

Wednesday, April 16th, 2014

This new horn design was introduced in 1934. It is attached direct to the 207 six cylinder engine and was so successful there was almost no changes through 1952.
As shown in these photos this 1934-36 horn was attached to a flat foot that secured it to the center of the intake manifold. A long nose directs the sound to the area very close to the radiator cooling fan.
A slight change to the exterior appearance occurred with the new 1937 216 cubic inch engine. Possibly to keep it away from the high temperatures of the exhaust manifold, the horn was relocated. It now was attached to the forward leg of the intake away from engine heat.
The “bell” part of the horn was shortened to keep it the same distance from the fan. There, it remained on cars and trucks with the 216 engine through late 1952.
It was so well designed it rarely required attention. A single screw secures the rear half circle cover. When removed the inner workings are exposed for an occasional tone adjustment.
1934 – 36
1937 – 52

Ignition Switch Changes

Thursday, February 11th, 2010

As with many other items on the Advance Design Series trucks, there were also changes in the ignition switches. Both Chevrolet and GMC shared there several switch changes during the sever year series.

In the beginning (1947-1948) a unique three position ignition cylinder and housing was introduced. This was a first for GM trucks. It related to a country with limited crime and a time when many people did not lock their houses. The switch allowed the truck to be started without a key.

By turning the cylinder and key to the far left, the ignition switch was locked. However, the middle position was the big difference! Here the ignition was still off but a small tab or teardrop extending down from the cylinder face allowed the driver an option. With a touch of a finger you could turn the cylinder to the far right with or without a key due to the teardrop.

This was a convenient feature for many owners, particularly on the farm. No longer did they worry about losing the key or having to dig when it was in a pocket. They simply moved the tab from the center to the far right and the ignition was on. A security feature was built in. The ignition could not be locked without the key, so there was no worry about it accidentally being moved to the lock position.

This three position switch, also used on the 1947 Chevrolet car, was discontinued about the end of 1950. GM then returned to the two position on-off cylinder and housing that would not work without a key.

Between 1947-1953 the switch and cylinder combination plus a one candle power bulb and socket was attached to a sheet metal housing. This assembly is screwed to the top of the lower dash lip out of sight. Only the round key cylinder face is seen by the driver. It extends through a larger hole in the dash. A resulting 1-1/16 inch circle opening between the dash and this cylinder face produces a lighted ring at night from the adjacent small bulb. This allows the driver to easily locate the switch in the dark.

In 1954, with the total redesigned dash, there was a complete change in the ignition switch. The threaded end of a die cast housing is held in the dash by a chrome lock ring. Only this ring and the key cylinder face is visible to the passengers. It is also the two position on-off type.

With the introduction of hydramatic transmission during these years the switches did not change. The starter motor was activated by a button near the headlight switch not by the ignition switch.

ignition switch 1

ignition switch 2

1954 Ignition Switch (above)

ignition switch 3

1954 Ignition Switch Rear View (above)

1947 – 1953 Horn Buttons

Thursday, February 11th, 2010

Both Chevrolet and GMC used the same steering wheel during the 1947-1953 Advance Design years. To keep the two makes just a little different the horn buttons had a separate design. Thus, the driver was always given a close view of the name of the truck he was driving.

horn button 1

Chevrolet: Horn cap is chrome and then painted with steering wheel color. The raised Chevrolet letters and surrounding ridges are free of the paint so the chrome is visible (above)

horn button 2

Horn cap painted to match the steering wheel with red lettering. No chrome. (above)

Battery Shields

Thursday, February 11th, 2010

As time progressed, GM realized their under floor battery position needed extra protection. The battery on the 1946 and older trucks were only protected by their partial tray. No doubt some hard working vehicles in rural areas lost their battery from fractures.

Thus, the 1947-1955 trucks were provided with a front vertical metal shield. The attached photos (coming soon) show a bare frame with this shield still in place.

battery shields 1

battery shields 2

1953 Horn

Thursday, February 11th, 2010

In 1953 Chevrolet/GMC trucks adopted the more modern relay activated horn. To keep cost low, GM used the same seashell type horn that had been on Chevrolet cars since 1949. It displays the number “689” in its die cast metal. In the Chevrolet Master Parts Catalog, the number when ordering a replacement was 199687.

Though the 1953 truck used the existing car horn, GM created a special right angle bracket to attach it to the small extension on the iron intake manifold. This bracket has become very rare today. Most people incorrectly think the 1952 and older horn should attach to a 1953.

1953 horn 1

1953 horn 2

1953 horn 3

1953 horn 5

1953 horn 6

1952 and older horn position (above)

1953 horn 4
Just right on a 1953!

1948-1953 Horn Bracket Location Changes

Thursday, February 11th, 2010

The horn location on the intake manifold of the Chevrolet 216 six cylinder changed position with the addition of the accessory oil filter. This oil filter was attached to the front of the intake manifold. A special shaped horn bracket was necessary to move the horn forward away from the filter. This bracket was included in the box with the new oil filter package.

From 1947 and older, even the 3 speed transmissions shifted on the floor. There was no column shift. Without a shift box on the steering column, the oil filter could be placed on the rear of the intake manifold. Thus, the moving of the horn forward does not apply during these early years.

The attached photos show the two styles of horn brackets used between 1948 and 1953. On 1954 and newer the horn is attached to the radiator support.

1948 horn bracket 1

1948 horn bracket 2

1948 horn bracket 3

1948 horn bracket 4

Speed Up 6 Volt Starting

Thursday, February 11th, 2010

One of the more common reasons for slow engine turnover using an original six volt system is under size battery cables. Most of today’s auto parts stores only stock the smaller diameter 12 volt design. Unknowing owners mistakenly replace their original worn cables with shinny new ones that are as much as half the diameter as needed. Two ground cables are also required: One from the battery to the frame and one from a starter mounting bolt to the frame.

Six volt starters require twice the electrical flow to operate properly. Don’t blame your six volt system for slow unacceptable starter motor speed! Many restorers go to the expense of changing their 6 volt system to 12 volts. They feel their original system was inferior and believe what they did was necessary. The problem could have been corrected with just adding the three proper cables.

Remember: Millions of cars and trucks were made with 6 volt electrical systems each year. If they had not operated correctly they would have been built with 12 volt systems!

Battery Cables 6 Volt

Buy Parts for 1934 to 1946 Trucks

1508 East 23rd St. Independence Mo. 64055   |   Phone: 1.800.842.1913

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