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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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| | | Joined: Oct 2006 Posts: 4,983 Master Gabster | | Master Gabster Joined: Oct 2006 Posts: 4,983 | A friend of mine (mechanic) just got a classic in for a gentle refurbish. It's a 1955 Thunderbird with only 9,000 original miles. It sat on blocks in a garage all these years. When the owner died his son inherited it and now I believe wants to sell it. It has the original tires and looks like brand new. The owner wanted him to convert ot 12 volts. I was surprised considering my folks had a 56 ford and I'm sure it had 12 volt ignition. Knowing how the big three built their cars based on what the competition was doing, I wonder if Chevy had advanced to 12 volt in 55 causing Ford to follow suit. Just curious... 
~Jim
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | 1955 Chevrolet trucks changed from 6v to 12v when the models changed during that year. GMC trucks stayed standard 6v through all of 1955 (even for the new 1955 Blue Chip trucks). 1955 Chevrolet cars changed to 12v at the beginning of the 1955 model year. However, this 1955 Thunderbird website says that 1955 6 cylinder Chevrolet cars were 6v and V-8 Chevrolet cars were 12v (while the V-8 Thunderbird in 1955 was 6v). The 1955 Chevrolet Passenger Car Shop Manual states that a 12v electrical generating system was used on all model cars. | | | | | Joined: Feb 2004 Posts: 29,771 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,771 | 55 Fords used a 6V positive ground system. In 56, Ford switched to 12V positive ground, along with Packard, Nash, and a couple of other auto manufacturers and then all the auto manufacturers changed to 12V Negative ground in 1957. This was done to standardize the electrical systems so aftermarket accessory manufacturers could simplify their inventories, among other reasons. Freightliner and a few of the other big truck manufacturers used 12V positive ground until the mid-1960's. The 64 Freightliner I learned to drive after getting out of the Air Force used a 12V + system.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Dec 2001 Posts: 14,522 Moderator: Welcome Centre, Southern Bolters, Legion Hall | | Moderator: Welcome Centre, Southern Bolters, Legion Hall Joined: Dec 2001 Posts: 14,522 | Tim is right on about Chevy being 12 volt. I've owned several 55 and 56 chevy's and never heard of or seen anything in 55 about a 6 volt.
For some reason always I always thought Ford was 6 volt in 55 and went to 12Volt in 56...??
....or maybe I'm confused! I go a little crazy when talking about Fords. | | | | | Joined: Oct 2006 Posts: 4,983 Master Gabster | | Master Gabster Joined: Oct 2006 Posts: 4,983 | 55 Fords used a 6V positive ground system. In 56, Ford switched to 12V positive ground, along with Packard, Nash, and a couple of other auto manufacturers and then all the auto manufacturers changed to 12V Negative ground in 1957. This was done to standardize the electrical systems so aftermarket accessory manufacturers could simplify their inventories, among other reasons. Freightliner and a few of the other big truck manufacturers used 12V positive ground until the mid-1960's. The 64 Freightliner I learned to drive after getting out of the Air Force used a 12V + system.
Jerry I always thought those 2.5 ton trucks carried 24 volt batteries. (2)
~Jim
| | | | | Joined: Feb 2004 Posts: 29,771 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,771 | Some of the cold-country trucks ran a series-parallel system. They put four 6V batteries in series to put 24 volts to the starter, then reconnected them to two 12V banks for charging and lighting purposes. Freightliner was one of the last holdouts using positive ground electrical systems. We had to be very careful when doing a boost start on rigs from that vintage.
Military trucks ran a 24V system, which made them somewhat compatible with the 28 Volt DC aircraft systems.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
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