Notices
1948 - 1956 F1, F100 & Larger F-Series Trucks Discuss the Fat Fendered and Classic Ford Trucks

12 volt positive ground

Thread Tools
 
Search this Thread
 
Old Jun 5, 2013 | 09:23 PM
  #1  
MN1967's Avatar
MN1967
Thread Starter
|
Trailering
10 Year Member
Joined: May 2013
Posts: 19
Likes: 0
12 volt positive ground

I just got a 51 F5. It has a 12 volt positive ground system. Has anybody converted their electronics to a neg ground and upgraded to an alternator? What all would be required to do this?
 
Reply
Old Jun 5, 2013 | 10:41 PM
  #2  
Bozworth's Avatar
Bozworth
Senior User
Joined: Aug 2011
Posts: 230
Likes: 0
From: Round Rock, TX
My 54 showed up with a positive 12v ground. Just swap the battery cables to make it neg. ground, remove the voltage regulator, and bolt on your preferred alternator. Assuming there's nothing too different between the electrical on a F100 vs. F5.

I'm sure some of the smart guys will be along soon to provide some wisdom.
 
Reply
Old Jun 5, 2013 | 10:56 PM
  #3  
Olweldinrig's Avatar
Olweldinrig
Senior User
Joined: Mar 2013
Posts: 431
Likes: 0
From: Edenwold Saskatchewan
Switch your pos/neg at coil,you won't get near the juice you are looking for.
 
Reply
Old Jun 5, 2013 | 10:58 PM
  #4  
Olweldinrig's Avatar
Olweldinrig
Senior User
Joined: Mar 2013
Posts: 431
Likes: 0
From: Edenwold Saskatchewan
A little OT but is a 56 pos or neg ground?
 
Reply
Old Jun 6, 2013 | 12:00 AM
  #5  
Bozworth's Avatar
Bozworth
Senior User
Joined: Aug 2011
Posts: 230
Likes: 0
From: Round Rock, TX
Olweldinrig, 56 was the year they introduced 12v, and i'm pretty sure it was negative ground.
 
Reply
Old Jun 6, 2013 | 12:32 AM
  #6  
Kurt G.'s Avatar
Kurt G.
Laughing Gas
15 Year Member
Liked
Joined: Jun 2007
Posts: 815
Likes: 29
From: Richland, WA.
Bozwoth you are correct 56 was first truck year for 12v . It was neg ground. Our 54 and my 55 was 6v pos ground. We used 56 gauges in the 54 and the 55. I also got a turn signal unit for the 56 and put it in the 54.
 
Reply
Old Jun 6, 2013 | 08:15 AM
  #7  
Olweldinrig's Avatar
Olweldinrig
Senior User
Joined: Mar 2013
Posts: 431
Likes: 0
From: Edenwold Saskatchewan
Thanks guys that's what I thought.I couldn't get the ol y in my 56 to run this week,I thought maybe this was part of problem.
 
Reply
Old Jun 6, 2013 | 09:05 AM
  #8  
MN1967's Avatar
MN1967
Thread Starter
|
Trailering
10 Year Member
Joined: May 2013
Posts: 19
Likes: 0
Originally Posted by Olweldinrig
Switch your pos/neg at coil,you won't get near the juice you are looking for.
Do you mean after switching the wires or if I don't switch the wires the juice will be limited?

Thanks
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

10 Ways Ford is LOSING to the Competition

 Joe Kucinski
story-1

Top 6 Best Deals Available on New Fords & Lincolns Right Now

 Brett Foote
story-2

This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level

 Verdad Gallardo
story-3

Top 10 Fords at 2026 Carlisle Ford Nationals

 Joe Kucinski
story-4

3 Best / 3 Worst Parts of Modern Ford Ownership

 Brett Foote
story-5

10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

 Pouria Savadkouei
story-6

Every 2026 Ford Engine Explained

 Brett Foote
story-7

10 Ugly Ford Trucks That We Still Kinda Love

 Joe Kucinski
story-8

10 Things Every Truck Owner NEEDS (2026 Edition)

 Michael S. Palmer
story-9

Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
Old Jun 6, 2013 | 09:51 AM
  #9  
Olweldinrig's Avatar
Olweldinrig
Senior User
Joined: Mar 2013
Posts: 431
Likes: 0
From: Edenwold Saskatchewan
Use a 12v coil and made sure you are hot on the+ side of coil(from ignition).It will run but not very good.A coil needs to be run in the right direction to get full voltage.Your spark will break up at higher rpms.
 
Reply
Old Jun 6, 2013 | 09:54 AM
  #10  
MN1967's Avatar
MN1967
Thread Starter
|
Trailering
10 Year Member
Joined: May 2013
Posts: 19
Likes: 0
Gotya. Thanks
 
Reply
Old Jun 6, 2013 | 09:56 AM
  #11  
raytasch's Avatar
raytasch
Believe Nothing
20 Year Member
Joined: Jun 2004
Posts: 7,519
Likes: 403
From: W. Central FL.
Club FTE Silver Member

Originally Posted by MN1967
Do you mean after switching the wires or if I don't switch the wires the juice will be limited?

Thanks
In very basic terms, yes. Efficiency of the coil is better with the polarity correct. It will run either way if all else is right.
 
Reply
Old Jun 6, 2013 | 06:00 PM
  #12  
38 coupe's Avatar
38 coupe
Cargo Master
15 Year Member
Photogenic
Photoriffic
Top Answer: 1
Joined: Aug 2010
Posts: 2,927
Likes: 136
From: Houston
Also remember to reverse the direction of the wire running through your ammeter or it will read backwards.
 
Reply
Old Jun 6, 2013 | 06:52 PM
  #13  
CharlieLed's Avatar
CharlieLed
Lead Driver
15 Year Member
Liked
Loved
Community Favorite
Joined: Aug 2006
Posts: 8,096
Likes: 656
From: Brentwood, TN
Club FTE Gold Member
Maybe I am wrong but I have never even heard of a 12 V positive ground system. I thought that all the pos grd systems were 6 V and that they all went to neg grd when they went to 12 V.

To the OP, if you ever plan on running anything in your truck that has a sold state circuit in it you better have it setup for negative ground. Transistors, diodes, etc do not like it when the polarity is reversed.
 
Reply
Old Jun 6, 2013 | 07:43 PM
  #14  
Jolly Roger Joe's Avatar
Jolly Roger Joe
Lead Driver
Joined: Jul 2011
Posts: 6,599
Likes: 34
From: Rockingham, VA
I'm sorry, but I didn't know any coil could sense which side was connected to power and which was connected to ground. Current flows either direction through a coil. What am I missing?
 
Reply
Old Jun 7, 2013 | 04:18 AM
  #15  
big job's Avatar
big job
Fleet Mechanic
20 Year Member
Photogenic
Photoriffic
Liked
Joined: Dec 2005
Posts: 1,603
Likes: 44
[QUOTE=CharlieLed;13230320]Maybe I am wrong but I have never even heard of a 12 V positive ground system. I thought that all the pos grd systems were 6 V and that they all went to neg grd when they went to 12 V.

Nope, in the commercial world this can go back into the early 1940s,
12 Volt pos. ground, and I worked on plenty of them. When we converted
the 1953 F900 (into a dump truck) that was 12 vt pos gr with 100 amp
alternator no doubt the fire body co did that. Heres another kicker,
I have origional 1959 Mark IV Continental my father bought only couple
year old. Get this its got an 80 amp "Delco System", ant that is listed
in the parts books. Optional of course. Dont think Henry would like that.
So this did exist.
 
Reply



All times are GMT -5. The time now is 02:58 PM.

story-0
10 Ways Ford is LOSING to the Competition

Slideshow: 10 ways Ford is losing to the competition

By Joe Kucinski | 2026-06-15 09:52:01


VIEW MORE
story-1
Top 6 Best Deals Available on New Fords & Lincolns Right Now

Some great targets in today's expensive world.

By Brett Foote | 2026-06-15 09:35:19


VIEW MORE
story-2
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level

Slideshow: The VelociRaptor Expedition gains a lift, upgraded suspension, Brembo brakes, and trail-ready equipment while retaining the stock 440-horsepower EcoBoost V6.

By Verdad Gallardo | 2026-06-12 11:01:55


VIEW MORE
story-3
Top 10 Fords at 2026 Carlisle Ford Nationals

Slideshow: Top 10 Fords at 2026 Ford Nationals

By Joe Kucinski | 2026-06-09 11:10:08


VIEW MORE
story-4
3 Best / 3 Worst Parts of Modern Ford Ownership

Based on years of owning multiple modern Ford products.

By Brett Foote | 2026-06-09 10:53:36


VIEW MORE
story-5
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

SPONSORED: From muddy boots to rain-soaked cargo, these upgrades address some of the most common frustrations Ford truck owners face every day.

By Pouria Savadkouei | 2026-06-08 18:50:34


VIEW MORE
story-6
Every 2026 Ford Engine Explained

Here's everything you need to know about every Ford engine available for the 2026 model year.

By Brett Foote | 2026-06-05 12:58:01


VIEW MORE
story-7
10 Ugly Ford Trucks That We Still Kinda Love

Slideshow: 10 ugly Ford trucks that we still kinda love.

By Joe Kucinski | 2026-06-03 09:51:16


VIEW MORE
story-8
10 Things Every Truck Owner NEEDS (2026 Edition)

Slideshow: the best gifts for dads & grads

By Michael S. Palmer | 2026-06-03 15:43:58


VIEW MORE
story-9
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-06-03 11:38:36


VIEW MORE