Ground straps
Lead Driver
Joined: Aug 2006
Posts: 8,093
Likes: 653
From: Brentwood, TN
The more you have the better...there can NEVER be too many. Engine to body to frame...all should be tied to a common ground. Many electrical issues are rooted in poor grounds, this is not a place to scrimp.
Fleet Mechanic
Joined: Sep 2010
Posts: 1,833
Likes: 467
From: Mason City, Iowa
Ground straps? I would use two, one connects from the negative battery cable connection point on the engine block to the frame, and the the other from the same engine block connection to the firewall. On my truck, I use the strap connected to the firewall as sort of a main grounding point. This is where I connect all of my gauges grounds, electric radiator fan ground, anything that has a separate ground wire connection runs to this point. In my case there are a lot of wires connected there, but it seems to work very well for me.
Fleet Owner
Joined: Jul 2004
Posts: 27,294
Likes: 1,055
From: NM
'56 would be negative ground, just to be clear.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Unless you just have to keep it OEM this is where you can make some easy, inexpensive improvements. Ford used the smallest gauge copper cable or strap they thought would work, and also as short as possible. This meant some compromises, electrically. While they did work when new, sort of, a lot of rust, paint, and corrosion over the years really makes things marginal. This causes major issues over time that shouldn't be overlooked.
For example just 0.06 ohms - six hundredths of an ohm, hardly anything at all - will reduce generator or alternator output by 30%! Voltage drop will burn up starters and solenoids, switches and motors, dim headlights, weak batteries. Over the years the negative ground terminal cable has connected in different locations depending on the vehicle and such but a bolt on the starter or bellhousing works well. The idea is to avoid a circuitous path through rusty parts. The starter of course draws more current than anything else.
For example just 0.06 ohms - six hundredths of an ohm, hardly anything at all - will reduce generator or alternator output by 30%! Voltage drop will burn up starters and solenoids, switches and motors, dim headlights, weak batteries. Over the years the negative ground terminal cable has connected in different locations depending on the vehicle and such but a bolt on the starter or bellhousing works well. The idea is to avoid a circuitous path through rusty parts. The starter of course draws more current than anything else.
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Fleet Owner
Joined: Dec 2000
Posts: 25,378
Likes: 5,387
From: Central PA
oops, you are correct, Sir! thanks.
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Lead Driver
Joined: Dec 2012
Posts: 9,718
Likes: 823
From: Wentzville, MO
56 was the first year for 12volt negative ground systems in F100s. The older F series were 6Volt positive ground. Yes, negative ground is when a strap or cable runs from the - post of the battery to the frame.
Couple of things to remember use the same size cable to ground that you do to power. So if you have a 00 battery cable going to your solenoid then ground the block with an equivalent strap or cable. Same applies to the Cab there's generally a 10 guage feed to the Cab so like wise you'll want a equivalent sized ground. Many say you'll need three grounds; block, cab and chassis. I would add an additional ground to the bed since the tail lights hang off of the bed (you could run a ground wire to the chassis). Electrically most of your problems will be caused by bad or missing grounds.
Couple of things to remember use the same size cable to ground that you do to power. So if you have a 00 battery cable going to your solenoid then ground the block with an equivalent strap or cable. Same applies to the Cab there's generally a 10 guage feed to the Cab so like wise you'll want a equivalent sized ground. Many say you'll need three grounds; block, cab and chassis. I would add an additional ground to the bed since the tail lights hang off of the bed (you could run a ground wire to the chassis). Electrically most of your problems will be caused by bad or missing grounds.
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