Ground strap composition

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70Duster340

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I see most OEM ground straps are made from braided metal. Why is this? Can a ground strap be made from insulated stranded wire?

Thanks
 
The wire mesh ground straps are very flexible and are less prone to fatigue failure. You can absolutely make one out of braided wire. 65'
 
The ground strap on a '70 is part of the negative battery cable & it is an insulated wire.
 
I believe that they are made from braid for two primary reasons:

1. Durability - the braid is very robust to mechanical vibration and stresses.
2. Current carrying capacity. For your electrical system to operate properly, it is best to have the grounds tied together as well as reasonably possible. Ground should be the same potential everywhere on the car. A big strap helps this.

A good sized wire would perform the same function electrically.
If it is designed properly (so it won’t break) it would also be the same mechanically.
 
Thanks, folks!!! I've seen them made from braided copper as well as braided tinned metal. Which would be a better choice?
 
I'm sure it is flexibility. Many newer cars had a pair of small braids, one from each valve cover to the firewall. There is considerable movement there
 
Good information. I had been thinking of working up a centralized ground system, with all the grounds running to one block. In my head it looked good, but it seems like it would be a lot of lengthy wiring to get the same results as the OEM locations.
 
As an FYI in my field of professional expertise aviation maintenance, all the grounding straps we use on aircraft are bare fine strand braded wire with crimped on ring terminals. This is for durability and reliability. Lots of vibration, and on such things as flight controls and landing gear doors which have grounding or "electrical bonding" straps on them, these components are always in movement. A fine wire stranded braded cable allows very good flexibility with low issues of breakage.

Typically when changing a bonding wire, you have to do an ohm check from the bonding wire to the adjacent structure next to it but not touching it to make sure your getting a solid connection. The main reason for the grounding wires is lightning strikes. If the whole external structure is electrically connected or bonded including moveable parts, when its struck by lightning, it will absorb the charge which will travel through the structure and exit out through the static dischargers (little antenna looking things on the back edges of the wings and wingtips) with minimal burn damage to the structure. Without a good bond I have seen stuff like composite wingtips burnt and charred off !!! This being said that's a lot of voltage that jumps through these bonding wires. Using a fine braded uncoated bonding wire for a body to engine ground on a car is a far superior way to do this.

Now back on topic, my 67 cuda came with a black insulated 12 gage wire with ring terminals at both ends as a ground. It appeared to be stock. I will be putting bare braded wire instead from the firewall to the back of the block. Also going to jumper a second braded cable from the motor mount plate on the engine side to the K frame as a secondary motor to body ground. My firewall ground I plan on using a steel riv nut or nutsert on the firewall for a 10/32 stainless screw and the braded cable. This will make sure I get the best ground possible with little to no degradation.
 
The star washers are a great addition to the ground straps. As well as a proper grease/paste to minimize corrosion.
Lack of grounds can cause many problems, saw a shift cable melted due to missing ground after a valve cover gasket was replaced.
 
moparmat2000 said:
Now back on topic, my 67 cuda came with a black insulated 12 gage wire with ring terminals at both ends as a ground.
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The would have been correct. It shows in the assembly drawings for 67-69, all cars, all engines, with slight variations on where it gets attached to the firewall.
Someplace, prob here or moparts, there was a discussion about when Chyrsler switched from using inuslated wire to braided ground strap in that location.
 
moparmat2000 said:
I plan on using a steel riv nut or nutsert on the firewall for a 10/32 stainless screw and the braded cable.
Click to expand...
I agree braided is best. I like nutserts as well. I installed 2 to mount my stock Ignition box for grounding purposes as well.
 
I had a GM something ( lumina maybe? I forget ) here once with strange electrical problem that turned out to be ignition switch. Anyway,,, It was previously a police cruiser. It had those braided ground straps on every hinged body part, hood, deck lid, everywhere I looked. I'm guessing tasers versus electronics was the reason for.
 
RedFish said:
I had a GM something ( lumina maybe? I forget ) here once with strange electrical problem that turned out to be ignition switch. Anyway,,, It was previously a police cruiser. It had those braided ground straps on every hinged body part, hood, deck lid, everywhere I looked. I'm guessing tasers versus electronics was the reason for.
Click to expand...

Radio noise. Another thing used on two-way radio equipped cars are little sharp springy contact fingers screwed into the hood fit area. The hood presses against them and they press against the mating surface, and hopefully provide a ground.

You can HEAR this if you have an AM radio. With the car idling and tuned to a weak station or in between stations, turn up the "noise." Then slowly open the hood. You will start to hear a marked increase

'Member Corvettes? Plastic bodies? They have a metallic structure around the ignition wires to reduce radio noise.

Hood to firewall grounding for two-way radio must be as short as practical because the wavelengths are so short. A basic 1/4 wave vertical whip on 450mhz for example is only around 6". that is the equivalent of a 9 FOOT whip at CB frequencies. So a single 6" long grounding strap does little at all on UHF
 
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