Electric ground doubt

[erne.castro]

Hi,

I'm rebuilding my FFR Roadster (I bought it already built) and one of the main things that was a complete disaster is the electric circuit, so I'm redoing it.

One big doubt I have is regarding ground wire. What I found is that tail section has everything with a ground wire that goes all the way to the dash section and connected there to the chasis. On the other hand, the front section has the lights, fan, horn with a short ground wire connected to the chasis right next to them.

My question is, which is the right way? If I have to tell, I would go with using everywhere the chasis as ground, but I don't know if there is any any issue I'm overseeing.

Thanks.
Ernesto.

[rich grsc]

The chassis makes an excellent ground. Just be sure you have a clean connection with good metal to metal contact.

[erne.castro]

Thanks! That's what I've thought!

[CraigS]

Exactly. All modern cars use the frame/body as ground. There are usually at least 6 or 7 ground points all around the car. Either a threaded hole or a short stud sticking up a little off the surface.

[GoDadGo]

Exactly. All modern cars use the frame/body as ground. There are usually at least 6 or 7 ground points all around the car. Either a threaded hole or a short stud sticking up a little off the surface.

Craig's point is exactly why I've got redundant grounds to the frame for all lights plus the fan.
The engine has two grounds from the frame to the engine block also.
Your point is well made as are your concerns.
Ground redundancy isn't a bad thing.

[mike223]

The engine has two grounds from the frame to the engine block also.



Just a point of interest.

These cars are notorious for eating aluminum radiators if the engine is not well grounded.

The massive current from the starter seeks all easy routes to ground - better make sure the radiator is not one of them - galvanic corrosion.

[GoDadGo]

Just a point of interest.
These cars are notorious for eating aluminum radiators if the engine is not well grounded.
The massive current from the starter seeks all easy routes to ground - better make sure the radiator is not one of them - galvanic corrosion.

Wow!
This issue never ever crossed my mind.
I've seen aluminum boats get eaten up, but this issue was totally off my radar scope.

[JohnK]

Since we're talking about grounding, can I piggyback with a question? If I want to add some grounding points around the frame and I don't want to weld on studs, are stainless steel rivet nuts a good solution for this or is drilling and tapping the frame better?

[rich grsc]

Just a point of interest.

These cars are notorious for eating aluminum radiators if the engine is not well grounded.

The massive current from the starter seeks all easy routes to ground - better make sure the radiator is not one of them - galvanic corrosion.

Sorry Mike but that doesn't make sense. The radiator isn't connected to the engine, rubber hoses, and coolant isn't a great conductor. Use the proper coolant solves radiator galvanic corrosion.

[mike223]

Since we're talking about grounding, can I piggyback with a question? If I want to add some grounding points around the frame and I don't want to weld on studs, are stainless steel rivet nuts a good solution for this or is drilling and tapping the frame better?

I prefer drilling + tapping.

Stainless doesn't conduct as well as regular steel (which doesn't conduct as well as copper).

I ran #2 welding cable from the battery (neg) to the frame motor mount (passenger side), and then grounded the engine to that.

Also grounded to the frame at the battery (my battery is in the trunk).

[mike223]

The radiator isn't connected to the engine, rubber hoses, and coolant isn't a great conductor.

Use the proper coolant solves radiator galvanic corrosion.



Proper coolant still conducts enough current to destroy an aluminum radiator in short order (if the engine is not well grounded).


https://www.mechanic.com.au/news/electrolytic-corrosion-in-radiators-demystified1/

http://www.super7thheaven.co.uk/aluminium-radiators-galvanic-electrolytic-corrosion/

https://www.advancedenergy.com/globalassets/resources-root/white-papers/galvanic-corrosion-white-paper.pdf

https://www.hotrod.com/articles/keep-your-cool-preventing-radiator-eating-electrolysis/


P.S. The proper term is "Electrolytic Corrosion" - sorry if that caused any confusion.

[GoDadGo]

https://www.flex-a-lite.com/radiator-anode.html

[mike223]

https://www.flex-a-lite.com/radiator-anode.html

I use one of those too.

[CraigS]

When Lexus started using plastic intakes they also added multiple ground wires between the intake, throttle body, and heads. It is super important on efi cars because a lot of the sensors run on 5V so it doesn't take much corrosion resistance to screw up the reading going to the ecu.