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Anyone here make their own grounding bar for the firewall?


BTF/PTM

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I now have the correct Nissan battery, correct Nissan battery frame and I just picked up fresh battery cables and some 10ga wire for making some chassis grounds.

I'd like to further improve things by making or buying a grounding bar that mounts on the firewall and holds the main battery ground lead and connects engine/chassis grounds. I think I can just bolt a basic bent bar to an existing bolt hole (would like to use two, but I only see one that's factory and readily available). Is there a kit that anyone has used that worked well? Has anyone just cut a chunk of copper or aluminum and bolted it to the firewall and run their ground leads to it? Input welcome.

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Fair question. I don't have a scientific answer for you, except that I know circuitry likes to have a ready path to ground and I've read that our cars after all these years can have deteriorated wiring so I was thinking I could help the situation a bit by giving the chassis fresh grounds.

Would it be sufficient for me to stick with the single bolt hole that's currently used (it grounds the chassis back to the smaller lead at the negative battery terminal)?

Also, while I'm on the subject, I have a question about engine grounds. It's a newbie question since (obviously) electronics aren't my strong point so I apologize in advance. I know that spark plugs are basically a big ground wire that jumps a spark and grounds that energy to the engine and then back to the battery; is there any need to ground the cylinder head via one of the valve cover bolts, or is there enough ground already with the main negative cable attached to the starter base/bell housing? The question comes from previously working with my early 90's Honda that had small ground wires in several places between engine and chassis. I know the cars aren't very similar, but I figure it's worth it to ask since I don't know how many ground leads my z had before I got it or how many it *should* have. Thanks :)

Why do you think the car needs a grounding bar?
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The amount and quality of grounding required has a lot to do with complexity and demands of the electrical system on the car. A stock 240Z has a very simple and low demand electrical system. Variations in baseline ground voltage have little effect on the car's performance.

Conversely, my racing 240Z that ran a MotecM48 EMS required a true zero ground as a baseline reference for the computers and coils. That took some work making sure everything was grounded to a good chassis point and ensuring any electrical device grounded to the chassis didn't leak voltage. I had a fuel pump relay that changed the ground from a true zero to .5 volts and that threw off the EMS. Isolating that relay fixed a couple minor problems.

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So it sounds like it's safe to say that, unless I start installing components with computing ability and bit-count feedback loops, a couple simple firewall grounds should be plenty. Not planning to do anything that advanced any time soon :)

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I added a NEMA12 box on the right fender to house all of the relays I added for the headlight upgrades (headlights, driving lights, fog lights), electric fan, etc. I have two #4 AWG wires tapped directly to the alternator for power and ground (properly fused). In the box I ended up using a standard aluminum ground bar that I bought at Lowes for the negative common to save a lot of wiring space.

If you are convinced that you NEED a ground bar, I would suggest looking to something similar. They only cost about $2-$3 each, and can handle more current than the car is likely to need.

Relative to the engine ground, there are two ground wires attached to the engine block. The negative side of the battery connects directly to a mounting bolt on the starter, and there is also a ground wire connected from the body of the alternator to the right side fender. With no more electrical devices than were present on the early Z cars those two are sufficient.

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I'm a big stickler for grounds. I personally have 2 gauge wires on my battery.

1) gold plated brass battery post terminal with a 2 gauge cable going to a 4 fuse Distribution block with 3 inputs, one of which has a 4 gauge wire going down to the starter.

The ground wire is connected to the battery via another Solid brass, gold plated terminal. There is an 8 gauge wire from there, to the firewall's stock grounding bolt. The 2 gauge ground wire goes from the top of the battery, down to the starter/tranny bolt.

There is also an 8 gauge wire from the starter/tranny bolt leading over to the stock engine harness ground bolt below the battery. I also have a 4 gauge ground wire going from the alternators mounting bolt, on the engine block over to the front crossmember's control arm bolt. (I needed a big bolt to use)

The picture below was when I first did the upgrades. The 4 gauge wire heading to the battery has now been replaced with 2 gauge wire. For obvious reasons.

By the way, Aluminum is Crappy for grounds or any kind of power transfer. Use Copper, tin, brass or gold plated brass or copper.

Dave

post-4921-14150810490923_thumb.jpg

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Considering the feedback thus far and that my z is completely stock, I don't think there's any need for a grounding bar just yet. I'll let that project wait. I have a tendency to get overly excited about new projects and start dreaming about absolutely every possible thing that could be improved :)

As for the voltage regulator bypass, I'm pretty sure the object in the picture below is it.

?action=view&current=voltageregulator.jpg

http://s132.photobucket.com/albums/q27/AwwsChwA/z%20parts/?action=view&current=voltageregulator.jpg

If installing my MSA 60-amp alternator and VR bypass plug is as simple as installing the new alternator and then disconnecting the stock VR and plugging the bypass plug into the wiring harness, that will be done tomorrow. I've been waiting on the installation to get feedback on it and make sure it's actually as simple as the claim states.

Thanks again for the continued help, everyone!

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If installing my MSA 60-amp alternator and VR bypass plug is as simple as installing the new alternator and then disconnecting the stock VR and plugging the bypass plug into the wiring harness, that will be done tomorrow.
Trust me, if anyone knows if it is just that simple, it's me. And yes, it is that simple.
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Well, yesterday I managed to plop a 17mm wrench squarely into the oil pan full of 4 quarts of dirty oil out of my friend's Subaru during an oil change, so dropping the 12mm wrench in this case doesn't seem too unlikely LOL

20 minutes, Tops. And that's going slow, dropping the 12mm wrench a few times.

Dave

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