The first article Electrical 1: Shocking Developments introduced our strategy for upgrading the electrical system. Time to get to work implementing that strategy!
As Captain Obvious has observed, electrical systems consist of two parts: power and ground. While power is obvious (pun intended), ground is often an afterthought. This makes the ground system a logical place to start for building a reliable electrical system.
The challenge with ground is that it uses the body and frame to provide an electrical path, often with poor connections. These connections are barely adequate when new and degrade over time. The battery ground is connected to the engine block, providing high current power to the starter. The engine block is then connected to the firewall with a single ground wire and a small screw. Various electrical components around the car are then grounded to the body.
Several months ago, as part of general preparation, I welded two bolts to the frame – one near the firewall ground point and one near the battery. This provides solid electrical connections to the frame with no chance of corrosion, making a high quality ground available to the entire car.
I then had two heavy duty ground wires custom made by GenuinedealZ. These ground wires were made from 4 gauge (4ga) tin-plated solid copper wire with heavy duty terminals and adhesive lined heat shrink tubing. What does all this mean?
Solid copper wire is a better conductor and stronger than aluminum or copper coated aluminum (CCA) wire. Low cost wiring is often CCA, which doesn’t hold up under severe service. Since copper wire by itself can corrode, a tin coating is used where it is likely to get wet. Tin coated wire is often called marine grade as it holds up to the harsh conditions encountered in marine use. Areas of a car that are exposed to moisture, such as under hood use, are good places to use marine grade wire.
Factory ground wires are often 12ga or perhaps 10ga if you are lucky, which was adequate in the 1960’s. As a point of comparison, 4ga wire was often used for the high current starter. When ordering these custom cables the cost difference between 8ga and 4ga is less than $1.00 per foot, so it makes sense to upgrade.
Heavy duty terminals, also made of tin coated copper, are sized for their application. In this case I have 1/4″ bolts for the frame ground and firewall ground and 3/8″ bolts for connecting to the engine block. One cable goes from the frame ground to the firewall bolt and the other goes from the firewall bolt to the engine block.
Sealing electrical components from moisture is a key to long life. Heat shrink tubing provides mechanical and electrical connection. Adhesive lined heat shrink tubing has a heat sensitive glue on the inside. When heated this adhesive melts and forms a waterproof bond. Adhesive lined heat shrink tubing is the standard for marine applications and is great for automotive applications.
The screw connecting the original ground wire to the firewall has been replaced by a 1/4″ bolt through the firewall. The firewall was sanded clean around the bolt hole for a good electrical connection, then the bolt was run through the two new grounding wires. After this the area around the bolt was sealed. Inside the car a 10ga grounding wire was attached to the bolt – this wire will be attached to a grounding block under the dash.
A dedicated ground line was run from the negative terminal of the battery to the other grounding bolt on the frame. This is currently a 10ga wire – it will be upgraded to a 4ga wire the next time I order custom cables. This grounding point will also be used by the power distribution box planned for high current loads like headlights.
The net result of all of this is a very solid ground system to support the rest of the electrical system. The existing body ground has been improved, which will help in general. Solid electrical connections of the body to the frame, engine block, and battery negative terminal will eliminate many potential problems. Using grounding blocks and dedicated ground wires for high current use cases will further improve electrical performance.
While not as exciting as other work, starting with the grounding system is key to electrical success.
These reminded me of a problem my Dad and friends had in the 1970’s working on an “older” vehicle. The brake lights would start failing after the car was driven for a bit in winter, but worked fine either in the person’s garage or when taken to a shop. I forget the vehicle exactly except I remember tail fins, but I do remember the solution was that chassis was not all at the same ground. If it got cold, the lights would stop working and you got a slight shock if you wore the right shoes (or you were checking the problem in the rain). In the shop, everything worked fine. Dad pointed out the ground cables for different parts of the chassis to me and then they took a bit of copper wrap cable and ran it from the back light section to the main body. The lights then brightened up and worked fine from then on.
Intermittent electrical problems are an absolute nightmare to track down!
This is a case much like software where a hard failure is actually a gift from the heavens. I hate intermittent electrical problems almost as much as software timing bugs.
Tail fins sounds like late fifties or early sixties – exactly what I’m working with. Combine the corrosion control of that era – more accurately the lack of corrosion control – and these problems were common.
A big part of the reason for tackling the electrical system like this is to try to avoid some of these troubleshooting nightmares. But I still suspect I’m going to end up chasing down some more gremlins in the tail lights…