Recently I had an opportunity to visit Rhode Island Wiring in, where else, Rhode Island. It was a fascinating tour for a restoration geek like me. I was treated to a very thorough tour by long time RIW employee Marsha. But first, why this tour, now? The answer to that is my recent retirement from my “day job” in nuclear power and my complete immersion in the restoration of the 3 Jaguar E-Types I have been hoarding, just waiting for this moment in my life. Discussions with several restoration authorities convinced me that RIW was their first choice for top quality authentic wiring harnesses.
Before we get into the specifics of my tour, let’s take a moment to think about why one would go to the not inconsiderable expense and effort of replacing the complete wiring system on an E-Type. After all, with the exception of the engine compartment, much of the wiring is out of sight and out of mind. There are really two answers. One is purely cosmetics. Wiring harnesses on early Jaguars were in many instances covered in beautiful, color coded woven cloth looms. The harnesses on most 50+ year old cars are very unsightly. Assuming the car is being fully restored with new paint inside and out, it would be a cosmetic travesty to re-install a dirty old harness. The other answer is for reasons of electrical reliability. Lucas Prince of Darkness jokes follow all British cars. Maybe not fully deserved but acknowledged. Part of the problem is the wiring end connections (flat terminals, bullet connectors, screwed fittings) which develop a layer of corrosion that inhibits the transfer of electricity. Furthermore the wires themselves (generally stranded copper) can develop a corrosion layer. And the insulation around the copper can break down, resulting in the worst case in shorts between wires. All of these issues are resolved with a new harness.
I recently placed an order from RIW for harnesses for my 3 E-Types. I have family in the Boston area and during a recent visit, decided to run down to their Kingston RI facility for my tour. RIW has been in business for over 35 years. In general, they can build quality wiring harnesses for cars built before the 70’s. A restorer can carefully remove their existing harness and send it to RIW. Note- I say harness but most cars have multiple individual harnesses that connect together. For instance my 63 FHC has 16 individual harnesses. RIW carefully documents the particulars of the harness, through inspection and dis-assembly. Where necessary, supplemental research of historical documents is performed to fill in missing details. The result is a harness configuration drawing supported by a spreadsheet that lists details such as wire size, color code, and termination descriptions. RIW tells me that they have performed this level of investigation and research on over 5000 cars since they were founded. Most of the cars for which they have supplied harnesses are listed in their catalog. For instance, I noticed a harness for a Jaguar D type listed, with the earliest Jaguar listed being a 1933 Swallow SS.
I asked Marsha about the history of covering wires with a cloth cover. She said that originally the bare wires would have been encased in a rubber covering, basically to insulate and protect the conductors. Since the color options for the rubber were limited, braided cloth coverings were introduced to allow a unique color pattern to be applied to the wire. Obviously, once a wire enters a harness and emerges at the other end, a unique color pattern is invaluable in allowing the correct wires to be connected to the various electrical devices in the car. The patterns can be a simple as a black covering with a single colored thread up to elaborate 3 and 4 color patterns. Later, as plastic insulation materials were introduced, basic color codes could be embedded in the plastic. Modern automotive wiring uses PVC plastic as it’s insulation. RIW uses this modern wiring for all its harnesses, to provide the best quality and durability. They have a vast inventory of wire on spools, both bare plastic wire in a wide variety of color codes and plastic wire covered in a wide variety of loomed color patterns.
I found their cloth braiding machines to be quite fascinating. These machines are quite old but I was told that their 3 machines stay busy braiding replacement wiring as supplies of a particular wire pattern become low.
Here is a link to a video that I took of the individual wire braiding machine in action.
Once a harness has been recorded on paper there are 3 steps taken to build most harnesses. The first step is the Build process. The paper work is used to cut all the wires needed to create a harness, which are placed on a pegboard. Once all the wires and tubes and such needed to build a harness are cut the builder binds the wires together in proper order.
Now the harness is ready for the Looming process. Most harnesses are loomed with cotton yarn on braiding machines. Some are just taped with plastic tape, depending on the original manufacturer and when the vehicle was made. The harness looming machine is also quite old and requires the active participation of the operator. Just like an individual wire, the loom threads can be color coded. Here are links to several videos I made of the harness shown above being covered on the looming machine.
Of course, not all cars used cloth coverings. Some used the familiar black plastic coverings. These are used where appropriate.
Once the basic harness is prepared it goes to Finishing, where it is verified by another technician for correct continuity of the various wires. Also at this time the proper terminations are crimped and soldered onto the wire ends. At this point, the harness is basically done. RIW packs each individual harness in a plastic bag along with the wiring diagrams and installation instructions. In some cases, existing components on the car must be re-used. These situations are noted by RIW when applicable. For instance, on the E-Type, the multipin bulkhead fitting on the bonnet must be re-used. This mainly is the case due to the total lack of current replacement fittings.
RIW can also take an existing harness and just replace the exterior harness loom. This option might be desirable when the original harness is in fairly good electrical condition but the cosmetics are poor. They also sell individual wires and supplies such as terminals, battery cables, and loomed spark plug wiring.
I must admit I get a little geeked out about this type of thing. That said, it was a fascinating look behind the scenes of a small business that is part archaeology, part cottage industry, and definitely important to maintaining the restoration hobby. Keep them in mind for your next restoration project.