DavidM938 wrote:Hi Ryan, are you sure you haven't been collaborating with Nik Blackhurst for the last year(s)? Let's review:take a late model big-engine complete driveline out of a donor car, stuff in into an older, smaller, lighter car that it won't really fit in, hack the poor little car to pieces, then completely rebuild every component in the most fiendishly complex way possible. Also, keep the drama going for months and months, and have the viewers (who are all a bit looney to be watching in the first place) waiting for the next episode just to see if the bloody thing will actually ever run! Do I have that about right? Anyhoo, keep up the craziness, but that thing better be stupid fast to make up for all that work! David in Nashville
Hah, I can't deny taking the long road most times, but I feel the result is worth the work. It had better be fast in the end, ultimately that's the whole point! Not long now, almost finished with wiring (que the mad scientist laugh).
And on that note, on to...
For the engine swap, the minimum wiring to get the thing fired up isn't bad, particularly if you opt to have V8R prep the engine harness for you (I did). You could certainly retain most of the factory wiring on the chassis side and just tie in where needed. However... I had a few things on the wish list for this car that meant there was more work to do.
Over the years of racing and modifying this car, the wiring has become a bit of a mess with things added, wiring cut to remove things, etc. etc. To eliminate any potential for issues for the future, I decided the best approach was to remove all of the existing wiring on the chassis side from the car and start from scratch with good materials, practices, and documentation. This is also the most time consuming approach, but c'est la vie.
Step 1 through 10 of a big wiring project is all planning, long before any tools or wires come out. As soon as you go down this path, if there's an issue in the future you can't just open up a factory service manual to check the wiring diagram. The ease or difficulty of service/troubleshooting in the future now comes down entirely to the quality of the documentation you create.
I began with drawing up an electrical diagram for my new chassis wiring:
Working off the electrical diagram, I made a spreadsheet listing each individual wire that would be present in the harness - including the wire's name/purpose and where each end terminates. Each wire is assigned a unique numerical ID. If you've ever tried to identify a certain wire in a harness you'll know the struggle that can be - even with the multitude of wire colors that factories use you still end up with duplicates of certain colors and you end up having to break out the multimeter to test wires and sort out what's what. By assigning each wire a unique ID and labeling the wire accordingly (more on that later) there is no guesswork left to do, just consult the master sheet and look up the wire number.
Here's a screenshot of the top of the list. All in, there's about 100 wires on the chassis side:
A great feature with having this in spreadsheet form means that if you stay consistent with the info you put in each cell then once the list is done you can sort the list alphabetically by whichever column you need. This was really handy during the build as I could easily switch between sorting by harness, numerical order, system, etc.
The remaining piece to the puzzle is knowing how to lay out the harness. The simplest method is to just start laying wires in the car from point A to B to get lengths, but I wanted to be able to build the harness out of the car and also have the plans so that everything is replicable in the future if necessary.
I took measurements on the car and then drew up the build plans:
Much of the above is a bit overkill. The key info there is the lengths between splits and the layout. The rest isn't necessary but I like to be thorough - with this plus the connector diagrams that I show just a bit further down, I could build a matching replacement harness without any need to refer to the car or the original harness.
With the planning sorted it was time to start laying out the harness. Transferred the measurements to a 4'x8' sheet of particle board with screws placed at each branch split for turning points.
Referring back to the wire list above, each wire gets labeled with cats ID number on both ends. Here is where the thermal label printer got a workout:
All of the wires used are milspec (shorthand for Military Specification) /32 series with tin plating and very abrasion/temperature resistant insulation. This stuff is a big jump forward from standard cross-link OE wire in terms of durability and is also more conductive and lighter weight. It sounds obvious but the wire is the core of the car's electonics and nothing else can make up for poor quality wire. IMO this isn't the place to scrimp.
With wires laid out and labels we begin to loom the harness. The black woven material is resin infused fiberglass braid that holds up to 1200 degrees. That gets finished at each end with short lengths of adhesive tube to prevent fraying and seal the wires where the harness splits. You can see that assembling the loom requires some forward-thinking because each section often needs several more various pieces sleeved over it that will be shrunk down later:
Also in the pic above is the bulkhead connector already assembled. That connector contains each wire that will pass from through the firewall into the engine bay, which makes it very quick and easy to disconnect the engine side of the wiring from the car so the engine can be pulled quickly without having to disconnect the wiring harness from the engine.
As I build the harness, I fill out a pin layout sheet for each connector in the harness. When I began the harness build this sheet had blank spaces next to each pin, and I filled the sheet out as I assembled connectors:
And a few progress shots of the harness in various stages of the build...
This is the main break point where wires split off towards the center console switch area and the fuse/relay assembly:
Finishing the wire terminations:
Same set of wires complete with connectors:
Similarly finished ends that go to the fuse/relay box:
Close-up of the connector that goes to the new digital dash. Re-pinned with the milspec wire, labeled, etc.
Wiring up the fuse/relay box:
Backside of the finished fuse/relay box, tidied up with service/strain relief loops on each wire:
The finished fuse/relay box and harness:
Finished main chassis harness (connectors to Racepack dash, OE brake pedal , GM gas pedal, fuses/relays, OBDII, all switches, tail harness, diff temp sensor harness):
About to get installed in the car! Also pictured are some of the secondary harnesses, switch assemblies, etc.