Original or Reproduction Wiring Harnesses
 

I'm restoring a 73 T/A and am wondering whether to use the stock wiring harnesses or buy new reproduction harnesses. The car's harnesses look to be in relatively good shape and not hacked to pieces. However, they are 50 years old with possible hidden corrosion. Does anybody have any words of wisdom regarding this dilemma?

The reproduction harnesses from American Autowire and M&H can be done section by section, as needed

The American Autowire modern upgrade kit must pretty much be done in one shot - front to rear - so quite a bit more work in one shot ( at least that was I have been told )

You want to risk 50 year old wires and connectors being safe? I don’t mean to sound snarky with that, it’s a legitimate question for one to ponder.

Repop harnesses remove a lot, if not all, safety concerns.

I’ve picked up from AAW most of the harnesses for my car, the one that I have not - dash - is the spendiest of them all. I plan to get up close and personal with it, a mag lamp and an ohm meter.

You didn’t indicate what level of restoration…full tilt original or something else adding modernization of things. AAW will custom make certain things into their harnesses, so you could upgrade different areas while still keeping the overall factory “appearance”.

Cost is always a concern, for most anyway, but I’ve had enough electrical “events” happen to not go through things with a fine tooth comb.

If you've got the wiring out of the car already for restoration, it's no question - buy & install new wiring. Reinstalling old wiring would be silly. If you left the original wiring in situ and it's in excellent shape, then maybe I'd entertain an argument for leaving it alone. But even then, I'd really highly recommend replacing all of it if you are restoring the car. Having fresh wiring will help you avoid all sorts of future headaches, dim gauges & headlights, etc.

Only original harness that is usually anywhere close to good enough shape is the dash harness. Assuming the car was treated and stored well over the years they are protected from UV and excessive heat. And of course assuming they are not hacked up.

If you are willing to pull the individual pins and sockets from the plugs and clean them up an original dash harness can work fine. On my 68 I basically replaced all the harnesses except the dash harness which was in great shape, but I pulled every single pin and socket and cleaned them and checked for problems.

Does wiring still oxidize within the insulation, though?

M&H no doubt. Did my whole car by myself in a day with NO reference points and only a wiring schematic I bought on eBay from a company that’s name eludes me at the moment. If you’re interested PM me and I’ll look up the schematic company. No kidding the whole car was done and working from naked to function in about 6 hours

ZeGerman ... depends a lot on what environment the car lived in, type of insulation, if the wire was undersized from the factory etc. Cars that spent their lives down south in humid weather, or close to the ocean ... going to have problems. Cars in the north with half the year cold, dry air ... you can find some very good harnesses.

Dash harness I used was from a 58K mile, northern car ... removed and stored in the 90's, and I found zero issues with it besides the sub harness to the blower motor which I replaced with new. Most of the terminals still shiny brass ... did have to replace the fuse clips in the fuse box. And yes humidity will creep up the wire under insulation but you can usually tell if there is a problem with close examination.

If money is not an object then there is probably zero reason to use an old harness though. BUT ... save the old one ... and leave all those factory kinks in it to help you remember the twists and turns it's supposed to have snaking around inside the car.

I replaced a few of the harnesses on our '67. I'm glad that I did. I knew that they were becoming brittle, especially the engine harness, but it really hit home after replacing them and inspecting the old ones. We've replaced the engine, A/C and rear lamp harness. The rear lamp really needed it as some of the lights were'nt working. The bulb sockets were old and loose. Best money we've ever spent on the car. I went with 'Lectric Limited because they had a good shipping arrangement to our location. But I've used M&H before. Both companies have an excellent product in my experience.

I put an American Autowire Classic Update kit on my car. No complaints at all. A lot of work. But the harness and instructions were great. I bought their crimping pliers also. They were a must have.

The engine harness was a no brainer. Replaced with M&H. For the front lighting harness I ordered the next size up wiring to reduce voltage drop and made it myself.
The dash and rear harnesses were in excellent condition but I still increased the size of the ignition wiring and starting circuit wires. Like Data, I inspected all the terminals and replaced those that appeared to be loose. Replaced some of the terminals in the fuse box and added a tab for the IGN opening in the event I ever need a full 12 volt ignition circuit.

I've used American Auto Wire and M&H in several restorations here and have been happy with both. Good quality products.

I have generally replaced the respective harnesses with phases of the restoration process - engine, a/c and front end when doing the whole front end restoration; the rear harness when doing the trunk and rear end; and the dash and interior when doing the interior resto.

On this current project of a ‘79 TA SE W72 Y84 WS6 4 speed car, looked at several sources for harnesses and related materials - all similar. Went with Lectric Limited and have been very pleased with the workmanship of their product and the accuracy of their reproduction of the original harness and related materials, such as the ground straps.

Like everything else with our hobby, need to research what it best for your project.

I've used imported repop, Painless and both types of American Auto Wire kits. Import harnesses I've installed in the past have had issues mainly with connections at the bulkhead, I'm more confident doing my own work. My favorite is American Auto Wire due to the flexibility for modifications and improvements that are built-in including modern relays and fuses. I just finished an AAW Classic Update harness in our '69 Bird. Since my ignition, charging, gauges, and audio have all been updated, the classic harness was perfect for me, all the correct wires were included. You can add or remove wires from the fuse block to fit your needs and extra circuits are there if needed. Some of the wiring is heavier than OEM and all the wiring is longer than needed, but it allows you to route it however you want and there are more grounds than factory. You also have to cut-to-length and terminate every connection, except for the main instrument panel connections, so labor time is longer than other choices. You can install it to stock components or modified. All of the connectors and wiring are excellent quality. As said, you'll need a good cripming tool.

After seeing a Dodge Charger on fire one day on the side of the freeway, I'm a firm believer in replacing old wiring, regardless of appearance.

Where do you stop replacing then?
I needed a Ned under hood harness, I used a mint original.

First, thanks to everyone for your excellent feedback. My project is a 73 SD455 T/A, and it is undergoing a rotisserie restoration. My thought in using the original wiring was to maintain originality. Based on my experience with previous projects (67 GTO, 70 T/A, 71 T/A, multiple Corvettes) is that repop parts, though shiny and new, often do not precisely match the originals. When it comes to wiring, I've decided to say the hell with originality. I will replace everything and save the time refurbishing the old stuff and avoid the possibility of an electrical fire.