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Should I replace my old wiring harness?

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Britishautobody

Jedi Hopeful
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I hear this allot from people who are restoring their vehicle. My first gut reaction response is absolutely YES! Your entire investment is at risk should you choose to reuse a old harness. I have seen wires that were underneath carpets that were bad underneath the tape wrap that one could not see until unwrapped.
If you were ever in a car that had a small wiring fire like dummy me you would understand how rapid a wire melt down can occur and how little time and helpless you will feel to react in such a short time. I would say the car I was in filled with smoke so thick in about 5 seconds ,I had to stop in the middle of the road because I could't see let alone breath the toxic smoke from burning wire insulation. There is the option too remove all of the tape wrap and inspect the wires and re wrap but there can still be unseen problems,and after the car is assembled do you really want to chase down those nightmares?
I restored a Monza for myself years ago and when I pulled out the harness and fusebox it had a couple of fuses blown and a bit of foil in one fuse location instead of a fuse. A reproduction harness is unavailable for this car because of no demand for one. So I had to reuse and inspect the harness and I will be darned if I am still having a dash light fuse issue and lost running lights last night,still not sure why.
My point is time and time again when you are trying to save money in a gray area it can come back and bit you in the butt, we put more emphasis on the nice wheels,cool dash etc. What about that cool new wire harness that will save us chasing wire gremlins and help us sleep at night knowing our pride and joy is wired properly with new wiring and tight connections.

My 2 Pence!
 
Do you know of a source for replacement wiring harnesses? I will be replacing all harnesses for my BJ7. Emailing and calling British wiring https://www.britishwiring.com/ only to have my email returned as undeliverable and I have not received a return call from the message recording…
 
There are two serious problems in older wiring:

1. The insulation materials used in the 50s and 60s were nowhere nearly as good as those available today. They hardened and cracked with age, allowing short circuits to occur easily. Combine that with (to be charitable) less-than-wise methods of mounting the cable, which often allowed chafing, and you can see that there could be a real problem.

2. Large parts of our cars' electrical systems are not fused. My Bugeye, whose electrical system is virtually a carbon copy of the MGA, does not have fuses in the headlight circuitry or ignition. A short circuit in either of these circuits virtually guarantees a fire.

Add to that, 50 years of unwise electrical mods by multiple owners, and you can see the problem.

If a harness is available for your car, you're home free. Even if not, there's really no reason why you can't make your own. Lots of people do that. Just take out the old harness, lay it out, and make new wires, one by one. Go carefully and check your work a lot. Add labels to the ends, as necessary. It's nice if you can reproduce the color code of the original wiring, but not absolutely necessary. Just be consistent (i.e., always use the same new color to replace a given old color) and keep records.
 
Hey Big6,
I have used Moss Motors for wiring harnesses on MG's and Healeys and always
found them to be excellent. You can also look at AH Spares in the UK.
Their stuff is great. Check the pricing as the shipping from UK to SC
can be 15 - 20% of the total order. www.ahspares.co.uk

Plus, replacing a harness is not that difficult if you label everything you
take off well, DO NOT disconnect anything from the dash until you have the
new one in place ( cut the old one off at the point where it goes through
the firewall so you can put the new one in place but leaving the other ends
of the old one still connected ). I did it from the boot forward to the
engine compartment. That is the critical area and the reason why you want
to keep the old one connected up as you lay the new one in place. The
biggest pain will be getting it through the firewall with it being so tight
under the dash.

Good luck,
Mike
 
I'm really surprised. My experience with British Wiring has been excellent. I had to build a harness for my Prefect as none were available. I purchased the materials from both British Wiring and Rhode Island Wire, both of which have been exceptionally helpful in the project. When finished, I will send the taped up harness back the Rhode Islans wire and they will braid the cover, for a price, of course.
 
Bayless said:
I'm really surprised. My experience with British Wiring has been excellent. ...
Click to expand...
Matt Bakes is top notch, so I am also surprised. Here is his number for Triumph Rescue; 610-845-8217.
 
I received a call back from British Wiring and ordered the harnesses for my BJ7. British Wiring indicated problems with their website and they are in the process of updating the online catalogue and online ordering.

If you do a price comparison with other vendors I found British Wiring has the most competitive pricing…
 
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