63 Karmann Ghia

[Viefhaus]

We’ve got a 1963 Karmann Ghia that we want to put a new wiring harness on. Possible problem is that it has a 1968 Super Beetle motor in it. The current wiring harness is homemade and the door handles are shaved with electric pop locks. We also want to upgrade all of the lights. I want everyone to see me in that little thing!
With all that, what do you all think we should do about the wiring harness and what brands are the best? Thanks!

[FJCamper]

Hi

You didn't say if you had converted to 12v yet. Are you using a 12v battery? Converting means not just a 12v battery, but 12v headlamp turn signals, wiper motor, etc. And a 12v starter.

Frank Camper

[Viefhaus]

Sorry. It has been converted to 12v.

[FJCamper]

We road race Karmann Ghias and if you have an old car, you have grounding problems from age and corrosion. Virtually any of the ready-made wiring harnesses will work. The issue with them is the crimping of connectors. You have to give every connector a drop of hot solder to guarantee low resistance.

https://www.youtube.com/watch?v=8gxMmW2t2rk

Then you must clean every contact point on the fuse box, chassis, etc., with spray electric contact cleaner. We actually add extra grounding points behind the dash and use double chassis ground straps, one at the battery and one at the starter.

[Piledriver]

A proper crimp is a cold weld.
It is a better electrical and mechanical connection than solder.

Aircraft and auto manufacturers stopped using solder after WW2 as it made for wiring connections that cracked/broke in use, due to solder wicking. Electrical wiring crimps were literally invented to prevent the problems of soldered connections, and soldered connections are only used where no crimp exists for the application or emergency field repairs.

If you feel possessed to also solder your crimps, do it lightly ONLY on the end opposite of where the wire comes out and don't overdo it, I use only "marine" style crimps with heat shrink with hot melt glue inside, provides seal and strain relief.

I use a proper ratcheting crimper with the correct die. (you can buy uninsulated crimps and the heat shrink already coated, use the die for uninsulated crimps) You can get a decent (IWISS) one with a good selection of die (7) from ALIexpress for ~$18, or a made in China unit with US branding at Home Depot for $35, with one die, and pay $20/ea for each additional die.
The die are interchangeable.

[FJCamper]

Piledriver, I concur with you 100%. Let me explain why I made the solder recommendation. I once was helping a friend sort out funny electrical problems in a Bug that had a new aftermarket wiring harness. In the beginning, we didn't suspect the harness. But I had the experience of working in Saudi with a Nigerian "electrician" whose only tools were a pocket knife and a pair of pliers with which he crimped on connecters.

The thing was his automotive wiring, sometime building whole harnesses, worked great. His ohmmeter was a 12vdc tail light bulb in a socket with alligator clips. He tested each wire and its crimped connector off a regular car battery. If the taillight dimmed, he redid the crimp or placed a drop of solder on the wire & connector.

Finally I got smart enough to test some of the new wiring harness connectors with my ohmmeter and we found a few very high resistance crimps that looked good but were the problem. So, my Nigerian fix after that was the solder drop. My Nigerian friend was high tech compared to his friends, who dug holes in the ground they could stand in to change oil of a car parked about them.

[Piledriver]

No offense intended, oddly I just had a similar discussion with a Marine EET about the same subject.

There ARE procedure in NASA docs and 00-25-234 as to soldered joints, but the preparation and strain relief requirements are significant.

Good crimps also rely on proper crimpers, so adding a touch of solder (not wicked past crimp into wire) and hot-glue lined heat shrink is probably the best solution to iffy crimps.