Building and installing wiring harness

[strictly]

First hi to everyone.

I often read the forum, and search for answers but in this case I'm stuck and need to ask some questions, so its nice to finally introduce myself and do so.

I am restoring a 1969 911T. I want to do the best job I can, and the idea of replacing the wiring loom has occurred to me. I know I can buy one from YNZ, Kroon, Maybe even Timmy2, Etc, and I might just do so.

Before I take the plunge and spend the $$$$ I thought I would ask to see if anyone knows the answers to the following questions, as maybe I can just build my own replacement. I have rewired quite a few cars, and have most of the tools.

Q1. If I were to buy a complete loom, which comes with all the connections fitted is it actually possible to fit the main front to back section, without cutting any connections off?

Or is the front to back section, which goes through the tunnel, without any rubber connections, just wires with those tiny connections. In which case i'm worrying for no reason.

Q2. I would like to duplicate the tape wrapping.

Surely this can't just be as simple as the normal black PVC tape you can buy. Was it even available then? maybe so.

Q3. Third and final question. There is the option of using of buying the old style thick PVC wire versus the newer thin wall wire stuff (i.e GXL).

I would like to think newer is better, but I know a lot of modern cars, have the new thin wall cable, and some have countless problems because its not as flexible, and it breaks easily...

If thin wall is the way to go. How to I match the wiring?

If I measure the wire (inner conductor right?) and it corresponds to 16 gauge (ok i know it should be metric). Can I just use 16 gauge thin wall, which will carry more current anyway, or should I go down a size i.e to 18g thin wall. I know it depends on amps, but in theory should I just keep the same size for safety?

Perhaps i'll just buy one already made from me, but I thought I would ask first, I could do with spending the money on the motor instead! lol.

[timmy2]

Q1- the main tunnel harness I built for someone recently was able to be pulled from the back to the front with connectors in place.

Q-2 Tape of the correct quality is available on eBay. Search for Elliot ETN1000E high temp low adhesive tape.

Q-3 I use TXL or GXL of equivalent or larger gauge for all circuits. I use a larger gauge for the main alternator wiring.
Vinyl sheathing is used as a cover for the main harness and is available online. (Waytek) The advantage of the newer wire is the ability to fit the 30 or so wires inside the main tunnel harness vinyl tubing easily.

I am currently (very slowly) building my first '69 complete car harness for someone and I can tell you there are a lot of small harnesses to build.
As well, there are many unique connectors that are rubber cast over the connectors. (Think rear connector panel)
There is a recent thread where a guy in Hungary is rebuilding them for his car, but it is a lot of work. (search differences in wiring)

To build an entire new harness, you will need multiple sizes and lengths of striped wire. Just write down the many color combinations you see on the print to get an idea. I currently have about 100 different ones on hand for the harnesses I am making.
I have had to have a number of the color combinations made as they are not readily available. The striped wires are generally twice the price per foot of regular colored wire. 6-250 ft reels of striped #16 wire I ordered this week was about $400. I think the smallest run Anaheim wire will do is 100 feet at about $23 to $45 a reel depending on gauge. Figuring you need about 30 color and size combinations for the main harness it will easily run you $600 in wire material costs buying reels of wire.
Then you will need to source the tape and vinyl sheathing as well as the common and Porsche only connectors etc.
Britishwiring dot com has a lot of striped wire they will sell you in small lengths, but they don't have all the combinations you will need. I have used them occasionally while waiting for custom reels to be made. I highly recommend them as they are fast and great to deal with.
Cycle terminal dot com is a good source for many of the terminals.

I build my harnesses for those that can't or don't want to. They are a lot of work and it is difficult to keep the price point as low as I do.
If I were to charge my normal hourly rate that I earn in my trade as an electrician, my prices would probably be the same or even more than Porsche!

Good luck in whatever you decide to do.
I am happy to answer any more questions you may have.

Dennis (timmy2)


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[strictly]

Hi Dennis,

Thanks for the reply. I have seen your work, and it is beautifully handcrafted. Very nice workmanship.

Thank you so much for the detailed reply. I find wiring incredibly therapeutic. Its so nice to be able to reproduce something new from something old. Perhaps i'll change my mind when I count the 100 or so wires I will need!!

Thanks for putting me at ease over the front to back, that was my main worry. It seemed a little crazy to make (or buy) a beautifully made harness and then cut the connectors off to get it through the tunnel!

Well for the moment, i'm going to continue with my research. If i get stuck, or my mind boggles over the wiring, then i'll send you my loom, or parts of it to clone. I'm certainly impressed. And I wouldn't even think to question the cost. I'm also a tradesman, and the price of good attentive workmanship should never come cheap. You always get what you pay for.

The only question that really springs to mind, is how you measure or choose the correct wire gauge to clone. As I understand it, I need to carefully strip the wire, and then count the strands. I can then look this up to get the gauge,and then I purchase the same gauge in thin wall, but in the correct colors.

Do you ever use the SXL wiring, or is the GXL good enough for the engine bay?

Any general comments about the thin gauge, someone mentioned there are various qualities available - any truth in that? or as long as they are SAE standard, then are they more or less the same?

Thanks again Dennis, I know you know your stuff

[timmy2]

All of the TXL and GXL I use is rated for the temperatures and oil etc it will see in an engine.
asapwire dot com is one supplier I use and they have a section strictly for automotive TXL wire. (250 ft roll minimum)
The SXL is very thin insulation compared to the other 2 and although tough, I haven't wanted to use it. The original wire is most likely GXL. I have a mix of TXL and GXL depending on the supplier I purchased from.

As far as selecting the gauge, you could download the '78 schematic from Pelican and write down the metric wire size indicated on each wire on the drawing as a starting point. Then there are charts to convert to AWG on the web.

Porsche really never changed the wire size through the years so you should be good to go. If the wire size converts to an 18, I would recommend using a 16.

Good luck.


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[strictly]

Hi Dennis

Thanks, really great advice, i'm alot clearer with how to proceed, and some great tips. Smart idea on the 78 for an idea of sizing! Ive also got a 356 ive decided i might as well do at the same time, so at least I can spread the cable cost over them both, and well i suppose i'll buy a few more porkers one day.

Thanks again, i'll try and post some pics of progress!

Luke