Date: Wed, 10 Jan 2018 11:06:39 -0800
Reply-To: Neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil N <musomuso@GMAIL.COM>
Subject: Re: Multi Conductor Shielded Automotive Wire Temperature Rating
In-Reply-To: <e355b3de-0b03-b25c-f308-f53a66fdef2f@sbw.org>
Content-Type: text/plain; charset="UTF-8"
Aviation applications. Of course! Thats great. Thank you. I have long
considered making my own harness so the pointers to tools and terminals are
most welcome.
Most of the non automotive specific cabling I've looked at has what is
referred to as a "drain" wire. I assume this is the shielding ground. I've
asked questions about this before here, but inside the Bosch Motronic
harness, though there are specific ground junctions (e.g. '200 shield'
ground). So far, it looks like they all terminate at the multi contact
connector at engine block. But I'm going to give that more study; it seems
to me that for an amateur altering a wiring harness, its all too easy to
mess up the grounding of something important like the knock sensor.
These new sensor wires will be routed along the upper portion of firewall
and will be covered with loom so won't be too close to the engine head or
exhaust. At one point, on my currently running "Jetta" swap, I did have
black corrugated loom see heat damage. But the exhaust was of a different
design then. I forget the measurement but that loom was about 1' away from
the exhaust down pipes. And, that loom was not a higher heat version with
the blue stripe.
The O2 wire size spec'd in Bentley is metric 1 so ~ 16 AWG but as you say,
the sensor wire could be smaller. I'm sure VW used 1 metric gauge because
they used a single multi conductor wire for the O2 "signal" voltage and
heater element. The RPM sensor uses metric 1 but knock sensor uses 0.5
metric.
Neil.
On Wed, Jan 10, 2018 at 7:24 AM, Steve Williams <sbw@sbw.org> wrote:
On 1/9/2018 8:54 PM, Neil N wrote:
>
>> I've been looking hard for a solution to my corroded O2, knock and crank
>> position sensor wires.
>>
>
> I'm spoiled by my days in avionics vocational school and maintaining my
> own aircraft, so I use aviation wire in the camper. Here's a Tefzel
> shielded, three-conductor, shielded, 22 AWG wire, available for $1 per foot
> from B&C Specialty Products:
>
> http://www.bandc.aero/22awgshieldedtriowhitetefzelwire.aspx
>
> For signal wire, I expect 22 AWG is adequate. I've used it for an
> aircraft fuel flow and oil temperature sensor, for example. In the camper,
> I use shielded 22 AWG for the stereo and unshielded 22 AWG for the ammeter
> shunt.
>
> Tefzel is a much tougher outer jacket than you can get outside of
> aviation. We use it in aircraft engine compartments without further
> protection. When it runs near exhaust components or cylinder heads, we
> wrap it in firesleeve for extra thermal protection. B&C doesn't carry
> firesleeve, so here's Aircraft Spruce:
>
> http://www.aircraftspruce.com/menus/ap/hose_firesleeve.html
>
> B&C also sells terminals and splices of much better quality than available
> most places. These have a two-stage metal crimp, so used properly the
> conductor is captured, then the insulation is captured for strain and
> vibration relief:
>
> http://www.bandc.aero/electrical-terminals-splices.aspx
>
> And an inexpensive crimp tool that makes it easy to achieve gas-tight
> crimps for longevity, especially in the engine compartment:
>
> http://www.bandc.aero/pidgstylecrimptool.aspx
>
> I've met Bill and Celeste Bainbridge, who run B&C, and I like buying from
> them. It's fun to browse the rest of their web site. Need a lightweight
> alternator for your homebuilt aircraft?
>
> Regarding shielded wire, remember to always ground all signal shields at
> only one point. Signal shields should be grounded near the instrument (in
> this case, the ECU?), and left open at the sensor end. Shields grounded at
> both ends invite noise from a ground loop. Here's step-by-step
> instructions for creating a clean shield pigtail to crimp a connector on:
>
> http://www.aeroelectric.com/articles/pigtail/pigtail.html
>
> That approach is simplified by using solder sleeves. They can be
> expensive, but Digikey sells them in small quantities. Be sure to check
> the diameter of the sleeve against the diameter of the shielded cable plus
> a pigtail:
>
> https://www.digikey.com/short/q8phf1
>
--
Neil n
Blog: Vanagons, Westfalia, general <http://tubaneil.blogspot.ca>
1988 Westy Images <https://picasaweb.google.com/musomuso/New1988Westy>
1981 Westfalia "Jaco" Images, technical <http://tubaneil.googlepages.com/>
Vanagon-Bus VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>
|