Fi Harness, Finished and its yellow so its faster Options

[F4i]

Just finshed the fi harness. Thanks to the board members who helped me find the factory connectors (IMG:style_emoticons/default/smilie_pokal.gif)

[dmenche914]

mesh is not the best material for in the engine bay. You really want to protect the wires from oils, and engine cleaning solutions, and mesh will not do that, also mesh may not give as much temp protection.

After pulling apart several harnesses, one thing became clear to me, if the stock wire was exposed, its insulation was more brittle, and stained, pull back the harness sheath, and the same wire further back was in better condition. A mesh just won't give the same protection as a solid sheath. I think it is mainly an oil / chemical contamination thing. Also the mesh, when it gets dirty, will be a pain to keep pretty looking, verses a smooth sheath.

Of course if you use the higher quality teflon insulated wire, chemical deterioration will be less of a problem than if using vinyl, or rubber insulated wire, but still the issue of dirt and oil looking ugly trapped in all that expandable webbing remains.

[TonyAKAVW]

I agree that the nylon webbing is not the best material for an engine bay. Heat shrink tubing is good, though the question about how it ages with temperature cycling warrants an investigation into the different kinds available. An alternative to shrink tubing could be some kind of high temp (silicone or teflon) sheathing that doesn't shrink, but provides similar protection.

Another important thing to keep in mind with dirt and chemicals is galvanic corrosion at the interface of dissimilar metals, such as silver plated copper (in the case of milspec teflon wire) and the brass, copper, or nickel plated lugs that comprise the connectors. At a minimum these should be covered by shrink tubing to prevent chemicals from intruding and forming rectifiers.

Keep in mind that strain reflief is important at the connector housings. The harness itself should be tied down in several spots so that the strain is distributed over the wire, rather than at crimped joints.

If you want to get really nuts about it, you could actually pot the connectors with some high performance epoxy. This helps strain relief, but makes it basically impossible to do future repairs.

Oh, and use only teflon wire. It's very expensive and hard to find but ebay can be a good source of it. You can get away with using a slightly smaller guage of teflon wire than regular copper wire since the resistance per length is lower, and the insulation will sustain higher temperatures. For maximum flexibility you can parallel multiple thin strands, though the current handling doesn't add to be quite as high as the number of wires in the bundle...


-Tony

[F4i]

(IMG:style_emoticons/default/agree.gif) Well said. Although you can go with a smaller guage of wire with the teflon I advise against it. The thinner insulation makes it difficult to crimp to the open barrel style terminal. You could solder the terminals after crimping to aid in strength,contact and corrosion prevention. M22759 mil spec wire is a good choice IMHO. Heat really does not touch it. You can obtain this stuff at your local aircraft parts suppliers. Companys Like API or Aviall carry it. Vibration is hard on things as well. Securing your harness well in cool locations (as said above) are going to help it live a long life.