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Old 01-11-2011, 05:30 AM
G. P. Burdell's Avatar
G. P. Burdell G. P. Burdell is offline
Rambling Wreck
Location: Southeastern U.S.
Join Date: Jan 2006
Posts: 1,696
Mein Auto: E46
And now I will bore everyone with talk of wire...

PTFE-Insulated Wire
In case anyone else with frayed trunk wiring is looking to use Teflon-insulated wire for this repair, I did some searching yesterday for ways to make waterproof splices that will stick to the surface of PTFE. It's possible to do so by chemically etching the PTFE surface first; after that's done, most conventional adhesives will work. Here's an example of an etching process, which seems pretty time-consuming.

Many sources also mention that the use of regular wire strippers on PTFE insulation is likely to nick the silver plating on the copper strands, but this page recommends an inexpensive Imperial brand stripper that you can get at McMaster-Carr.

XLPE-Insulated Wire
I mentioned XLPE (crosslinked polyethylene) insulation in an earlier post - it meets SAE standards for wiring in the engine bay (-51 deg. C to 125 deg. C). It's readily available from several sources, including KayJay Company and Pegasus Auto Racing.

If you're going to go with XLPE, you need to get the thinnest specified insulation (TXL) in order to make a bundle that passes through the rubber covering from the body to the trunk lid. The 18-gauge XLPE-insulated wire I have in the garage is apparently either GXL or SXL, the medium and heavy thicknesses. These wires make too big a bundle.

XLPVC-Insulated Wire
There's also irradiated PVC, sometimes abbreviated XLPVC. It's PVC that has been exposed to electron beam radiation, making it tougher, more heat-resistant, and more abrasion-resistant than regular PVC. This wire (-55 deg. C. to 80 deg. C) can't take engine bay heat like XLPE can, but the thickness of XLPVC insulation is comparable to that of PTFE insulation, which means I'll be able to keep the bundle diameter down. A local supplier has seven different colors of a mil-spec XLPVC wire available. It's about one-third the cost of Teflon wire, and it doesn't require chemical etching to get heat shrink adhesives to bond to it.

So it looks like I'll be going with the mil-spec XLPVC-insulated wire instead of Teflon. I have no doubt that Teflon would last longer in this application, but XLPVC would allow me to make waterproof splices much more easily and at lower cost.
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