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Sheathing frustration

Practical Motorsport Wiring - Club Level

Relevant Module: Practical Wiring Harness Construction Skills > Installing Sheathing

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Discussion and questions related to the course Practical Motorsport Wiring - Club Level

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I've looked online but can't find any help. I'm trying to put heatshrink on 10-12 feet of two 18g wire but it seems impossible. Is there any tips or tricks to get it through such long heatshrink?

What heatshrink are you refering to? You should be using DR-25 for that application. If you can't it through, it could be because you are using a diameter too small. Finally, using a bit of isopropyl alcool help getting the wire through.

Proper size, and if its still being difficult tape something rigid to the the two wires and 'inch worm' it along.

Doing a really long run (anything over 4 or 5 feet is a long run), can be very challenging. There are a couple of hints and tricks that I use:

-- regardless of technique, you always need to push something through the tubing. Keeping the tubing straight, and pre-straightening the thing you are pushing straight really helps. I often put a weight on the far end of the sheathing, so I can pull the tube straight while feeding -- works good until the last few inches, then I need a helper to hold the tube so it can be open.

-- I have a long piece of stiff wire (piano wire, sourced from McMaster-Carr) that I have bent a hook at the end (180 deg, 1 in long, as tight as possible). I feed this through the sheathing, then tape the wires to it, and pull it back though dragging the wires.

-- If just pushing wire (or hose) through the sheathing, try using a compressed air nozzle to blow air along with the wire. This frees up the wire and move the sheathing around freeing stickly spots. I learned this trick from an old F1 mechanic.

-- If it just won't go, you need to use the next larger size of heat shrink tubing. I am forever trying to use stuff that is too small for long runs, it will work for shorter runs (2-3 ft, but not for longer).

I think the key to succeeding, is just to not give up. You will eventually win, and it will feel great!

Yes! So get a small wire. Use a butt connector to crimp the wire to the end of it. Feed the wire in. Use some brake cleaner, spray it inside the heat shrink to help it slide easily. I stand on tables at work and do it like this all the time.

I can make a video if you want me to.

Thanks for chiming in with suggestions everyone!

And welcome Edgar!

We usually reply within 12hrs (often sooner)

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