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Wiring Fundamentals: Booting

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Booting

07.18

00:00 - Booting is the process of using dual wall heat shrink to seal the sheathing at the ends of our wiring harness, to either the wires themselves, or the connector body if it's compatible with the operation.
00:11 The connectors at the ends of our wiring harness are the part that suffers the most abuse and by using a boot to add some strain relief, we can increase the life expectancy of our wiring harness substantially.
00:20 There are two types of heat shrink we use for this purpose, Raychem SCL in an application where we want the sealing boot to remain rigid.
00:27 And Raychem ATUM in a situation where we want to retain an amount of flexibility in the boot.
00:33 This flexibility can be helpful if a connection needs to be made in a tight spot in the engine bay.
00:38 We'll look at two examples of booting using both of these materials.
00:42 We'll terminate the main trunks of our sample injector harnesses to DTM six way connectors, one of which is capable of accepting a sealing boot and one of which is not, demonstrating both techniques.
00:52 The first example we'll have a look at is booting this DTM six way connector onto our expandable braid sheathed injector harness section.
01:00 Now you need to be very careful of the order in which you undertake this process as it is possible to pin your harness into your connector and then realise that you cannot get your sealing boot in place.
01:12 So for that reason I have left this connector unpinned and we're going to install our sealing boots first.
01:20 I've got two different sizes of Raychem ATUM here and the reason for that will become apparent when we undertake the booting process.
01:28 But simply it is because this larger size of ATUM we need to seal onto the back of this connector, will not recover small enough to tightly grip this expandable braid section.
01:39 So we use another section of ATUM on the expandable braid to increase its diameter slightly which this sealing boot can then recover onto.
01:47 So we'll put these pieces of ATUM onto our wiring harness.
01:52 In this instance we could actually install them from the other end but that's not always going to be the situation when you're working on a harness.
01:58 So it's best to just adopt the practice of getting your sealing boots in place before pinning your connector.
02:04 So I'll go ahead and I'll pin this wiring harness into our connector now.
02:15 So with that connector pinned into our wiring harness, we can go ahead and recover the first of our ATUM sections onto the expandable braid, so that's the smaller section here.
02:26 And we're going to recover that close to the connector.
02:29 Now the recovery temperature of Raychem ATUM is 175 degrees celsius.
02:35 I've got our heat gun set to 200 degrees celsius.
02:38 We know that'll be a safe temperature for our expandable braid, and it will allow the heat shrink to recover nice and quickly.
02:44 So I will go ahead and recover that now.
02:55 With that smaller section of ATUM recovered onto our expandable braid, we can have a quick look and see that the inner dual wall lining of the ATUM has melted and bitten and keyed nicely into the expandable braid.
03:09 So that'll be held in there very tightly now.
03:11 We're going to recover the larger section of ATUM onto the back of our connector here.
03:18 And the smaller section of ATUM has added the necessary diameter that when this recovers, it will adhere to the smaller section of ATUM.
03:27 So just help that process along, we are gonna get some of our 150 grit sandpaper and just abrade the surface here to really let the inner dual wall of this heat shrink key into that surface, so I'll go ahead and do that now.
03:51 With that surface abraded we're gonna be able to recover our larger sealing boot here onto the smaller section of ATUM and ensure that it'll key into it nicely and remain well sealed.
04:02 So we'll go ahead and recover this in place now.
04:12 With our ATUM heat shrink boot fully recovered, we can perform our visual inspection, and we can see here that it has adhered nicely to the back of our DTM six way connector.
04:23 And it has also recovered nicely onto our smaller ATUM section.
04:28 It's still got a little bit of flexibility to it, which is really gonna help in a tight spot in the engine bay, but it's not gonna pull off our connector so that sheathing is gonna remain in place and reliable for the life of the wiring harness.
04:41 The next example we'll undertake is with our injector sample harness section that's been sheathed with Raychem DR25.
04:50 In this example we're going to use our sealing boot to seal that DR25 to the wires themselves.
04:58 So it's the same situation as before, you really need to think about the order in which you're going to do this.
05:03 And we need to install our sealing boot first and then pin our connector.
05:07 The reason we're going to seal this SCL boot onto the wires in this instance is we're using a connector which isn't set up to accept a sealing boot, so it's going to be our only option.
05:19 I'll go ahead and pin this wiring harness section into this connector now.
05:26 With that connector pinned, we can now slide our SCL sealing boot into place, and we can see the section of DR25 that we're going to have to abrade here, as we want the inner wall of this SCL to really key into that DR25 nicely.
05:41 So I'll go ahead and abrade that now.
05:46 With the end of our DR25 sheathing abraded, we can slide our SCL boot into place where we're going to need to recover it onto the wiring harness section.
05:56 I've got our heat gun set to 200 degrees celsius again as we know that'll be safe for our DR25.
06:02 I should mention that these DTM connectors we're using here are made from a fibreglass reinforced plastic.
06:07 Does have a very high melting temperature so that 200 degrees celsius is also fine for them.
06:12 So we'll head over to our heat gun and recover this in place now.
06:23 With our SCL boot recovered onto our wiring harness section, we can take a quick look and we can see we've got a nice even bead around the DR25 here that has keyed really well into that abraded surface.
06:35 And it's gripping tightly onto the wires here as well.
06:38 So that's gonna provide good strain relief and really seal that sheathing onto these wires, making sure it's not gonna come loose or move at any stage.
06:47 At the professional motorsport level, you can get specific moulded heat shrink boots for this purpose.
06:51 Unrecovered, they have a very large diameter which means you can reliably fit them over the connector bodies.
06:57 When you recover them, they form specific shapes, but they are a much more advanced topic.
07:03 We cover them in our advanced motorsport wiring course.