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Practical Wiring - Professional Motorsport: Step 5 - Following the Construction Plan - Part 1

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Step 5 - Following the Construction Plan - Part 1


00:00 - The fifth step of the HPA 10 step motorsport harness construction process is the one that we've actually finally been waiting for, we're going to follow our construction plan and we're going to start physically building the harness.
00:13 Now because we've put so much effort into our design and generating our construction plan, this step should be resonably straightforward.
00:21 However it is likely to be quite lengthy and that's where our construction plan is really going to help as well as we're going to be able to keep track of where we're up to and when we do get interrupted, we're going to be able to resume work and ensure that we haven't missed any steps.
00:35 I've got my workspace set up here, trying to keep things nice and tidy, as tidy as possible really does make a difference when you're building a wiring harness, you will get a better result if you're working in a nice clean area.
00:50 I've got my documentation easy to hand and I've got my materials and tools in my tray here for the first build stage that we're going to undertake.
00:59 Quick talk about the tools that I've got here and some of the setup that I've done prior to actually starting the build stage.
01:07 I've got my wire strippers here and because we're going to be dealing with a 22 gauge wire being crimped into size 22 autosport pins, I've set my strip length to between 3.8 and 4.8 millimetres before I start.
01:22 It's gonna give me a really nice consistent stip length and mean that I don't have to worry about that throughout this build process.
01:30 We are going to be crimping those pins onto our wires as well, so I've got my crimping tool here set up with the correct positioner in place for those size 22 pins as well.
01:41 I've also got the connector I need in there, the pins obviously and the wiring we're going to be using as well.
01:48 So we're going to jump straight into the process.
01:51 I'm going to start with the connector here which is our 1435 Autosport connector.
01:58 And this is our sensor interface connector.
02:01 Now we are going to have to be holding this in a vice so the first thing I'm going to do is actually put some Kapton tape around here, just so when we are holding that in the vice, it's not going to mark the surface at all.
02:12 We should be OK because the vice here does actually have soft jaws, but every little bit of protection helps, and Kapton tape's really good for this because when you remove it, it's not going to leave a residue behind.
02:29 With that prepared, we'll pop that to one side and we'll have a look at the first of the wires that we're going to pin into our sensor interface connector.
02:38 They're going to form the core of this first harness section and they are our CAN bus wiring.
02:45 So we have some pre twisted CAN bus wiring here and having a look at our physical layout sheet, we can determine the length of that wire that we're going to need.
02:55 From that documentation here, we're going to need a 600 millimetre run of our CAN bus wiring.
03:01 The amount that we've got here is actually quite a lot longer than 600 millimetres, but I'm not going to trim it back at this point, as that extra length might end up actually being quite helpful when we come to our concentric twisting of the layer above this.
03:16 So I'm just going to leave this its full length for the moment and probably when we get to our first test fit stage on the vehicle is when I'll trim this one back.
03:24 Looking at the end of our wiring here, we've actually got a little bit of a ragged cut so we're just going to trim that off and make sure we've got nice parallel ends there.
03:34 So when we strip those back they'll be really easy to pin into those size 22 Autosport pins.
03:41 Going to untwist a good portion of this wiring and straighten it out there.
03:46 We do need to get that into our wire strippers so we do need to untwist a reasonable amount back.
03:53 It's not going to harm your CAN bus signalling at all, that short length there, of untwisted wiring.
04:00 So don't stress too much about that.
04:02 The other reason we're going to need a bit of length there as we're going to have the service loops in this wiring right before they're pinned into the connector which isn't going to work if it's still twisted together.
04:12 So I'll get my wire strippers here, the Ergo Elites that I've got our correct wire strip length set on in our size 22 position there and strip the end of these wires.
04:32 We can now get our size 22 Autosport pins that we've been supplied with that connector and pin them onto these wires here.
04:41 Now I've said size 22 Autosport pins, whereas the connectors we're using are actually Souriau 8STA connectors because that's what our supplier had supplied us with but they are actually interchangeable and Autosport size 22 is just what I'm more used to saying so it's likely to be the term that I'll use throughout the rest of the course.
05:01 Getting that pin into place there.
05:04 Nice and easily, making sure there's none of those errant wire strands out the side.
05:08 We've got full copper engagement there with still a little bit of our copper wire strands visible which is exactly what we're looking for.
05:17 Get that into our crimping tool here, just making sure that we have that on the right setting for our size 22 wire.
05:24 We want it on crimp setting four which it is, so that's going to be correct.
05:28 So we can get our wire and terminal inserted into place and undertake that first crimp operation.
05:37 It's just being a wee bit tricky, I have double checked and we do have the right positoner in place here.
05:43 There we go.
05:46 And squeeze those handles all the way.
05:49 And our first crimp is complete.
05:51 Gonna have a quick optical inspection now to make sure that that's gone well.
05:55 You can see we've got nice even indentations all the way around that wiring.
06:00 And our inspection hole is not deformed and I can see our copper conductor strands through it, so that's gonna be a nice reliable crimp join there.
06:09 Go ahead and get the pin on the other wire now.
06:20 I've got good crimped pin connections there so we're going to get those installed into our connector body.
06:25 I'm just going to put our pottle of pins away as nothing is worse than knocking those over when the lid is off them.
06:31 I'm going to get my service looping tool and my insertion tool out and at the ready, and have a quick look at the documentation just to confirm where these are getting pinned into the connector here.
06:42 Now because we have designed our concentric lay up to match the pin out of our connector and we're working with the core of the harness at the moment, it is going to be pinned into the centre most pins of the connector.
06:54 Just having a look here, pin 37 is going to be CAN low which is our green wire, and pin 36 is going to be CAN high which is our white wire.
07:03 So this is going to be an easy pinning job because I've got nothing else in the way, so I'll go ahead and get those into place now.
07:11 This is exactly as we went through in the lesson section of the course, just go my wire in my installation tool here, everything at the ready, finding the right pin there which for our CAN low is going to be right in the middle, pin 37.
07:24 And get that into place.
07:28 With a nice click there I can withdraw that installation tool and that's locked in place.
07:34 Get my CAN high wire in pin position 36 as well.
07:39 Now at this point I'm going to get some service loops put into this wiring here, as once we build the next layer of the harness, we're probably going to lose easy access to those wires.
07:49 It is going to be best to do that now.
07:52 We'd need to be careful at this stage though and have a think about how this connector is actually going to be situated in the car.
07:58 It's going to have a right angle boot coming off it which means our wiring harnesses are going to have to exit it at a right angle as well.
08:06 We're going to want to make sure that our service looping is contained within that boot as well.
08:11 To help with that, I've taken a screenshot from our manufacturer's documentation for the particular boot that we're using, and I've scaled it to be 1:1.
08:21 So this way I can hold it up next to our connector and ensure that everything is going to be done in place.
08:29 The other key detail that we need to keep in mind here is not only that the wires will be exiting the connector at a right angle, but the orientation of that right angle in regards to the pin one location or the up position of our connector body here.
08:44 What I mean by that is the mounting plate that is going to be on the firewall of our RX7 is going to mount in a particular location and the harnesses are going to exit in this direction.
08:58 So we want to make sure that when this connector is pinned into place, connected up, that our wires, our harness is constructed in such a way that our wires nice and easily exit in the correct direction.
09:10 So because I've got that mounting plate here on the bench, this is actually really easy to do 'cause I can hold this in the correct orientation and simply put those service loops into our wiring, making sure that they're going to fit beneath our boot there and get everything in place.
09:27 Now for these service loops I am putting them as far up those wires as I can while still keeping them in this area of our moulded boot here.
09:37 I like to stagger my service loops so as they get closer to the connector, they move outwards on the harness.
09:44 It gives a nice tapered appearance as much as possible if a right angled connection that we're using here and makes the boots fit a little bit nicer and just everything be a wee bit tidier.
10:01 With that wiring pinned and looped into place, we can actually pop this to one side and just clear off our work area here a little bit and have a look at our build guide.
10:12 So you can see here that we have prepped our core wiring from the sensor interface outwards and we've pinned it into that connector as well.
10:19 Next stage of the plan is going to be to prep our layer one wiring.
10:23 So our layer one wiring is our five twisted shielded pairs.
10:27 That's three standard twisted shielded pairs and our two thermocouple twisted shielded pairs.
10:33 Prepping that wire is going to consist of cutting it to the correct length and actually installing flying leads that are going to make a connection to the shield braid at the connector end there as well.
10:45 We'll then get that pinned into place and then we're going to have a look at twisting that first layer around the core there.
10:51 So I'll go ahead and I'll get my wire cut to length and we'll have a look at making a connection to those shield braids.
11:26 Got my sections of wire cut to length now.
11:29 While I am going by my physical build documentation here to get the lengths of these wires, I am adding around about 20% to those lengths when I actually cut them.
11:40 This is going to account for any length of the wire that's lost due to the concentric lay and also any wire length that's lost through the branch points.
11:49 It's going to make sure that at the other end of the harness from our interface connectors here, we've got enough length on those wires to trim them back and have them be the right length to reach the points they need to be.
12:00 With our wires cut here, that's our three standard twisted shielded pairs and our thermocouple wiring, I'm going to strip back the outer jacket and make our solder shield connection using our small sections of standard 22 gauge wiring here, to that shield braid.
12:17 Exactly as we've shown in the lessons section of the course.
12:20 The length that I'm going to strip back here is actually going to be quite long.
12:24 And I'm then going to get all three of those wires the same length by trimming them and that trim length is going to be determined by where we want the service loops to end up behind that connector.
12:37 With my razor blade I'm simply scoring around my wire there, just lightly, making sure you don't actually cut all the way through if you can avoid it.
12:47 And then when we bend that cable that jacket is going to break nicely along that score line there.
12:56 Then exactly the same procedure except along the length of the cable here.
12:59 And we'll get that section of jacket removed.
13:08 With that cable jacket removed, I'm going to bunch up our shielded braid past the end of the jacket here and we're then going to trim that shield braid off, giving us a nice portion of that braid there to make our solder shield connection to.
13:28 We can now strip a section of the insulation from one of our flying lead wires here.
13:33 The same strip length that we've used for our size 22 pins is going to be absolutely fine for this situation so I don't need to reset this.
13:44 And we can get that installed in place and get our solder shield on there and get that shrunk down.
13:58 We've got our first twisted shielded pair cable prepper here.
14:01 Going to pop that to one side and get on with the others here.
14:04 I'm going to do the two thermocouple ones next as if you remember when we were designing the pin out for our harness, we had to actually double up on a shield pass through pin for our two engine position sensors.
14:17 So once I've done these cables which are exactly the same as the one that we've just done, we'll pause and have a look at the slight difference of combining these two shielded wires in to one flying lead.
14:50 For our final two twisted shielded pair cables here which is our engine reference and engine sync signals, we are going to be making a single flying lead connection to both of those shield braids.
15:02 The initial preparation is exactly the same.
15:05 I've simply scored and removed a section of the outer cable jacket and then trimmed back that shielded braid, keeping things nice and even there so the amount of shielded braid I've got exposed is equal.
15:18 We're then going to use a slightly larger size of solder sleeve here.
15:22 And I'm going to fit that over both wires, put a single flying lead into place, head over to the heat gun and get that shrunk down.
15:34 I've got all of that layer one wiring prepper now with our flying leads for the connection to the shield braids.
15:40 it's time to get our pins installed onto this wiring and get it inserted into our connector.
15:46 At this point you really need to be careful about where you're going to place these solder shield connections underneath the connector boot here.
15:54 You want to make sure you're going to leave yourself enough room for the rest of the layers afterwards and of course keeping everything underneath that boot so your sheathing can slide up the harness and it can all be really nicely sealed.
16:07 To make sure that's going to be as easy as possible, I find with solder shield or splice connections like this, it's easiest to locate them directly behind the connector like this, and actually service loop back in the other direction, and pin and go down into the connector.
16:24 It's going to leave you enough room to work with the outer layers, still keeping everything really nice and tidy.
16:30 So I'm going to trim the wires on this cable off to the correct length now, strip them, and get some pins installed into place.
16:52 With our pins crimped onto our wire ends there, it's time to get this installed into our connector.
16:58 Just having a quick look at our pin out documentation here, you can see that we'll be pinning the shield braid into pin 35 of this connector, working backwards 34 and 33 is going to be our white blue wire and our white wire.
17:14 This is going to be our knock sensor signal cable.
17:17 So we're gonna get this installed into our connector here.
17:21 I'm going to go about this a slightly different way.
17:23 I'm going to get these pins started in the back of the seal on the connector here.
17:27 I'm then going to get my insertion tool and use that to push them all the way home.
17:32 Can be a little bit easier to get things lined up like that when you're working with a cable that's got more than one wire coming out of it so you need to be dealing with more than one pin at a time.
17:56 I've got my wires sitting there in place now, we can get our insertion tool, and using our service loops, we can get that tool into place and get those wires all the way down into that connector body, looking for that nice click, meaning that that pin is all the way home.
18:17 I've got that cable pinned into place now.
18:20 Service loops are all in the right spot and it's looking quite nice and tidy.
18:24 That is the first of the cables of the layer one that we're going to be twisting down this harness section.
18:30 We now need to go ahead and get the rest of the cables pinned and installed into that connector body.
18:37 Keeping those service loops within the portion that will be covered by that connector boot in behind the harness here.
18:45 Using our wee 1:1 scale diagram is really handy for that.
18:49 Looking at our pin out diagram here we can see the next cable we're going to deal with is our ref sync, so that's our engine reference and our engine sync sensor signals and the single ground flying lead from those as well.
19:03 So I'm going to have to do that cable in one shot as they are now joined together at this end with that solder shield.
19:10 it's exactly the same process that we've just shown though so I'm gonna go ahead and get those cut to length, the pins installed, and get that into our connector body.
20:25 I'm going to get the thermocouple cabling installed into this connector now.
20:29 This is exactly the same procedure.
20:31 There is one variance though in that we are going to have to be careful that we select our specific thermocouple pins to crimp onto this wiring.
20:40 That's gonna help us keep our unbroken chain of thermocouple material throughout the harness.
20:45 I've got those pins here but you do definitely want to make sure you don't get carried away with this procedure and accidentally crimp the wrong pins into place.
20:55 We'll get these cables installed, then we can look at securing this point and beginning our twisting operation.
22:57 I've got all of those layer one cables installed into the back of our connector now.
23:01 A couple of points to go through when undertaking that process is that the thermocouple wire that we're dealing with actually has internal conductors of 24 gauge so this meant that when crimping those, I did need to take my DMC tool here and adjust it to position three to ensure that we were getting the correct amount of crimp on those pins.
23:22 Really important point there.
23:24 Also when I was pinning in our ref and sync sensor signals that have got that combined shield braid, I had to be very careful that I didn't mix up those pairs of wires, so that's the white and the blue white wires.
23:37 As where they come out of the solder shield it is actually possible that they could get mixed up and you'd have the wrong pairs heading to each sensor.
23:45 Just another thing to be keeping an eye on there.
23:48 With all those cables in place I've put a temporary cable tie here just to keep them nicely organised while sorting out our service loops behind here, just to get them as compact as possible.
24:00 That organisation with that cable tie there is actually in a specific pattern.
24:05 It is going to match our concentric twist pattern which we can see on our example harness section here.
24:12 As we're not going to put some Kapton tape around this layer to keep it all supported, we're going to mount that in our vice, stretch out that core wire, and twist that first layer.
24:23 I've got my Kapton tape here so we're simply going to tape around those solder shield braids.
24:30 It's going to be a pretty good point to tape around and keep everything nice and as tightly organised as possible.
25:00 With everything taped in place and supported, I've actually gone ahead and taped a small section of rag around that harness bundle as well, as we're going to put that in our vice here and just anything that can spread the load out across those wires is gonna make things a wee bit easier as we are going to have to put that central core wire under a little bit of tension and then keep these layer one wires under a bit of tension as we twist them along that length as well.
25:25 So I'm going to pop this in my vice now, get my second vice out on the bench here, and string out that core wire, and then we'll have a look at the twisting process.
25:40 I've got our wire set up in the vice here, our central core CAN wiring, under just a little bit of tension.
25:46 Not too much as I don't want it to slip in the vice at this end and it is protected at this end with some rags wrapped around that cable as well and we don't want to straighten out our service loops at this end either.
25:58 This first layer of any concentric harness build is usually the trickiest as you don't have that underlying structure on which to lay to keep everything nicely supported.
26:10 So we've got that under enough tension as possible as that does make our job just a little bit easier.
26:17 I've got our five twisted shielded pair cables now, which following our build documentation there, are going to be wrapped around this in a left hand lay.
26:26 Now from our physical construction document we can see that it's going to be 270 millimetres from the edge of our bulkhead connector plate here where this exhaust gas thermocouple wiring is actually going to branch out.
26:40 I'm going to twist a fair distance past that and then we're going to have a quick test ft up with our bulkhead mounting plate and we're going to support the twist back at the point where it needs to branch out and then untwist a section.
26:54 It is usually quite a bit easier to twist past where you need to then support it at the branch point and untwist that section.
27:04 So I'm simply going to start twisting these around much as we've showed in the lesson section of the course.
27:12 There's absolutely no difference from that process, even though we are using twisted shielded cable here wrapping around an unshielded twisted pair.
27:21 Because we've undertaken our test harness section, we know this is going to give us a good circular cross section with a complete lay.
27:29 So we'll get started on that now.
27:32 Probably going to do these three twisted shielded pairs and then bring the thermocouple wiring in to fill in the layer, and just supporting as I go with cable ties along the length.
28:47 With that first layer twisted into place, we've ended up with a nice flexible harness section.
28:54 It's got that good circular cross section that we're looking for and it's gonna be a really good base to build those following outer layers on.
29:01 Just double checking that we have got the correct orientation heading away from our connector here which is at a right angle, directly opposed to the number one pin there.
29:11 At this point I can get our flange mount, which is going to be in the engine bay of the RX7 here.
29:17 I can actually install this connector.
29:20 And the point we're going to take a measurement from is right at the edge of this flange here, as that's where we've measured from in the engine bay.
29:27 So we know our branch point is going to be 270 millimetres from there.
29:30 So I can get my tape measure out and take a measurement 270 millimetres from that point and I'm simply going to make a mark there with a sharpie, but we are then going to come back and support the harness at that point with Kapton tape and actually unwind the twisted section that we've got there.
29:54 And at that point we're going to continue through with the next process of our build sheet.
30:22 With that wiring untwisted, we'll have a look at our build sheet and talk about the next operation that we're going to undertake.
30:29 We can see we're going to twist our core wiring from our branch point A to our branch point B and our core wiring from our branch point B to our branch point C with a left hand lay.
30:40 Now because of the design of this harness, all that core wiring is the same.
30:44 It is our three twisted shielded pairs for our knock, our ref and our sync sensors.
30:51 So all that means is I'm going to twist these three twisted shielded pair wires together, actually at the moment all the way to their end and then when we get to the point of finalising the position of branch point C we will untwist them the length that they need to be.
31:05 To do this I'm going to put some rag around our harness here so I can support it, get it mounted in our vice, and just by hand, twist those wires together as we're forming a core.
32:11 That is the first part of our first build stage now completed.
32:15 We've got our layer one installed into our connector here twisted around that CAN bus core and fully laced and supported.
32:25 It's really nice and flexible and is exactly what we're looking for.
32:29 Heading away from branch point A here, we have our core also now twisted together and laced, so there's going to be branch point B and then branch point C along here as well.

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