Wiring

The existing loom was a real mess, with some of the cloth sleeved wires cracked and flaking off, lots hacked and butchered by a previous owner and almost all of them under the bonnet joined…badly. A new loom would cost in the region of £400 but wouldn’t be suitable anyway because I intend to make some important upgrades. The original loom had a grand total of two fuses which is clearly not suitable for a modern restoration. Also I’ll be replacing the dynamo and voltage regulator with a modern alternator, changing the amps gauge for a volts gauge as the old one cannot handle the alternator output current, adding a Hi-Fi system and amplifiers to match the one in my newer Jag, adding a reversing light and relocating the battery in the boot. So clearly a ‘stock replacement’ wouldn’t be worth buying. I’m no stranger to car electrics, well, at least the rudimentary wiring fitted in my early vehicles, so I intend to make my own wiring loom. It looks to most people to be a complicated minefield, but when you break it down, it’s simple enough if you take it one circuit at a time. If you want the lights to work, you don’t need to wire the whole car, you just need to wire the lights. Do that a dozen more times for the other components and you’re done.

I’ll be fitting a modern fuse box and relay box so the system will be much safer. The cost of the wires however is always a stumbling point for bespoke looms, it’s not cheap as you need to have many different colours and a few different gauges. A better option is to buy a loom from a donor vehicle and strip it for the components. I managed to get one from ebay from a high end Mercedes, so this obviously had all of the additional wiring for the extra features so was perfect.

I spent a few hours stripping it down, and now I need to organise and categorise each one.

Update December 2022

So, the loom above, when stripped down, didn’t actually yield as many usable wires as I’d anticipated. Bum! So, after some further searching, I managed to find a complete loom from an Audi Q series car that was being stripped due to a cambelt snapping and toasting the engine. It was reasonably cheap and reasonably close. Well, close enough to collect it and also take the wife on a jolly, still getting back home in the same day!

The last loom was a massive job to strip and organise the wires, and now I had another even bigger one to do. It took me a day or so, and this time I labelled the length of each piece too, which was something I only thought of after I completed the first one. Never mind, better half labelled than none. Almost done here -

I think that I now have sufficient wire to complete the loom, plenty in fact, and I still have some bits that I haven’t stripped yet. I did the easy/best bits first.

As the original fusebox was about the size of a matchbox under the bonnet, trying to find a space for a more substantial unit to house the additional fuses and relays was a bit of a conundrum. In the end I copied someone else’s idea had a brainwave and decided that, as there was no room under the bonnet, the next best thing was under the passenger dash area. A hinged panel will drop down to give easy access to the fuses and relays, but can then be screwed back up to be both discrete and secure. This is also a busy area with the wiring loom, so an ideal place to tap into the circuits without too much redirection.

I had a large piece of aluminium which will serve as a base. After far too many fitting attempts, I was eventually happy enough with the size and shape and committed the card template to the sheet. There was a slight cutout for the heater vent and a bend of about 30 degrees at the midpoint. I managed to perform the bend without too much drama because the aluminium is reasonably soft. But I really need to take some time to make a metal sheet brake (metal bender) which will make life so much easier. Anyhow, I have two banks of fuses, the larger will be for switched supplies, and the other smaller unit for permanent or unswitched supplies. With a total of eighteen fuse slots available, I’ll be able to vastly improve the safety of the electrics. There are also six relays, in two banks of three, which will supply the high power items such as high beam, fograngers, horn, etc. To make the interface more user friendly, I also have a bank of twenty connector strips.

Being old-school, my first instinct was to plan to solder all of the electrical connectors. The last thing I want is to have any issues due to poor connectivity. But after a fair bit of research and consulting with The Google, I had my mind changed when I discovered the more modern crimping tools that are now available to the home user, especially as they are very reasonably priced. Just had to wait a week for a suitable device to be delivered from China. They are available from more local suppliers, but they are exactly the same item, just twice the price. Being in no particular rush, and also being particularly tight, the wait was insignificant.

Before fully committing to this new fandangled device though, I first performed a few ‘test crimps’ to make sure that they were of sufficient quality for both the electrical connectivity and the mechanical integrity of joint. I was more than pleased with the tests, so it’s full steam ahead with the crimping. (Despite some part of me still wanting to run a slither of solder over them ‘just to be sure’, I think that I will try my best to resist and put my trust in these. Old habits and all that.)

Update - What happened in January then?

I’ve been busy over the last month, so not a great deal has happened really. "What, again??" I hear you shout. Yes again, I'm afraid. Firstly Christmas, and then five cars to get through their MOT's, each requiring a few minor bits and bobs to sort out, which they inevitably discover on these tests. Also got a little distracted with my new toy (more later).

The main fuse/relay board has been wired completely apart from the 40amp wiring which I'm waiting for terminations for. I should have enough fused circuits now to make for a safer wiring loom, and relays for all of the high power, high current items. I’m quite happy with it, although if I did this again, I think I could have made it slightly neater. Regardless, it'll be tucked away under the passenger dash, so not the end of the world.

The original battery location under the bonnet has been taken over by the upgraded dual circuit brake servo and master cylinder, so I now have to find a new home for that. The traditional place is in the boot, so that's what I will do. I knew I needed to relocate the battery early on in the build, so when I did the underside, I pre-installed rivnuts all the way down the nearside chassis rail for the cable to run along, so that will save a job under the car. It's all well and good fitting the battery in the boot, but there obviously isn't a way to attach it there. So the next job then is to build a battery tray and find a method of retaining it. I made a basic battery tray from four bits of angle iron welded together.

Then I needed a way to securely hold the battery in the tray. I had considered two lengths of threaded rod with a retaining bar over the top. This was a popular method back in the day, but this does, to my mind at least, look a little industrial. Modern designs use lower brackets to clamp down on the stepped bottom edge of the battery and is far neater. This is what I went with and they turned out quite well, despite taking much longer than their simplistic design would suggest. The top piece has an elongated hole to allow the movement required to adjust and this is located over a captive bolt which I welded onto the tray.

That's as far as I got before it all came to a halt for me to play with my new toy.

I'd wanted a blasting cabinet for a long time, so when a friend of mine said he was getting rid of his, I jumped at the opportunity. Really, I bought this three years later than when I needed it the most, and should have bought one when I was doing the body and running gear. But, I have it now. I gave it a try with a spare inlet manifold I had in the garage, and after making some tweaks, I was pleased with the results. It came with a load of glass beads media, which is good and gentle for alloy components, but I've ordered some aluminium oxide media that will be a little more aggressive.

February 2023 Update

So, what did I do in February? I know, I know. It's mid-March now. I bet you guys have been on tenterhooks waiting for the next update yeah. Yeah? No? Oh, OK. Well, here it is anyway.

More wiring. Firstly, because I decided to upgrade the fuseboard etc, I needed to have a wiring diagram to follow. Obviously none exist for my particular circumstances, so the first thing was to draw up a completely new wiring diagram. I used the original one as a template to work from, and then added the bits I upgraded, and removed the things that were no longer required. It's still 'work in progress' so please don't consider it as the final draft, and heaven forbid, please don't copy or use any of it. I hold absolutely no responsibility if you copy it and your car catches fire!! There are a few things that I still need to sort out, but it's 90% complete. The wipers are one of the things left to do. Because I've not decided on the final position of the motor, I may well use a different motor model. So no point in working out the wiring just yet, as the requirements may differ.

So, now running the wires. Firstly I decided to tackle the centre dashboard. This is where a lot of the wiring culminates, and it's a bit of a rats nest. It's difficult to try and keep things looking tidy, especially when you don't have a definitive plan. It has helped enormously however, that because I'm now using relays for all of the high current components, many of the wires can be a lot smaller diameter as the current draw of a relay is significantly less. This means they take up less room and are more flexible to route. So here is how it looked before fitting, and again once the dash panel was popped back into the car.

Fuseboard aside, the second biggest accumulation of connections is around the steering column stalks and main dash area. The auto gearbox has a mechanical lever to operate, with little electrical connectivity other than a backlight for the gear position indicator, so that was straightforward enough. Next was something I'd been dreading. My original indicator stalk was long past it's best with the main plastic component broken, it was never going to work again. A complete new replacement, if you can find one, is in the order of £250 for anything decent. £100 for something that was only marginally better than what I already have. So, after much deliberation, I decided to ditch the whole thing and buy a modern equivalent. The closest one I could find, and the one I ended up with was a direct replacement for an MGB. I needed to increase the diameter of the column clamp and used an offcut of stainless bar as a template for this. Then I cut off the indicator stalk and fitted the old one from my redundant switch-set. It's all working well and overall I'm pleased with the result, but the quality of the replacement part isn't up to the standard of the original. It was only £30, so I shouldn't have raised my hopes too high. The indicator action isn't really that positive, so I may re-visit this again as a winter project on day.

I then refitted the cowl which surrounds all of the switchgear on the column. These parts are obviously old, and were made from a material that was fragile even when new. I guess you know where I'm going with this. Yes, I slightly overtightened one of the screws and one of the three mounting points gave way. I don't recall if there were originally rubber bushes on these or not, but I think going forward, there will be for sure. I don't want a repeat of this. So, after a bit of 'JB Weld' and an overnight wait, I'm back on track. All fitted on and after a slight trim of the aperture to accommodate the marginally different position of the new stalk, I'm done.

Next up, the front half of the car. I ran the wiring for all of the front lights, the horns, thermostat sender, etc... I've decided that I will be ditching the mechanical, engine powered fan in favour for a modern electric equivalent, so the wiring for this was also installed. Another modern upgrade I decided to fit is a central locking system. These are not expensive from your favourite online auction site, and after a few weeks for it to wing it's way from China (where else!), it was laid out on my garage floor for testing. All worked fine, so I now have the additional wiring for this to include along with the rest. Some of the bullet connectors look a little bit suspect, so I'll be replacing those with some solid soldered joints once the lengths have been confirmed.

The car was originally fitted with a dynamo and all of the accompanying paraphernalia which that it required. I decided to use a modern alternator with an in-built regulator, and this literally needs three wires. What a difference. Some of the later cars were fitted with an alternator and they had a different alloy bracket from the steel one I had. I sourced one and had at last, an excuse to try out my newly acquired blasting cabinet. It came out quite well, but I may well powder coat it for an even better result. My son has bought all of the equipment and has mastered the technique, so that will be done soon. One thing it needs however, is a small spacer to make up the gap for the differences in the alternator designs.

So, that leads me to my next disclosure. I bought a lathe! It's something I've been wanting for a long, long time, and this humble spacer was the justification I was waiting (praying?) for. Anyhow, here it is. It's a Clarke CL430 which is in great condition. It's larger than a desktop model, but clearly not as big as a full sized lathe. It will be perfect for the jobs I intend to do on it, I just need some tuition to prevent me causing damage to the work, the lathe or me! Fortunately my dad has 40+ years’ experience as a machinist, so I'd best get the teabags and biscuits ready.

Update - End of March 2023

Having had a look over my new lathe, I attempted to make the spacer that I needed for the alternator (above, remember?). It was a first attempt but it did actually fit, although the surface finish wasn’t the best. I found out afterwards that the steel was not the best quality (You didn’t even know steel came in different qualities? No? Me neither!) and also I used a steel, slightly blunt tool. Since this, I’ve had much better results with tungsten carbide inserts. So here it is.

I'd spent ages wiring up my fuseboard/relayboard and had never tested it. It's not like it's rocket surgery, just simple discrete circuits, but there's always a chance that I'd made an error. So I was really pleased when I tested it out with a battery and a couple of fly-leads. All of the relays operated correctly, some requiring a positive supply to switch, and others like the horn and engine fan needing a switched earth to work. But all were fine along with all of the fused circuits. It's a nice feature on the fuseblocks I bought actually, there's an LED adjacent to each fuse, and if a fuse blows, then the LED illuminates for easy identification. I have fuses for most accessories, so if for example the high-beam stops working, then the first thing I'd look at is the fuse for the high-beam, and they're clearly marked. But still, it does make identification simpler I suppose. I postponed fitting the fuse/relay board for the time being as I need to test fit the glove box (which it sits under) to ensure I get the placement right. So instead I started on the power cable from the boot mounted battery to the starter solenoid under the bonnet.

As you know, I'd already made the battery tray and so I set about fitting it to the boot when I realised that if I bolted it down through the angle iron base, the bolts would stick up and prevent the battery from sitting flush on the bottom of the tray. I wouldn't call it a mistake, more of an evolution in the design. To work around this I drilled the holes smaller than planned and tapped a thread so that I could screw in studs rather than use bolts. I then welded them in place as I didn't have confidence that the limited thread length would be sufficient to hold everything down securely enough. It turned out quite well and I was glad that this oversight didn't cause too much rework. After painting the hole edges to prevent future corrosion, I fitted the nyloc nuts from underneath and I was happy with the result.

The cable was connected using large crimped terminals. The tool for this is quite a hefty piece of kit, certainly compared to the one used for the normal wiring, and requires a vice grip to make the connection.

The next thing to consider was how to get the battery power out of the boot. I'd already decided to take a route under the car, so I needed to exit via the boot floor. I had considered a heavy duty grommet because I prefer the cable to have as few joins as possible. It takes a fair bit of current, so joint free is obviously the best option. However I'm wary that the cable can rub with movement, and in time could potentially short out to the ground on the edges of the hole. So rather than use a grommet, I opted for a bulkhead terminal. It safely passes the boot floor and has a secure connection either side. This decision was compounded somewhat by experience. Although not exactly the same scenario, I remember as a teenager when I had a classic Mini and after going down a gravel track (I cannot confirm or deny that it was 'at speed') a large stone kicked up and knocked the power cable into a seam on the chassis, splitting the insulation. It shorted out, quickly followed by acrid burning smell and some smoke! I was fortunate that no further damage was caused to the car, probably due to the fact the battery was on it's last legs anyway, and this was just the excuse it needed to give out altogether. Not sure that my Dad knows to this day the reason for the jumpstart I needed 'out of the blue' one night. No major drama, but it did teach me a valuable lesson. Anyhow, here’s the bulkhead fitting. Note, I did paint the edges before fitting.

I'd always thought a battery isolation switch would be a good idea as the car will be laid up for the winter months. This will ensure there's no chance of battery drain and of course an added bit of safety. I’ve not fully tightened the bulkhead nut yet as I’m waiting for rubber boots to arrive so that the terminals will be fully insulated.

I'd already planned the route for the cable whilst the car was still on the rotisserie, and all of the rivnuts had already been fitted in the nearside chassis leg in readiness. I'd done this as I thought it would make running the cable a bit easier. How right I was! Had they not been done earlier, there is no way I could have fitted them at this late stage. The exhaust and heat shields would have made it impossible to drill them. But they had been done and running the cable was a reasonably easy affair. The cable looks close to the exhaust in this first photo, but it’s far enough away, also I removed two sections of the heatshield to facilitate the cable fitting, and these need to be put back on.

So, the cable is now routed to the front of the car but I'm unsure of the best way to reach the solenoid which lives at the very top of the bulkhead. More on this next month....................