Lotus Elan

Rats nest

PostPost by: Bigbaldybloke » Mon Aug 31, 2020 12:33 am

Mike, I’ve looked on eBay and can’t find the offer I made use of which was 50m of cable comprising 10 x 5m lengths of whatever colour you wanted. A couple of companies are advertising suitable cables in up to 80 colour combinations, I used 1mm square thin wall tri-rated cable for most applications as it’s rated to 16.5 amps which is suitable for almost all services except the alternator and feeds from the starter solenoid to the ignition switch, the horn compressor supply and a few other services. I added additional relays and fuses on all the lights cooling fans etc with a larger feed to the fuse block then individual wires to each headlamp main and dipped lamp etc. so max load for each cable was around 60 watts so approx 5 amps so the 1mm sq cable was amply rated and is actually smaller in overall diameter than the original cables so easier to make into a harness and manipulate around the car and engine compartment.
The cables I used most of were black, white, purple, purple/white, green/red and green/white. The longest runs are for the rear harness which on mine was ok so I just used the original with new bullet crimps and connectors. I did splash out on the special bullet crimping tool which was expensive but does an excellent job. Longest run apart from the rear is probably not more than 3m, but as I was always told when I worked on industrial instrumentation, when pulling in a cable you are better looking at it than for it, as they don’t stretch!
Don’t forget to replace the grommets in the bulkhead where the cables pass through!
I can send pictures of the dashboard wiring and how I added the relays and additional fuses in you need them.

Cheers

Simon
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PostPost by: mikealdren » Mon Aug 31, 2020 7:43 am

Sounds good, I was also wondering about putting a bulkhead connector rather than grommets but that's still just an idea.
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PostPost by: alan.barker » Mon Aug 31, 2020 9:09 am

mikealdren wrote:Sounds good, I was also wondering about putting a bulkhead connector rather than grommets but that's still just an idea.

If you put a Bulkhead connector you will get the same problem as many classic TVR owners.
Imho don't.
Alan
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PostPost by: Bigbaldybloke » Mon Aug 31, 2020 10:18 am

Problem for bulkhead connector is size. A decent quality one that could take the power and give a good water tight connection would probably be rather bulky. Also could be messy as for some wires such as lights and indicators you have three harnesses to join together at that point and trying to get two wires on the car side of the connector is going to be challenging and also means the dashboard would be permanently connected to the rear harness unless that also had a multi plug to connect it. Nothing is impossible, but not sure it’s worth the effort, although when I look at the mass of wires interconnected behind my glove box I do wonder if I should have done something different, but, it did all work first time!
If I was going to do it I’d make the dash harness have two multi connectors, one for the rear and one for the engine and I’d have the engine harness to a multi socket bonded into the bulkhead such that the connecting side was in the dry inside the car rather than the other way round.
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PostPost by: mikealdren » Mon Aug 31, 2020 3:39 pm

Yes, I agree with all of that. I'm currently thinking about having harnesses with multiway connectors for the dash, cabin, engine bay and rear end. Possibly even door connectors to make removing doors easy. Probably overkill...

I'm looking at modern replacement column stalks that would give me wiper controls so I would have a spare switch. I would possibly use the 2 speed wiper switch for sidelights/headlights, using relays the current would be fine. I'd then replace the twist switch with a USB point. Lots of ideas at the moment.

Moving the fuse box should also reduce the rats nest behind the dash. Everyone seems to choose the glovebox but I'm wondering where else I might put it (or them?).

How did you wrap the harness? There are lots of option nowadays although tape still seems good for keeping damp out under the bonnet.
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PostPost by: mbell » Mon Aug 31, 2020 6:20 pm

A custom loom is on my longer term plan as my wiring looks like Matt's and plan to add AC so need some changes in the wiring.

My basic plan is to try and make it modular with the dash as the main connection point. So will have engine bay, rear, door looms that connect to the dash via connectors. The aim is that the dash will be removeable by disconnect the various looms from it, with out need to remove any connection on the dash (e.g. switches). We'll see how feasible that is when I get to designing it.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Bigbaldybloke » Mon Aug 31, 2020 7:23 pm

The car does effectively have a series of harnesses as standard, dash, engine, rear including interior lights, one for each door. So having a multi plug for each is quite feasible with careful planning of the dash harness. It’s just the standard dash harness terminates in bullet connectors, either single or double ones.
As I have electric headlamp pod motors instead of vacuum, I wired it such that when you turn the headlights on the motor operates to put the pods up, so the vacuum switch becomes redundant and as I have added the later spotlights, I got a Triumph push pull switch that fitted in this position using the original knob with the lamp symbol on it. I looked at two column switches and even bought a pair from a Mini but didn’t want to modify the original column surround so didn’t proceed. Instead I fitted an electric washer pump and again raided the Triumph parts bin for a twist and push switch. The only thing I don’t yet have sorted is getting the wipers to come on automatically and do a couple of wipes after using the washer. There is an after market interface that does this, it’s not quite straightforward as you have to override the parking function of the wipers but there is an article somewhere on here that goes into that. As for what to use to enclose the harness, there are many options, I went for the mesh type expandable tube with heat shrink at the ends to finish it. Not original but neat and available in different diameters so you can use thinner stuff as the harness gets thinner as wires come out to switches, sensors etc. I didn’t use one harness going to everything under the bonnet, it uses an awful lot of wire and in true Chapman spirit that’s unnecessary weight and cost. I actually had several harnesses coming through the bulkhead grommets and heading directly to their destination rather than looping right round the engine compartment to get to things like the reverse light switch, brake light switch, coil etc.
I fitted the fuses and relays on the left side inner wing top surface and used the radiator mounting as an earth bar for everything under the bonnet. Will go and take a few pics!
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