Once again Agnetha is up in the air with wheels off. This time she’s being prepped for receiving a reconditioned set of Hydragas displacers from The Kennedys and having her suspension pumped up for the first time in many years. This will be a huge milestone as it’s almost the last major repair to do before testing! But let’s not get ahead of ourselves. While I wait for the displacers to make their way to the Slavic Paradise I wanted to try a small upgrade that could improve Agnetha’s safety in modern traffic.
It’s an in-joke in the classic car world to talk about having headlights like a glow-worm in a jar. Headlights on older cars tend to be dim due to a) the ridiculous physical length of the headlight circuits, and b) surface oxidation of the copper strands in the wiring loom and switch-gear. Even for a small car like the Allegro the headlight circuit is very long, starting at the battery, going through the firewall, into the centre console where the headlight/sidelight switch is located, then up into the steering column and around the main beam / flash stalk, back through the firewall, along the wing into the right-hand headlight and then under the radiator into the left-hand headlight. It’s insane, really. Even from the factory the total resistance would have been considerable, and after several decades it will be quite a lot more.
Indeed I had noticed the wiring and switches would heat up quite quickly with the headlights on. So the net result is dim headlights and the constant threat of an electrical fire or a sudden loss of headlights – not something I want to be thinking about on a dark night at 90 kph in the middle of the Polish countryside. Luckily there is a solution that is cheap and fairly simple to install: A classic car wiring loom. These normally come in the form of a ready-assembled kit that can be installed “over” the original wiring loom without interfering with it. While looking online I saw some classic car specialists had these for sale at very silly prices. But it’s just not worth paying a lot for these things – they’re all made of the same components and it does not need to be anything special. I bought the cheapest piece of crap I could find – for about £11!
The kit works by powering the headlights through a pair of relays (one relay for the headlight, the other for main beam). The current only travels a short distance over brand new wires, reducing the resistance by reducing the length of the circuit and also avoiding the increased resistivity of the original, now rather oxidised wiring. The original wiring is kept in place, however, because it’s used to control the relays by supplying voltage to energise the relay coils. Since this requires very little current, there are no longer any issues with resistance heating. Installation simply involves connecting the “big red wire” of the kit to the positive terminal of the battery, connecting the output plugs of the kit into the headlights, and connecting one of the original headlight plugs (the one nearest the battery) into the input socket of the kit; the remaining plug from the original wiring is then redundant and can be taped-up. It’s then just a case of testing and tidying things up.
And this is when I found the one and only snag. While the headlights and main beam worked as expected, the main beam flash wasn’t working when the headlights were on. I could hear the relay clicking but there was no change in the light pattern. After some poking around I realised this was because the relays were wired in such a way that the main beam could not be switched on if the headlight relay was in the “on” position. This was solved by bridging the wires connected to terminal 30 on both relays. With this in place the main beam flash was working, as was everything else.
I haven’t done any scientific tests to prove how big an improvement this is. I’ve just looked at the headlights and said “wow they’re brighter” and felt the wiring to be sure they no longer heat up. For 11 quid I’d call that a result. Much brighter headlights and no more hot plastic smells!
Projekt Agnetha 