The Inside Track - Keeping your Vintage & Classic Car on the Road - Electrical Musings

The Inside Track - Electrical Musings

We have created 'The Inside Track' for all our fellow Car Enthusiasts, and plan to publish useful articles from time to time to help you keep your Vintage & Classic Car on the road.  We are lucky to be surrounded by Experts who are not only share our passion for Motoring  but  who are trusted friends who are happy to share their insights and knowledge.  We hope you find this article useful.

The Inside Track

Keeping your Vintage & Classic Car on the Road

 Andy Seager’s Electrical Musings

 Are your sparks where you really want them?

 As a ‘go-to’ person for car electrics I have witnessed many issues that could have been avoided with a few minutes of care and maintenance. In some cases the owner of the car has narrowly missed a fire – or worse I’ve been presented with the aftermath of one, which results in wholesale replacement of large sections of the car’s wiring at some considerable and mostly avoidable expense. There’s no ‘black magic’ to car electrics and some simple observations and remedial work can make all the difference to reliability and the avoidance of sometimes catastrophic outcomes.

 Winter is a good time to think about your car electrics, you have some downtime time in which to execute some remedial work. Old cars shake and vibrate, which often leads to chafing and sometimes complete failure of old wires and suspect joins. Continuous temperature changes under the bonnet conspire to harden insulation, which cracks and allows the ingress of moisture. Our cars tend to issue oil into areas that can affect the electrical integrity of joints – much of this can be attended to before it results in a long wait on the roadside for the inevitable recovery ride home!

 Here are few things you can easily take a look at and remediate where necessary.

 1)     Battery leads: are they in good condition and free from obvious signs of chafing on the insulation?  Are they connected to the battery nicely without corrosion or that horrible white fluffy deposit? Are there any visible signs of stray strands that need to be tidied? If you’ve lost a few strands – re-make the connection, or buy a new lead!

 Is the earth connection to the chassis clean and well made? Is the engine properly earthed? It’s surprising how many poor starting cars can be remedied with a new earth strap, easily fitted between a bell-housing bolt and the chassis (or body in the case of a monocoque)

2)     Wire integrity: Any hard and cracked insulation is a failure waiting to happen, any wires that look suspect should be replaced – don’t take chances or wind tape around them, that is not a solution! Take a look at places where wires go through bodywork, drillings in the chassis, headlight bowls etc. Can you see any missing grommets or signs of chafing? Deal with it now and not on the side of the road! Thin pieces of rubber can be folded around wires and slid into exit holes then held in place with a cable tie – there’s often no need to disconnect anything to get a gromet over the wires.

 Are there any joins that have been made to extend wires or make connections to additional consumers? Are the joints secure and well-insulated? Twisting wires together and winding tape around them is a big no-no! Crimped joints are also not ideal because of vibration and continuous temperature fluctuations. Soldering and heat shrink sleeve is a permanent and robust solution – someone you know has a soldering iron!

 If you have any wires that are just wound around screw terminals – fit a proper ring terminal, it takes a few minutes and reduces the risk of connections failing while the car is running.

 Check the fuse box and make sure that there is no corrosion or heavy tarnishing around the fuse clips – a little bit of WD40 can work wonders (but don’t drown it!)

 Are there any tight wires? Always ensure there’s some slack and that wires are not pulled around sharp corners or edges – if it’s not long enough, replace it or extend it properly with a soldering iron and some heat shrink! Look at screw terminal joints and make sure there are no stray strands – if you’ve lost strands re-terminate, don’t just cut them off!

3)     Your dynamo: (make sure the car is switched off) – don’t be scared to remove the dust band and take a look inside. Take time to look at the internal connections to each of the brushes – if you see insulation problems or suspect connections deal with them – or seek advice from a specialist. 

 Make sure the brushes are not worn right down or that any of them have worn unevenly, and that they are free to move in their guides against the retaining spring pressure – a seized or tight brush will result in a charging failure. 

 Take a look at the commutator, you’ll see a series of copper segments interspersed with insulating material, the gaps between the copper segments should be free from copper particles and carbon dust (that will have worn off the brushes) – if it looks clogged carefully scrape the junk out with a small jeweller’s screwdriver or pointed (but not sharp) tool, go easy and try not to scratch the commutator surface. Make sure any junk that comes out is not left in the machine. 

 If there is any oil or grease covering the armature and/or the brushes remove the dynamo from the car and carefully clean it with clean rag and white spirit or methylated spirit – DON’T use thinners or any other solvent. 

 If you’re not comfortable with doing the work but the dynamo is a mess inside have an experienced person take a look for you, most dynamo failures result from maintenance neglect – do it now, not when you want to be out in the sun with the roof open!

 4)     Coil and Distributor:  Check that any connections to both the coil and the distributor are sound – again soldering is better than crimping. Distributor wires are very prone to hardening because of engine heat – if the wires feel rigid or look cracked replace them now! If you’ve used the live terminal on the coil for a supply to another ignition-switched consumer – then think about how that switched supply might be tidied up. Having multiple connections on the coil is not good practice especially because that circuit is often not fused.

5)     Non-fused consumers: It’s a dangerous game to play! Often old cars are ‘upgraded’ with such things as spotlights, cigarette lighter sockets and electric cooling fans – MAKE SURE these are all fused with the right value, any electrical breakdown could cause a short to earth, which unfused will probably result in a fire. If necessary, fit an auxiliary fuse box. Tapping off an existing circuit with a high fuse value does not protect your car!

 6)     Lamps: Remove lenses and inspect bulb sockets – sort out any corrosion or heavy tarnishing. Make sure the light unit is not wet or damp, and that it is properly earthed. On vintage cars it’s not good practice to rely on the mechanical connection between the light unit and the body of the car because any corrosion will increase the resistance of the path to earth. Where possible run an earth wire from the light unit to the chassis and make sure you have a sound paint-free connection.

 7)     Peace of mind: It’s never a good idea to leave old cars unattended with the battery connected, old wires and old consumers with aged insulators break down and/or get damp, you can never be 100% sure that when you walk away from the car something is not waiting to fail. Fit a battery isolator and switch the car off when you leave it. Battery isolators come in all shapes and sizes, some fit directly to the battery terminal and take minutes to fit – a few minutes work might save you much heart ache! 

 A few simple tricks and a couple of hours will pay dividends! As an old instructor once told me ‘when trying to resolve an electrical problem, use your eyes and your nose first, 90% of problems can be resolved without the need of flashy test kit’ and he was right!

 Happy Motoring, Andy Seager

January 2020