Top 10 Rules to keep your classic car electrical system in top condition.

I have mentioned before that classic car maintenance is like a religion and the fixes and checks we perform are the rituals for practicing this religion. Occasionally one needs the aid of a priest. And once in a while we must turn to a God of some form when all else fails…and I use the word God in the sense of a “creator”.

Enter ‘Mr Gremlin Slayer’. OEM wiring loom designer and master auto electrician, sporting the code name Slayer, he is fit to rub shoulders with the ancient Greek Gods should they ever grace us with their presence again. With over four decades of experience, Mr Slayer must remain anonymous because he knows everything there is to know, from the very beginning when a wiring loom was just a twinkle in his eye through to the actual birth of his design.

When I first met the gentleman in question I knew straight away that I was fortunate to have a huge bank of knowledge and know how to tap into. Mr Slayer turning up to help me with a few classic car projects was the equivalent of being set the task to take a package from London to Scotland…you expect a bulky box in a Transit van (nothing wrong with a Transit, I love them) but it would simply be enough to get the package there, nothing above and beyond. Instead I was handed a delivery note belonging to a small parcel in the glovebox of a McLaren SLR, a car that would get the job done but offer so much more to the experience. Now here we open the door to a comedy moment…I have never been near an SLR so this is probably where someone in the know highlights it hasn’t got a glovebox. But I’m sure you take my point.

Over the course of a few months I watched in fascination as Mr Slayer set about breathing life into electrical components and putting to sleep electrical gremlins at the classic car hire firm I used to work for. And in the process I made a good friend.

A friend on which I have called upon to share with us at Trade Classics his top ten classic car electrical pearls of wisdom. And I posed perhaps the hardest question there is to answer. Is there a car from the past fifty years that stands out as electrically superior and reliable? Here is what Mr Slayer had to say;

“Ok Mike, in a nutshell, classic car owners should keep an eye out for the basics.
Ensure the battery is fixed down properly, terminals are in good condition and fit/have fitted a cut off switch.Charge it regularly every 3/4 weeks if the car is not in regular use. Ensure the battery cables themselves are in good condition and have the routing and clipping checked.

  1. Fuses – check they are the correct rating and free of corrosion – all in professionals if you are not sure.
  2. Accessory wiring – beware of ‘get it working for now wiring‘ bodged jobs and get any’strung across’ spurious wiring checked and removed if redundant. Think ‘BBC’ – Beware Blue Connectors!
  3. Dynamo/Alternator and their associated wiring – get them checked professionally to make sure they are suitable and in good order.
  4. Wipers – check linkages, arms, blades and cables, excessive wear will cause electrical failure, especially if it rains in the summer too.
  5. Washers – keep good quality fluid in the tank and check for proper operation every month.
  6. Switches – make sure they work without fiddling and you know exactly what each one does (a mate’s daughter was late for her wedding, really late in fact as the stand in driver did not know the classic Jag had twin tanks!)
  7. Lights – ensure good quality bulbs have been replaced recently and all are working as they should.
  8. Consider a new loom if the wiring is over 30 years old – the looms are available from specialists for most old British cars – have it inspected professionally, proper routing and clipping is very important.
  9. Always ensure that the cooling fan system is properly switched, fused and wired. Most pre 80s cars will have had an after market electric type fan fitted by a DIY/well meaning mechanic. Ensure the control thermostat is set correctly and the gauge is working and reasonably accurate. Closely linked to the engine cooling is the oil pressure gauge and lamp itself.  Engine rebuilds are costly and often the result of a chain reaction stemming from cooling system failures, started by a dodgy electric cooling fan set up or a non functioning oil lamp.
  10. Try to avoid DIY modifications to add things like alarms, trackers, central locking, power windows.

And as for your other question, now that is a big one to answer Mike! In terms of reliability in most areas including electrics you would be hard pushed to beat a Merc SL from early cars to late 80s. Does that pan out with your experiences?”

I nodded. It did indeed. The R107 80’s SL is a die hard motor car in all aspects.

“They are made from top quality materials. Designed and installed with durability in mind, some would say over engineered. For example silver plated terminals in most connections and the terminal systems are very robust and clearly expensive. They are so reliable that I don’t see many with faults, maybe the odd hazard switch or an after market alarm bodge up causing issues”.

Yet again Mr Slayer had hit the nail on the head, the only part I remember ordering for a 300SL from 1987 was a hazard light switch. And it was not very expensive.

Ans thus to summarize, there would be no harm in employing the skills of an auto electrician near you to infuse some of the ingredients the mighty 300SL was made with along with Mr Gremlin Slayer’s top ten tips…how smug would you feel down the pub gently slipping into conversation that you have silver plated terminals on your MGB?*

So Trade Classic readers, I hope this has been a helpful article, stay tuned for more top tips on how to keep your metal children healthy.

Oh yeah, and if you like my articles then you can have them delivered straight to your lovely inbox – simply subscribe to my blog.

*This phrase should only be used in car related conversations with like minded individuals, not as a chat up line.

Mike Atwall
This article was written and published by Mike Atwall. Mike works for Trade Classics as an in-house journalist and copywriter and has many years’ experience in the classic car sector – for over 8 years he was the General Manager of the Classic Car Club in London and responsible for a fleet of over 100 cars worth multi-million pounds. So there’s not much Mike doesn’t know about makes, models, maintenance and idiosyncrasies of these old cars. Mike’s a true petrol head with a deep passion for the classics and he loves to talk cars all day, so why not write a reply on this article below.

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