Are Lucas electricals as bad as everyone says?


Not specifically a Lucas problem unless Triumph used Lucas advisers to design their wiring. On my 59 TR3A, the one thing that has puzzled me the most is that the battery is grounded to the body just above the battery. The engine where the starter, the highest current accessory, lives is grounded to the chassis by a small braided strap across the rubber engine mount. There is no specific ground between the body and chassis except for a dozen or so body mount bolts that are mostly insulated by rubber strips here and there. That is why I ran an extra cable from the battery ground directly to the bell housing. Absolutely no problems getting full current to the starter that way. I don’t need the little ground strap around the engine mount that way as nothing electrical is connected to the frame anyway. I also put in several relays to take the load off of the Lucas switches and that has worked well for many years now.


I bought a 1980 Spitfire new. Had the alternator replaced twice under warranty. Same with the electronic ignition. After the next failures I had the alternator rebuilt locally by a guy who said “I know what’s wrong with it” and used a domestic diode pack. The ignition was replaced with diode fired system. Never had any issues after that…


Similar problem for me. My 1974 TR-6 with overdrive went through 3 alternators in one year. Finally, a friend suggested changing to an AC-Delhi unit from a Chevrolet. Perfect drop-in replacement and nary a problem ever - except with the brake lights. Long, long unpleasant story on that issue. Still, I wish I had that car back but then, I collect Fiero…


I remember getting on a Delta (ex Pan AM) Airbus A310- and when I greeted the flight attendant in Vienna I noticed a sign on the bulkhead-Electricals by Lucas-we touched don at JFK 8 hours later and the plane occasionally shows up at our airport for Fed Ex so maybe the stories as you say are only partially true


As a British car mechanic, I can tell you that most of the stupid jokes about Lucas electrics are made by the people that don’t understand any thing about electrics and specially the ones that are thinking that their yank tanks are so much better and therefore not further looking or even worst thinking then the length of their nose or by the muscle car guys another body part.


I had very few electrical problems on my 79 Triumph Spitfire, far more mechanical problems.

I had the bonnet off the car several times. Every time, I labeled each wire so I could reconnect it all correctly. And yet, the labels we’re always only about 80% correct when I reinstalled the bonnet. I’ve had that problem on no other car.

Another oddity was the turn signal / horn. The left turn signal would make the horn briefly honk. (Or was it the right? No matter) The turn signals worked fine so I never messed with it.

Fun car! Not suitable as a daily driver, but fun!


Thank you for explaining what so many “would-be/shade-tree” mechanics" don’t realize. I wish the American companies had a color coded system like the British, as it would be far easier to diagnose problems.
As many have pointed out that the “ground” is often at fault, and that has been the case for many LBCs. A major example is the rear lights with their twist socket connections; the ground has a thin piece of copper only “touching” the metal surround, and often gets corroded. A light fiberglass brush cleaning and a quick solder contact and your problem will be solved.
There are quite a few other ones I cold go into, but that would take too much time

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Owning three Lotus currently and a total of seven in my life (so far) I love this! Reminds me of my favorite Lucas joke: “What are the 3 positions of a Lucas switch?” Answer: “Dim, Flicker and Off”.


I do know that on my 1957 Metropolitan once we by-passed the lucas voltage regulator completely and installed a separate new fuse block and reversed the positive ground to negative ground everything has been working great. Of course it still drips a little oil, but remember it was built by the Brits and everything they built dripped oil. I just keep a drip pan under it when it’s parked in the garage.


I never cease to be amazed that British cars are condemned for their electrics, SU carburetors, etc. etc. You would think no-one could get around in their cars over there, to listen to some of the people commenting here! Let’s face it, there are design flaws in many cars, including those built in the US.
Having lived in England and the USA and owning four classic British cars including a Lotus, I feel I can comment (And yes, I do all my own car work other than machine shop stuff.). It is, in my experience, in part a matter of American mechanics not being familiar with the British way of doing things. A similar problem happens to American cars in England, BTW - some of my friends with American iron in the UK curse their cars as much as I see some respondents curse their GT6s here. But there is another reason, I think. Many British cars - particularly sports cars - are bought here as toys and are thus left idle for much of the time. When I was growing up a friend’s older brother ran a Bugeye Sprite as his daily driver and it ran fine for him, even in the notorious British rain. The key - it was driven daily. I would also say that I concur with the several mentions here that Lucas electrics tend to be simple, and, importantly, can generally be dismantled and fixed. I wonder how many of today’s vehicles will be restorable in 50+ years with all the sealed electronics which tend to give trouble even when quite new. I just waved our friends off to the Vancouver BC All British Field Meet show (celebrating Bentley’s 100th birthday) - they drive their 1924 Bentley 3-Litre all the time and the 300+ mile drive one-way to Canada from Portland, Oregon is typical for them (with a side trip via ferry to Orcas Island on the way.) Original generator, starter, magnetos…


I’ve found Lucas electronics to be exceptionally reliable - in my driveway. It’s when I’m 150 miles away that they seem to use up a month’s worth of profanity.

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Having restored and preserved many old british bikes the problem I’ve found commonly is the insulation itself rots away. The cloth wasn’t great but could survive in dry climates, that said in the mid to late 30s they started switching to natural rubber insulation, this worked alot better in the wet British climate but rots away with age and becomes rock hard and brittle. Now when working on anything older than about 1963 I just resigne myself in to having to replace the harness.



'zactly. The first choice for Darth Vader was actually Zenier Diode, but of course it was already taken. Who needs a “real” voltage regulator when you can use the electrical equivalent of a total loss oil system? :wink:
Regarding the original question “are they as bad…?” Yes. Yes they are. They don’t corner the market in horrible, but they get the lifetime achievement award. I suspect the intermittent wipers in my '97 GMC Jimmy were a copy of an original design from Lucas (or Ben Franklin) . They were self-correcting, however. The wipers would stop, you’d go off the road. The vibration from crashing through the underbrush would cause the wipers to come back on, so you could find the road again. Wash, rinse, repeat.


I have a 1979 Triumph Bonneville motorcycle that had a Lucas ignition system on it and it lived up to its Prince Of Darkness name. The first thing I did was replace all the wiring and electrical components. From that point on I have not had any electrical problems.


With the old Lucas electrics, poor design is the main issue. Many comments here like “keep your grounds clean” indicate Lucas should have taken care of this. On my 1969 BSA Rocket 3 restoration, I did buy a NOS harness but added a ground return from every electrical component back to the main grounding point near the battery. All the electrics have worked flawlessly since. Relying on frame grounds with British bike vibration is asking for trouble.


agreed, I went to an aftermarket electronic voltage regulator and ign. system on my BSA A65. Compare a '60’s British bikes electricals with the Japanese or H-D of the same era and no comparison in reliability.


I owned a '64 Giulia Veloce for a while. Evidently, in their attempt to make everything electrical top-grade, they outsourced some components away from Marelli. The ignition system was tried-and-true Bosch, like from a Volkswagen (good), and for the wiper motor and rigging, they went to the country with the foulest weather. 'Nuff said.



I have owned British cars for 40 plus years and one has to compare Lucas electrics and SU carburetors with SEX. Do you how to keep a h==d on =ar=? Don’t fuss with it.


RE: SU Carbs: I grew up on carters & holleys, it took me 4 rebuilds for my first SU. Why? I was making it too hard!! They are genius in simplicity and function very well when you take the time to learn it.

UNFORTUNATELY, the same can not be said of Lucas wiring. I have never been more frustrated with my MGB. 3 ignition switches, a failed diode in the emergency braking system caused the starter to engage with no key in the car (True: Google it, I’m not the only one.) Mine did it in a parking garage and rammed the grill into the wall until the battery died (left it in 1st). I came out to find it smashed and dead. Fast forward 1 year – still unknown cause of an under dash electrical fire which cause a lot of damage. The car hasn’t moved since. I have gutted ALL wiring and went with an American made wiring harness. Mr. Lucas is no longer invited to my home.


Just to keep this non-discriminatory, I got rid of a Buick Roadmaster because, when you started the car, it decided to cycle the door locks up and down until you had driven it for a few minutes. It would occasionally also turn the wipers on when you started it. At least you could turn them off. The dealership would tell me it was fixed and as soon as I started the car to drive home, I would discover that the only thing that changed was the balance in my checking account. Did DELCO ever partner with Lucas?