Car Restoration Projects

Many historic vehicles have dashboard clocks and it’s one carry-over that features commonly in modern top-shelf cars, giving them ‘class’. Here’s a brief history of the Smiths car clock and some advice on restoring them, courtesy of Alan Lindsay, of the Humber Car Club of Australia.

A modern Lexus with an analogue dashboard clock

First up, when asked about the history of analogue clocks, nearly all non-horologists will cite the Swiss as being historical leaders: wrong. 

Several European countries developed mechanical clocks from around the 13th century, but the English led the way in accuracy, culminating in Harrison’s chronometer that made it possible for mariners to calculate longitude for the first time. (That’s why Greenwich in London became the Prime Meridian and the site of Greenwich Mean Time {GMT or UTC + 00:00}.) The Brits also invented the electric clock.

S Smiths & Sons had been in the clock making trade since the mid-1800s, then made a move into the automotive business in 1927, with the purchase of KLG spark plug manufacturing and also the takeover of clock and instrument maker, Jaeger. Smiths electrified clocks and instruments were released in the early 1930s and quickly became standard equipment on the dashboards of top-shelf UK car models.

Even 21st-century Rollers have analogue dashboard clocks

Now over to Alan Lindsay:

The purpose of this essay is to make the reader familiar with the workings of the venerable Smiths electro-mechanical clock that graces the dashboards of many of Britain’s finest automotive offerings, including ,of course, our Humbers. 

It recounts the trials and tribulations I encountered in getting my clock to tell the correct time more than twice a day and having succeeded, I have some advice for those who wish to repair their clocks.

There was a time when a good clock was a cherished item. A mantle clock, often received as a wedding gift was expected to last a lifetime or a gold watch, given as a reward on retirement for decades of valued service to an employer. (You only have to look at the value of antique time pieces on the Antiques Roadshow to appreciate the worth of old time pieces – Ed.)

Today however we are literally surrounded by clocks, from your phone, the computer you sit in front of, GPS units and just about every kitchen appliance – even in my reverse-cycle air conditioner. They are ubiquitous and so accurate that we practically ignore them and treat them as disposable. 

As an aside, the approved clock in my aeroplane is worth thousands and has died after five years, but a matchbox-sized digital clock – five dollars from Temu – that I stuck in my tractor continues to work perfectly.  

There was a time, when Humbers graced new car showrooms, that a clock fitted to an automobile was tangible proof of the quality of that vehicle and the attention to detail the manufacturers went to to provide the discerning motorist with a comfortable and well appointed cabin. 

A stopped clock, however, proclaims that the vehicle is somewhat jaded and past its prime: once noticed, it is difficult to ignore. I must confess this is a rather petty cause for concern, given the horological extravagance of today’s world, but an inoperative clock is still a point of annoyance to me.

How does a clock work? Today we can rely on the precise vibration of a quartz crystal, accurate to a fraction of a second,  or, in the case of a GPS, the radio decay of Caesium in a distant orbiting satellite, providing accuracy measurable in terms of the life of the universe.

However, in days past, a clock used a pendulum. A strange feature of a pendulum is that it has a given period. That is, it takes exactly the same time to swing back and forth, irrespective of whether you give it a big push or a little push. It is a natural time keeper. 

You might remember the slow swing of the pendulum of a grandfather clock with its signature ‘tick-tock’ as the escapement allowed the hands to advance one cog at a time for every swing. A large, falling weight providing the impetus to keep the clock running. 

Now it’s self evident that a pendulum is hardly practical in a car jolting over rough roads. In its place are a spring and balance wheel assembly, which also has a period. The wheel spins back and forth, winding and unwinding the delicate snail spring, in turn allowing the hands to progress one tooth forward on the escapement wheel.

What provides the energy to drive this tiny wheel? The balance wheel is placed next to an electric coil and at the right moment the coil is energised by a tiny set of contacts. This causes the wheel to rotate, just like an electric motor. The impulse is only momentary, because the balance wheel’s rotation is arrested by the winding up of the spring, so the wheel then moves back in the opposite direction and the cycle repeats itself. 

Our Smiths clock is a fine, well made device with a jewelled movement. It is accurate, for the period in which it was made and its movement is extremely reliable, considering the harsh environment it endures, exposed to shock, vibration, extremes of temperature and dust. Its Achilles heel is the diminutive set of contacts, that, like the points in yesterday’s cars, are prone to burning and degradation. 

My clock is close to 60 years old and has performed, by my calculations, nearly two billion individual cycles of the minuscule pin on the balance wheel wiping the whisker contact. It might not be perpetual motion, but it is in the ballpark and every time the circuit is made and broken, the most microscopic of arcing must occur, causing the carbonisation of the contact area. Cleaning and readjusting the whisker contact became somewhat of an obsession for me. 

I have spent countless hours delving with tweezers into the innards of my Humber’s clock in an attempt to breathe life back into its mechanical heart and then watching the mechanism – like a cat waiting at a mouse hole – as the movement ticked away on a test bed. Then I tried to determine why, for no apparent reason, the balance wheel that at one moment seemed to swing so determinedly, stopped.  

Having run it on a test bed for days, I would reinstall it into the car only to have it fail overnight. I have become rather proficient at removing the clock from the dash that’s always an unpleasant task and fraught with the risk of creating unlooked for problems with the nearby wiring while rummaging behind the dash. 

At one stage I sent my clock to a specialist instrument maker for repairs at no small expense. It ran like a clock (pun intended) for a year or so, then stopped.  Very disappointing! 

I trawled the Internet for information and found some excellent articles, including some specifically written for our Smiths Jaeger units. The Hillman website has a very good piece.  My knowledge of clock movements increased but still the pesky electrical contacts, deep within the movement, defeated me. 

In desperation I considered having a modern quartz movement fitted, but the cost was prohibitive and somehow it seemed like admitting defeat. 

And then I came across the a British company, Clocks4Classics. They have basically developed an ‘electronic ignition system’ for our clocks, while retaining the original movement. In short, they replace the electrical contacts with a tiny optical trigger. 

The trigger is activated when an electric eye ‘sees’ a simple black line that is stuck to the rear of the oscillating balance wheel. Much like an optical electronic ignition, every time the black line passes beneath the ‘eye’ it provides an impulse of energy and there’s nothing to burn or wear out. 

The video that they put on the net explaining the workings of the clock and the installation of their kit is superb. Of course, YouTube made the rather complex task of installing the kit look easy, but, as I gazed down at my ageing, plate-sized hand, I worried if I could really perform the job. 

I purchased a kit for about the cost of a tank of juice. Fortunately, it was not polarity sensitive and would operate on positive and negative earthed cars – one less thing for us drivers of antediluvian British cars to worry about. If only all electrical items were so tolerant…

As an aside, what does positive earth really mean? Which way do the electrons actually flow, and why did cars change from positive to negative earth? You might be surprised at the answer! (Think electrolytically – Ed.)

The kit sat on my mantelpiece for weeks, daring me to tackle the installation. At last: a cold front with rain and freezing winds arrived, ensuring that I was house-bound. This was the perfect opportunity, so I could put it off no longer.

I can’t imagine attempting the task anywhere but in the most well lit, comfortable and clean area. My workshop, where considerable heavy engineering takes place, repairing and maintaining farm machinery, was not an option. 

Special permission was obtained to convert the kitchen table into a work bench! (That’s amazing – Ed.)

The written instructions accessed by the Internet were unbelievably good. I battle to assemble an Ikea bookshelf, but the succinct step by step instructions provided left no room for doubt. They anticipated where problems would occur and offered solutions. We are so conditioned to the appalling Chinglish instructions that accompany most purchases, It’s easy to forget how precise and descriptive our English language actually is.  

The first part of the disassembly had me in familiar territory, but the act of cutting the wires to the solenoid windings marked the irrevocable point of no return. This was closely followed by the removal of the balance wheel and its delicate hair spring. I was well and truly in the wilderness. 

At one stage I thought work would grind to a halt, when I was faced with the removal of three of the minutest screws that secured the face to the movement. Nevertheless, the kit manufacturer had anticipated this bottleneck and offered advice as how to proceed. 

At last the disassembly was over and there was a brief hiatus as bearings and gears were cleaned with a cocktail pick and lubricated with a smear of clock oil. I had reached that watershed moment on any repair job when disassembly ceases and reassembly begins. 

The new circuit board fitted perfectly and there was no ambiguity. This was in stark contrast to an electronic ignition kit I bought for the Humber that, like a cheap suit, fitted everything and touched nothing. Now that was a waste of money! 

Halfway through the reassembly came the magic instruction: ‘Connect to a 12volt source and test the mechanism’. Sure enough, as predicted, when the current was connected, the balance wheel did its little dance and three seconds later, like the beating heart of a tiny but robust bird, swung into life. I felt a Frankenstein-like thrill: “It’s alive! It’s alive!”  

The remaining reassembly was straight forward and the clock was reinstalled into the car. The clock then went into its regulation stage and every day I checked the time and made a small adjustment via the regulation screw on the face. 

Eventually I got the accuracy down to about a minute per week. That was about six years ago and the little clock ticks on, counting down the heartbeats of our mortal coil:  it may well outlast me.

At this stage I would definitely recommend Clocks4Classics and suggest to anyone with an inoperable Smiths clock and a modicum of technical ability, to have a go at repairing it. 

Of course, as with the French Revolution, it’s too early to tell if the cure was successful. We’ll have to ask the car’s next owner, in about 50 years’ time! 

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