By The Metric Maven
Bulldog Edition
One Autumn afternoon I was driving along back roads in the Rockies with my friend Thern. I had been discussing some aspect of metric and he posed a question: “The Model A had only one metric part on it, what is it?” I was floored there was any metric part on Ford’s Model A. I thought about it a while, gave up, and then asked him to reveal the answer. His reply was that it was the spark plugs. They had 18 mm threads. Thern possessed a vintage Ford Model A repair manual and had taken note of this fact. The reason for metric threads? The Europeans were way ahead of the US in the design of spark plugs. Belgian engineer Étienne Lenoir is credited with the invention of the spark plug in 1860. I looked on some Model A forums, and sure enough, there are discussion threads about why the spark plug threads are metric, and asking if they should be reworked so that “standard” spark plugs can be introduced, and such.
I was quite surprised there was any metric part on a Model A. It is the iconic American automobile. When the first Model A was introduced in 1903 John Shafroth was still making his bid to make the US a metric country. It is reasonable to state that well over 99% of the parts which comprise a Model A are Ye Olde English. Today over 99% of the parts in a US made car are metric. Only the bolt heads on the battery post clamps are not metric (those that are used for the bracket to hold the battery in place are metric). Thern tells me that on modern cars (newer than mine) the battery clamps are now generally metric. Pat Naughtin in his first newsletter (Metrication matters – Number 1 – 2003-06-10) mentioned the fact that people in the US do not realize they are driving metric cars, because that fact is not on display:
I wonder why the USA is the last nation in the world to admit the extent to which they use the metric system of measurements. For example, of the 10 000 parts in a modern car, made in the USA, all of them are measured in millimetres to the nearest tenth of a millimetre. But because the speedometer is labelled with the letters ‘mph’, drivers in the USA are generally convinced that they are driving an ‘English Units’ automobile.
Our road signs are all in medieval units, and so there is nothing that would directly indicate that American cars are well over 99% metric.
In an earlier essay I have examined the intellectual grip that familiarity has over simplicity or change. In another I point out that for over 3000 years the design of a bee hive did not change until the 19th century. In the US, innovation has often been associated with a decrease in profit. J.P. Morgan is reported to have said after he had consolidated the majority of electrical providers into General Electric: “Research is unnecessary if you have no competition.” A changeover to the metric system is simply an unnecessary business expense when viewed this way.
In recent years I’ve been exposed to engineering designs at a number of firms. When they use metric, it is often with millimeters, and nothing else metric. I’ve seen more than one situation where a customer is from outside the US, and appears to assume that because the drawings are in millimeters, that the design is metric. In one situation I unintentionally created a brouhaha when I asked if the fasteners were all metric. It was clear I had unknowingly asked a politically incorrect question. They were not. The customer was not happy as they thought the design was completely metric.
What I have noticed is that companies which state they use metric are often creating Potemkin designs. As long as millimeters and meters are invoked the design is thought to be metric, but in fact the rest of the design is left in Ye Olde English. I’ve seen situations where medieval measure screws are used, and in an attempt to “accommodate” metric fasteners, a Ye Olde English screw size that is as close as possible to a metric one is chosen. No newtons per square meter or liters or grams make an appearance, only millimeters do. It is hard to know what motivates this Olde English death grip, it could be some cultural identification, or simply a resistance to change. The use of metric and Ye Olde English in a design is designated as a PigFish design in this blog. Rather than become metric, NASA made the “International” Space Station a combination of medieval and metric. I discuss this in my essay When PigFish Fly.
Whatever the motivation, it demonstrates that left to their own devices US business, education, and all other aspects of our everyday lives will remain as they are—Ye Olde English. Resistance to a government mandate for metrication, is simply equivalent to promoting the continuation of our archaic measures and design methods. As each year goes by without a metric mandate in the US, we become more anachronistic as a nation and as a culture. The only thing Americans seem to be good at these days is talking, and when the subject is the metric system, it is seldom in a positive manner.
If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:
The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website, but the book has them all in one place in print. The book may be purchased from Amazon here.
The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.
The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.
Ford used the “Model A” designation twice for completely different vehicles, 1903-04 and 1927-1931. The vehicle you picture is the later model and used a 7/8-18 Champion 3X plug (7/8: dia. thread, 18 threads per inch) according to many sources. One example:
http://www.modelafordclubtampa.com/engine_spec.html
I have not been able to find a spec for the spark plug in the earlier open runabout.
Metric spark plugs….fascinating!
I ran into this situation some years ago. We were looking for a company to do some assemblies. I was one of the people to tour the shop. Most of their customers were foreign companies that had operations in the US and their requirements were to be metric. But, this shop only did whatever metric was specifically specified. They tried to get away with as much USC as they could.
As far as metric hardware was concerned, anything that they purchased from overseas did have metric hardware. Anything that was specified to be metric was metric, but if they could get away with it they went out of their way to make sure some USC hardware was incorporated.
One particular component that came to mind was formable bus-bar. They had a package of it on a bench and the one engineer pulled a piece out and went out of his way to tell me how many gauges it was. But I could plainly see from the description on the package that the size was 50 mm wide by 3 mm thick or 150 mm^2 size. I brought this to his attention and inquired as to why he would talk gauges for and obviously metric product while pointing to the box and multiplying 50 x 3 in front of him.
He stuttered for couple of sentences of some unintelligible gibberish before he went silent.
When the tour was over I told him I didn’t like hybrid products. If the end users requests metric, then the whole product should be metric, not trip over myself trying to see how much USC I can get away with just to be spiteful and nasty. Silence again. We never did do business with that company.
We did get a number or overseas bid requests and they had to be metric. Of course they were getting more and more clever. If you tried to sneak in USC parts, like screws, they would catch it during the approval process and reject it. If they saw a 3/8 bolt on a part, they insisted it be changed to M!0 x 1.5.
The back and forth submissions and corrections usually added 3 months or more time to get a final approval. Did we learn our lesson? No, the next time we got an overseas bid request we submitted drawings littered with USC (except for my portion) and the cycle started over again. Even conversations with the chief engineer to use only metric for overseas bids went nowhere. We were determined to force these people to try to accept USC and only reluctantly use metric when and only what they specifically requested.
So, it doesn’t surprise me that as time goes by less and less of these bids from American companies are accepted.
If you track how these changes happen – very slowly – then suddenly unavailable and people forget.
I go to pawn shops and look for strange tools – long or thin wrenches etc.. What I am seeing now is the metric tools sell out rapidly – so they don’t offer much if any for the used – now obsolete – english sets.
What I hate the most is having to have both – just bought an imported pole saw – with a mix of metric and english… As usual – metric countries are more so on paper than in reality.
But it is moving – I’ve had metric socket wrench from back in the early 1970’s – I now use them for the wide variety of chores more than 75% of the time.
There was a time when slotted screws were the norm – they are not a good idea in that slips that injure and damage are common. If we look at how the change to Phillips head has happened it provides a model of what to expect for the change to metric. I refused to specify or use slotted screws starting back in the 1980’s – Today they are rare – more often frustrated with screws intended to block repairs than a slotted one. One has to be able to deal with them – but they are mostly an annoying thing of the past. My local hardware store still has some – but less every year. They now have as much space for metric machine screws as the obsolete ones.. Thing do change – slowly yes – así es la vida.