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The General Motors Metric Story

The General Motors Metric Story

From the May/June 2007 issue of USMA’s Metric Today.

by Don Hillger

General Motors and Metric Steel

In 1973 General Motors Corporation (GM) announced its plan to go metric. Metric conversion had been under consideration for some time, but was thought to be too costly as recently as 1967. That, however, changed as automobile manufacturing became more international in nature.

The GM plan included four basic components, outlined in a press release at the time:

  1. New product development will be metric from the start. This includes items already in the development stage.
  2. Service parts already in production will remain unchanged.
  3. Supplier coordination will be implemented as required.
  4. While metrication is being accomplished, some capital equipment (tools and machinery) with dual measuring capability will be required.

To minimize conversion costs, GM decided to metricate only when a machine or part was due for replacement. That replacement was specified in metric units, resulting in little or no additional cost.

Suppliers were informed of the decision to metricate specifications and design. Of the 40 000 suppliers at the time, little if any resistance was encountered, because purchasers at GM were willing to work with suppliers to overcome any problems.

Metrication was accompanied by a reduction in the number of sizes required for any given part. A good example of such rationalization was fan belts, where more than 900 old sizes were reduced to fewer than 100 new sizes. Because of the need for replacement parts, an enormous warehousing operation is needed, and by reducing the number of parts, the costs associated with part proliferation can be reduced. Through this rationalization GM was able to recoup its conversion costs and turn them into profit.

Similarly, the number of steel sizes were reduced by deliberately designing a logical progression of sizes, and fewer of them, during metrication. This process was extended into many areas, so that small costs associated with going metric were more than made up through rationalization.

In another example, the switch to metric standard wire sizes permitted the use of fewer sizes to adequately cover GM’s needs. This more efficient wire use alone produced a cost reduction of more than $1.6 million annually, a savings in a single division that exceeded the company’s annual metrication costs, with benefits that continued far into the future.

Training was expected to be costly, but only 10–15% of GM employees required training, and that training took less time than originally predicted. Sometimes as little as an hour was sufficient, because training was tailored to the needs of each job. GM summarized its training philosophy as: Teach only those who need to know, only what they need to know, and only when they need to know it.

GM chose dual units when dealing with the public, rather than the metric-only goal for its operations. As a result, of course, some customers are unaware of the metric transition that took place at GM and in the rest of the automobile industry. Some consumers still think American cars and trucks are non-metric, not realizing that the automobile industry changed long ago to reap the benefits of a single measurement system.

Material for this article came from various articles written about the GM conversion to metric, both in published literature as well as in past metric newsletters.