They seem to be manufactured to a standard that was in place about 75 years ago. SInce then, automobiles have incorporated so many quality improvements that aircraft stuff, which is still stuck in 1940, looks pretty poor. What other industry puts felt bearing seals in their wheels? Or still uses Buna-N O-rings when there are many superior materials available? Or still uses contact points in their magnetos? Even lawnmowers, for the last 15 or 20 years, have used a breakerless magneto ignition. Seems to me that Mercury outboards incorporated that in about 1972. Bendix and Slick could probably eliminate about half the maintenance, and double the reliability, if they used it.
Improvements imply, to a hungry lawyer, that the old stuff was defective and worthy of a lawsuit, if he can find someone who has come to grief with the old stuff. So things move forward very slowly. And sometimes very quietly, as with the Champion spark plug integral resistor. And most of the time any improvement is effectively resisted by government, which imposes an enormous burden on the manufacturer who modifies anything or comes up with a better way.
Dan
