Measuring the speed of “The Fastest Metal Cars in the World” was a one year event. In 1970 Mattel made both single-lane and dual-lane speedometers for Hot Wheels.
These purely mechanical toys use no batteries or electricity. For such an inexpensive toy, the design structure is quite remarkable. As cars enter the speedometers they are tilted 30 degrees onto their side where they first contact a plastic bar that automatically resets the speedometer needle to zero, then they hit a paddle mechanism that pushes the needle around the dial and records the speed of that pass.
On the underside of the speedometers is a dial that allows the spring sets to be adjusted which regulates how “fast” or “slow” the needles will move. On the “fast” setting the springs are fairly loose and will allow the needle to move a long way around the dial and record a high speed value. On the “slow” setting the springs are tighter and restrict how far the needle will move, thereby recording a slower speed value.
It stands to reason that every kid wants to see the highest possible speed on a race set but there are situations, primarily with high speed Sizzlers, where you want to slow the cars down a bit as they hit the paddle mechanism.
The other purpose of the tensioning dial is to balance both sides of the dual-lane speedometer. You run a car through one side of the speedometer and set the tensioning dial to give a particular speed. Then you take the same car and run it at the same speed through the other side, tensioning the dial, so that the second speedometer gives the same speed reading as the first. If you happen to be running two single-lane speedometers side by side the same procedure would apply.
Here are the instructions for the single-lane speedometer.
And here’s the instructions for the dual-lane speedometer.
In general, it’s always been true that certain Hot Wheels cars work better on some sets than others. With the speedometers I find that the fastest readings are determined more by the front end design of the car than by the speed of the car.
Cars with a square front end will hit the paddle mechanism more solidly and push the needle further around the dials. So, even though my purple 2007 Shelby GT500 is faster than my magenta 1971 Plymouth Road Runner, the rounded front end of the Shelby will usually record a slower speed than the square front end of the Road Runner.
Here’s an example of what I mean from my YouTube Channel: Smackeral Cafe.
What should you look for when purchasing a 1970 Hot Wheels Speedometer? Ideally, on the top of the dials, the needles should be sitting at “Zero”. And on the bottom, the tensioning dials should be sitting on “Fast”. Any other position will place extra tension on the speedometer springs and, over 40 plus years of storage, those springs will stretch out and make the speedometer less functional.
So there you have it. The 1970 Hot Wheels Speedometers.
They show you that Hot Wheels are still fast. Still fun.