Stepper Motor Gauges — Instrument Technology Part 1

What To Look For In Aftermarket Gauges

Spin the clock back more than a few decades. In my neck of the woods, it was common (almost mandatory) to have a Sun Tach bolted to the dashtop of a hot rod or race car. Under the dash was either a trio of Sun or Stewart Warner gauges. Those gauges included an oil pressure gauge, a water temperature gauge and an ammeter. The ammeter was obviously electric but the other two were usually mechanical.

It worked and it was (and it still is) incredibly important to have gauges in a modified car. But times have changed. When it comes to information about your engine (and in some cases, the drive train pieces behind the engine), the more accurate your information and the easier it is to decipher, the better off you’ll be. Just as important, there have been major developments on the gauge front in the past few years, and what was hot technology a few short years ago, could prove to be old news today. Thanks to the folks from Speed Hut ( – manufacturers of the Revolution series gauges shown here — for sorting out the latest in performance instrument technology. Check it out:

What’s Best: Mechanical, Electric or Electronic Stepper Motor Gauges?

So what’s hot and what’s not when it came to aftermarket instrumentation, particularly, which is better, mechanical, electric or the latest stepper motor instruments? The answers might surprise you: All three configurations can be built into an accurate gauge, but the truth is, the determining factors more involve installation and application than gauge accuracy. For example some of today’s stepper motor configuration gauges combine the ease of electric gauge wiring with a full sweep dial face like the mechanical gauge. What follows is a short list of advantages should help you to make the decision for a specific application:

Mechanical Gauge Advantages…

Mechanical gauges have a full 270° sweep which makes them easier to read accurately. Mechanical gauges do not require 12V power to operate. They make direct physical contact with the item they are reading. Obviously, this is accomplished through tubing or lines, which eliminates the need for electric signals. Mechanical gauges are ideal for vehicles that operate on voltages other than 12V, with no voltage at all (magneto applications) or operate on a battery with no generator.

Electrical Gauge Advantages…

Electrical gauges have a 90° sweep. They do not have large connectors and tubing coming out the back of the gauge. Given the design, they can be mounted in more unusual positions without connections showing. The design allows them to be easily installed in tight areas. It’s also easier to install the gauge a great distance from the item being measured (which may be important in certain applications). An electric gauge prevents fluid from entering the passenger compartment.

Electronic Stepper Motor Gauge Advantages…

Stepper motor gauges have a full 270° sweep such as a mechanical gauge. Like an electric gauge, they do not have tubing or large connections originating behind the gauge. Additionally, the configuration of the gauge allows it to be mounted great distances from the source if necessary. Modern examples tend to be shallower than either older electric instruments or mechanical versions. That makes them easy to mount in tight confines. Finally, some companies such as Speed Hut offer a huge array of options such as integral warning lamps, in-gauge turn signal indicators, tachometer shift lights and so on

Gauge Sizes

Most manufacturers offer at least a couple of different sizes when it comes to gauges. Typically, they either have a 2-1/16-inch face or a 2-5/8-inch face. Anything smaller is tough to read and anything larger is often difficult to package. When it comes to tachometers and speedometers, the normal sizes are 3-3/8-inches and either 4.5-inches or 5-inches in diameter. Some companies though, offer gauges in much larger size ranges. For example, you can get tachs as small as 2-1/16-inches. They’re not easy to read (especially for us old guys), but they can be fit into tight locations.

As we pointed out above, instruments with the shallowest mounting surfaces are today’s electronic stepper motor models. They’re considerably smaller (from a depth perspective) than other gauges.

So far so good, but what are the most common instruments you should consider? Check out the following photos for more. In addition keep your browser pointed to Racing Junk and watch for part 2 of the series: