Seven-post shaker rigs are all the rage in NASCAR racing these days. The rigs cost about $3-million to install at a shop, or cost many thousands of dollars to rent. 
Not long ago, top race teams had shops that featured good lighting, professional sets of tools, a chassis jig, an engine room, and, if really well-equipped, a dyno to check horsepower. If you happened to be Dave Marcis, well, he had a good set of tools, good lights, and several great pairs of wingtip shoes.
First, let’s touch on the dyno, which is a fair correlation to the shaker rig development. Officially called dynamometers, today’s dyno is a highly technical machine that allows an engine to be attached, started and allowed to run for however many hours at whatever RPM ranges desired. The corresponding information given is priceless, and it’s all printed for ease of comparing how much power the engine produces, and how modifications influence power and torque.
Yet, back in the mid-’80s, I sat down for a lengthy discussion with Jere Stahl at his business in York, Pa. Stahl is known for his drag racing championships, dyno tuning, cam profiles and especially his header construction business. (He also drove a sprint car a short time at Williams Grove Speedway for you history buffs.) If you weren’t running Stahl Headers back then, they say you were missing out on a few extra horses. To this day, Stahl still produces some of the best exhaust tubes you can buy.
As I looked at and talked to Jere about his state of the art dyno, he quickly changed “gears” about what meets the eye isn’t necessarily so, especially as I was referring to “state of the art.”
Specifically, although Stahl indeed had a great dyno room, he told a story about Robert Yates I’ll never forget, explaining in detail how Yates’ initial “state of the art” dyno preceded many of the big-name teams in usage and results.   
Surprised I was when Stahl explained that Yates’s initial “dyno” was nothing more than an airplane propeller that Robert had attached to a rear-end housing and then to an engine. This “Yates dyno” allowed Robert to gauge how much force the engine was producing via the propeller’s wind speed and pitch.
When contacted recently, Yates quickly remembered the dyno and confirmed Stahl’s story.
“Yes, Jere’s story is true. It was 1982, and we had just won the Daytona 500 with Bobby Allison. Then, we went to Rockingham, and did lousy. On the way home after Rockingham, I’m in the airplane with Bobby Allison and I said, ‘how about if we put some propellers on a rear end housing and we’ll build a dyno (to test our engines)?’ In two or three days, we had this airplane prop dynamometer running, and to this day, it is actually one of the better dynos we’ve ever used.”
Yates, who began his racing career with Holman-Moody back in 1968, explains that his homemade dyno achieved a certain rpm with a distinct prop pitch, and it gave about four different prop pitches depending on the engine’s power.
“I remember I used Navaho props,” Yates continued. “One was a three blade and one was a four blade. It pulled the air in the center and pushed it out, and we used a stock rear end housing with a locker in it. I remember I had a digital tach on it, nothing fancy.”
Back to the shaker rigs. I remember initially the four-post shaker, which has been around for decades and used mostly in the manufacturing industry. Ford, GM, AMC and Chrysler used four-post shakers to test shock absorbers, springs and if the car would develop squeaks. Each tire had its own “shaker post” to sit on, which would move up and down and sideways to simulate road conditions.
Race teams, meanwhile, didn’t worry about rattles and squeaks yet were intrigued with the shaker theory. It all started when Adrian Reynard of Team Reynard in Indy Car and Formula One began to improve on a four-post rig.
Reynard figured that if more hydraulic posts were built into the four-post system, the teams could learn more about their race car. Today, the seven-post shaker provides complex suspension information as if the race car were actually on the track. 
Thus, if you want to win, you’ll either own a shaker or be willing to rent time on Reynard’s ARC-developed seven-post shaker near Indianapolis or other “rentable” seven-post shakers, like the one at Ohlins USA in Hendersonville, N.C.
Some say “monkey see, monkey do,” but in this age of NASCAR and corporate sponsors, it’s now “money see, money do.”