Overdrive for Vintage Camaros
Installing a Gear Vendors Overdrive in a First-Gen F-Body
Story Larry Weiner - June 19, 2011 09:00 AM
We live in a day and age of rapidly escalating fuel costs, to say nothing of the constant outcry from environmentalists about the carbon footprint, global warming and air pollution caused by vehicles powered by internal combustion engines.
It’s no secret that the vintage and muscle cars are often held up as examples of what is damaging the environment. The ever-tightening emissions standards and mandatory smog testing of older vehicles clearly illustrates the direction where this is headed.
Most of the data used by government bureaucrats and environmentalists to blame our collector cars for harming the environment is flawed for a wide variety of reasons. Unlike regular daily drivers, the annual mileage of most classics is nominal, often no more than 500 to 1,000 miles per year. In addition, these vehicles receive a high degree of maintenance and are generally driven very carefully. Regardless of the efforts of influential organizations such as SEMA and Goodguys, it’s safe to say that the pressure on the collector car hobby is not going to ease up.
With that thought in mind, there is something we can do that will dramatically improve the performance of our vehicles while simultaneously further discrediting many of the arguments against them. A proven driveline component is readily available to significantly enhance fuel economy and reduce greenhouse gas emissions by 25 percent while increasing vehicle performance. It’s called an overdrive.
We take it for granted today in new vehicles, as most manufactured since the early 1980s have been equipped with transmissions that include an overdrive. The majority of classic cars and virtually none of the mighty muscle cars from the golden era were equipped with an overdrive. The result is that these vehicles, especially those equipped with high numerical final drive ratios, deliver marginal fuel economy because they operate at elevated engine rpm, especially when driven at highway speeds. Installing an overdrive is the practical solution to this problem and the good news is that it’s easy to do.
This story will illustrate how simple it is to make your vintage Chevy a modern highway cruiser thanks to a Gear Vendors overdrive. This is the most popular overdrive conversion for factory transmissions, with over 100 applications. The Gear Vendors unit is manufactured right here in the United States, just like your classic Chevy.
Our 1967 Camaro SS350 is equipped with its original Muncie M20 four-speed manual transmission and 12-bolt differential with a 3.73 gear set. Since fourth gear in the transmission is a 1:1 ratio, with the 3.73 gear, every time we reached 55 miles per hour, the Camaro felt like it was ready to be shifted to the next higher gear. The problem was that we were already in fourth, and there weren’t any more gears left.
Although the vehicle only weighs 2,940 pounds, which is light by today’s standards, the high gearing resulted in a busy engine and mediocre fuel economy. Here in Southern California, the 18 wheelers run faster than the double nickel in the slow lane. Because we like life in the fast lane, and certainly wanted better fuel economy, to say nothing of doing our part to help save the environment, we decided to install a Gear Vendors overdrive in the Camaro. Gear Vendors offers a 22 percent overdrive, turning our 3.73 gear into a 2.91 final drive. This lowered the rpm at 70 mph from 3,700 to 2,886, making our Camaro SS far more freeway friendly. Goodbye semi trailer trucks, hello fast lane.
Living life in the fast lane will not be limited to the freeway. While the Muncie M20 is a robust design and was a state-of-the-art transmission in the 1960s, today a four-speed is something of an anachronism. The Gear Vendors overdrive brings this legendary muscle car transmission into the 21st century. It not only provides the Camaro with an overdrive, but it also enables you to split the gears in the Muncie, and take full advantage of the benefits of both the transmission and the overdrive.
If you really want to maximize the versatility of the combination, get ready to shock your friends and competitors by starting in first gear like a conventional manual. Upshift using the overdrive to first over, a lightning shift that will make your vehicle act and sound just like an automatic. Then, leaving it in overdrive, shift normally to second and third. During the shift to fourth, press the button on the Gear Vendor shift knob and you’ll get the regular fourth gear ratio and then follow that up with fourth over by pressing the button again. The result is a fully functional six-speed transmission that retains the tactile feel and precision you expect from a Muncie, complemented by the advantages of the Gear Vendors overdrive.
Follow along with us as the master technicians at Gear Vendors install one of their under/overdrive units on the 1967 Camaro and turn it into a muscle car with a newfound ability to compress time and space while achieving fuel economy that will rival that of many small import cars.