Notably, the drop gears can be swapped with the transmission still in the car. “At Indy, my top speed was about 140 mph, around here my top speed is about 125 mph, and then out at Sonoma I geared for 117 mph. “Between Indianapolis Motor Speedway, running around here, and Sonoma Raceway, I have three different drop gears,” Prather explains. Flop those drop gears so they’re a 26/22, and now you’re multiplying the gear ratios by 1.182. Swap the drop gear to something like a 22/26, and the drop gear multiplies all of the internal gear ratios by 0.846 before spinning the output shaft. The EGMT comes equipped with a 24/24 drop gear – that means it offers a 1:1 ratio for the internal gears. For a guy running a Mazda, you have final drive options of 3.9, 4.1, 4.3, 4.4, and so on, with three drop-gears, you can come up with a ratio that was never made – that’s a big advantage.” “One of the things I always liked about the PBS is you have a drop gear in the back so that you can change the rear differential ratio to one that was never possible – that is a huge advantage. “This transmission has all of the advantages of the PBS, but with a modern twist,” says Jesse Prather of Jesse Prather Motorsports, who helped Mazda Motorsports and EMCO in the development of the EGMT transmission. Our old transmission didn’t come with drop gears, so our experience on this topic was limited. For example, like the older PBS, the EGMT is designed to use all five of its forward gears for racing, with drop gears in the back to allow for easy gearing changes. What’s in the boxĪt first glance, the EGMT 5-speed, dog-engagement transmission produced by EMCO Gears for Mazda Motorsports looked like everything we wanted, plus more. At the time, we daydreamed about fitting the Mazda Motorsports EGMT setup into our project RX-7, but with a price tag just shy of $10,000, it was out of our reach – or was it? Now facing a $4,000 bill to bring our current transmission back to life (and knowing our current setup may face a similar rebuild cost in another four years) we began to look deeper. Rewind about a year and Mazda Motorsports had just introduced a new line of parts for its aging-but-still-popular PBS dog-engagement transmission Mazda Motorsports was also finalizing its new EGMT dog-engagement transmission. Over the years, we’ve tried to find close gear ratios in a variety of transmissions (Miata gears in a stock RX-7 transmission, RX-8 transmission, syncro-based gears from companies like Quaife) but none of these options offered gearing splits as tight as we wanted – and, in most cases, they were using parts designed for street driving, not racing. Since the rotary engine produces all horsepower and virtually no torque, rotary-powered racecars seem to benefit greatly from very short gearing splits. The secret to speed is a transmission that best utilizes your engine’s power band – and can handle racing conditions. Consequently, while prepping for the 2018 SCCA National Championship Runoffs we discovered the transmission had been abused enough that we were facing a $4,000 repair bill – close to what we paid for the transmission itself. The used transmission did well in our project RX-7 from the moment it was installed, but because this setup is a mixture of race parts and street components, things break. Hewland offers a variety of gear ratios, and you get the speed benefits of shifting without the use of the clutch. This hybrid setup is used by numerous racers in the SCCA road racing community as, with some cajoling, the magic internals will fit in pretty much any rear-drive Mazda housing ranging from the RX-3 to the NC Miata, and does so relatively affordably. Unfortunately, the project’s funding petered out before we touched the transmission.įast-forward to December 2013 and we picked up a used transmission that had Hewland dog-engagement internal components in a stock RX-7 housing. Once everything was thoroughly mapped out, we rescued a 1990 Mazda RX-7 from the junkyard and began to thrash, ultimately building the car for SCCA’s E Production class for a hair over our modest budget. In 2011, when SportsCar magazine’s project RX-7 SCCA road racing car was just a glimmer in our eye, we built a glorious spreadsheet listing the budget of what we thought the build would cost.
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