Nuts, I’m Confused
Eight Is Enough
Q I just read the Drivelines section of the Aug. ’12 edition of your magazine and noted in the “Ram 1500 All-New For ’13” item that “Chrysler is aiming for best-in-class fuel economy for its light-duty Ram . . . engines will be available with an eight-speed automatic transmission.”
It seems like eight speeds for an auto tranny is just too many. The environmental waste associated with making all those extra gears would more than negate the ever-so-slight fuel savings. I really feel there’s no excuse to have more than five speeds for an automatic or manual transmission. I mean, come on, we’re not talking commercial big rigs here. All these speeds fix one problem but create another.
Mike M.
Alameda, CA
A I ran your question by the experts at Ram Truck and received this response:
The Ram Torqueflite 8 transmission (8HP45) offers eight gear ratios in a transmission package that has similar to lower weight and size and actually fewer parts than most competitive five- or six-speed transmissions.
This is enabled by modern simulation programs that can identify innovative geartrain designs that give the desired ratios and efficiency.
The First gear ratio of 4.71 allows more efficient torque multiplication versus leaving the torque converter open longer during launches, while on the other end a 0.67 Eighth gear ratio allows low-rpm cruising at highway speeds.
The small and even steps between these eight ratios allow for imperceptible, nonbusy shifting even with eight gears.
The fuel economy gains from the transmission are achieved not only by having the eight evenly spaced ratios maximizing the use of the engine torque curve, but also by having a best-in-class transmission efficiency due to its unique design.
Unlike the other six- and eight-speeds on the market, the TorqueFlite has only five clutch packs and only two of those are open in each gear, which greatly reduces drag.
James Adams
Chief Engineer RWD Automatic
Transmission, Ram Truck
I recently drove the ’13 Ram 1500 with the eight-speed transmission (“First Drive: Ram 1500 Refresh,” Dec. ’12). Not only do I think it’s going to work out great, but I really hope it finds its way into the Jeep Wrangler behind the Pentastar V-6.
The goal of a multispeed transmission is for efficiency. It keeps the engine in its optimal rpm range almost all the time. The multiple gear options keep the engine from revving or lugging, thus improving fuel economy. The low First gear of the transmission is perfect for off-road use, and it helps get heavy loads moving from a stop. The multiple overdrive gears allow the engine to rev calmly at highway speeds when less power is needed.
Imagine riding a bicycle. A single-speed bike is great when you’re a kid with a lot of energy, but as you get older you realize a multispeed bike allows you to get moving from a stop, climb hills, and speed along open road or trail without overworking your legs and lungs.
Mike, you bring up a good point about the value of complexity. The fact is the manufacturers of the world are constantly striving for better and better products, and oftentimes this means more complexity. For example this eight-speed transmission is very neat and works well but it is completely computer controlled. There is no mechanical shifter. Of course, most vehicles have been using drive-by-wire throttles for years, so a drive-by-wire transmission isn’t really that unusual. Plus, these controls allow the transmission to shift smoothly and hold the best gear for the vehicle at any given situation, but still allow driver override if need be. In addition, the transmission has intelligence to learn from output speeds and wheel speed sensors what the axle gear ratio is. This allows it to compensate and adjust shift patterns accordingly, which is perfect for guys like us who like to change axle gearing when going to larger tires.
It is human nature to have a fondness for older technology, but though a carburetor and three-speed manual transmission worked great in the 1940s to the 1970s, the computer age is not going away. The OEMs are constantly striving for the next best thing, be it eight-speed transmissions, small engines with turbos, or direct-injection gasoline engine technology. Luckily, there are still plenty of off-road enthusiasts who work at these OEMs and they can apply technology to make their trucks work great off-road as well as on-road. And never fret—there are plenty of old trucks out there with fewer gears and less high-tech powertrains you can rebuild to be your perfect 4x4.
Since your question seems relevant to many readers I’m picking you as this month’s Nuts, I’m Confused winner, and I will send you an Ultimate Adventure 2012 shirt.
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