Up To Standards
- Subject: New transmission technology
- Unit: Zeroshift manual transmission
- Essential Reading: Rebuilder, Diagnostician
- Author: Mike Weinberg, Rockland Standard Gear, Contributing Editor
The old saying “The only thing that is constant is change” has never been more true than in today’s automotive manufacturing. We have seen the bankruptcy of Chrysler and General Motors, which 20 years ago was unthinkable. China has arrived as a manufacturing giant for all types of products and, with a billion plus people with rising income levels, is poised to become the largest new-car market on the globe. India and Brazil have leaped ahead economically and will become players in this market.
Technology is developing at a pace so rapid it is hard to keep up with. The need for more fuel- and emissions-efficient vehicles is leading that development, as well as the huge enhancement of vehicle electronics. All of this puts our industry in a position of constant learning and adaptation if we are to stay in business and grow.
The development of new and different transmissions will be unbelievable in the next decade, and the only way to survive is to identify and learn this new technology. The conventional torque-converter-driven automatic transmission that we have worked on for decades is about to disappear in new-vehicle production. We now have five-, six- and seven-speed torque-converter-driven automatics and varieties of “hybrid” automatics in the never-ending march to better fuel economy and lower emissions.
The environmental crowd is touting true emission-free vehicles powered by electricity as the answer. I doubt that this is any more than a passing phase, as these vehicles will never be economically viable. Even with improved batteries, the concept is basically unworkable for many reasons. The first is limited range for the average traveler, and the second is the laws of thermodynamics. Is it more economical to get rid of a fossil-fuel engine in the vehicle but place an increased demand on utility power plants that are fueled by either nuclear, coal, petroleum or natural gas? You still have the demand for fossil fuel to charge the batteries, only we have changed it from the vehicle to the utility provider. When people find out the cost of replacing batteries, and the expense of a brake job on a vehicle with regenerative braking, the bloom will be off the rose.
Advances in gas- and diesel-engine technology are creating vehicles that are much more fuel efficient at lower costs. Further into that equation, it is natural to have transmission technology advance to create transmissions that will get 15%-20% better fuel efficiency at a lower cost. The first thing to go will be the good old torque converter. The new technology eliminates the built-in 10% slippage in an unlocked converter and gets rid of 25-plus pounds from the crankshaft.
The manual transmission was always more fuel efficient than a torque-converter-driven automatic, except for the skill level of the driver. The conventional manual transmission shifts at closed throttle; the automatic shifts at open throttle, reducing the emissions curve. If you take the driver out of the equation, it is much simpler to calibrate the emissions, which is the goal of the government. How about an “automatic” manual that uses a clutch but has no clutch pedal and uses computer control to shift without the driver input while balancing emissions and fuel economy electronically? That technology is here now, and more is coming. Our job is to learn how to live with it and to make it an income source.
The names of the different transmissions may be unfamiliar and need to be learned. They all have a common background, which is a gear-driven transmission without a torque converter. The planetary transmission with a fluid coupling will slowly disappear as the advantages of these new units are perfected. Less weight, lower cost of manufacture, lower emissions and better fuel economy will make this happen.
The first step in the development was the “manumatic” transmission, which still used a torque converter but allowed the driver to shift automatically or by using a different gate on the shift lever or “paddle shifters” to manually operate the unit. These have been around for a long time and have been known by many trade names: Acura, Sequential Sportshift; Alfa Romeo, Sportronic and Q-Tronic; Aston Martin, Touchtronic; BMW, Steptronic; Chevrolet, Tapshift; Dodge, Jeep and Chrysler, Autostick; Ford, Selectshift; Honda, iShift, S-matic, MultiMatic and Sportshift; Hyundai, Shiftronic and HI VEC H Matic; Infinity, Manual Shift Mode; Jaguar, Bosch Mechatronic; Kia, Sportmatic; Land Rover, Command shift; Lexus, E-Shift; Mazda, ActiveMatic; Mercedes Benz, Touch Shift; Mitsubishi-Sportronic, tiptronic, Allshift, Nissan- Xtronic, Porsche, Tiptronic & Tiptronic-s; Saab, Sentromic; Saturn, Tapshift; Subaru, Sportshift; Smart, Softip; Toyota, ECT & Multimode manual transmission; Volkswagen, Tiptronic; Volvo, Geartronic.
The next developmental step is the semi-automatic transmission, which is also called the electrohydraulic manual transmission. This design uses a manual clutch that can be either a wet or dry clutch, with no clutch pedal. When the driver selects a gear, electronics and hydraulics operate the clutch through a computer-controlled program without driver input. The computer also will control the throttle to match revolutions on downshifts.
These units can have an automatic position in which the unit shifts at desired engine-speed levels through computer control and have a manual mode in which the driver can go through the gears as if it were a manual unit.
BMW used a system called SMG (sequential manual gearbox) on the E36 M3 and then had an SMG-II on the E46 M3. This unit has both automatic and manual shift modes. The transmission computer uses multiple programs with six levels to control the upshift and downshift speeds in the manual mode and five settings to control the automatic function. This is a true sequential unit in which the driver must go through each gear to get to the next, with no “H” pattern. The one downside to sequential units is if you lose one gear you cannot drive around it. Volkswagen created a sequential transmission, E Gear, for the Lamborghini Gallardo and then introduced the same gearbox into the Audi R8, calling it R tronic.
Going forward we have the dual-clutch transmission (DCT). This design uses two clutches and two input shafts. The clutches can be wet or dry type. The input shaft is hollow with a second input shaft inside of the first, each driven by a different clutch. One input shaft drives the odd-numbered gears (1, 3, 5) and the other input shaft drives the even-numbered gears (2, 4, 6). Gears can be preselected by the computer so that upshifts and downshifts occur in milliseconds, very smoothly.
This technology was first introduced in the 2003 VW Golf MK4 R32. This appears to be the unit with the broadest usage, and most future development investment is going there. BorgWarner has made a very large investment in this technology and has partners in many countries for development and production. Other manufacturers are hard at work developing these designs, including Fiat Powertrain Technologies, Getrag, Graziano, LuK (Schaeffler Group), Ricardo and ZF. You will find DCTs in BMW, Chrysler, Fiat, Ford, GM, Honda, Hyundai, McLaren, Mercedes Benz, Mitsubishi Fuso trucks and buses, Nissan, Peugeot-Citroen, Porsche, Renault, Volkswagen and Lotus.
Although the DCTs are a great improvement in fuel and emissions economy and shift very quickly, another advance that will one day be incorporated into the units eliminates the typical synchronization system. A British firm called Zeroshift has devised a groundbreaking new design to synchronize shift speeds without the typical synchronizer (blocking) ring. This system is seamless and shifts without having to change throttle position.
A Mustang equipped with a Zeroshift gear train gained five car lengths on a similar Mustang equipped with a present-day manual transmission from a dead stop to 60 mph. The shifts are so smooth that there are no steps on the torque curve. Zeroshift is partnering with other transmission and car manufacturers to incorporate this technology down the road. The company also has developed an eight-speed manual transmission for front-wheel-drive cars that feels like a CVT but has much greater torque capacity in a lighter, compact package.
The Boy Scouts weren’t wrong. “Be Prepared” is a good way to live your life. This technology is here, and we need to become familiar and experienced with it. There are other questions that need to be addressed, and we will learn more as this drama unfolds. Will the manufacturers make these parts available to us, or will this be a “captive” item? Will these units be rebuildable or sold only as complete assemblies, making the repair facility into a diagnostic and “swap” shop? In the past we always overcame the roadblocks to parts supply thrown into our path, and I am sure we will figure out our place in this area. The key to solving the problems of the future will be to embrace the technology and become expert in it.
Two drive rings with alternating faces share a common hub and allow drive in one or the other direction; one ring takes up drive, the other eliminates the backlash that is common in dog-shift transmissions. When conducting a Zeroshift, the unloaded ring is moved with considerably less force than that of existing transmissions. Engine synchronization is conditioned by a control system to ensure a seamless torque transition.