The FEV cost teardown study (EPA/FEV 2010) had the following issues: (1) the baseline was not a four-speed automatic transmission but was a five-speed transmission, and (2) the six-speed transmission had a Ravigneaux gear set, whereas the five-speed transmission has three planetary gear sets, which is more complex than the Ravigneaux gear set. The three planetary gear sets require nine control elements (four disc clutches, three disc brakes, and two sprag clutches), whereas the six-speed transmission with the Ravigneaux gear set only requires six control elements (two disc clutches, three disc brakes and one sprag clutch). FEV recognized these issues by providing the following statement in their study:
In regard to the 5-speed automatic transmission, many of innovative ideas implemented into the 6-speed automatic could have been incorporated into a new 5-speed if it were to be redesigned. The most obvious NTA (New Technology Advances) would be adopting a similar Ravigneaux geartrain design, which could conceivably have the same financial benefit recognized by the 6-speed automatic.
This was an unusual teardown cost analysis since the five-speed transmission contained more hardware (i.e., approximately 150 more parts), and was generally more complex, than the six-speed transmission. As a result, the six-speed transmission established a zero-cost baseline from which an incremental cost for the five-speed was established. The majority of the incremental cost increase of the five-speed over the six-speed was associated with the two additional clutch packs, the need for a counter shaft assembly, and some additional gearing.
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