Differences in C4 and C6 Transmissions
The Ford Motor Company manufactured the C4 and C6 three-speed automatic transmissions. These two automatics were very similar, but the C4 transmitted power for compact and mid-size passenger cars with six-cylinder for small-block V-8 engines. The C6 was essentially a heavy-duty version of the C4 used in trucks and passengers cars equipped with big-block V-8s and some small blocks. Both transmissions used a Simpson planetary gear set.
Other People Are Reading
-
Background
-
The C4 and C6 automatics were simply designed three-speed transmissions derived from Ford’s original FMX/Cruise-O-Matic/Merc-O-Matic transmissions that debuted in 1951. Although Ford was a latecomer to producing automatics, the automaker developed the universal gear selection pattern of P-R-N-D-L. The pattern is now the standard for all automatics because it places neutral between “Drive” and “Reverse” to reduce the potential of damaging the transmission by accidentally shifting from “Drive” into “Reverse.” Ford launched the C4 in 1964, hence the number “4,” and the C6 in 1966. Ford replaced the C4 in 1983 with the C5, which was a stronger version of the C-4 with a torque converter lock-up clutch. The C6 remained in production until 1996 when the Automatic Overdrive, or AOD, transmission replaced it.
C4
-
The C4 was lighter and more durable than the original Ford-O-Matic versions of the 1950s. In 2011, it remained a favorite for performance and restoration enthusiasts with Fords equipped with small-block V-8s. The hydraulically control rear-wheel drive C4 featured an aluminum case with a separate bell housing. Model year 1964 versions had a five-bolt bell housing, and the 1965 and later C4s had a six-bolt bell house. Some leftover five-bolt versions found their way onto some 1965 Fords. The C4’s gear ratios were 2.46-to-1 for first gear, 1.4-to-1 for second, direct drive 1.00-to-1 for third and 2.18-to-1 for reverse.
-
C4 Applications
-
Ford installed the C4 on the Ford Fairlane, Galaxie, Falcon, LTD II, Ranger, Thunderbird, Mustang, Fairmont and the Mercury Cougar. Most Fords equipped with the 200-cubic-inch inline six-cylinder engine received the C4 as an optional automatic.
C6
-
The C6 and the C4 shared the same gear ratios. Ford designed the C6 to fit into any car or truck equipped with the C4. The C6 differed from the C4 because it was quieter and shifted more smoothly. It also had a torque capacity that was great enough to accommodate future Ford engines with greater horsepower and torque output. The C6 also employed a Borg-Warner flexible shift band to improve shifting and durability, which was a first for any automatic transmission. Unlike the C4’s bell housing, which had a two-piece casting, the C6’s bell housing had a single piece casting.
C6 Applications
-
The C6 matched Ford cars and trucks equipped with the small-block 351 Windsor, 351 Cleveland V-8s and 390, the big-block 400-, 428- and 429-cubic-inch V-8s, and diesel engines. The 1970 1/2 Ford Falcons equipped with performance V-8s received the C6. Other vehicles equipped with the C6 included the Ford F-Series pickup, Bronco sport utility vehicle, Fairlane, Galaxie, LTD, Torino, Thunderbird, Lincoln, and the Mercury Comet, Cougar, Meteor, Montego and Monterey.
-
