Early Bronco Ford C4 Automatic Transmission

Early Bronco C4 Automatic Transmission

From 1973 to 1977, the early Bronco was offered with the option of a column shift, Ford C4 3-speed automatic transmission. Prior to 1973, all early Broncos were built with 3-speed manual transmissions. The Ford C4 automatic was used in many applications and is a popular choice for classic Fords. There are many aftermarket parts available to beef up the strength and performance of this reliable little automatic transmission, making it a favorite from rock racers to daily drivers.

The early Bronco C4 automatic was a pan-fill transmission. The pan-fill C4 automatic receives transmission fluid through a dip stick tube which goes into the right side of the transmission pan. During the same time period, Ford also used a case-fill style of the C4 automatic, but this style was never used in the Ford Bronco. In a case-fill automatic transmission, fluid enters the transmission through a dip stick tube going into the case of the transmission.

The flexplate in early Bronco automatic transmissions was a 164-tooth flexplate with a 28-ounce imbalance. Case-fill Ford C4's were available with 157 and 164-tooth flexplates. The bellhousing and torque converter used on the Ford C4 was specific to the flexplate being used. It's important when sourcing a C4 for your early Bronco that you note this information.

Automatic Transmission Conversions

Typically, the Ford C4 automatic is used on early Broncos in conjunction with either a stock Dana 20 transfer case or an Atlas 2 transfer case. The overall length of the C4 automatic in a 66-77 Ford Bronco varies a bit depending on which of these options you select. The C4 bellhousing measures approximately 6" OAL (overall length), and the body of the Ford C4 auto transmission measures about 11". The Dana 20 transfer case is around 11.25" in length and the corresponding adapter housing is 7.375" OAL. In contrast, an Atlas 2 transfer case is longer at 13.75" in length, but the C4 adapter for an Atlas 2 is just 3" long. This results in close to a 2" shorter assembly when using an Atlas 2 transfer case as opposed to the stock Dana 20.

Wild Horses supports the do-it-yourselfer by offering individual parts and adapters for your early Bronco automatic transmission swap. Please keep in mind many of these parts have been specifically fabricated to go with other parts we offer. It will be up to you to determine if these parts will suit your needs.

Early Broncos use what is called a "Flare Case" C4. As such the bellhousings we carry will be for this type of C4. This style will also go along with the 164 tooth flexplate and pan mounted dip stick/tube. The tranny to bellhousing bolt pattern will be different than the "Step Case" style C4. This style C4 uses a case mounted dip stick/tube and will have a 157 tooth flexplate. For further information and pictures describing these differences please check out this article written by Paul Pearson.

Some of the parts needed when converting from a manual transmission to a C4 automatic, include: Ford C4 Automatic Transmission with Bellhousing, Torque Converter, A/T Starter, A/T Transmission Cooler & Cooling Lines, Shifter (Floor Shift or Column Shift), A/T Transfer Case Input Shaft, Neutral Safety Switch & Wiring, A/T Pedal Assembly. *You may need a new carburetor to use the C4 Kick-Down.