The early Mustang has such a large following that it is sometimes forgotten that the car from day one has had a rich performance heritage. Besides the ever popular and dependable small and big block engines that were installed in early Mustangs, the transmission choices that Ford decided to back up the engines actually made the cars perform to their highest potential. Ford equipped the early Mustang with four different 4-speed gearboxes, The Dagenham, the Borg-Warner T-10, the Ford-built Toploader and the Warner SR4, which was used in the Mustang II. The English-built Dagenham was only installed behind the six-cylinder equipped cars. Since this article is about V8 equipped Mustangs, this transmission will not be discussed here.
The Borg-Warner 4-speed, which was built from 1957-77, has been offered in a variety of ratios and models over that twenty year production. Six design variants can be recognized and features synchronization on all forward gears. It also features a spur sliding gear in the tailhousing extension that engages the rear of a two-step reverse idler to provide reverse. The case uses a 9-bolt side cover that also helps in external identification. Only the 1965 and 1966 Mustangs used the early design Borg-Warner transmission.
The Ford T & C (Transmission and Chassis Division) Toploader transmission was primarily developed due to the fact that the Borg-Warner transmission was not stout enough to stand up to the rigors of racing, especially with the new 427 engine being developed for the Ford racing program. What the Ford engineers came up with is undoubtably one of the
strongest and most durable transmissions ever built. The primary contributor to the transmission’s strength is the transmissions case strength, due to the “top loading” of the gear set. Almost of Mustangs’ high performance engine applications used the Toploader transmission. The lower horsepower 260/289 engine applications used the Borg-Warner box.
The Warner SR4 was a top loaded transmission with a single-rail shift mechanism mounted on the tailhousing. It was synchronized on all forward gears with a sliding gear reverse incorporated into the 1st/2nd gear synchronizer clutch. It used a die-cast aluminum maincase that used casting numbers that began with ” 13-32-065-9xx”. It was used all four years (1974-77) in the Mustang II.
Borg-Warner Transmission Specifics
All early 1965 Mustangs used a 25-spline output yoke, used in both the Borg-Warner T-10 and Toploader applications. All later Mustangs in 1965 changed over to a more durable 28-spline yoke. A course 10-spline imput was used on the T-10. The standard length imput shaft was 8 1/2 inches long and was used on all engines except the 427. The 427 imput shaft is 8 15/16 inches long and seems to be quite rare today. Most of the Mustang Borg-Warner transmission used a cast iron maincase and tailhousing for greater strength, although the Shelby equipped cars used an all-aluminum unit for the obvious weight savings over it’s cast iron sibling. The early Mustang T-10 transmission used either a 2.64:1 or 2.74:1 first gear ratio that used the 8610 alloy gear set. Borg-Warner also produced a special set of 9310 alloy gear sets for their early T-10 and Super T-10 transmissions. These gear sets were designed for extreme racing conditions and were used as standard equipment in some of the 1963-early 1964 big block full size cars with the 352/390/406/427 engines. By the 1967 model year, the Borg-Warner 4-speed had been totally replaced by the Toploader transmission in Mustangs. It would be the 1974 model year before Borg-Warner would again build a transmission for the Mustang, the Warner SR-4, which was installed in the Mustang II.
Ford Toploader Transmission Specifics
As stated above, the Toploader transmission began replacing the T-10 in Mustangs in 1965, and remained in production until 1973. In fact, the Toploader was re-introduced as an overdrive tranny that were being built by Tremac in Mexico.These OD transmissions are basically the same 4-speed Toploader, and the new gears will drop into many older Toploader cases. The early 1965 Toploaders used a 25-spline output yoke, while the later version went to a more durable 28-spline output yoke. Toploaders produced from 1964 through mid-year 1965 have a 1 1/16 inch diameter (25-spline) imput shaft while the later 28-spline imput shaft maintained the same diameter. There was also a heavy duty 427/428/429 close ratio Toploader that was used in some high performance applications that used a 1 3/8 inch 10-spline imput shaft with a 31-spline output shaft. There were several tailhousings that were used for different applications. The Toploader used either a 2.32:1 or a 2.78:1 first gear ratio in early Mustangs up through 1971.
Early Mustang Transmission Application Chart
|
Model Year |
Engine
|
Transmission |
First Gear Ratio |
Gear Ratio Spread |
|
|
|
|
|
|
|
1965 Early |
289 |
Warner T-10 |
2.74:1 |
2.74/2.04/1.50/1.00 |
|
|
|
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1965 Late |
289 |
Warner T-10 |
2.74:1 |
2.74/2.04/1.50/1.00 |
|
|
|
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1966 |
289 |
Warner T-10 |
2.74:1 |
2.74/2.10/1.60/1.00 |
|
|
|
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1967 |
289 |
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1968-73 |
302 |
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1969-73 |
351 |
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1967-69 |
390 |
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
|
|
Ford Toploader |
2.78:1 |
2.78/1.93/1.36/1.00 |
|
1968 |
427 |
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
1968-71 |
428,429 |
Ford Toploader |
2.32:1 |
2.32/1.69/1.29/1.00 |
|
1974-77 |
302 |
Warner SR4 |
2.64:1 |
2.64/1.89/1.34/1.00 |
