60 - 63 Transmission and differential notes.

It is interesting that the first gear in the two-speed Fordomatic starts at 1.75, which is the same ratio as second gear on the manual three-speed. The lugging effect is minimized though, because of the torque multiplier that the automatic provides on initial take-off. It is also interesting how the 1.75 first gear on the Fordomatic almost splits the difference between the 2.46 first and 1.46 second gears on a C-4 automatic. The 3.2 differential gears make the car run at about 3000 rpm at 60 mph. That means the comfortable highway cruising speed would be 55 mph, which is exactly where they set the 1974 national highway speed limit. It sort of explains why that 55 mph limit was selected back then. The gearing ratios indicate that the design engineers in the early 1960's Falcons were more concerned with low speed performance than highway cruising. They probably figured that most driving would be off the interstate and that it was more important to be able to merge into city traffic and be able to dart across an intersection that to cruise at 75 mph. Most of the other cars on the interstate in 1963 would have been 1950's vintage and they were slow too, for the most part. A 1959 Ford V-8 only produced 100 horsepower. It is also interesting that there were two different 4-speed manual transmissions that were used. One for the 170 and another for the 260. The higher torque from the 260 allowed the use of a higher bottom gear than was used for the 170. The maximum torque on the 260 is available at 2200 rpm, which translates to 42 mph for an automatic and is a mid-range speed. That lets you get the advantage of the low gears on take off and then get the maximum engine torque when you need it as you shift into the Fordomatic second gear. Very nice.

I excerpted the following info from "Falcon Performance Portfolio 1960 - 1970" and "1963 - 63 1/2 Illustrated Pricing & Specifications Manual".

* * * * * *

Fordomatic Transmission gear ratios: 4.20*, 1.75, 1 (1960-1962)
Fordomatic Transmission gear ratios: 4.47*, 1.82, 1 (1963)
3-speed manual transmission: 3.29, 1.75, 1
4-speed manual for 170 Six: 3.16, 2.21, 1.41, 1
Sprint 4-speed manual for 260 V-8: 2.73, 2.04, 1.51, 1

*1st and torque converter. The Fordomatic has a torque converter multiplication of 2.40 when the turbine is stalled providing a maximum overall reduction of 4.2 when the throttle is hit hard. Stall is an operating condition where the turbine is stationary and the engine throttle is wide open, making the rotational speed of the impeller as high as possible. Stall can be approximated to when a vehicle moves from rest. Maximum torque multiplication occurs instantaneously as the vehicle begins to move.


Attachment 2703

Performance
1960 144 2375 lbs with a 3.10:1 differential
Top speed = 87 mph.
3-speed: 0 – 60 mph in 19 and 17.7 seconds and 20.8 for the ¼ mile@ 64 mph.
Fordomatic: 0 – 60 mph in 25.1 seconds and 23.9 for the ¼ mile@ 59 mph.

1961 170
3-speed: 0 – 60 mph in 14.3 seconds with a 3.20:1 differential.
Fordomatic: 0 – 60 mph in 15.2 seconds with a 3.50:1 differential.

1963 170 Convertible 2,475 lbs
4-speed: 0 – 60 mph in 19.6 seconds and 22.7 for the ¼ mile@ 64 mph with a 3.50:1 differential.
Fordomatic: 0 – 60 mph in 21.6 seconds and 22.2 for the ¼ mile@ 61 mph with a 3.20:1 diff.
1st (1.82 x 2.4 = 4.37), 1st 1.82, 2nd 1.00

1963 ½ Hardtop (2980 lbs) and Convertible (3081 lbs) 260 V-8
Top speed: 105 mph @ 5000 rpm.
4-speed: 0 – 60 mph in 9.5/12.1 seconds and 18.0 for the ¼ mile@ 73 mph with a 3.25:1 differential.

A car with a 13” wheel 175/80 tires is calculated to run 60 mph at 3037 rpm with a 3.25:1 differential. Side walls = 0.8*175 = 140 mm = 5.5 inches. Diameter of wheel + tire = 24 inches.