Model A & B

Ford Garage

F-150 TOD Transmission Conversion

Tremec T170FT RTS


OEM Application: 1984 - 1987 Ford F-150
Ford Type: Four-Speed Manual TOD
Top Shift Overdrive
Manufacturer: Tremec
Tremec Type: T170FT RTS
Remote Tower Shift
Case Material: Aluminum alloy
Fully Synchronized: All forward gears
are helical type
in constant mesh
Lubricant: 3.5 US Pints
1.7 Liters
SAE 80W
D8DZ-19C547-A
(ESP-M2C83-C)
or equivalent
Notes: RTS Remote Tower Shift
TOD Top Shift Overdrive

The 1984-87 Ford F-150 top shift overdrive (TOD) is a four speed manual transmission with fourth gear as an overdrive. This transmission has been a popular choice for Model A and early V8 Ford overdrive conversions, and a number of people have made complete kits available to do the conversion swap.

This overdrive transmission was made for Ford by Tremec, and it is known as a T170FT RTS. It was produced in three different overdrive ratios for use in Ford pickup trucks.

Ford Parts and Service Division
Service Manual Description:

The top shift overdrive (TOD) is a four speed manual transmission with fourth gear as an overdrive.

It is fully synchronized. All forward gears are helical-type and are in constant mesh. The forward gear changes are accomplished with synchronizer sleeves.

Reverse is provided through a reverse idler sliding gear which slides on a reverse idler gear. The reverse idler gear is in constant mesh with the countershaft gear. In reverse the spur-type gear on the reverse idler sliding gear meshes with the gear on the 1-2 synchronizer hub.

The top mounted shifter operates shift rails in the transmission cover assembly. The first-second fork and the reverse fork are attached directly to these rails.

The third and overdrive shift fork is attached to a shift rail which is mounted in the transmission case.

Third and overdrive are shifted by means of a shift pawl mounted on a rail in the transmission cover, contacting an overdrive shift control link in the transmission. This shift control link contacts the shift fork in the transmission.

A shift interlock system located in the transmission cover prevents the engagement of more than one gear at a time.

The transmission case, cover, and extension housing are aluminum. The mating surfaces of these components are sealed with Anaerobic Sealer (Gasket Eliminator).

Tremec T170FT RTS TOD Specifications

The overdrive ratio of a Tremec RTS transmission can be identified by a sheet metal tag which is riveted to the front RH side of the case. This is useful when evaluating a loose transmission at a junk yard or swap meet.

The first three characters on the tag should be 'RTS', and be immediately followed by a two-character code as shown in Column 1 in the table below. The two-character code will identify the overdrive ratio as originally built.

Specification compilation courtesy of Al Berry
Transmission Codes % OD Gear Part Numbers and Tooth Counts
Tremec ID Tag Ford Code Ratios Main Drive Countershaft 1st 2nd 3rd 4th OD
RTS
AD, AE, AJ,
BJ, BP, BU,
BV, BZ, CS
B
(302 CID V8)
(300 CID I6)
27.6%
1st=3.2506
2nd=1.9213
3rd=1.0000
4th=0.7837
E0TZ-7017-B

21T
D0UZ-7113-A

32T-35T-23T-15T
D9BZ-7A029-B

32T
E0TZ-7102-A

29T
Direct

E0TZ-B340-B

18T
RTS
AA, AF, AH,
AK, BN, BR,
BW
C
(351 CID V8)
37.9%
1st=3.0061
2nd=1.7766
3rd=1.0000
4th=0.7246
E0TZ-7017-C

22T
E0TZ-7113-B

31T-35T-23T-15T
D9BZ-7A029-B

32T
E0TZ-7102-A

29T
Direct

E0TZ-B340-B

18T
RTS
AB, AC, AG,
BM, BS, BT,
BY
D
(300 CID I6)
41.1%
1st=3.2506
2nd=1.9213
3rd=1.0000
4th=0.7087
E0TZ-7017-B

21T
E0TZ-7113-A

32T-43T-23T-15T
D9BZ-7A029-B

32T
E0TZ-7102-A

29T
Direct

E0TZ-B340-A

20T

For reference, the table above also shows the Ford part numbers and tooth counts of the various gears in each transmission.

The transmission overdrive ratio can also be identified by the Ford transmission code printed at the bottom center of the VIN/GVWR/Tire Information label (applied inside the drivers door opening) of a Ford F-150 pickup truck.

1987 F-150 2WD Regular Cab, Six Cylinder with Tremec 27.6% OD Code B

If the label identifies the transmission as a 'B', 'C', or 'D', it will be a Tremec RTS transmission of 27.6%, 37.9%, or 41.1% overdrive, respectively. This information is illustrated in Columns 2 and 3 in the table above.


Installation Considerations

It is recommended to use the Model AA four-speed transmission clutch (bell) housing rather than the Model A three-speed transmission clutch housing as the basis for the conversion.

The 1929-31 Model AA truck clutch housing is shorter fore-aft than a Model A three-speed housing and requires less (if any) modification to the frame center crossmember for clearance to the transmission. It does however require fabrication of brake and clutch pedal mounting provisions.

Modification to the Tremec transmission involves:

The Model AA throwout bearing hub, clutch release shaft, arm, and pressure plate are used. A 1949 Ford clutch disc is sometimes used.

Alternatively, a 9 inch diaphragm pressure plate and matching clutch driven disc for a 1983-88 Ford Thunderbird or 1984-86 Mustang SVO 2.3L turbocharged four cylinder can be mounted to a lightened and faced Model A or B flywheel by drilling and tapping six additional holes. The Thunderbird's 9 inch clutch disc hub has the same 1-1/16 inch x 10 spline as the Tremec RTS input shaft.

The shift lever opening position in the floorboard and mat is slightly affected. A provision for mounting the emergency brake handle to the transmission must also be fabricated.

The system conversion based on the Model AA clutch housing also requires the shortening of the Model A torque tube, drive shaft, and rear radius rods approximately 1-1/2 inches.

Drivability Recommendations

Overdrives are a Physics problem, not just a Mathematics problem!

Increased Torque and HP at the right RPM are required to go faster, not just mechanical overdrive gear ratios!

Any vehicle would benefit from the added engine torque and horsepower of a 5.5 or greater compression ratio cylinder head and a Stipe IB330 camshaft.

Essentially, top vehicle speed will occur when aerodynamic drag equals power output.
Proper gearing keeps the engine RPM in the useful range between "just below max torque" to “around max power” for all road speeds.

Model A Torque and Horsepower Curves

Highlighted below are the relative drivability improvements of various transmission gearings compared to stock Model A gearing. Assumptions are based on stock tire sizes and engine configuration.

Proper gearing also avoids lugging the engine at low RPMs and destroying Babbitt bearings!
Lugging occurs when the engine is operated under load and below peak torque for any length of time.

Also, don't forget to improve your brakes!

Drivability Considerations

Green-shaded transmissions in Column 1 are preferred for improved drivability over that of the stock Model A
Transmission Rev 1st 2nd 3rd 4th % OD Notes, Drivability Recommendation
Stock Model A
1928-31

(200 CID I4)
3.745:1 3.12:1 1.85:1 1:1 ~ ~
  • 4.11 rear axle in a heavy-medium weight car and/or hill terrain.
  • 3.78 rear axle in a medium-light weight car.
  • 3.54 rear axle in a light weight car and/or flat terrain.
Stock Model B
1932-34

(200 CID I4)
3.383:1 2.820:1 1.604:1 1:1 ~ ~
  • 4.11 rear axle in a heavy-medium weight car and/or hill terrain.
  • 3.78 rear axle in a medium-light weight car.
The taller 1st and 2nd gear ratios of the Model B (and early V8) transmissions improves the drivability and shift points greatly compared to that of the Model A transmission.
Mitchell Synchro
15% 1st

(200 CID I4)
2.71:1 1.85:1 1:1 ~ ~
  • 4.11 rear axle in a heavy-medium weight car and/or hill terrain.
  • 3.78 rear axle in a medium-light weight car.
Taller 1st gear ratio is similar to Model B.
Mitchell Synchro
15% 1st & 2nd

(200 CID I4)
2.71:1 1.61:1 1:1 ~ ~
  • 4.11 rear axle in a heavy-medium weight car and/or hill terrain.
  • 3.78 rear axle in a medium-light weight car.
Taller 1st and 2nd gear ratios are similar to Model B.
1931 Ruckstell
Dual High

(200 CID I4)
2.50:1 1.00:1 0.80:1 ~ 25%
  • 4.11 rear axle in a heavy-medium weight car and/or hill terrain.
  • 3.78 rear axle in a medium-light weight car.
1st gear ratio is even taller than Model B.
2nd gear ratio is direct, 1:1.
3rd gear ratio is a 25% overdrive, not 1:1.
Increased engine Torque and HP are highly recommended.
F-150 TOD
Code B
Tremec RTS

(302 CID V8)
(300 I6)
3.25:1 3.25:1 1.92:1 1:1 0.78:1 27.6%
  • 4.11 rear axle in a heavy-medium weight car and/or hill terrain.
  • 3.78 rear axle in a medium-light weight car.
  • 3.54 rear axle in a light weight car and/or flat terrain.
1st and 2nd gear ratios are similar to stock Model A.
Increased engine Torque and HP are highly recommended.
F-150 TOD
Code C
Tremec RTS

(351 CID V8)
3.01:1 3.01:1 1.78:1 1:1 0.72:1 37.9%
  • 4.11 rear axle in a medium-light weight car with added power.
  • 3.78 rear axle in a light weight car with added power and/or flat terrain.
Slightly taller 1st and 2nd gear ratios compared to Model A.
Increased engine Torque and HP are required.
F-150 TOD
Code D
Tremec RTS

(300 CID I6)
3.25:1 3.25:1 1.92:1 1:1 0.71:1 41.1%
  • 4.11 rear axle in a light weight car and/or flat terrain.
1st and 2nd gear ratios are similar to stock Model A.
Increased engine Torque and HP are required.

More related information on Ford Garage:

  1. For more Model A & B related information, use the Site Search box at the top or bottom of this page.
  2. Model A Ruckstell Dual High Transmission
  3. Model A Mitchell Synchronized Transmission
  4. Model A & B Rear Axle Gear Ratios
  5. Model AA Four-Speed Transmission Clutch Housing

December 2017