Model A & B

Ford Garage

F-150 TOD Transmission Conversion

Tremec T170FT RTS

Fifty-seven pages of detailed official Ford disassembly and reassembly photos, diagrams, and instructions

The 1984-87 Ford F-150 TOD Top (shift) OverDrive is a four speed manual transmission with fourth gear as an overdrive. (The SROD is a Side Rail (shift) OverDrive with a tail shaft shifter, not top shifter)

This top shift 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 F-150 (and some limited F-250) full-size light-duty 2WD and 4WD pickup trucks.

With its tower-located cane shifter, the RTS transmission has been a popular choice for Model A and early V8 Ford four-speed overdrive transmission conversions, and a number of people have made complete kits available to do the transmission swap and conversion.

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).
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)
Driven 80W-90 GL4
or equivalent
Notes: Case has no drain plug
TOD = Top shift OverDrive
RTS = Remote Tower Shift
According to the information published in the official Ford Parts and Service Division TOD and SROD Service Manual, the three different overdrive ratios produced in the Tremec T170FT RTS series transmissions are identified as 'B', 'C', and 'D'.

Code 'B' = 27.6% overdrive (302 V8, 300 I6)
Code 'C' = 37.9% overdrive (351 V8)
Code 'D' = 41.1% overdrive (300 I6)

These Ford code letters are utilized in Columns 2 and 3 in the Transmission Specifications table below to organize the part gearing information of the three different overdrive builds.


Tremec T170FT RTS (TOD) Identification

There is both a Ford part number and a Tremec part number cast into the LH side of the aluminum case. The first (1984) style case is marked RF-E4TR-7006-AA and C-2604877, and the second (1985+) style case is marked RF-E5TR-7006-AA and C-2605524.

You may also find a similar four-speed 'RTS style' non-Jeep-input, top shift aluminum case transmission, but without Ford casting numbers or logo, and having only a Tremec case number C-2605275.

These 'RTS clones' were made by Tremec, but are not marked 'RTS' on the steel tag. I believe they may have been non-Ford replacement F-150 transmissions supplied by Tremec to aftermarket transmission shops. Anybody know different?


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 Tremec tag should be 'RTS', and be immediately followed by a two-character alpha code as shown in the pic above, and in Column 1 in the table below. The two-character alpha code will identify the overdrive ratio as originally built by Tremec.

Beyond identifying the OD ratio, the two-character alpha code following the 'RTS' will identify the original transmission assembly as being for a 2WD or 4WD, and identify which speedometer drive gear it was originally equipped with.

Other than identifying the specific transmission OD ratio, the RTS two-character alpha code is unimportant in adapting the T170FT to the Model A or early V8 Ford.

The various other codes stamped on the Tremec tag identify the production date, the Ford service designation number, and the Tremec unit serial number.



Tremec T170FT RTS (TOD) Specifications

The Transmission Specifications table below shows the Ford and aftermarket part numbers and tooth counts of the various gears in each RTS transmission configuration.

Peach-shaded cells indicate parts which are still generally available new in the aftermarket.
Transmission Codes % OD Ford, Tremec, and Aftermarket Part Numbers and Tooth Counts
Tremec Codes
T170FT
Steel ID Tag
Alpha Codes
Ford TOD Service Manual
OD Ratio
Letter Code
Ratios Main Drive
Input Gear
8-7/8"
10 spline
308 bearing
(2 distinct)
Countershaft
Cluster Gear
(3 distinct)
(+1 RUG)
1st
Gear
(1 shared)
2nd
Gear
(1 shared)
3rd
Gear
Slider
4th OD
Gear
(2 distinct)
(+1 RUG)

RTS wide

AD, AE, AJ,
BJ, BP, BU,
BV*, BZ*, CS
*=obsoleted

B

(5.0L V8 /
302cid V8)
(4.9L L6 /
300cid L6)
27.6%

1st=3.2508
2nd=1.9213
3rd=1.0000
4th=0.7837
21T

D8UZ-7017-A
E0TZ-7017-B
2604484
T170-16F
T170-16N
32-35-23-15

D8UZ-7113-A
D0UZ-7113-A
2603740
T170-8C
32T

D9BZ-7A029-B
2604300
J8132389
WT170-12B
29T

E0TZ-7102-A
(2604232)
2605214
T170-21F
Direct 18T

E0TZ-7B340-B
2604242
T170-11J

RTS narrow

AA*, AF*, AH,
AK, BN, BR*,
BW
*=obsoleted

C

(5.8L V8 /
351cid V8)
37.9%

1st=3.0061
2nd=1.7767
3rd=1.0000
4th=0.7247
22T

D8UZ-7017-B
E0TZ-7017-C
2603806
T170-16G
T170-16P
31-35-23-15

E0TZ-7113-B
2603243
T170-8J
32T

D9BZ-7A029-B
2604300
J8132389
WT170-12B
29T

E0TZ-7102-A
(2604232)
2605214
T170-21F
Direct

18T

E0TZ-7B340-B
2604242
T170-11J

RTS wide

AB, AC, AG,
BM, BS, BT,
BY

D

(4.9L L6 /
300cid L6)
41.1%

1st=3.2508
2nd=1.9213
3rd=1.0000
4th=0.7087
21T

D8UZ-7017-A
E0TZ-7017-B
2604484
T170-16F
T170-16N
32-43-23-15

E0TZ-7113-A
2604234
T170-8H
32T

D9BZ-7A029-B
2604300
J8132389
WT170-12B
29T

E0TZ-7102-A
(2604232)
2605214
T170-21F
Direct

20T

E0TZ-7B340-A
2605212
T170-11H


Orion Iron T170F SMOD
Goldilocks Gearing
Taller 1-2 for Model A Ford
(never configured in an RTS)
27.0%

1st=3.0061
2nd=1.7767
3rd=1.0000
4th=0.7874
22T

D8UZ-7017-B
E0TZ-7017-C
2603806
T170-16G
T170-16P
31-34-23-15

1978-84
Iron SMOD RUG
D8UZ-7113-B
2603745
T170-8D
32T

D9BZ-7A029-B
2604300
J8132389
WT170-12B
29T

E0TZ-7102-A
(2604232)
2605214
T170-21F
Direct

19T*

1978-84
Iron SMOD RUG*
D8UZ-7B340-B
2603744
T170-11D


300 I6, 302 V8
wide ratio
Ford Iron T170F SMOD
RUG CL, CD?,
27.6%

1st=3.2508
2nd=1.9213
3rd=1.0000
4th=0.7837
21T

D8UZ-7017-A
E0TZ-7017-B
2604484
T170-16F
T170-16N
32-35-23-15

D8UZ-7113-A
D0UZ-7113-A
2603740
T170-8C
32T

D9BZ-7A029-B
2604300
J8132389
WT170-12B
29T

E0TZ-7102-A
(2604232)
2605214
T170-21F
Direct 18T

E0TZ-7B340-B
2604242
T170-11J


351 V8
wide ratio
Orion Iron T170F SMOD
RUG CB
27.6%

1st=3.2508
2nd=1.9213
3rd=1.0000
4th=0.7837
21T 32-35-23-15 32T

D9BZ-7A029-B
2604300
J8132389
WT170-12B
29T

E0TZ-7102-A
(2604232)
2605214
T170-21F
Direct 18T
Component Parts Part Numbers
RTS Aluminum Main Case WT170-1F
E4TZ7005B
Main Drive (Input) Gear Ball Bearing
Main (output) Shaft Ball Bearing
308L4
40mm ID x 90mm OD
x 23mm Wide , lock ring
D8OZ-7025-A
KOYO 83763-1
E5TZ-7025-C
Front Bearing Retainer
Overall Length 3-7/8”
Outside Diameter 1-3/8"
For 1-1/16" shaft
WT170-6C
326724A
Main (output) Shaft
2WD (23-11/32")
32-37-28 Spline
WT170-2K
E0TZ7061C
2604483
Main (output) Shaft
4WD (19-11/32")
32-37-31 Spline
WT170-2M
2604466
E1TZ7061C
Counter Shaft WT296-3
2602657
Reverse Idler Shaft WT296-35
2602658
Reverse Idler Gear
16T
WT170-10B
2603617
Reverse Idler Sliding Gear
19T
WT170-10C
WT296-10C
D9BZ7D223A
2605066
1-2 Synchro Sleeve
w/ Mainshaft Reverse Gear
WT296-81
2605139
1-2 Synchro Hub & Sleeve Asm 1AT170-80B
2670167
3-4 Synchro Hub & Slider Asm 1AT170-2.5B
1-2 Fork WT170-23/23E?
3-4 Fork WT170-23A/23F?
Reverse Fork WT170-23B/23G?
4th Gear (O.D.)
18T
1978-84 Iron RUG
?Use w/ T170-8C Cluster Gear
32-35-23-15T to update
from 41% to 28% OD
WT170-11C
D8UZ7B340A
2603737

IMO, the "Goldilocks" Tremec RTS transmission for a Model A would be a combination of the the 1st and 2nd gear ratios of a Ford "Code C" transmission, combined with the 4th gear overdrive ratio of a "Code B" transmission.

Refer to the Drivability and Suitability ~ Recommended Combinations section at the bottom of this web page for further explanation of why that configuration would theoretically be the "Goldilocks" transmission for an early Ford conversion.


1985 F-150 2WD Regular Cab Pickup
1987 F-150 2WD Regular Cab, Six Cylinder with Tremec T170FT RTS transmission

When still in a vehicle, the Tremec RTS/TOD transmission can also be identified by the Ford transmission family "B" (Tremec OD) 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, as shown above.



Installation Considerations

It is recommended to use the Model AA truck 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 its use requires less (if any) modification to the frame center crossmember for clearance to the transmission and U-Joint covers.

Both the Model AA and BB truck clutch housings have the same critical dimensions. The inside diameter of the opening for the transmission front drive gear retainer is 4-3/4 (4.750) inches. The fore-aft dimension between the flywheel housing contact surface and the transmission case mounting surface is 5-9/16 (5.5625) inches.

The Model BB clutch housing does not have any front radius rod (wishbone) mounting provisions compared to a Model AA housing, but the BB housing is necessary when using a Model B/BB flywheel housing and oil pan. Model AA and BB flywheel and clutch housings are not interchangeable with each other. They must be paired along with the oil pan.

Use of either the Model AA or BB clutch housing does however require fabrication of brake and clutch pedal mounting provisions. A provision for mounting the emergency brake handle to the transmission must also be fabricated.

The shift lever opening position in the floorboard and mat is slightly affected, moving rearward from the stock Model A.

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.
Modification to the Tremec transmission itself involves:

The Model AA throwout bearing hub, clutch release shaft, arm, and pressure plate are used.a 1949 Ford clutch disc. A Ford 8N-7550 clutch disc, A C5NN-7600 pilot bearing and C0NN-7580-A throwout bearing can also be 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.



Drivability Considerations

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.

Stock Model A Torque and Horsepower Curves
Improper gearing results in lugging the engine at low RPMs and destroying Babbitt engine bearings!

Lugging occurs when the engine is operated under load at below peak torque for any length of time.

Also, don't forget to improve your brakes!

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

Drivability and Suitability ~ Recommended Combinations

Blue-shaded attributes are equivalent to the stock Model A.
Green-shaded transmissions, ratios, and attributes are preferred for improved drivability compared to stock Model A.
Yellow-shaded attributes are questionable, and Violet/Red-shaded are the least desirable.
Three Speed
Transmission
Rev 1st 2nd 3rd 4th % OD Optimal Drivability and Suitability ~
Recommended Combinations and Usage Notes
Stock Model A
1928-31

(200cid L4)
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

(200cid L4)
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.
When coupled with a 28% Mitchell driveshaft overdrive unit, this transmission approaches the "Goldilocks" solution for both low speed and high speed drivability, though without a transmission overdrive gear.
1931 Ruckstell
Dual High

(200cid L4)
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.
Mitchell Synchro
15% 1st

(200cid L4)
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.
Synchronized 2nd and 3rd gears.
15% Taller 1st gear ratio is similar to Model B.
Mitchell Synchro
15% 1st & 2nd

(200cid L4)
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.
Synchronized 2nd and 3rd gears.
15% Taller 1st and 2nd gear ratios are similar to Model B.
When coupled with a 28% Mitchell driveshaft overdrive unit, this transmission approaches the "Goldilocks" solution for both low speed and high speed drivability, though without a transmission overdrive gear.
Four Speed
Transmission
Rev 1st 2nd 3rd 4th % OD Optimal Drivability and Suitability ~
Recommended Combinations and Usage Notes
Stock Model A
(200cid L4)
3.75:1 3.12:1 1.85:1 1:1 ~ ~ BASELINE REFERENCE
Tremec
T170FT RTS

F-150 TOD
Code B

27.6%

5.0L/302cid V8
4.9L/300cid L6
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.
Fully synchronized.
1st and 2nd gear ratios are similar to/worse than stock Model A.
4th gear (overdrive) ratio is more favorable for Model A and early V8 era Fords compared to code "C" and "D" transmissions.
Better suited for highway driving and/or underpowered engines.
Increased engine Torque and HP are highly recommended.
Tremec
T170FT RTS

F-150 TOD
Code C

37.9%

5.8L/351cid 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.
Fully synchronized.
Taller 1st and 2nd gear ratios are much more favorable compared to stock Model A.
4th gear (overdrive) ratio is less favorable for Model A and early V8 era Fords compared to code "B" transmissions.
Better suited for city driving and general driveability.
Increased engine Torque and HP are required for highway driving.
Tremec
T170FT RTS

F-150 TOD
Code D

41.1%

4.9L/300cid L6
3.25:1 3.25:1 1.92:1 1:1 0.71:1 41.1% Not Recommended - no benefits for most cars!
  • 4.11 rear axle in a light weight car and/or flat terrain.
Fully synchronized.
1st and 2nd gear ratios are similar to/worse than stock Model A.
4th gear (overdrive) ratio is very unfavorable for Model A and early V8 era Fords compared to code "B" and "C" transmissions.
Increased engine Torque and HP are required.
Goldilocks
Gearing


27.0%
3.25:1 3.01:1 1.78:1 1:1 0.79:1 27.0% For Model A and Early V8 Ford.
(never originally configured in an RTS by Ford)
See Specification Table at top of page for parts required.
  • 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.
Increased engine Torque and HP are highly recommended.
Blue-shaded attributes are equivalent to the stock Model A.
Green-shaded transmissions, ratios, and attributes are preferred for improved drivability compared to stock Model A.
Yellow-shaded attributes are questionable, and Violet/Red-shaded are the least desirable.

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