Model A & AA

Ford Garage

Three Speed Transmission Case Variations

This page details the five major types of the three-speed transmission case A-7006 used during Model A Ford production.

All Model A transmission cases were cast iron. In addition to being used in all Model A cars, the three-speed transmission was used in Model AA trucks until the introduction of the four-speed truck transmission in 1929.


The table below shows the progression of identifying features of each major type of three-speed transmission case. The distinctive or incremental change from case-to-case is highlighted in bold.

Part
Number
Type Usage & Description 1928 1929 1930 1931
A-7006-A(R) 1
  • For use with the multi-disc clutch
  • Large diameter rear opening for A-7138-A(R) reverse idler gear shaft (with oiler scoop and collar)
  • No threaded bolt holes (for A-7050 front bearing retainer)
  • Uses two A-7119-(R) bronze countershaft (cluster) gear thrust washers
  • Rear bore for main shaft bearing machined with integral bearing support flange
  • Front bore for main drive gear bearing machined with integral bearing support flange
1927 n/a n/a n/a
A-7006-A 2
  • For use with the multi-disc clutch
  • Small diameter rear opening for A-7138-B reverse idler gear shaft (with oiler scoop)
  • No threaded bolt holes (for A-7050 front bearing retainer)
  • Uses two A-7119-(R) bronze countershaft (cluster) gear thrust washers
  • Rear bore for main shaft bearing machined with integral bearing support flange
  • Front bore for main drive gear bearing machined with integral bearing support flange
July n/a n/a n/a
A-7006-B 3
  • For use with the single plate clutch
  • Small diameter rear opening for A-7138-B reverse idler gear shaft (with oiler scoop)
  • Four 5/16-18 threaded holes for A-7050 front bearing retainer bolts
  • Uses two A-7119-(R) bronze countershaft (cluster) gear thrust washers
  • Rear bore for main shaft bearing machined with integral bearing support flange
  • Front bore for main drive gear bearing machined with integral bearing support flange
Oct ? n/a n/a
A-7006-B 4
  • For use with the single plate clutch
  • Small diameter rear opening for A-7140 reverse idler gear shaft (without oiler scoop)
  • Four 5/16-18 threaded holes for A-7050 front bearing retainer bolts
  • Internal case thrust bosses enlarged to eliminate two A-7119-(R) bronze countershaft (cluster) gear thrust washers
  • Rear bore for main shaft bearing machined with integral bearing support flange
  • Front bore for main drive gear bearing machined with integral bearing support flange
Dec n/a n/a
A-7006-B 5
  • For use with the single plate clutch
  • Small diameter rear opening for A-7140 reverse idler gear shaft (without oiler scoop)
  • Four 5/16-18 threaded holes for A-7050 front bearing retainer bolts
  • Internal case thrust bosses enlarged to eliminate two A-7119-(R) bronze countershaft (cluster) gear thrust washers
  • Rear bore for main shaft bearing machined with groove for A-7070 snap ring
  • Front bore for main drive gear bearing machined with groove for A-7045-B snap ring
n/a March

The Type 1 and Type 2 cases were used with the early multiple disc clutch and flywheel, and the Type 3, 4, and 5 styles were used with the single plate clutch and flywheel design.

The multiple disc and single plate clutch designs also used different clutch housings (bell housings) and inspection covers, transmission main drive gears, and clutch actuation components including shafts and levers.

The illustration above shows the difference between the A-7138-AR reverse idler gear shaft used with the Type 1 case, and the and A-7138-B used with the Type 2 and Type 3 cases.

The Type 4 and early Type 5 cases used the same later idler shaft shown above, but without the oil scoop or cross drilling (under number A-7140), and in conjunction with a revised gear and bushing assembly providing for lubrication.

The later Type 5 cases used shafts with revised notches on the ends, and used a thinner shaft retainer and shorter bolt as shown in the illustration below.

Shown above are the notch and retainer designs of the Type 4 and subsequent early 1930 Type 5 reverse idler gear shaft A-7140, countershaft A-7111, and retainer A-7155 compared to the revised designs used with the later 1930 Type 5 transmission cases.

There are a variety of different three-speed gear shift housings (towers) as well, however all shift housings are functionally interchangeable with any three-speed transmission and case.


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 & Model 46 Service Transmission Case 46-7006
  3. Model B & Model 46 Transmission Case Variations
  4. 1928 to 1934 Double Sealed Transmission Ball Bearings
  5. 1928 Transmission Shift Tower & Lever
  6. Model AA Four Speed Transmission Case Cracks

April 2016