Subaru 4AT Phase 2 - Transmission Digest

Subaru 4AT Phase 2

One of the more-frequently asked questions in calls ATSG receives regarding the Subaru 4AT Phase 2 transmission is, “Where do the leaf springs go for the 2/4-clutch and low/reverse-clutch-pack stack-up?” Figures 1 and 2 show the position and configuration for the 2/4 pack, and figures 3 and 4 show the low/reverse pack.

Subaru 4AT Phase 2 

Technically Speaking

Subject: Locations of clutch-pack springs; solenoid identification and specification
Unit: Subaru 4AT Phase 2
Essential Reading: Rebuilder
Author: Wayne Colonna, ATSG Transmission Digest Technical Editor

Quick Tech, Part 1

Technically Speaking

  • Subject: Locations of clutch-pack springs; solenoid identification and specification
  • Unit: Subaru 4AT Phase 2
  • Essential Reading: Rebuilder
  • Author: Wayne Colonna, ATSG Transmission Digest Technical Editor

Quick Tech, Part 1

One of the more-frequently asked questions in calls ATSG receives regarding the Subaru 4AT Phase 2 transmission is, “Where do the leaf springs go for the 2/4-clutch and low/reverse-clutch-pack stack-up?” Figures 1 and 2 show the position and configuration for the 2/4 pack, and figures 3 and 4 show the low/reverse pack.

The next-most-asked question has to do with solenoid identification and specification. In Figure 5, the TCC duty solenoid can be identified by the blue connector, the low-clutch timing solenoid has the gray connector, and the red/pink connector is for the pressure-control solenoid.

In Figure 6 the green connector identifies shift solenoid 1 and the yellow connector identifies shift solenoid 2.

The black connector shown in Figure 7 identifies the 2/4-brake timing solenoid and the red/pink connector identifies the 2/4-brake duty solenoid. Also shown in Figure 7 is the transmission-fluid-temperature (TFT) sensor snapped in place where the ground wire for the 2/4 duty solenoid is attached.

Figure 8 provides a connector pin-out and a solenoid resistance chart.

One of the many differences between the Subaru 4AT and the 4AT Phase 2 is that the transfer-clutch solenoid and valve-body assembly now are mounted on the back side of the main case instead of being in the extension housing (see Figure 9).

A change was made to this solenoid and valve-body assembly, as illustrated in figures 10 through 14.

The change reduced what Subaru describes as oil-pressure vibration in its bulletin numbered 16-67-04. Although the solenoid, the valve and valve-body assembly have been redesigned, the spacer plate did not change (see Figure 15).

Figure 16 is an oil schematic that shows in part the difference between the previous-design and the updated-design transfer solenoid, valve and valve-body housing while still using the original spacer plate. The part number for this updated assembly is 31942AA130.

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