The AR5 has a unique shift system. A single shift control shaft (281) operates four shift shafts.
The shift control lever (500) fits into a socket on the shift control shaft (281). Positioning the
lever or finger of the shift control shaft (281), in the gates of the shift shafts, operates the 1st/2nd
shift shaft (211), the 3rd/4th shift shaft (231) and the 5th shift shaft (251). Moving the shift
control lever (500) side-to-side allows the lever on the shift control shaft (281) to engage into one
of the three gates. Moving the shift control lever (500) forward and reverse selects either position
of the particular shift shaft. The 3rd/4th shift shaft (231) is the top shift shaft. A bolt holds the
3rd/4th shift fork (230) in place on the shift shaft. When shifted in position, a detent ball (287)
and spring (288) located in the top of the intermediate case, holds the shift shaft. The 1st/2nd shift
shaft (211) is the second shaft from the top. A bolt holds the 1st/2nd shift fork (210) in place on
the shift shaft. In addition, the 1st/2nd shift fork (210) slides on the 3rd/4th shift shaft (231).
Using two shift shafts for the shift fork, keeps the shift fork square to the synchronizer sleeve. A
small shift shaft interlock pin (292) in the 1st/2nd shift shaft (211) prevents the other shafts from
moving. Interlock pins (291), located in the intermediate case on either side of the 1st/2nd shift
shaft (231), contact the small interlock pin (292) and lock into a notch on the shift shafts,
preventing multiple shift shaft movement. The 5th shift shaft (251) is located third from the top. A
roll pin holds the 5th shift fork (250) in place on the shift shaft. In addition, on the 5th shift shaft
(251) is the reverse shift lever (274). The reverse shift shaft (271) is the bottom shift shaft. The
shift shaft does not move. An interlock pin, in the intermediate case, holds the shaft in place.
Instead, the shift shaft has detents for the detent ball and spring located in the reverse shift lever
(274). When moving the 5th shift shaft (251) forward, the retaining clip at the rear of the reverse
shift lever (274) moves the reverse shift lever (274). The reverse shift fork (270) swivels on the
reverse shift lever (274). The reverse shift fork (270) pivots on the reverse shift fork bracket
(272) in order to increase the movement of the reverse shift fork (270). To help prevent a mis-
shift to the reverse position, a reverse restrictor (91) is located in the extension housing. When
going into reverse, a finger on the shift control shaft (281) contacts the plunger on the reverse
restrictor (91). Compressing the spring gives the driver a restricted feel when shifting to reverse.
Detent balls and springs hold the 1st/2nd shift shaft (211) and the 5th shift shaft (251) in the shift
positions. On the right side of the intermediate case are the detent plugs for accessing the detent
balls and springs. Even though there is a detent plug for the reverse shift shaft (271), no detent
spring and ball is located there. To aid in easy shift operation, the front case shift shaft bushings
(295) and the intermediate case shift shaft bushings (296) support the 1st/2nd shift shaft (211), the
3rd/4th shift shaft (231) and the 5th shift shaft (251). Supporting the shift control shaft (281) at
each end are the extension housing shift shaft bushings (297).
Power Flow - Forward Gears
2007 Hummer H3
2007 TRANSMISSION Manual Transmission - Aisin AR5 - H3