The ZF S6-650 is a six-speed transmission. All of the
six forward gears and the reverse gear are fully synchronized. The six-speed
gear is an overdrive ratio. The six-speed gear is located on the rear
of the countershaft.
The transmission consists of three aluminum cases. The front case includes
the bell housing. The main shaft and the countershaft front bearing races
are installed in the front case. The bearing races are shimmed to preload
the main shaft and countershaft bearings. There is also a main shift shaft
bearing in the front case. The shift control lever housing mounts to the
front case.
The intermediate case supports the main shaft and the countershaft.
The bearing races for the main shaft and the countershaft center bearings
are installed in the intermediate case. To support the shift shaft, shift
shaft bearings are used in the intermediate case The shift shaft interlock
plate and the shift shaft detents are located with the intermediate case.
The rear case also has bearings for the main shaft and the countershaft.
The bearings are not preloaded. The rear case contains the reverse gear idler
shaft and gear. The rear case also has a bearing for the main shift shaft.
If the vehicle is RWD, an oil seal is used in the rear case. If the vehicle
is 4WD, a sealed bearing is used on the rear of the main shaft. The six-speed
gear along with the reverse/first speed gears are located in the rear
case.
All of the speed gears are supported by a double row needle bearing.
The inner bearing races for the needle bearings are replaceable.
The shift lever moving the main shift shaft (5) selects the transmission
speeds. By moving the main shift shaft front-to-rear and side-to-side rotation
will allow the levers on the front internal shift control lever (1)
to engage the notches on the 4th/5th speed gears shift shaft or the 2nd/3rd
speed gears shift shaft. Further movement of the main shift shaft front-to-rear
and side-to-side rotation, the levers on the rear internal shift control
lever (3) will engage in the notches on the reverse/1st speed gears
shift shaft or the 6th speed gear shift shaft. The shift shaft block (4)
on the main shift shaft, which is teeth to the interlock plate (2),
moves the interlock plate to lock in the notches on the non-selected gears
shift shaft, thus preventing the non-selected shift shafts from moving.