As anyone had trouble with loosing 4-high? When i put it in the 4-high postion it acts as if its in neutral. I still have 2-high, neutral, and 4-low. Any suggestions would be great. Thanks.

Beersy50


'89 F-350 Dump truck 7.3 5 speed 4x4

 

This would be a transfer case problem...... usually the shifter linkage is worn externally or internally......

If you need the manual for the BW1356 I can send it......
Just click on my name and email me with subject: BW1356 manual


Mechanical Operation

In the 4x2 mode, torque from the transmission is transferred to the front input shaft, which in turn drives the output shaft that drives the rear axle.

The 2W-4W shift is accomplished when the 2W-4W shift fork moves the 2W-4W lockup collar to engage the drive sprocket on the rear output shaft splines. The drive sprocket turns the chain which turns the front output shaft driven sprocket on the front output shaft and the front driveshaft.

The high-low shift is accomplished when the high-low shift fork moves the high-low lockup collar to engage the planetary gear set assembly to the output shaft. Torque for the input shaft is then transmitted through the sun gear, which then turns the planetary gear set. The planetary gear set, which is now engaged to the output shaft, provides a reduction.


Neutral

With the shift selector in neutral, no power is transmitted to either front or rear. All the planetary gears turn freely with the input shaft, and the chain sprocket floats freely on the output shaft.


Power Flow in Neutral



The following illustration shows a cross-section of the planetary gear set. At the center, attached to the input shaft, is the sun gear. This gear meshes with four gears that surround it like planets (which is why this component is called a planetary gear). In turn, the four gears mesh with an outer gear called the annulus. (Annulus is another word for ring.)

As the sun gear turns, the four planetary gears attempt to rotate. If the output shaft is locked to the planetary gear (as it is in low gear), the planetary gears "walk" around the inside of the annulus providing a gear reduction. If the output shaft is locked to the sun gear (as in high gear), the input and output shafts rotate as a single unit.




2-Wheel Drive -- High Range

When the driver selects 2H, the reduction hub at the center of the planet carrier assembly slides forward, putting the transfer case into the high speed range (direct drive). The input shaft and the rear output shaft are locked together. This results in direct drive, straight through to the rear driveshaft. In addition, the 4-wheel drive locking collar is disengaged so none of the 4WD components turn.


Power Flow in 2H




4-Wheel Drive -- High Range

In 4-wheel drive -- high range (4H), the planet carrier assembly stays where it was in the 2H shift. The action of the shift lever causes the 4-wheel drive lockup hub to move rearward, locking the chain sprocket to the rear output shaft. Now, both the rear and the front wheels are being driven in the high range.


Power Flow in 4H




4-Wheel Drive -- Low Range

To get maximum pulling power, the driver selects 4L. When this happens, the reduction hub moves rearward, and the planet carrier assembly is locked to the output shaft. With the annulus unable to turn, the planetary gears "walk" around the inside. The result is that the planet carrier assembly now turns more slowly than the input shaft. Because the planet carrier assembly is now locked to the output shaft, the output shaft now rotates at a slower speed than the input shaft. This action increases the pulling power available to the wheels. It's like having an additional set of lower gears for extra power.


Power Flow in 4L

 

[quote=PLC7.3;6499254]This would be a transfer case problem...... usually the shifter linkage is worn externally or internally......


Well I thought it was the external linkage also, so I fabed my own and that stoped the problem of it falling into neutral when the truck isn't under load. Is it a bad idea to continue to drive the truck this way, because I'm gong to need it for plowing this winter? What is involved in the repair? Thanks PLC7.3



Beersy50