NV5600 Conversion to

NV5600 Conversion to

Fuller FO 8406

Fuller has been using a variety of 5 and 6 speed transmissions in mid-sized trucks for many years as well as larger 9, 10, 12, 15 and 18 speed transmission in over the road trucks.

The 5 and 6 Speed transmissions come in synchronized and un-synchronized versions as well as final drive at 1:1 (FS series) and overdrive at .78 (FSO series). You can convert a FO series transmission into an FSO with standard off the shelf parts.

FO8406 purchased on Ebay for $152.50 and was

intended for our 2001 Dodge 3500 4 X 4.

This FO8406 is new and was intended for a 2006 International truck. The are some significant differences between the IHC unit and the units produced by Fuller for other markets. The input shaft is 2" X 14 spline as opposed to 1.75 X 10 spline for the standard FO unit. The 6th gear drive on the input shaft also has one more tooth than the standard FO unit. The counter shaft mating gear is also different. Since this transmission was intended to be shifted electronically, it is unsynchronized. The front bearing cover is much larger than than the one on the FSO6406.

Most of the gears match both the FSO6406 and FSO8406. To convert this transmission to a FSO8406, change the input to a 1.75 X 10 tooth, counter shaft gear and front bearing seal,

The photos show a complete FO8406 and a disassemble transmission with the upper and lower shaft gear train. Note the differences between the 1.75" shaft and the 2" shaft on the right.

This photo is showing the rear bearing cover and a 38 tooth flange drive for purposes of determining how to make an adapter to mate the transfer case to the Fuller transmission. The case adapter in photo #3 is from an automatic. Most married transfer cases have the rear bearing retainer machined into the case so it becomes part of the transmission such as on the NV5600. Still a challenge to get this resolved.