Join Date: Jan 2008
Location: Rio Rancho, NM
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The NV5600 tranny is from my 2001 Dodge 3500--3rd failure.
The NV5600 was the biggest option Dodge offered and realized that it was not the best choice, but the ONLY choice Dodge had to keep the truck line going. They made changes to the input shaft and synchros but it was only a band aid to the overall problem--not stout enough for the 5.9 Cummins in a light duty truck. The same engine in mid-range trucks with Fullers never had the problems Dodge did. Failures with the G56 are also starting to pop up. Will the G56 go the route of the NV5600 ???
The 11" clutch/flywheel setup has also been an issue and and expensive when compared to the Fuller 14" clutch/flywheel at less than 1/2 the cost of Dodge parts.
Many rebuilders have tried to come up with fixes for the NV5600 and include such things as billet shafts, improved synchros, drilling the bearing races with oil holes, installing oil filters and oil coolers; lastly, overfilling the transmission. The only way you can do this is to remove the shift tower and fill from inside the cab through the tower hole unless you have the tranny apart and drill a fill port above the "full" line.
Heat is what affects the NV5600 the most. The synchros are most affected followed by bearing failures. Sheared input shafts is more common on transmissions with a 1-1/4" shaft as opposed to the later 1-3/8" shafts. On the NV5600 in the photo, the rear carrier bearing seized.
There are die hard NV5600 proponents that will argue that the NV5600 is the best transmission ever made and that the truck is being misused, over loaded, improper oil being used and the list of reasons goes on. When you buy a 1 ton long bed Dodge truck with 4:10 rears, its going to be used, which usually means hauling loaded OTR or pulling loaded trailers. Otherwise it's not a truck, it's a passenger vehicle or grocery getter.
That's enough--I'm done venting.
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Fuller Trans Install since 2008
2001 Ram 3500, Single cab 12' flatbed, 2" cab lift, Fuller FSO-6406A
Home of Fuller 4 X 4 Conversion Kit
Last edited by chansey; 04-30-2011 at 09:51 AM.