Nv5600 problems

[rolncoal82]

I'm at my wits end with this thing main shaft bearing went bad due to lack of oil and also melted the needle bearing in first gear. I replaced first gear all bearings synchronizers and main shaft put back together to book specs and it made it one mile down the road before doing the same thing. It took out the needle bearing on first gear and tried to walk the gear on the shaft. Ordered all new parts again and it made it 8 miles before the same thing again. There is no vibration no sound nothing to indicate it's not right then it just locks up and all you have is first gear and neutral. It still moves in neutral like it's hung in first. All my end play and backlash were set to book spec so I'm lost to what is causing this. :bang

 

[chris lang]

Some guys have a modified shaft that has bigger oil passages for the front bearing. That's a common failure for nv5600 from what I've researched when I rebuilt mine.

 

[jimbo486]

Some guys have a modified shaft that has bigger oil passages for the front bearing. That's a common failure for nv5600 from what I've researched when I rebuilt mine.

Does simply overfilling by a quart or more help with that?

 

[BigPapa]

What fluid you running?

 

[smokinVE]

I'd start looking at the case. With new parts and the same failure sounds like you are having a deflection issue either the main shaft or counter. You may not be able to see it with the case on the bench.

 

[chris lang]

Most guys run an extra quart. The fact that yours ate itself so fast makes it sound like the oil ports in your shaft are plugged or you didn't have the correct end play.

 

[rolncoal82]

The shaft itself does not have oil ports the face of the gear and some washers are machined to allow oil to the bearings. I ran amsoil and 6 quarts and set end shaft play on both shafts at .004 the book calls for 2/6 on both so I split the differences. It's eating the needle bearing on first gear which mars the face up and destroys the synchronizer and turns the thrust washer into a cone from trying to walk the gear off. What gets me is there is no vibration no noise no anything through all gears at 70 mph then it will just start binding up and about lock the tires up. It will only go into 1st gear and will also move in neutral it will go in reverse but binds up. Tranny on the ground shafts feel good and turn freely so I'm at a loss I'm leaning towards the case but can't physically see anything wrong so we are going to just put a used one in and cut our losses.

 

[mhuggler]

The shaft itself does not have oil ports the face of the gear and some washers are machined to allow oil to the bearings. I ran amsoil and 6 quarts and set end shaft play on both shafts at .004 the book calls for 2/6 on both so I split the differences. It's eating the needle bearing on first gear which mars the face up and destroys the synchronizer and turns the thrust washer into a cone from trying to walk the gear off. What gets me is there is no vibration no noise no anything through all gears at 70 mph then it will just start binding up and about lock the tires up. It will only go into 1st gear and will also move in neutral it will go in reverse but binds up. Tranny on the ground shafts feel good and turn freely so I'm at a loss I'm leaning towards the case but can't physically see anything wrong so we are going to just put a used one in and cut our losses.

Did you ever find a cause for the failures? Mine keeps eating the pocket bearing for no apparent reason. It's definitely a lack of lube, but I don't know how or why.