NV5600 dead again!!!!

[MMeier]

Well, at least this time it let me get home, been hanging up in gears lately when hot. Then just as I get in from Okla this morning and unload trailers, would not let me get 3rd, 4th, or 6th. Does it sound like a synchro problem or something else, thankfully I had my original redone, hopefully correctly, find out Monday when my boys put it in.

 

[VTomasso]

Just my $.02...

Hi MMeier,



Sorry to read about that. Usually the NV's are pretty tough, no? You didn't mention if the other gears are working OK. If so then my theory is probably useless.



Just for grins you might want to have a look at your clutch master and slave cylinders. I had an experience once with an old Mercedes 240D where the clutch worked fine until the engine got hot, then bang! clutch to the floor and stayed there. Freaked me out the first time it happened, right in a toll plaza. Limped her home floating the gears. After cooling down it worked fine. Very strange. Stranger still I could repeat it. I think that the slave was growing enough with the heat to let the fluid bypass an already worn out piston, hypothetically at least.



Replaced the slave cylinder and it was fine after that. Perhaps your clutch is not disengageing completely. My NV is a stiff shifter. Works fine as long as I'm not in a hurry. If I didn't know that these boxes were inherently like this I would think that I had a clutch release problem.





Hope this helps.

Regards,

-V

 

[MMeier]

Yep, other gears work "normally". No noises either, just was out playing with it since it is cooled off and no difference, can get 6th ( misinfo before, long 2 days,LOL) Goes into 1st and 2nd OK , I'm thinking a synchro took a dump or maybe a bent shift fork, anyone else? Will be putting in the rebuilt unit Monday and hope it works OK, just as i need it for work, 6200 miles the past 2 weeks, it decides it does not want to function, go figure.

 

[Buffalo]

Hi Mark,



Sorry to hear of all your NV-5600 problems. Do you run the stock, Mopar fluid in the trans?



I wonder if an aftermarket, high quality, fully synthetic lube might extend the life of your trans?



You might get ahold of Quad4X4.com in Roberts, MT. & see if they have any suggestions as to how to help your trans. survive, longer.



Joe F. (Buffalo)

 

[MMeier]

Hi Joe! Been running the Pennzoil Synchromesh fluid in this one, on the advice of the shop that rebuilt the original. this one I feel has not worked quite right since it went in the beginning of summer, had to take back out and run trans to SLC, then they wanted the whole truck (took 2 weeks) still the same. If the one going in seems " right" to me I'll take this one to them and have them go through it also. Might stick a set of Fast Coolers on it and see if they might help.

 

[TRAMPLINEMAN]

Your luck sounds about as good as mine. I don't know too much about manual trannies, but if the synchros are out of mesh in one gear wouldn't they be out in all gears? You know, you could always go with a built auto!

 

[MMeier]

You know, you could always go with a built auto!

Now now Mikey, we both know better then that!!! :-laf

 

[betterthanstock]

It looks like the 4500/5500 will have a real transmission behind them, not the G56, the next one up (whatever the number) and with a 0. 74 overdrive, almost identical to the NV5600.

I think that one will last through a couple of rebuilds on the Cummins, and is lighter than the NV5600.