Engine/Transmission (1998.5 - 2002) NV5600 Failed Output Shaft

[RustyJC]

I sold my 2002 3500 dually (ETH/DEE) to an acquaintance when I took delivery of the new truck in my signature in Sept 2010. The truck had 46,500 miles on it, was running an Edge EZ, DD2 injectors, BHAF and Jardine exhaust with, of course, a SBC CON O/FE - a mild towing rig for pulling our 5th wheel that dynoed at 347/762. We never had a problem with the truck and sold it only because of a physical problem that forced me to move to an automatic.



I recently ran into the buyer who told me that he had just been forced to repair the NV5600 because of a failed output shaft (in his words, it "twisted off"). Naturally, I felt bad about this, but not bad enough to pull out my wallet!! The current owner is an OTR trucker, and I'm afraid the NV5600 failed due to his "big rig" habits (floating shifts, low RPM lugging, etc. ) that he carried over into the 3500, but that's just speculation on my part. He wanted me to "pull some horsepower/torque out of the truck" to save the rebuilt transmission, so I unplugged the main plug on the EZ, leaving the boost fooler feature connected.



Just curious - have any of you ever heard of or run into this type of failure on an NV5600 at these mild horsepower/torque levels? Any thoughts on what could have gone on here?



Rusty

 

[NIsaacs]

The current owner is an OTR trucker, and I'm afraid the NV5600 failed due to his "big rig" habits (floating shifts, low RPM lugging, etc. ) that he carried over into the 3500, but that's just speculation on my part.



Just curious - have any of you ever heard of or run into this type of failure on an NV5600 at these mild horsepower/torque levels? Any thoughts on what could have gone on here?



Rusty

My guess is you are correct also maybe poor oil change habits or let it get low on fluid. I change every 36k, if you keep it clean and full, (I do not overfill) they last forever. I don't think he will like the lower power and is not nessessary.



Nick

 

[Slow Six]

My NV 5600 had a 6th gear failure plus the rear diff needed a rebuild. That is when I removed the power upgrades.

 

[Gary - K7GLD]

I've got the power mods and figures seen in my sig, and while our 5er is only a 24 footer, it's been all over and across the USA - I *DO* overfill the transmission and have both coolers and a filter installed - absolutely no issues...

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[NIsaacs]

forced to repair the NV5600 because of a failed output shaft (in his words, it "twisted off"). Any thoughts on what could have gone on here?



Rusty

I would think that in order to break an output shaft something in the transmisson seized up at highway speed and probably loaded. It is a sure bet that the transmission was low on fluid to create the heat nessessary to seize a bearing.



Nick

 

[JMetzger]

I have about the same HP/Torque as the truck you sold with 99,000 miles. I pull our 32 ft Holiday Rambler all over the country & not had any problems. Change oil about every 30000 to 35000 miles, I also don't try to drag race or speed shift the transmission. I think a lot of it is people don't use there heads & realize that it is a truck not a high performance car. I also DO NOT overfill the transmission.

 

[mfurrh55]

I thought i read in a thread way back issues in the 50s, about the shaft on the first nv5600's being weak, they had a replacement you could buy for it, I know they have 2 different splines in the 5600, one is a 10 and the other is an 8

 

[NIsaacs]

I thought i read in a thread way back issues in the 50s, about the shaft on the first nv5600's being weak, they had a replacement you could buy for it, I know they have 2 different splines in the 5600, one is a 10 and the other is an 8

You might be thinking of the input shaft. The early one's used 1. 25" with the later models using 1. 375" I am not aware of the main shaft being different, but that don't mean much:-laf



Nick

 

[RustyJC]

This was a 2002 ETH (HO) truck - it had the large input shaft. I never heard of a change in output shaft configuration.



Rusty

 

[Sticks]

Operator error. The NV5600 is damn near bullet proof and can handle way more than an EZ and 80hp injectors.

I've got 60k on mine with upgrades, The first 40k with an EZ and 80hp injectors, another 15k of that with an Edge Comp, and the last 5 with the items in my sig line.

 

[JMetzger]

Here is what I received from John Holmes about over filling the NV 5600 in 2010
John Holmes John Holmes is offline
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Hi, sorry it took so long, but I've been on the road. Yes, the early transmissions had the fill plug too low in the case. As I recall there was a TSB on those, but later models had the location moved upward. Have them check for TSBs against your VIN at C. Dodge. If you're really concerned, jack up the truck and tilt it upward on the side of the plug and then fill it.
Tell everybody I said Happy Thanksgiving from Texas. John
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[HBarlow]

The NV-5600 in my '01 lasted 302k mostly towing miles and didn't actually fail then. I had unknowingly allowed fluid level to get a little low and the large bearing became worn and noisy. When disassembled Standard Transmission's bench tech discovered noticeable wear on the sixth gear probably due to the fact that I always allowed it to pull down to 1600 rpm on long grades. Bill Stockard warned me against that practice but I stubbornly allowed it to pull at peak torque. I worked the truck pretty hard for its entire life but never tried to quick shift it, perform drag strip launches, or otherwise abused it. The truck was only mildly modified with Bosch RV275 injectors and used a standard clutch.

I've never heard of a NV-5600 twisting off the output shaft. My guess would be driver technique or driver error caused the reported failure.