Engine/Transmission (1998.5 - 2002) How Does the 6sp. Take It?

[KIseminger]

I saw a spec somewhere that the 6 speeds in the Dodges are rated to take up to 550 ft/lbs of torque. Obviously many of you are pushing well beyond that. I have heard that that this trans holds up pretty well (as mine has). Any experiences/comments/thoughts to testify to this?



-Kyle

 

[SRadke]

I believe that rating was/is for the 5 speed.



-Scott

 

[KIseminger]

Here was the info I was refering to



http://dodgeram.org/tech/transmission/nv5600_spec.html

 

[SRadke]

This shows the torque rating of the 5 speed at 460 ft. lbs. There are many TDR members that run the 5 speeds in applications over 500 hp.



Physically the 6 speed is twice the size of the 5 and they have far less strength issues. The 5 speed requires a couple upgrades including a fully splined mainshaft and larger imput shaft to sustain that power level. The 6 speed takes it as is.



-Scott

 

[DPelletier]

No, the rating WAS for the NV-5600, but it was changed to 600 ft lbs for the '04. 5 "600". There have been no changes to the transmission itself. I have also heard that the NV-5600 is used in MDT applications at higher torque ratings. Some early NV-5600 (model year 2000) had some issues like grinding, etc. but there have been very few problems since. The ratings are what they need to be, nothing more. I wouldn't read too much into them. The NV-5600 is the strongest transmission available in a light truck IMO. Many people have been running at higher power levels and I've yet to hear of a failure due to this. At 150 lbs heavier than a NV-4500, the 5600 is a brute of a transmission and offers many HD features. I expect mine to be a good match with my Cummins when it comes to reliability and longevity.

An interesting aside is that the new Duramax LLY (590 ft lbs) is only available with the Allison and not the ZF six speed (common to the Ford and GM products). This tells me that GM likely doesn't believe the ZF can take the 590 ft lbs. Of course, it could also be driveline related as the Allison defuels in 1st and 5th and so isn't really putting out 590 ft lbs except in 2,3 & 4th.

Also kind of makes one wonder why the 590 ft lb rating when DC's 600 ft lb rating was already anounced. Obviously something prevented them from going to 605 ft lbs!

I am starting to get off topic, so I'll stop now .



Dave

 

[KIseminger]

Thanks, then what I had heard is true.

 

[WadePatton]

Mine groans sometimes, but I've been putting 800+ FP to it for a long time. Over 1000 these days.

 

[Gary - K7GLD]

I guess a more meaningfull question would be, are stated torque numbers meant to apply to absolute PEAK, short-term applications, or relatively longer applications such as heavy pulling up slopes and such...



We already know FAR higher PEAK power has been applied to these trannies, both the 5 AND 6-speed versions - leads me to believe ratings are more related to steady-state loads for longer periods of time.



If true, in our normal use, MOST of us are not likely to overstress the trannies, and those ratings are more of interest to commercial/industrial users who are more likely to place higher long-term loads on them.



Then of course, there are the overweight and BOMBED RV haulers towing 25,000 lbs. in the Sierra or Rockies...

 

[KIseminger]

Thanks Gary, that is a good answer

 

[WadePatton]

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