Is the G56 just a souped up NV4500?

[RJOL]

I've taken a close look at the info about the G56 and I'm beginning to wonder if this is the setup I want. My 2001 had the NV4500 5 speed with a 4:10 axle. Its highest gear, 5th, was rated at 0. 75. The NV5600 has a rating of . 073. The new G56 has a rating of 0. 79. One of the reasons I'm getting a new truck is to get rid of the 4:10 axle and get into something that is more economical for daily driving. I'm beginning to think that the G56 will be more like a NV4500 4:10 setup in its highest gear. Maybe I should be looking for an early 2005 or 2004. 5 with an NV5600...

 

[gone99]

I'm not sure of the link, but I do know that if you go to the Mercedes medium duty trans site, you'll find all the specs. The 1st gear =6. 7 ratio. The over-drive=. 73 ratio. The unit uses 9qts of ATF and weights 300Lbs. dry. It is also rated for a max of 660ft/lbs of input torque, and has a max of GVWR=60,000!

 

[dhill]

I'm not sure of the link, but I do know that if you go to the Mercedes medium duty trans site, you'll find all the specs. The 1st gear =6. 7 ratio. The over-drive=. 73 ratio. The unit uses 9qts of ATF and weights 300Lbs. dry. It is also rated for a max of 660ft/lbs of input torque, and has a max of GVWR=60,000!

I sure wished that was true, but the specs from Dodge and MB are

1st=6. 29

2nd=3. 48

3rd=2. 10

4th=1. 38

5th=1. 00

6th=0. 79



torque rating = 428 ftlbs



capacity = 12. 7 pints



At this point the only rear end gears are 3. 73. Mine should be here mid March.



Dave

 

[klenger]

I revised my gear speed calculator worksheet at http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls for the G56. I agree that the G56 with 3. 54 axles would be sweet. With the closer 5 to 6th gear spread, you could tow all day long in 5th gear at about 60 MPH at around 2200 RPM and then run empty at 74 MPH in 6th at at 2200.

 

[RJOL]

Thanks Klenger... That helps a lot in seeing just what the difference between the two trannys will be.



In 6th (OD) the NV5600, at 65mph, would be running at just under 1900rpm. With the G56 it would be just over 2000rpm. At 75 the NV5600 would turn just under 2200rpm while the G56 will turn just over 2300rpm.



How much will this effect MPG? Could I expect to get 5% less mileage with the G56? This could be significant over many thousands of miles.



Now the question is: Would it be better to find a pre G56 2005 with the known NV5600 or take the 2005 with the unknown G56 and see what happens...

 

[XJSuperman]

I sure wished that was true, but the specs from Dodge and MB are

1st=6. 29

2nd=3. 48

3rd=2. 10

4th=1. 38

5th=1. 00

6th=0. 79



torque rating = 428 ftlbs



capacity = 12. 7 pints



At this point the only rear end gears are 3. 73. Mine should be here mid March.



Dave

I don't see how that TQ spec is right? THe cummins in the '05's is putting out 610... hows this transmission supposed to handle towing when it can't handle the stock TQ rating?

 

[dhill]

I don't see how that TQ spec is right? THe cummins in the '05's is putting out 610... hows this transmission supposed to handle towing when it can't handle the stock TQ rating?

Look here, remember these torque figures are NM's not ftlb's so you have to convert.



http://benzworld.org/news/news.asp?id=106





Dave

 

[Gary - K7GLD]

"In 6th (OD) the NV5600, at 65mph, would be running at just under 1900rpm. With the G56 it would be just over 2000rpm. At 75 the NV5600 would turn just under 2200rpm while the G56 will turn just over 2300rpm.



How much will this effect MPG? Could I expect to get 5% less mileage with the G56? This could be significant over many thousands of miles. "



I doubt towing MPG will be worse - maybe even better with the new transmission IF it allows more use of OD. I do almost all my towing in OD with my 5600 and our relatively light 24 ft 5er - and would undoubtedly spend lots more time down in 5th if we had a heavier RV - the new setup might provide an excellent compromise that keeps you in OD longer with heavier loads.

 

[Tim]

I just did the conversion and 580 nm = 427 ft lbs.



Over the input torque rating by 50%? That makes me nervous.

 

[RJOL]

... I doubt towing MPG will be worse - maybe even better with the new transmission IF it allows more use of OD. I do almost all my towing in OD with my 5600 and our relatively light 24 ft 5er - and would undoubtedly spend lots more time down in 5th if we had a heavier RV - the new setup might provide an excellent compromise that keeps you in OD longer with heavier loads.

You may have a point, Gary, but if I'm only towing 10% of the time, I would think that the OD difference could amount to a lot of extra fuel, over thousands of miles...

 

[EEdmondson]

My next set of tires will be taller so I can cruise at a lower RPM. I still find myself wanting to shift into 7th gear. The G56 needs a 3. 54 option.

 

[JTryles]

I just did the conversion and 580 nm = 427 ft lbs.



Over the input torque rating by 50%? That makes me nervous.

That's gotta be a typo on that web site... the NV5600 was rated at what? 1000 ft*lb or somthing and you are telling me D/C is putting in something rated at only 430??? No way.

 

[Gary - K7GLD]

"That's gotta be a typo on that web site... the NV5600 was rated at what? 1000 ft*lb or somthing"





UMMMm - as *I* recall, the later 5600 was actually rated at around 400 ft lbs at the input shaft, earlier ones with the smaller diameter shafts were less than that...

 

[JTryles]

"That's gotta be a typo on that web site... the NV5600 was rated at what? 1000 ft*lb or somthing"





UMMMm - as *I* recall, the later 5600 was actually rated at around 400 ft lbs at the input shaft, earlier ones with the smaller diameter shafts were less than that...

I was confusing the transfer case, rated at 1400 or so, with the NV5600... whoops.



Well, if the later 5600's were "only" rated at 400 and everyone has been BOMB-ing them with great success (how many have actually killed one?) then perhaps the new G-56 rated at "only" 430 will do just as well? I'm still dumbfounded that D/C would use a transmission (NV5600 or G-56) that is rated at LESS then what the engine can produce STOCK?!?!?!? Am I missing something here???

 

[Gary - K7GLD]

Actually *I* suspect that rating is more of a steady, or relatively CONTINUOUS operation rating, rather than an instantaneous or short term one...

 

[JTryles]

Actually *I* suspect that rating is more of a steady, or relatively CONTINUOUS operation rating, rather than an instantaneous or short term one...

You've got to be correct IMHO, as there'd be a whole mess of busted up 5600's out there otherwise!!!



See this link for a little more G56 info:

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/15022215/gotomsg/15026013.cfm

 

[KCJackson]

Bottom line... Cummins holds approval privileges for any transmission Dodge uses - no automatic was allowed with the HO until the 48RE - so if they gave their thumbs up to the G56, it should be good to go.

 

[gone99]

If the NVG5600 was factory rated at 560 ft/lbs of torque and the new one is 430 ft/lbs, isn't the new one inferior? Put another way, the old NVG4500 was made for a gas engine and was replaced with the 6-speed. Now, we're going full circle with a new ( gasoline designed) 6-speed that is exactly the same as the HEMI trans just to save a buck! What a joke. I bet Ford will use the NVG5600.

 

[Buffalo]

Nv-5600

From what I've heard, the plant where the NV-5600's were built has been shut down and a lot of the machinery used in the manufacturing of this trans. has been sold.

So, it looks like Ford will not be getting the NV-5600. It's probably too bad because, from what I've heard, the dual mass flywheel is giving them a lot of trouble. Same thing with the Chevy's. I believe they share a common 6-sp. trans. (ZF???).

I sure hope Dodge isn't going to experience similar problems with their dual mass flywheel.

Joe F. (Buffalo)

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