WACTD

There's been lots of discussion lately comparing the Mercedes G56 (photo above) to the now-obsolete New Ventures NV5600. I had seen plenty of good data on both while researching my truck purchase, and with all the rumors and opinions flying around I thought it would be useful to pass some of it along.

Initially I was convinced that I wanted an NV5600, to the point of trying to find a leftover 2005 on the lot somewhere. But the more I read, the more I liked the G56, until finally it became my transmission of choice.

The G56 is NOT a brand-new transmission. Production began at least as early as 2002 in Brazil, with production expected to reach 100,000 units annually by 2005 (and those projections were before the Americans decided to deploy it across the Ram product line).

MB's recommended applications for the G56 are "light vehicles, from 7 to 10 tons, and medium ones from 11 to 12 tons". These are not "light duty" transmissions, folks... they were originally designed for trucks MUCH bigger and heavier than ours.

See this link for more on these stats:

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

It happens that MB builds whole trucks, not just transmissions. So let's consider an example of the vehicles into which MB itself puts the G56:

http://www2.mercedes-benz.co.uk/cont...20CV%20506.pdf

With respect to the concerns about gear ratios being better in the NV5600 vs. the G56:

1st is a lot lower, but the higher gears are quite close. 4th and 5th are the same or nearly so, while 6th is just 8% lower. I, too, would rather have a higher ratio particularly in 6th, but you're not going to get much improvement with the NV5600. There's just not that much difference.

Also note the comment regarding weight. While researching trucks, I noticed that the gross weight of a manual 2500/3500 was higher than an auto (?!?), with a resulting lower load capacity. Some Dodge folks had attributed this to the weight of the manual transmission, which I dismissed as nonsense until I saw the above quote.

So with the G56 you get a 6 speed manual that's been in production since at least 2002 (the earliest press release I could find that mentions it), was designed for much heavier applications than we are ever likely to see, probably had a production history of at least a quarter-million units before appearing in our trucks, has very similar ratios to the NV5600, weighs much less (yielding better load capacity and MPG), and is in use across a broad range of MB and Chrysler products (leading to good familiarity and support at local dealers).

I wish my G56 had better gearing at the top end, but otherwise I'm really happy I have the G56 and not the NV5600.

v8440

You raise some very good points, and I feel better about my truck having a g56 in it now. One thing I have seen people concerned about (myself included) is the fact that the g56 has an aluminum case, vs the cast iron case of the 5600. The fear was that the case might distort under heavy loads, allowing gears to wear abnormally or even break. I have yet to see anything about that happening, so I guess they did their homework when they designed the case.

WACTD

It's definitely possible to build VERY strong closed sections from materials other than steel or iron - including aluminum. Frankly, the aluminum housing never even crossed my mind as a concern. I was far more worried about being the "first production year" (read: beta test site) on a "new, untested transmission". Knowing there is plenty of history from hundreds of thousands of production units before mine was built laid that to rest. My worries about it being too flimsy, as well, were answered by seeing it deployed by MB in their own medium-duty trucks.

I wish it were convenient to swap out the 6th (and perhaps 5th) gears, but otherwise I have nothing to complain about.

rammtuff

I too think the G56 is a fine trans. I do think that someone "oopsed" about the final drive ratios, and the G56 makes the truck rev higher on the interstate.
Aluminum is plenty strong. It just has to be mixed correctly. Acura makes a car, the NSX, which is almost totally aluminum and is a very stiff chassis car.
I believe people are afraid of change. 2nd gens came out people dissed them. 3rd gens came out too quiet. on and on.
The same people will crawl outa the keyboards and ***** and moan about the Asian 6 spd auto that is rumored to be in the trucks. Yes some will fail. Even some Cummins engines fail (stopped and helped a trucker with a '05 Cummins pulling doubles on I90 this weekend. A rod had windowed the block. It had 20k on it) Some people don't like the dual flywheel setup. We have not heard of masses of the G56 breaking on these chat boards (unlike 6.0 PSD problems)
If I could get a 3.55 diff ratio I'd rather have a g56. It took 100k for this NV5600 to shift properly. The G56 I have driven shifted well off the lot.

J BODY

I drove a G-56 equipped 06 with a Gear Vendors on it. THAT made the truck waaaaay better! Gave back the low rpm freeway cruising speed that most the g-56 guys miss.

Cargun

I like the comment about "higher power output". I assume that means the G56 is a more efficient trans than the NV5600. That means that even if it has a lower 6th gear it may get better MPG because of improved drivetrain efficiency.

signature600

Yep, spend $40K+ then have to put a $2000 OD on it Just one more thing to go wrong, but then again, that's why I drive a '95, not an '05

The NV 5600 made MY truck waaaaay better, too

But remember, to each his own I wouldn't mind a stout aluminum tranny, but I want highway gears, too!
Chris

WACTD

That was "higher power INPUT". I presume that means the G56 can handle greater incoming power from the engine than can the NV5600, which suggests the G56 is a stronger unit overall.

Cargun

Doh... that's what I get for trying to comprehend stuff in the morning

HeadsBikesMopars

I too have an '06 with the very good G56 trans. and I do like it. Shifts really smooth. Only thing is reverse location..not really a problem..just an adjustment is all. 8% lower in 6th?? 8% is a little over 150 rpm @ 65 mph. Not really a big problem for me. JMHO, Terry.

IA_James

The G56 having reverse the same as 1st ratio-wise is very cool, backing a trailer in reverse is too fast with 3.73's unless feathering the clutch. However, I spend ALOT more time in 6th than R.

Windscreen

Show me some hard data that says the G56 has a higher input rating than the NV5600. The only Benz data I've seen is on the link above that quotes 580 Nm (428 ft*lb). That said, the link to the Benz medium duty truck page shows an application with the G56 that has an engine making 498 ft*lb. You'll also note that the next size up truck that makes 597 ft*lb goes to the beefier G85 trans. That's about the same torque as our ISBe Cummins.

Now, I haven't seen any definitive specs for the NV5600, but a quick Google search turns up input torque ratings quoted anywhere between 550 and 650 ft*lbf. Either way, significantly more than the G56's rating. Its possible that MB just is very conservative on their rating. As folks start hot rodding and turn up the torque on their engines, we'll see if the G56 holds up as well as the venerable NV5600.

Steve

MikeyB

If I remembered correctly the duty rating for the NV5600 and the G56 is about the same. We are not talking peak torque rating, but overall torque rating for the general life of the transmission.

MikeyB

WACTD

Also, keep in mind that ~50% of the power generated by the engine goes right out its exhaust ports. That's what powers the turbocharger, which itself recovers roughly half of that power and is one of the reasons our engines are so much more efficient than normally aspirated ones.

Jeff in TD

Good info WACTD.

I know that the difference in the ratio of 6th isn't that significant, but to me the NV's 6th gear is too low as it is, and the G just makes it worse. If you were going to tow heavy all the time, or drive on 55 mph highways it would probably be fine, but if you have occasion to try to keep up with traffic in a 75 zone for an extended period of time the engine is really wound up.

Also, I found it interesting that a company that deleted rear wheel liners, deleted passenger door key hole, and stopped painting radiators in an apparent effort to save a few bucks would turn around and put in the more expensive DMF with the G?

Anyhow, I don't have anything against the G, or alloy case transmissions, I just suspect that the decision was made to not spend the extra money to have a version of the G built with ratios more suited for our application...