what happened withe G56 SBC was tearing apart

[ilovetrains]

Ahhh, but all of those tcase HAVE a different designation... the NP241D, the NP241DHD, the Rubicon is a NP241JR (IIRC), and there is a NP241C (chevy), and others I presume... and a D44HD is the same as a D44 short of number of lugs at the wheel (general statement, I know there are a few oddballs)... they all have 16 spline (old) or 30 splines (new) at the carrier, they all have 1-1/16 (old) or 1-3/16 (new) ujoint caps... and ALL those D44s have different designations D443BFJ, D443EF, D443CF, etc, etc, etc... in general short of the addition of CAD, the center portion of a D44 hasn't changed much since 1970.



So I would expect the same for the G56 (maybe we aren't privvy to that information??). And the NV4500 had the upgraded input shaft midproduction... I don't believe the NV5600 was ever really "touched", but I agree with the numbers... they can write down different numbers all day long that look good, but are for conditions we would never see (ie. low torque, high HP, hi torque, low HP, low speeds, hi speeds, etc, etc, etc. ).



steved

That is much of my point. Ask someone what transfer case they have and they will respond 241, even though the internals may not have one piece in common with another 241. I cannot wonder if this is the case with the G56. I am not making any blanket statements here, but I do have some faith in DC designers and engineers that they would not replace a proven transmission with one that is rated to handle significanlty less power.



We all throw around the G56 nomenclature because that is what a build sheet tells us is the transmission name. What if this is actually a G56HD or G56C or whatever else they might call it.



I bring up this point becuase people here keep saying this is the same transmission used on Europena brand medium duty trucks but I have not seen anyone link to something that backs up that statement.



If someone knows more about this, please chime in here.



We have heard from other psters that service techs who went to class for the G56 were surprised by how beefy it is, etc.

 

[hasselbach]

You don't get to use all 600 or 610 ft-lbs of torque in the lower gears. The computer reduces the output until your in 3rd or 4th. That is how the transmission can be rated like that. I don't know if the auto is the same. You are not putting the same kind of stress on the transmission in the upper gears. This info was printed on the bottom of a dyno chart from Cummins.

No true, a common misconception.

 

[AKAMAC]

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



A DC site with production info.

 

[Gary - K7GLD]

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



A DC site with production info.

MORE to the point, is THIS quote:



"Transmissions G56, G60 and G85 have the respective torque of 580, 600 and 850 Nm. Model G56 is applied to light vehicles, from 7 to 10 tons, and medium ones from 11 to 12 tons; model G60 may equip medium vehicles from 12 to 14 tons, and semi-heavy ones from 14 to 17 tons; and model G85 is destined to heavy vehicles. "

 

[tsi_2baad4u]

Okay, 580Nm is 427lb ft as stated earlier. Yes the quote is there. I think there is some merrit in the fact that this page is from 2002. Could they have changed the G56 between 2002 and early 2005 and made it stronger? Time will tell.



I'm hard headed. I still don't believe that DC would select a transmission not capable of holding even factory power. Bean counters just don't miss that kind of stuff. I think there is more behind the scenes than what we have info for.

 

[nickleinonen]

Bean counters just don't miss that kind of stuff.

unless they colabrated with the engineers who designed that transmission and found out how much load it could take in all the gears, and found it acceptable in strength for a stock output engine... ? say the transmission was underrated/overdesigned to accept ±150% the torque input of it's rating, then it would fall right into the power band that the 600's make right now [427x1. 5=640ft/lbs]

 

[steved]

Or DC hoping for a lot of manual transmission work to keep their auto trannies from feeling lonely!



I agree... that is sorta what I stated above... a transmission can have different ratings dependant on the RPM, input torque, input HP, vehicle weight, duration of loading, peak torque vs continuous torque, etc, etc, etc. There are a bunch of varialbes... as long as the selected ones provided a "good" range, then they use it.







steved

 

[opjohnny]

Look at page 29 TDR issue 45 in the fine print above the torque output table it says "(Torque Mgmt. set to 460 ft-lbs in 1st gear )". I knew I read that someplace. So I was wrong about 2nd and third. The truck must have a way of knowing it is in 1st. That is how you can keep a less then 600 ft-lb rating on the NV5600 behind it.

 

[jwilliams3]

I know I get full power out of 2nd gear.

I hit 50psi sledpulling in HI range when in 2nd gear.

 

[ilovetrains]

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



A DC site with production info.

That is interesting. A 2002 news release regarding transmission to used in commercial service in Europe or Southern America. So three years later DC starts using a transmission with same model designation, but presumably it must have different capacities to meet the requirements of the vehicle it was placed in.



Does DC not have some internal figures that they rely upon in rating vehicle equipment? There are enough DC employee's on here that they should be able to tell us.

 

[hasselbach]

Look at page 29 TDR issue 45 in the fine print above the torque output table it says "(Torque Mgmt. set to 460 ft-lbs in 1st gear )". I knew I read that someplace. So I was wrong about 2nd and third. The truck must have a way of knowing it is in 1st. That is how you can keep a less then 600 ft-lb rating on the NV5600 behind it.

Only for commercial vehicles, not our trucks does this apply.



Service manual states differently.

 

[klenger]

Where is this discussed in the service manual?

 

[opjohnny]

This chart is from Cummins and states that it is for the Dodge version. Has anyone ever seen max boost in 1st gear? In a 325 hp version? The waste gate is computer controlled is it not?

 

[hasselbach]

This chart is from Cummins and states that it is for the Dodge version. Has anyone ever seen max boost in 1st gear? In a 325 hp version? The waste gate is computer controlled is it not?

The only wires connected to the NV5600 are the back up light wires. There is no sensor wires which tell the computer which gear the truck is in, so I'm not sure how it would actually interface with the computer for gear selection. (unless there is a pigtail connection that I am unaware of).



Also, the least stress that a transmission has to it is in first gear (other than the output shaft). The input shaft and internal gears have the least amount of load on them in the lower gears (less resistance against torque input). So if in fact torque management actually occured say in first gear, then it would be to preserve anything post output shaft, not to preserve transmission parts.



On the duramax for example, in first gear low (4wd only), torque is controlled in first gear, but not to preserve allison, but rather for the transfer case, ie as stated in service manual as well.

 

[hasselbach]

Where is this discussed in the service manual?

In my 2004 service manual, it is somewhere in the ECM section. I have loaned out my manuals, so I can't dig it up right now.

 

[Bob V]

The only wires connected to the NV5600 are the back up light wires. There is no sensor wires which tell the computer which gear the truck is in, so I'm not sure how it would actually interface with the computer for gear selection. (unless there is a pigtail connection that I am unaware of).



The ECM can figure what gear you are in by engine RPM and vehicle speed, but I agree, lugging in 6th gear would be harder on the tyranny than running in 1st gear. However, the torque multiplication through the trans would be harder on the transfer case (if you have a 4X4) and drive train, and that is more likely why there might be a power reduction in the lower gears.

As far as the G56 All we can do at this point is guess of how they will hold up. I am not worried at this point, they have some miles on them now and they are not failing at a high rate. I honestly think that for the most part DC has been doing a good job in making sure the drive train is up to the task. Input torque ratings may not mean a whole lot as one manufacturer may post the max torque for intermittent use and the other my be constant duty, with two different manufacturers, who knows how they get their numbers.

Bob V

 

[JayWm]

stock until my wife goes out of town again.



That's a good one..... Oo.

 

[ilovetrains]

The only wires connected to the NV5600 are the back up light wires. There is no sensor wires which tell the computer which gear the truck is in, so I'm not sure how it would actually interface with the computer for gear selection. (unless there is a pigtail connection that I am unaware of).



The ECM can figure what gear you are in by engine RPM and vehicle speed, but I agree, lugging in 6th gear would be harder on the tyranny than running in 1st gear. However, the torque multiplication through the trans would be harder on the transfer case (if you have a 4X4) and drive train, and that is more likely why there might be a power reduction in the lower gears.

As far as the G56 All we can do at this point is guess of how they will hold up. I am not worried at this point, they have some miles on them now and they are not failing at a high rate. I honestly think that for the most part DC has been doing a good job in making sure the drive train is up to the task. Input torque ratings may not mean a whole lot as one manufacturer may post the max torque for intermittent use and the other my be constant duty, with two different manufacturers, who knows how they get their numbers.

Bob V

That is an interesting point. If the G56 units that the 2002 press release is making referenced to were rated for continous input being that they were intended for commercial use, we may be talking apples and oranges here.

 

[dmurdock]

That is an interesting point. If the G56 units that the 2002 press release is making referenced to were rated for continous input being that they were intended for commercial use, we may be talking apples and oranges here.

Yes, it would be continuous. The only people who use max figures are salesmen and people engaged in ******* contests. :-{}

 

[steved]

dmurdock: You don't know that... as far as I can tell, GM, DC, and Ford are all in a ******* match to see how much HP/TQ they can make.



Think about it... your truck is actually putting 600ft-lbs of torque to the drivetrain for how long? Once you roll down the road, how much does it need then? At last check, the big three were in a race for the top... they aren't going to change trannies everytime they up another 10 ft-lbs of torque (over that said transmission's rating)... they are more worried about sales than overall durability... that is why they have service departments.



GM is getting up to the HP/TQ point in stock form that the allison was already failing with just a box added to the previous generation... as far as I know it is the same allison... they just allowed the computer to finally shift into 6th gear. All the LT makers are starting to push the limitations of their equipment... when do we say that buying a small International to tow out 20k pound toys is a better option than towing it with our pickup???



And DC definately didn't change from the NV5600 to the G56 because of durability issues of the 5600. They did that for sales... easier shifting and quieter trannies bring better sales...





steved