Choosing a g56 vs a nv5600

[KPear]

Hello all. As of late, I have been looking for used 5.9L cummins Rams (2005-2007 era). I am looking for the highest outputs they made with that engine (325hp, 600-610lb-ft). I am also looking for something that will be reliable and last a long time with basic maintenance and repairs. For these reasons I've been looking at getting a 6 speed manual vs an auto. I've focused in on the G56, due to its higher gearing, which I think will be useful since I plan on putting 35" tires on the vehicle as soon as I get it. I am looking for feedback in regards to a few issues:

1) I've heard that the NV5600 is generally considered a tougher transmission, due to its iron construction (vs the g56's aluminum) but that it doesn't shift as "nicely" (subjective I know) as the g56. Is that correct?

2) Is the g56 generally reliable with basic care/maintenance? I have no plans whatsoever to tune this engine for horsepower or drag times. I plan to turn this vehicle into a travel/hunting/exploration rig, so I have no need to mess with the engine. Should the G56, despite its "weaker" construction, be fine in that situation, other than perhaps replacing the dual mass fly wheel?

3) Is the G56, in stock form, able to handle oversized tires, like 35"?

4) Are parts for the NV5600 hard to get since New Venture went out of business?

5) Are there any reasons, which I haven't already noted, why I should consider one transmission over the other, given my intended use for the vehicle?

I have keyed in on the g56, but if push came to shove, I wouldn't be opposed to buying a truck with a NV5600 as well, so long as parts and replacements are available. I guess I'm just looking for feedback on if either one will be better suited to my needs. Thanks.

 

[Regcabguy]

The G-56 has tighter gates and is plenty stout. Consider chucking the dmf stock clutch and replace with an SBC smf clutch and swap the ATF+4 fluid with Amsoil MTG 75-90. Mine's got 70K on it carrying a 2K# camper,35" tires and + 130 rwhp. The maintenance records are what is important. Either trans is fine. The OKHD will handle my 9K# load,35's and Smarty sw#7 5th floored Zero slip. The whole setup is near silent. Stoked.
Salta wheels someday.

http://www.aev-conversions.com/shop/salta-hd-trim-ring

 

[jgillott]

Over 100K on my G56 on the stock clutch. As mentioned above, the DMF is the major issue.

 

[Tuesdak]

Both transmissions wear out. You can build the automatic to take some power. Just get used to the idea of buy a truck and then $mod$ the transmission. Torque Converters are a complete world of there own say if you stall it for a big turbo. You should look at all years and then drop the programmer on it for the power you want. Frankly the HO 2003 has enough power stock out west in extreme grades unless you want to drag race lights. (This viewpoint is from towing extreme grades aka holding or getting up to the speed limit.) IMO HP wars, power levels, above that are nice but cost transmissions, MPG, and really are not needed. The Manual Transmission WILL slow you down over an automatic. Keep that in mind when shopping.

The single advantage to the NV5600 is the higher OD ratio than the G56 in the pre-emission years. Some say there isn't enough main shaft supports and the aluminum case flexes too much on the G56 when used hard.

The NV5600 is heavy and requires oil changes often, IMO at 20K miles, as it shears it's oil down. Must be overfilled by 1 quart. It is spinning all the gears all the time. As it's heavy it takes time to change speed and gears period. You literally can feel when it's ready to drop and and don't be afraid to double clutch it. It is flat temperamental when cold. PTO oil coolers are a good idea to add as well as the Eaton Fuller string filter Gino's Garage sells. Or Quad 4x4 as Gino's doesn't list the full kit at the moment.

Don't lug it in OD or any other gear. It's a Manual and this means you have to change gears often as the situation calls for it. I see firsthand the engine and transmission damage done when you just leave it in 6th while towing as the PO did to my truck. This said you have a lot more control with a MT as to the gear and pushing in the clutch stops the engine from pushing you no matter what the ECM is wonked out on and doing. (Some vehicles I have owned the ECM tries to push through the brakes and stop signs as the throttle won't back off reliably when commanded to do so by my right foot.)

To get the best feel out of a NV-5600 replace the shifter bushing on the end of the stick. Core Shifters has them. This tightens the gates up some.

You will read about fussy oil as some transmissions like a specific oil as they shift better.

Parts are available for the NV-5600. IMO not enough advice is given out to just freshen the damn thing up now and then and get the "flat" worn out syncro's replaced. IMO if you have it out for any reason spend the $1200 to have it freshened up. Making a mod to lube the rear bearing should be done at this time. Standard Transmission and Gear of Tucson or Texas are very good choices. Still shifts slow vs a sports car, but, much improved feel with less bump and grind shifting.

 

[KPear]

Thanks for the feedback. Like I said earlier, I'm not deadset on getting a truck with the G56, but the higher gearing does make more sense due to the tire size I plan to use.

That said if I find a truck with the NV5600 for a good deal, I wouldn't hesitate to buy it. It sounds like both transmissions are fairly reliable at stock power levels, though I'm not too sure about spending $1200 to "freshen up" the NV5600...I'd much prefer to have a transmission that requires basic maintenance and thats it.

 

[cerberusiam]

I'd much prefer to have a transmission that requires basic maintenance and thats it.

An ideal that is much easier ascribe to than achieve. There isn't a transmission in the lot that is rated to be behind the ISB, compromises have and will need to be made. IF you drive it correctly, IF you maintain it correctly, and IF you got parts are up to the task it will be quite reliable. Any of them will be.

However, it takes 60 seconds or less stuck in bog hole to undo all that and require a tow home. Inherent problems of LD parts mated to an MD power plant.

 

[Shadrach]

When I bought my 03 the NV5600 was in need of repair, as was the engine - so I never drove it in stock form. I had driven company truck with the NV5600 before. I chose to replace it with a G56, an 08 version, because of several reasons. One was the gear ratios. I used a SBS Con OFE clutch and it handled the modified and fresh 305 HO engine just fine. My friend chose to replace his Getrag in his 93 with the same version of G56 and clutch. He is pushing 400 HP and the truck weighs about twice that of my 03. Neither of us had any issues with the transmissions. He will also be replacing the NV4500 in his 97 with a G56 soon. Because we are in a colder climate than most of you we used ATF+4.

My current truck has 6 speed auto ( 68RFE) and I like it.

David

 

[Grizzly]

I have an early 05 with the NV5600 and I'm glad it came with that transmission. I'm happly with it and have never had an issue with it. The big reason I wouldn't want the G56 is the DMF. Sure it can be changed out for a SB for a sizeable sum of $$$. My good friend and nieghbor has an 06 DRW with the G56. He's had issues with it and wishes he had the NV5600. I'd look for a 04.5 or early 05 with the NV5600.

JDoremire's post #4 is very good and informative.

 

[AH64ID]

There are two different gearing options for the G56. The AD ran from 05.5-07.3 and, aside from 5th, is geared lower than the NV5600. The AE ran from 07.3-07.4 (very few of these) and has a lower 1st and 6th, identical 5th, and higher 2-4.

Personally I think the ratios in the AD G56 are ideal for someone who tows. My dads 06 has this trans and I really like the gearing over my NV5600. The OD ratio on the NV is only a benefit when empty at 65 mph plus, which isn't very common for me. Over 70% of my miles have been towing this year.

My NV5600 does shift much better than the G56 in my dads 06 and the G56 in my buddies '10. Both of which I have a decent amount of miles in.

Yes the NV has the iron case that is supposed to be stronger but the G56 has been around longer and with more hp (07.5+) and torque (13+) than the NV ever received stock. The G56 is not a weak trans, thou there are a few that think it's pure crap, and has lived well behind the CTD. The DMF is a weak point thou, as mentioned.

 

[Motorhead]

I own one of the 5.9, 2007 that has the AE ratio, G56. Same trans that was put behind the '07.5, 6.7 ltr engine. I bought the truck new with the advice from the guys here on what to look for as far as production dates to get the AE trans. It has a .74 6th and towing with oversize tires (285-75-17), I felt a little over geared in 6th. 5th gear or direct, same ratio on both G56's, was nice in that on long 15 mile grades, I could run 55mph and not be running the engine speed at 2400 rpm or so. The NV5600 has a .72 6th I believe and would be geared higher yet with over sized tires. If you want to run 35's and keep the 3.73 diffs, you might be best served with the AD ratio, G-56 as it has a .79 6th. And as said above, will be better for towing. I ended up putting a stock set of tires back on for towing and I put the OS tires and wheels back on after travel season. I ALSO am very careful about towing the hills in 6th. I limit 6th to no more than 10 psi boost on a long hill in 6th otherwise I down shift. I ditched the ATF early on in my trans and the DMF. I ran the Synchromesh oil for a while and now run DELVAC Full Synthetic 50wt transmission oil. I am currently running the South bend clutch and it has worked well.

 

[Tuesdak]

Thanks for the feedback. Like I said earlier, I'm not deadset on getting a truck with the G56, but the higher gearing does make more sense due to the tire size I plan to use.

That said if I find a truck with the NV5600 for a good deal, I wouldn't hesitate to buy it. It sounds like both transmissions are fairly reliable at stock power levels, though I'm not too sure about spending $1200 to "freshen up" the NV5600...I'd much prefer to have a transmission that requires basic maintenance and thats it.

Frankly it's a flawed plan to choose a transmission because you think you can get away with not having to rebuild it. You have no idea how the PO abused it and that doesn't even count random failures that kill a transmission. Yes, you can get long life out of one, but, don't bank on it. The Dodge autos are not noted to be reliable at stock power levels. Neither is the NV5600 with the low factory oil level and rear bearing lack of lube locking it up ruining the case problem. Add more oil and PTO coolers to get the heat out of the cast iron case appear to be cheaper than modding an auto. Automatics cost more to mod. Basic rebuilds start at $1200. Any hard parts add to the cost. The NV5600 number was with bearings and syncros only. A clutch job can cost $2000 for parts and labor if you get a good expensive aftermarket clutch.

So with clutches being a wear item there really isn't any savings over the auto. The NV5600 without the DMF could be cheaper IF you don't have to do a clutch as odds are the G56 DMF will fail on you. The G56 being lighter you may haul out yourself to save labor cost.

Don't forget the cost to haul the transmission out as the NV5600 can be turned down by some shops that don't have equipment rated to handle it. Cost being $5-800 to haul it out for a clutch etc. another $1200 to freshen the trans up at that time is a good idea esp if you are doing the NV5600 case lube mod.

The MT's are approved for an exhaust brake where the auto's are not - year specific. Engine braking in general is another discussion.

Transmissions behind a automotive diesel are a wear item. Always have been vs. the life of the diesel engine. Some of the newer autos are changing this reputation, but, not pre-emissions Dodge transmissions.

Pick a truck you like and have a warranty or cash in the bank to overhaul the transmission when that day comes. Same for injectors and other expensive wear items. Not the end of the world and no reason to avoid a truck because of the rep of the transmission. Now Emissions are another story worth avoiding model years over.

 

[RVTRKN]

Had/have both, hands down the NV5600 is far superior than the G56, in fact I'm getting ready to convert my 07 to a NV5600. They run hot when repacing ATF for the heavier favored oil. Mine has cost me a lot of money in SMF and a cooling system for it. Will post more later.

 

[RVTRKN]

Hello all. As of late, I have been looking for used 5.9L cummins Rams (2005-2007 era). I am looking for the highest outputs they made with that engine (325hp, 600-610lb-ft). I am also looking for something that will be reliable and last a long time with basic maintenance and repairs. For these reasons I've been looking at getting a 6 speed manual vs an auto. I've focused in on the G56, due to its higher gearing, which I think will be useful since I plan on putting 35" tires on the vehicle as soon as I get it. I am looking for feedback in regards to a few issues:

1) I've heard that the NV5600 is generally considered a tougher transmission, due to its iron construction (vs the g56's aluminum) but that it doesn't shift as "nicely" (subjective I know) as the g56. Is that correct?

Yes, it is a tougher trans, and it did seem a little notchy, but only when it/mine was cold.

2) Is the g56 generally reliable with basic care/maintenance? I have no plans whatsoever to tune this engine for horsepower or drag times. I plan to turn this vehicle into a travel/hunting/exploration rig, so I have no need to mess with the engine. Should the G56, despite its "weaker" construction, be fine in that situation, other than perhaps replacing the dual mass fly wheel?

Yes, the trans is reliable as long as you don't exceed Dodges GCW ratings. The DMF can last as long as you are not hard on it.

3) Is the G56, in stock form, able to handle oversized tires, like 35"?

Probably, I keep mine at the stock size though, again its subject to your driving and usage.

4) Are parts for the NV5600 hard to get since New Venture went out of business?

Yes and No, Blumenthal's is Dodge's official rebuilder for this transmission and they now manufacture some parts for it, or sources out parts to rebuild them. They will sell parts as well, if you need them.

5) Are there any reasons, which I haven't already noted, why I should consider one transmission over the other, given my intended use for the vehicle?

Good question, but its subject to opinion. My opinion is, yes it would, but at the first sign of trouble it would be replaced with the NV5600.

I have keyed in on the g56, but if push came to shove, I wouldn't be opposed to buying a truck with a NV5600 as well, so long as parts and replacements are available. I guess I'm just looking for feedback on if either one will be better suited to my needs. Thanks.

Overall the G56 was designed for a different vehicle, it was designed for medium duty and was geared low in the transmission as well as the differential. So the low HP/Torque box trucks they were installed in probably had a better success story. Mercedes sourced them and changed the ratio's to replace the New Venture transmission. But they were not satisfied with the initial G56 for the CTD and changed the ratio's again, as the AD vrs AE versions.

 

[RustyJC]

The OD ratio on the NV is only a benefit when empty at 65 mph plus, which isn't very common for me.

That totally depends on the axle ratio. My 2002 ETH/DEE (NV5600) dually had 4.10s, and 6th gear was required for highway towing at speeds over 60 MPH.

Rusty

 

[AH64ID]

That totally depends on the axle ratio. My 2002 ETH/DEE (NV5600) dually had 4.10s, and 6th gear was required for highway towing at speeds over 60 MPH.

Rusty

Yes, but the G56 isn't offered with 4.10's in the pickup. The NV5600 and 4.10's has a similar final drive ratio to the AD G56 and 3.73's.

 

[RustyJC]

I made no reference whatsoever to a G56, and neither did you. Your statement was directed at the NV5600 and the use of 6th gear, as was my response. Please see the phrase I quoted - looks like a pretty clear, absolute statement to me.

Rusty

 

[6speed]

Have you guys seen what the temps are in the 5600 when towing in 6th. I have, and they get hot. try 240+. I always tow in 5th, but I have a GV in mine. I have 240K on my 5600, its filled with the extra oil and maybe a little more. Even when towing in 5th over (GV) it will still run 190. But so does the rear end with the Mag Tech cover. I'm every bit of 26K. They cool down fast when I stop for breaks, and it takes a while to heat again. Towing in 6th is not good on any of these manuals. But that is my opinion, and I sticking to it.

 

[RVTRKN]

Yes, but the G56 isn't offered with 4.10's in the pickup. The NV5600 and 4.10's has a similar final drive ratio to the AD G56 and 3.73's.

I take it that, thats the newer trucks. I chose 3:73 from two choices, 4:10 or 3:73 for my 07 C&C AE-G56 . Both trucks (look at sig) run @ 2050 rpm's in sixth @ 70 MPH

 

[AH64ID]

I made no reference whatsoever to a G56, and neither did you. Your statement was directed at the NV5600 and the use of 6th gear, as was my response. Please see the phrase I quoted - looks like a pretty clear, absolute statement to me.

Rusty

My comment was a comparison of the G56 and NV as that was the main basis for this thread. IMHO the G56 has a better OD ratio for using the truck to tow. That was my point. Since the G56 doesn't get 4.10's in a pickup I didn't bother with a NV and 4.10's.

The AD and 3.73's is great since 5th can be used faster and 6th can be used slower.

The NV and 4.10's is something I have heavily considered. It would be nice in 6th but I am not sure about the rest of the gears.

 

[RVTRKN]

Have you guys seen what the temps are in the 5600 when towing in 6th. I have, and they get hot. try 240+. I always tow in 5th, but I have a GV in mine. I have 240K on my 5600, its filled with the extra oil and maybe a little more. Even when towing in 5th over (GV) it will still run 190. But so does the rear end with the Mag Tech cover. I'm every bit of 26K. They cool down fast when I stop for breaks, and it takes a while to heat again. Towing in 6th is not good on any of these manuals. But that is my opinion, and I sticking to it.

You need to invest in this system I developed for my G56, running at 250*+ with only 15K GCW. The heat exchanger bolts up to any third gen Dodge CTD radiator, at least all of the ones I've looked at. The molding is there to hang it and bolt it to the radiator, even has the clips molded into the radiator for the lines that sweep from it. The 3rd gen radiator is the same for Manual or Auto equiped trucks. I turn it on @ 180* and it keep temps @ 160*-180*. The only question on the fit, are for the pre 04.5 CTD in Comifornia, due to the lower output than the standard/high output versions. I refused to purchase one until the 04.5 were available in Comifornia. I seem to remember a smaller radiator, for that version, but I might be wrong.