NV5600 vs. G56

[Wayne M.]

Thanks Gary. I feel the same, but I have a body resto planned, and fluid film treatments planned going forward.
I’ve never done anything with the clutch or trans other than change the oil. I must have 2 million shifts on it and it feels fine, but I feel that the slave/ master is going, so I will replace that soon. Don’t worry, I’ll be PMing you on clutch ideas when the time comes.

 

[RVTRKN]

My brother will not sell me back my 04.5 . He looked all over the internet for a low milage 6spd NV5600 truck and never found one in 2010. So he asked me if I'd sell him mine, so I reluctantly agreed, besides I had two CTD's. Comifornia wanted me to DPF it, claiming I was now a fleet, by 2013 (if I remember correctly) I did tell them to go pound sand that it is a private vehicle, but I'd still have to fight them. Boy do I miss that truck, I don't need the 3500 anymore and that 2500 would pull all of my toys. But when my G56 blows up, it'll be a better truck, with the NV5600 installed.

I learned right after I bought my 04, that 05’s have a rams head on the tailgate. 04’s don’t.

And I went stait into the parts department and bought one for my 04.5.

 

[EricViviano]

I own both.

Having to rebuild the NV5600 right now due to synchro failure. Caused by lack of lube/incorrect lube by previous owner. Be sure to dump 6 qts of oil in through the shift tower on a stock trans. Runs Amsoil Synchromesh fluid. Heavier pedal effort as noted especially with aftermarket clutches, cured by HD hydraulics from South bend/Valair. The 5600 was also noted for having weak snychro springs, CDX makes some nice upgraded springs for firmer crisper shifts. The extra oil is necessary as the fill plug does not achieve the correct lube level.

G56 has the garbage dual mass clutch. After you get rid of that, it's a great trans. Owned lots of them. There are MANY opinions out there on lube, what I like is to fill with the factory spec of ATF+4 then 1 qt of Lucas synthetic oil stabilizer through the shift tower. Quiets the trans with a regular clutch and adds a bit more viscosity.

 

[Jnemjo]

I've been driving a G56 for the last 5 year's in a 2006 3500 dually 4X4 crew cab. I primarily commute but I tow/haul all the time. Hay, gravel, sand, flooring, furniture, etc. The only thing that makes that truck actually work is towing our approx. 14,000 lb horse trailer about eight times a year. One of those times is from Vancouver, WA to Tulsa, OK and back through the Rockies in June. At 100,000 I up graded the clutch and flywheel with the South Bend G56-OK-HD. The solid flywheel makes the G56 chatter like crazy when under 1,000 RPM's. South Bend recommend replacing the ATF+4 with Schaeffer 239 S Superlube and to add one more quart than factory recommend. It reduced the noise by half. It does run hot for a manual but that might be why the G56 has an aluminum casing to help get rid of the heat. I installed Fast Coolers where the PTO covers are with a TDS cap on one side that allowed me to install a temp probe. Driving empty it runs around 140 degrees Fahrenheit. Towing the 14,000 lb trailer around 200 degrees Fahrenheit. Also I do run a mild tune. Calibrated Power CSP5. I wouldn't worry about the aluminum case as long as you don't plan to run 1,000 HP, drag racing and sled pulling. Engineered correctly aluminum can be pretty strong. Also I heard somewhere most folks don't know the G56 is supposed to be rebuilt approx every 150,000 miles. Personally I love my G56. The clutch is soft to operate even with the aftermarket clutch and it shifts so smooth, still with 120,000 miles on it. My buddy has a NV5600 and to me it's like driving a tractor. Clutch is stiff, shifting is clunky. This is just my experience and opinion with the G56.

 

[RVTRKN]

The G56AD will run cooler because of the lower gearing. With my 07 G56AE, the temp when unloaded will easily get over 200*, any load and its over 250*. But the cooling system I developed, I can keep it in the 160*-180*. Are you running 4:10 rear diff as well?

 

[GCroyle]

My buddy has a NV5600 and to me it's like driving a tractor. Clutch is stiff, shifting is clunky. This is just my experience and opinion with the G56.

If you really want to compare trans to trans then each trans must have its OEM design flywheel, fluid and all clutch components and not be worn out.

You can take either of these trans and make it miserable with an old worn clutch, not up to specs hydro's, wrong non OE fluid not mention mileage and condition of the trans. A stock disc is the quietest and the HD disc almost always compromises the noise limiting characteristics of the torsion damper in favor of a torsion damper that is stronger but less able to dampen gear noise. And changing the facings from fiberglass to a different facing, almost it's own thread. You're gaining torque capacity and an almost certain compromise to engagement smoothness.

I just put a stock clutch in my 203K+ NV5600 (not rebuilt) and a fresh fill of Valvoline Syncromesh, correct hydro's and it puts a smile on my face to drive it and shift it.

Gary

 

[Jnemjo]

Are you running 4:10 rear diff as well?

3.73. I think it was you that posted pictures of the cooling system you made for your G56. I was sure to save them. Very cool and if I ever decide I need it as well, will be doing the same.

 

[BDaugherty]

Im coaching a friend to buy a 5.9, and I may be going to drive a G56 truck this week. I’m so used to my 5600, I’d like to get some feedback as to some characteristics of this gearbox, and anything to be on the lookout for.

TIA!

IF a G56 clutch has been converted to a solid flywheel, the hydraulics will probably be unique to that setup. Not a big deal until you have to replace them. Just one thing to know or try to find out in advance. I wouldn’t want to be the shop trying to figure out why a clutch won’t work right even with new hydraulics.

 

[Wayne M.]

I appreciate the advice and enjoy the exchange on this thread, but regarding the OP, this truck thing won’t happen for my friend. Yet. He’s pretty much sold on getting one, it’s just when.
Thanks again.

 

[jgillott]

I appreciate the advice and enjoy the exchange on this thread, but regarding the OP, this truck thing won’t happen for my friend. Yet. He’s pretty much sold on getting one, it’s just when.
Thanks again.

Did the one he was interested in not work out?

 

[Killgore]

I am really enjoying this discussion; (my antique and its' operator, an old relic). Turning 290,xxx trouble-free miles, my AD version is primarily used to pull our 19,500 lb. home on wheels. The tune is stock, but after replacing the injectors years ago I added all kinds of additional filtration. The G-56 sports the South Bend G56-OKHD with their hydraulics, Trans-Cool units on the PTO ports, and an analog gauge. Yes, when Mobil SHC-DC became unavailable I started using Delvac 50 based on test results conducted by somebody with impressive credentials, and I overfill by an additional quart based on knowledgeable opinions on here as well as the recommendations of Standard Transmission in Ft. Worth. My temperatures running all over the South during the heat of Summer approach 220 degrees and according to Standard Transmission this is not detrimental although when approaching this point I back off on the throttle. When shifting, I go through the gears like I am driving a Mack truck, with that little pause or double-clutching 2-3 and 3-4. There is a fair amount of racket from the transmission which I associate with the SBC clutch , but removing my hearing-aids makes it all bearable. I appreciate being allowed to inject my experience although I can't make a comparison between the G-56 and NV5600. The G-56 has served me well.

 

[jgillott]

I am really enjoying this discussion; (my antique and its' operator, an old relic). Turning 290,xxx trouble-free miles, my AD version is primarily used to pull our 19,500 lb. home on wheels. The tune is stock, but after replacing the injectors years ago I added all kinds of additional filtration. The G-56 sports the South Bend G56-OKHD with their hydraulics, Trans-Cool units on the PTO ports, and an analog gauge. Yes, when Mobil SHC-DC became unavailable I started using Delvac 50 based on test results conducted by somebody with impressive credentials, and I overfill by an additional quart based on knowledgeable opinions on here as well as the recommendations of Standard Transmission in Ft. Worth. My temperatures running all over the South during the heat of Summer approach 220 degrees and according to Standard Transmission this is not detrimental although when approaching this point I back off on the throttle. When shifting, I go through the gears like I am driving a Mack truck, with that little pause or double-clutching 2-3 and 3-4. There is a fair amount of racket from the transmission which I associate with the SBC clutch , but removing my hearing-aids makes it all bearable. I appreciate being allowed to inject my experience although I can't make a comparison between the G-56 and NV5600. The G-56 has served me well.

I am also running the South Bend G56-OK-HD. Great towing clutch by the way.

I have stuck with ATF-4 in mine. My noise isn't that bad actually and shifts smooth as silk. I got a chuckle out of your hearing aid comment. I also wear hearing aids and I call it wife mode (mute). Without them on, I can't hear it anyway so it certainly doesn't bother me.

 

[Wayne M.]

Did the one he was interested in not work out?

He’s not ready yet. He’s primarily a biker that wants to ramp the bike in back and drive to locations he’s gotten too old to hit anymore on 2 wheels and nothing else, And lo buck camping. That’s why he wants a 8 footer.

 

[jgillott]

He’s not ready yet. He’s primarily a biker that wants to ramp the bike in back and drive to locations he’s gotten too old to hit anymore on 2 wheels and nothing else, And lo buck camping. That’s why he wants a 8 footer.

For his use, any old regular cab long bed would fit the bill.

 

[Wayne M.]

For his use, any old regular cab long bed would fit the bill.

True, but I think he wants to eventually blend in a RV into the mix. Also he’s a diesel mechanic/ gear head as well, and wants the ultimate, somewhat affordable Cummins experience. Pre emission is the only way to go.

 

[RVTRKN]

I see you have a 07 built before 1/1/2007, what is the G56, is it an AD or AE version?

I am also running the South Bend G56-OK-HD. Great towing clutch by the way.

I have stuck with ATF-4 in mine. My noise isn't that bad actually and shifts smooth as silk. I got a chuckle out of your hearing aid comment. I also wear hearing aids and I call it wife mode (mute). Without them on, I can't hear it anyway so it certainly doesn't bother me.

 

[jgillott]

I see you have a 07 built before 1/1/2007, what is the G56, is it an AD or AE version?

AD. Oct 2006 build 5.9.

 

[RVTRKN]

Then I'll assume the G56 for the 5.9 is the AD and 6.7 is the AE.

 

[jgillott]

Yes, except for a few 5.9's that were built right at the end of the run. Motorhead's truck was a December build and he has the AE with the 5.9l.

 

[jetsbiker]

Dad put 160K hard towing miles on his 06, all with more power than stock and never had a single issue. His DMF even made it to 120K miles and was replaced prior to failure.

At 160K miles his G56 shifted beautiful, and often better than my NV5600 with fewer miles... and my NV5600 shifted better than every other NV5600 I had driven.

I know @RVTRKN made a cooler for his, but based on the sheer number of them on the road, with more power than any OE NV5600, and a higher GCWR than any NV5600 if they had issues there would be a lot of info on them. There just isn’t any, they are a pretty damn tough transmission. If you look around here it’s always the same few folks bashing them.

No doubt the NV5600 is a great transmission, but so is the G56.

At one time I considered swapping a G56 in for the better towing ratios but couldn’t really justify the cost.


Long story long... he should be good with either trans, assuming they have been properly maintained.

I have the G56 in my 2006 Ram 3500, no issues after 245K miles. I have a smarty tuner and lift kit.