NV5600 vs. G56

[Wayne M.]

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!

 

[GCroyle]

Wayne,

I've spent time with my NV5600 and a bit of time with a G56 but it's been a few years since G56 shifting. I'm gonna take a pass on the straight stick vs the bent stick but I'll comment on the STOCK clutch feel possible issues. But I do think these are meant to be slow shifting boxes, don't race 'em.

NV5600 has a firmer truck pedal effort where the G56 feels almost like an import, much softer less pedal effort. That's the way their DNA is and just take either out hit 5th and floor it, doesn't slip? Good.

But where almost everything I mentioned above falls apart is IF the clutch is NOT STOCK then it's a whole new chapter of pedal and clutch signature.

I don't know what the parts availibility is NV5600 vs G56 but I'll bet the G56 variants is the longest running HD pickup transmission ever just based on model years in the market, mid '05 to what '18, '19, maybe '20? not sure but a long time. That should mean a strong parts market to service that trans with.

Gary

 

[AH64ID]

What year?

The NV5600 has a better stock clutch, but the likelihood of a stock clutch on a 5.9 G56 isn’t high.

If he tows the early AD G56 has an amazing OD ratio of .79. It makes the truck feel like it has an extra 200 lb/ft at 60-75 mph towing. If empty, it sucks some fuel!

 

[RVTRKN]

The NV5600 is the better trans, and the G56 is adequate at best. There is a good write up on the G56, which shows its weaknesses by Joe Donnelly in 06 (If I remember correctly), in the TDR magazine. I have 70K miles on both transmissions and I really miss the NV5600. The one known weakness with the NV5600 is the main shaft bearing lube issue. It is correctable, but the trans has to be rebuilt. I'd like to note that my brother has the 04.5 now, and has never had any trouble with it. Blumenthals is the official trans rebuilder for the NV5600 and manufactures parts for them. Ram had Blumenthals warranty them during the period that the NV5600 was still under warranty, but they were no longer available. The G56 runs hot and a real trans cooler needs to be installed to circulate the oil to a heat exchanger. I've spent thousands of dollars modifing the clutch and cooling system to eliminate the worst flaws of the G56, out of necessity. If a good condition NV5600 truck can be found, that is what I'd buy. When my G56 gives up the ghost, it will be converted to the NV5600. The G56 DMF is also weak, but keeps the G56 quiet, once its converted to the SMF it is noisey. You might want to recommend a Aisin auto optioned CTD, they are far superior and reliable than the 68rfe, and can easliy handle the torque of the CTD.

 

[AH64ID]

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.

 

[Wayne M.]

Thanks so far!
I didn’t intend this to be a debate session over the 2 units. I’m only looking for issues like the DMF, and how would I know there’s a problem with it?
Any shifting issues? I think I recall that they may leak!

It’s a ‘06 reg cab 8’ bed ST.

 

[GCroyle]

First does it still have the DMF?

The DMF's big failure mode is advanced internal DMF wear that causes trans gear noise. In particular a death rattle at shutdown or when you pull thru a drive in, window down, trans in N and engine running it's rattle time for trans. Early DMF's also had a bushing that allowed big vibration problems as secondary was wobbling and out of balance. Bushing got better in later models.

Isolating trans or DMF noise is really helped by knowing what clutch is in the truck rather than what clutch MIGHT be in there.

The DMF and its matching self adjusting stock clutch would be the quietest system but extra "stuff" adds complexity to what was a simpler system.

 

[CVR222NV]

I don't have any experience with the NV5600 but I replaced my first DMF at 99,000 under warranty with another DMF which was recently replaced (189,000) with a SBC DD3250 due to lost throwout bearing. I was definitely experiencing clutch slippage on the on ramp accelerating but didn't realize how much. I now know what it feels like when 100% of the power (stock tune) goes to the ground. Also really like the lower gearing in all gears of the G56AD transmission and is the reason I didn't swap out the 3.73's for 4.10's. I did a lot of research on transmissions recently because I thought I had a transmission problem but RVTRKN convinced me my noise issue was normal. However, it seems that there were certain transmission shops hot rodding the NV5600 transmission (1000hp). I didn't see that with the G56 apparently because of the aluminum case. In the end I think it was the DMF that was the issue with the G56 configuration and once that was remedied I really like how it operates. I'll also add that I spoke to the folks at Blumenthal and they are also the official Dodge remanufacturer of the G56 transmission.

 

[jgillott]

Wayne, the biggest tell tale sign for me with my failing DMF was that ongoing slight vibration that I had at highway speeds for quite some time. With the new clutch and single mass flywheel, that vibration is gone.

I have the early ratio G56. As mentioned earlier, the 6th gear ratio is a great towing gear. Mine was a October 2016 build and I have the AD ratio trans. I believe Motorhead's truck was a December 2016 build and he has the AE if I recall correctly. So, there was a very short build window for that AE trans behind the 5.9L.

 

[RVTRKN]

My 07 C&C was one of the first to get the new AE version. I believe over half way through the 06 MY, they switched to the AE from the AD. This was a horrible time trying to find out info on the G56, even postings about plastic gears. It was worse for me, because the two options for transmssions were the unknown Aisin and little known G56, for the C&C trucks with the CTD option in 06. The G56 AD was installed in very late 05 through late 06. In fact the 05 CTD production had stopped installing manual transmissions until the factory could be retooled, to support the G56. The AD version is very rare and is the better trans due to ratios that pull alot better and generate less heat. The G56 was designed by MB for the South America market for their medium duty box trucks. When MB put them behind the CTD, they found out the market didn't like the ratios with 4:10's, so they changed it to the current ratios. My 04.5 NV5600 and 07 G56 C&C has the same RPM's at 70MPH with the 3:73 rear diff.

 

[AH64ID]

Just to clarify, are you taking production year or model year? Nearly all vehicle talk is in model year, regardless of production date. My 05 was built in 04, but it’s referenced only as an 05.

The AD G56 ran from 05.5 thru early 07. It was only the last of the 07 5.9’s that got the AE G56, making the AD 5.9 more common and the AE quite rare. AD G56’s behind 5.9’s are not rare at all, as most of the G56’s behind the 5.9 have AD ratios.

You can look two post up and see how late in the MY07 5.9 run the AD was available.

Aside from a few, I want to say less than 100, OE mistakes, of which a recall was issued, 4.10’s were never offered with a G56 in a pickup. AD G56’s are often confused for having 4.10’s thou, due to their lower ratios than the NV5600 in all gears except 5th.

All 6.7’s got the AE ratio G56.

 

[Wayne M.]

Thanks guys. Still haven’t seen this rig yet. He’s doing his homework, and I’m trying to get him to join up here. He’s a very old friend of mine.

 

[jgillott]

Thanks guys. Still haven’t seen this rig yet. He’s doing his homework, and I’m trying to get him to join up here. He’s a very old friend of mine.

If it is a northeast truck and it has the original clutch and oil pan, factor ~$2000 to do both if he does the work himself with a South Bend Clutch and Cummins oil pan and related parts. I hate to throw the oil pan in the mix of things to look at, but he needs to consider that also if it is original.

 

[RVTRKN]

AH64ID, if thats the case, then the 07 MY (Model Year) C&C built in 06, should have the AE G56 which was offered with 4:10's. My 07 C&C was built early in 07. I will assume your correct about the 4:10 issue, it makes since. I never checked into the regular pickup builds on line, during 06 when researching my build for the C&C.

 

[AH64ID]

AH64ID, if thats the case, then the 07 MY (Model Year) C&C built in 06, should have the AE G56 which was offered with 4:10's. My 07 C&C was built early in 07. I will assume your correct about the 4:10 issue, it makes since. I never checked into the regular pickup builds on line, during 06 when researching my build for the C&C.

Yes you have the AE ratio, which can be noted by having nearly the same cruise rpms in 6th that the NV5600 has.

I haven't since the Aisin became available in a pickup, but 4.10's with a G56 has long been an option with the C&C, just not a pickup.

 

[RVTRKN]

My 05 was built in 04, but it’s referenced only as an 05.

Yes, you were one of the lucky few to get the NV5600 in an 05 MY.

 

[Wayne M.]

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

 

[GCroyle]

Yes, you were one of the lucky few to get the NV5600 in an 05 MY.

Me too! Oh boy.

I actually tried to get the G56 in 2005 when I was looking for a 5.9L, new technology etc. Dealer, yes we found your truck it's in GA be here is a day or two. Truck is transferred, I slide underneath and a monstrous cast iron case is smiling back, OK it's everything else I wanted, I'll still take it.

I'm at 203K on the NV5600 and just did a fluid change, found Valvoline has a syncromesh fluid with same Chrysler number as Pennzoil. Valvoline is in the trans.

https://sharena21.springcm.com/Publ...2d889bd3/1a3e1219-f005-e811-9c13-ac162d889bd1
https://www.valvoline.com/our-products/grease-gear-oil/synchromesh-mtf

Only been in a few hundred miles but shifting feels just fine. It's tow ready.

 

[Wayne M.]

Gary, I’m glad you still have yours. I’m starting to feel a bit lonely. Lol

 

[GCroyle]

Gary, I’m glad you still have yours. I’m starting to feel a bit lonely. Lol

Wayne,

From my cold hands. That's how someones gonna get it and I have the only key.

I just put a new clutch, FW, fork in it two weeks ago. Not one tracer of oil off of RMS so I left that sleeping dog alone. Chassis is looking just fine, never been in salt or any salt spray stuff.

I was interested to see how a respectfully driven (I hope) facings and friction surfaces would look after 80-100K I actually didn't write down install mileage. Duh. I know I have smelled the disc several times almost always backing my rig into a camp site backing going UP a slight grade and trying to spot the Airstream in it's site. And I always tried to minimize the slip time. The facings looked great, lots more wear available, both castings shows what I class as WORK appearance not abused appearance. Many I bet would have left the FW alone. The only oh snap was the condition of the bearing, it was singing but you could not hear it over the truck. Pilot good condition still had grease.

Looking at a new set of tires by late august, might switch from Mr. Bib to Continental https://www.continentaltire.com/product/terraincontact-ht-lt-26570-r-17-121s/? plus $100 rebate and less than Mr. Bib.

And before anybody thinks about reporting this as an add for a clutch, don't bother. I'm retired from 39 years in the clutch business.

Gary