NV5600 vs G56

[JohncJordanIII]

I don’t care about strength, racing or parts being costly. I haul and tow that’s it it will barely run empty since I have a take home car. Just asking campfire style about experiences. Do one buck more than the other going in reverse. Going up hills difference in catching gears. Just asking a community for experiences and if there is a failure that makes you bias that’s fine too just no finger pointing lol

 

[NIsaacs]

Some good info here.

https://www.turbodieselregister.com/threads/nv5600-vs-g56.267305/

 

[petersonj]

I think that either transmission is a good choice; however, I can only share my personal experience with the NV5600. I have currently logged 380,000 miles on the truck. The transmission is original with a rear seal replacement being the only repair through its life. One replacement clutch at 297,000 miles - replaced with stock clutch - 355:1 gears.

I don't tow all of the time, but there are times when I tow a lot. Since July, I have towed a load of pavers for seven 220 mile one-way trips across five 5,000 ft mountain passes each trip. Each load is 20,000 lbs combined weight (scaled). I use sixth gear all of the time, if sixth gear will easily hold the hill, I use it. I have made many local trips with the dump trailer, as well this summer. Shifting gears on hills (up or down) is smooth, but I do make a point of matching engine rpms to road speed during shifts.

As of yet, I have not heard or felt anything abnormal with the transmission. All synchronizers are working as they should.

As far as your question about bucking in reverse, I have never had that issue. I don't think bucking in reverse would be a transmission related issue - maybe contaminated clutch facing, or a ceramic disc, or possibly extremely worn rear suspension could cause the issue.

- John

 

[JohncJordanIII]

I think that either transmission is a good choice; however, I can only share my personal experience with the NV5600. I have currently logged 380,000 miles on the truck. The transmission is original with a rear seal replacement being the only repair through its life. One replacement clutch at 297,000 miles - replaced with stock clutch - 355:1 gears.

I don't tow all of the time, but there are times when I tow a lot. Since July, I have towed a load of pavers for seven 220 mile one-way trips across five 5,000 ft mountain passes each trip. Each load is 20,000 lbs combined weight (scaled). I use sixth gear all of the time, if sixth gear will easily hold the hill, I use it. I have made many local trips with the dump trailer, as well this summer. Shifting gears on hills (up or down) is smooth, but I do make a point of matching engine rpms to road speed during shifts.

As of yet, I have not heard or felt anything abnormal with the transmission. All synchronizers are working as they should.

As far as your question about bucking in reverse, I have never had that issue. I don't think bucking in reverse would be a transmission related issue - maybe contaminated clutch facing, or a ceramic disc, or possibly extremely worn rear suspension could cause the issue.

- John

Thanks for the bucking part. I think you’re right about ceramic discs. I test drove a g56 and I hated it felt to much like a car and it has a aftermarket clutch that hated reverse

 

[AH64ID]

I have a fair amount of time behind both transmissions in 3rd gens. They both have pros and cons. The ratios of the AD G56 are hard to beat for a towing transmission.

Are you talking bucking as in hopping while slipping the clutch in reverse? Or bucking as is fighting to go into reverse?

 

[Ozymandias]

Clutch works the same in reverse as in forward gears.
No difference there.

Fun part, Auto Trans does the bucking in reverse too*, at least mine but heard from others with same problem. I guess the axle winds up in the springs with the torque applied in the other direction, but that's just a guess as there is No bucking using low-range, even with the Hubs unlocked sending all torque to the rear axle.

*especially backing up a hill it is so bad one wants to release throttle to stop it.

 

[JohncJordanIII]

I have a fair amount of time behind both transmissions in 3rd gens. They both have pros and cons. The ratios of the AD G56 are hard to beat for a towing transmission.

Are you talking bucking as in hopping while slipping the clutch in reverse? Or bucking as is fighting to go into reverse?

I am referring to clutch engagement like feathering in and out when doing precise slow backing

 

[JohncJordanIII]

Clutch works the same in reverse as in forward gears.
No difference there.

Fun part, Auto Trans does the bucking in reverse too*, at least mine but heard from others with same problem. I guess the axle winds up in the springs with the torque applied in the other direction, but that's just a guess as there is No bucking using low-range, even with the Hubs unlocked sending all torque to the rear axle.

*especially backing up a hill it is so bad one wants to release throttle to stop it.

My 48re did that but I found out my rear diff was serviced without additive. Replaced fluid with mopar diff additive and that cured the bucking.

 

[JohncJordanIII]

I asked about reversed where I thought I heard some people complaining using reverse with a load that some of them got so frustrated that some used 4LOW to combat it

 

[petersonj]

I thought I heard some people complaining using reverse with a load that some of them got so frustrated that some used 4LOW to combat it

Backing a trailer requires slow ground speed. Backing a trailer in high range is inviting poor clutch performance and a shortened clutch life. I use low range, not because I am frustrated, but because it gives the needed slow ground speed for precise control without excessively slipping the clutch.

Since I have the CAD unit on the front axle, I have modified the shifter to utilize 2WD low range. Even if I didn't have this modification, I would still use 4 Low for backing a trailer. Maybe start with 2 High during a sharp turn on asphalt to avoid wheel hop, but go right to 4 Low when the rig straightens.

- John

 

[ILIANBG]

Hi everyone. I am in the same boat - trying to educate myself as much as I can about both options in the Gen 3 (5.9l) trucks. I am also looking for a good used truck with manual transmission. I had a NV5600 in my Gen 2 and I am familiar with it.
Lately though more and more people are recommending the G56 as a better shifting transmission with good ratios for towing, but not as good for non-towing speeds because of transmission gearing. I don’t tow but usually I am loaded with a lot of tools and materials in the bed and on a lumber rack. Rarely I would rent a dump trailer for a dump run. I am a carpenter.

What are the rpms in 6th gear driving 70 or 75mph with the G56 in a Gen 3 truck with a 5.9l engine?
Ilian

 

[Regcabguy]

Hi everyone. I am in the same boat - trying to educate myself as much as I can about both options in the Gen 3 (5.9l) trucks. I am also looking for a good used truck with manual transmission. I had a NV5600 in my Gen 2 and I am familiar with it.
Lately though more and more people are recommending the G56 as a better shifting transmission with good ratios for towing, but not as good for non-towing speeds because of transmission gearing. I don’t tow but usually I am loaded with a lot of tools and materials in the bed and on a lumber rack. Rarely I would rent a dump trailer for a dump run. I am a carpenter.

What are the rpms in 6th gear driving 70 or 75mph with the G56 in a Gen 3 truck with a 5.9l engine?
Ilian

Facebook has a Cummins for sale section and Marketplace has rams in there all the time. The Cummins for sale deal though has a buttload of owners with negative offset firepit rims and ridiculous lifts. Craigslist is another source.

 

[ILIANBG]

Facebook has a Cummins for sale section and Marketplace has rams in there all the time. The Cummins for sale deal though has a buttload of owners with negative offset firepit rims and ridiculous lifts. Craigslist is another source.

Thank you so much sir. I remember meeting you once with Bob4x4. You had a Gen 2 if I remember correctly. Yes, it’s so hard to find a well-cared for Gen 3 manual these days. I keep looking almost daily.

 

[NIsaacs]

Hi everyone. I am in the same boat - trying to educate myself as much as I can about both options in the Gen 3 (5.9l) trucks. I am also looking for a good used truck with manual transmission. I had a NV5600 in my Gen 2 and I am familiar with it.
Lately though more and more people are recommending the G56 as a better shifting transmission with good ratios for towing, but not as good for non-towing speeds because of transmission gearing. I don’t tow but usually I am loaded with a lot of tools and materials in the bed and on a lumber rack. Rarely I would rent a dump trailer for a dump run. I am a carpenter.

What are the rpms in 6th gear driving 70 or 75mph with the G56 in a Gen 3 truck with a 5.9l engine?
Ilian

With a 5.9 you will only have the choice of 05.5-07.5 year model tucks with the G-56. Here are the ratios for the two transmissions. The faster ratio was only offered in the 6.7 trucks.

With 3.73 gears, 32" tire, sixth will be 75 mph at about 2323 rpm, with the 5.9.
#ad

 

[AH64ID]

With a 5.9 you will only have the choice of 05.5-07.5 year model tucks with the G-56. Here are the ratios for the two transmissions. The faster ratio was only offered in the 6.7 trucks.

With 3.73 gears, 32" tire sixth will be 75 mph at about 2323 rpm, with the 5.9.
#ad

Late 2007 5.9's did get the AE ratio G56. There aren't many, but they are out there.

75 mph in 6th with stock tires is 2420 with an AD-G56 and 2267 with an AE-G56.

Stock tires (265/70R17) only roll at 30.7".

 

[Ozymandias]

Axle ratio has way bigger impact on road speed then the transmission.
Both transmissions will be fine combined with the right rear end ratio.

 

[ILIANBG]

Thank you so much guys! I really appreciate it. It really puts this in perspective. I think I would like to get the G56, just because I never owned a truck with it, and so many recommend it.
But if I find a good, clean tuck with the NV5600, I will not pass that by. These trucks are getting really hard to find.
Thank you again guys, and I’ll keep my eyes on these forums. And if anyone knows someone with a manual Gen3 with the 5.9L, please let me know.
Ilian

 

[NIsaacs]

Axle ratio has way bigger impact on road speed then the transmission.
Both transmissions will be fine combined with the right rear end ratio.

Thats easier said than done unless you gear it yourself. Using '06 as an example, the G-56 had one ratio, 3.73. This is per the Mopar truck brochure.

It also says (new to me) the G-56 was only offered in the 2500. The 3500 required the automatic, with two rear axle choices, 3.73 or 4.10.

 

[AH64ID]

Thats easier said than done unless you gear it yourself. Using '06 as an example, the G-56 had one ratio, 3.73. This is per the Mopar truck brochure.

It also says (new to me) the G-56 was only offered in the 2500. The 3500 required the automatic, with two rear axle choices, 3.73 or 4.10.

The early 4th gens had some axle ratio options with the G56, but only for a few years. 3.42 or 3.73.

Sounds like a brochure error. The towing charts show the G56 on both SRW and DRW 3500’s. 4.10 were only offered with the 48RE. There were some G56 trucks built with 4.10’s but they were recalled. Some serious rpms at highway speed with a AD-G56 and 4.10’s.

 

[NIsaacs]

The early 4th gens had some axle ratio options with the G56, but only for a few years. 3.42 or 3.73.

Sounds like a brochure error. The towing charts show the G56 on both SRW and DRW 3500’s. 4.10 were only offered with the 48RE. There were some G56 trucks built with 4.10’s but they were recalled. Some serious rpms at highway speed with a AD-G56 and 4.10’s.

The OP was only interested in the 5.9 trucks so I didn't research any 6.7's or 4th gens.

Or the towing charts have an error.

I do recommend he upgrade to the 6.7 trucks and get the factory exhaust brake.