Dodge Cummins Diesel Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #1 · (Edited)
I figured I'd start a thread dedicated to this since there seems to be some interest in my build thread.

I tore up my nv4500 and don't want to spend the money to rebuild it with stronger parts. Instead, I've picked up a G56 out of an 05 with 60K on it. I'll also be getting an nv271 with zero miles on it to swap in as well. Last, I've picked up a new South Bend DD 3250 to put in and will be selling the one that's in the truck (It has maybe 20K on it)

From the research I've done I'll have to rebuild the crossmember by making a mount 1.5" lower and 3.5" to the rear. I'll then have to get both driveshafts rebuild for the correct length and correct yokes.

If anyone has any advice, questions, or comments let's hear em!
 

·
Registered
Joined
·
326 Posts
I would invest in a G56 girdle
 

·
Registered
Joined
·
5,777 Posts
How much torque can the stock G56 handle on internals?
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #4 ·
Not sure how much it can handle, but it has to be more than the nv4500.

I'd like to keep this thread purely about the swap if that's possible. Thanks guys
 

·
Registered
Joined
·
1,919 Posts
I swapped an nv5600 in a 12v that was originally a 47rh. The auto drive shafts worked for it, I think a g56 is shorter though. Maybe something to look into, may be able to use stock driveshafts.
 

·
Farm Mechanic
Joined
·
2,146 Posts
Does the shifter come through in the same location as the earlier transmissions? It always looked to me like the later 3rd gen trucks had the shifter coming out much closer to the dash. Not sure if this is simply differences in the dash styles though. Just a thought in case you have to redesign your lower console - same goes for the transfercase shifter if that will come through any differently.
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #7 · (Edited)
I swapped an nv5600 in a 12v that was originally a 47rh. The auto drive shafts worked for it, I think a g56 is shorter though. Maybe something to look into, may be able to use stock driveshafts.
Shafts are significantly different. Thanks for the tip though

Does the shifter come through in the same location as the earlier transmissions? It always looked to me like the later 3rd gen trucks had the shifter coming out much closer to the dash. Not sure if this is simply differences in the dash styles though. Just a thought in case you have to redesign your lower console - same goes for the transfercase shifter if that will come through any differently.
The shifter is located almost exactly where the nv4500 was. The shifter for the np271D is going to be the same as the np241DLD as well.


Here's more info for those curious!





So lots of info. I've now got everything bolted up and am waiting on driveshafts to be built / modified and finding a plug for the reverse switch.

Now, the build. The first thing we did was stuff the new south bend clutch in. It's the "same" as the clutch I had before, just made for the g56. We then decided totake a few measurements of the transmission and transfer cases. The shifter location on the g56 is almost identical to the nv4500, so there was no need to cut the floor. We then jacked up the front of the motor and attempted to stab the transmission... No go. The small loop on the top of the trans (You can see it at the front of the picture I already posted) kept hitting the pinch weld. So I cut it off. It then went in nice and easy, like it should. With it bolted up and supported we took the truck to the lift and took it to the top.
From there we started on the transfer case. The np241 has a "block" of vacuum lines running into it to actuate the CAD. Turns out the 4x4 light on the nv271 works the exact same, so we were able to screw that in. The shift lever is also identical, so we bolted that up. We then stuck the Tcase in to check fitment.






It's close to the frame, but it doesn't hit!.



Then onto support the aluminum beast. We were able to use the stock support and bolt it directly to the g56 rather than using the adapter the nv4500 uses.
Here you can see we cut the center section out because it had to drop around 3/4 of an inch. We also had to cut part of the left side to make clearance for the driveshaft.


From there we used 1/4in plate drop the center section. We also made a 45 degree cuts to make strength for the new plate. Where it flattens out we used a rosebud to heat it up and beat it flat. It was the same process to plate the section cut out for the driveshaft. Here you can see some beautiful beads laid down by my father. I believe I'm a good welder, but he is an excellent welder.








From there we bolted everything up tight. The next step was mounting the skid plate. Because of the monster transfer case it had to drop an inch and the nut that mounted the plate had to be removed. I didn't get any good pictured, but I also ground the spacer on the bottom and welded a nut on to hold the plate.
It sits lower, but I feel having a skid plate is a necessity with what I use the truck for.






Now I'm searching for the plug to make the reverse lights work. The drivveshafts should be done by the end of the week and hopefully she'll be rolling again friday.
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #9 ·
Got a quote from the driveshaft shop yesterday. They cut me a deal on the rear shaft because it was balanced less than 500 miles ago. 140 with the new yoke, cut to the right length and balanced.
The front shaft needs all 3 U joints, and a centering ball kit. It's also being lengthened so that one is going to cost 330.
 

·
Registered
Joined
·
5,777 Posts
That's not bad for "custom" drive shafts.
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #11 ·
The swap is DONE!!!!
Got the driveshafts stuck in, and fluid in the transfer case.
I got the new hydraulics INSTALLED, but they must be different on the 3rd gens. My clutch petal is sitting just below my brake petal, meaning the clutch only disengages on the Very bottom of the stroke. I plan to make a new end in the machine shop this week.

I hooked up the reverse light by cutting switch where it clips to the harness. I then soldered wires to the exposed prongs. From there I heat shrunk it and hooked it up to the truck's harness using spade connectors and taped them up tight.

I was told from a reputable source that the 4x4 actuator for the CAD would not stick low enough into transmission to actuate, but it works just fine. I do have a problem with the Tcase though... It won't shift into 4H while moving, otherwise it will grind. It shifts just fine sitting still, so I'll have to see if it needs to go in for warranty.

Now for the good news! This thing shifts like a beauty!! Even better than the nv4500 IMO. Dropping it into a gear from a stop is very easy, unlike the 4500. I can even drop it into reverse at a stop with ease. With the 4500 I always had to drop it into 4th before reverse.Having 6 gears really changes the game. The truck stays right in the middle of it's power band instead of the big jump between 3rd and 4th gear.
I don't like the OD ratio though... the .79 instead of the .74 really makes the rpms jump up at cruising speeds. I'm around 2100 @ 70mph. 2400 @80mph. I may go with a set of larger tires to drop my rpms back down, but we'll see.
 
  • Like
Reactions: gh0stman

·
Registered
Joined
·
362 Posts
Ya I prefer the 6 speeds over the 5 soeeds. Always seemed like I was in the wrong gear. Would a g56 be a straight swap with an nv5600?
 

·
Mopar1973Man.Com
Joined
·
26,259 Posts
I've driven both the NV4500 and NV5600 transmissions. I tend to like the Nv4500 way less gear rowing. Being both 4th and 5th on a NV4500 are the same to NV5600 and G56 transmissions you not gaining a lot really on the highway. The only thing is filling in that bit of void on 3rd 4th in the 5 speed.

I got to ask what fluid did you decide on using TFaoro?
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #14 ·
Ya I prefer the 6 speeds over the 5 soeeds. Always seemed like I was in the wrong gear. Would a g56 be a straight swap with an nv5600?
The 5 speed didn't seem abnormal to me. I've been driving dodge 5 speeds since I got my license (dodge dakota, my dad's 96 12V and now my 02)

I don't think it would be a direct swap. I'm not sure if the length is different, but I'm almost positive the crossmember would not bolt up without modification.

I've driven both the NV4500 and NV5600 transmissions. I tend to like the Nv4500 way less gear rowing. Being both 4th and 5th on a NV4500 are the same to NV5600 and G56 transmissions you not gaining a lot really on the highway. The only thing is filling in that bit of void on 3rd 4th in the 5 speed.

I got to ask what fluid did you decide on using TFaoro?
I've driven the 4500, 5600, and now my g56. G56 would win my vote 100% of the time, and I'm not saying that just because I put one in. It shifts smoother, goes into gear easier, and seems to be very reliable even at "higher" HP levels.

I haven't tried it yet, but I'm sure you could jump from 3rd to 5th and it would be just like driving a 4500. I haven't towed anything yet (still letting the clutch break in) but I know it's going to make a world of difference. The truck never comes out of its power band. I can even shift it quick enough to keep 20psi between shifts on stock fueling.

I haven't decided on a fluid yet.... It's got royal purple ATF in it that has around 1000 miles on it, so I'm not in a huge rush. I plan to keep researching and to find out what will work best for me.
 

·
Registered
Joined
·
326 Posts
Did you try sourcing a 56A out of a 6.7 pickup at all? I've been thinking about this swap for a long time myself but won't do it without the later g56 specifically because of that overdrive ratio
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #16 ·
Did you try sourcing a 56A out of a 6.7 pickup at all? I've been thinking about this swap for a long time myself but won't do it without the later g56 specifically because of that overdrive ratio
I did... $2700 for one with 140K on it. I got a $1200 Tcase and a trans with 60K on it for that much.

I filled up the other day and netted 18.9 with a lot of in town and a lot of 80+mph driving. I don't think it's affected much, but time will tell. If it does I'll just throw bigger tires on it.

Little more info on the swap. The transfer case shifter rod needs to be lengthened a couple inches to put the 4x4 shifter back into the correct place. I also had to lengthen the adjustment on my clutch. I bought south bend adjustable g56 hydros, but because they're for a 3rd gen they don't push the petal far enough forward. At full extension, the clutch was just below the brake petal.
 

·
Mopar1973Man.Com
Joined
·
26,259 Posts
So what did you select for fluids?
 

·
Registered
Joined
·
179 Posts

·
Registered
Joined
·
439 Posts
Very Nice Install.
2 Questions

1 Why did you need to notch the left side of the CM for the DL? ,,,, Others I've seen pics of haven't needed to. Do you have a lift?

2 Transfer case linkage. Did you need to modify it. I know the rod needs to be lengthened 3or4 inches.
Most G56 in stalls I've found on the web are in 94-97s they build a bracket to mount the 94-97 TC linkage on and tweak it to make it work right..
I know the 98-02s TC linkage mounts to the trans tunnel. I like the idea of using a 98-02 TC linkage on my upcoming install beats making a bracket if I don't need to.
 

·
Registered
Joined
·
4,916 Posts
Discussion Starter · #20 ·
Very Nice Install.
2 Questions

1 Why did you need to notch the left side of the CM for the DL? ,,,, Others I've seen pics of haven't needed to. Do you have a lift?

2 Transfer case linkage. Did you need to modify it. I know the rod needs to be lengthened 3or4 inches.
Most G56 in stalls I've found on the web are in 94-97s they build a bracket to mount the 94-97 TC linkage on and tweak it to make it work right..
I know the 98-02s TC linkage mounts to the trans tunnel. I like the idea of using a 98-02 TC linkage on my upcoming install beats making a bracket if I don't need to.
1: I have an NP271 Tcase in it, not the the factory 241. It is significantly wider than the 241 and even goes into the frame a bit in one spot. It'll also help clear the 3" lift when I get the chance to put it in.

2: I just had to lengthen it for the longer trans and longer transfer case. The pivot point is integrated into the tunnel like you're saying, but it shouldn't be hard to make one on yours.

Any other questions just ask away.
 
  • Like
Reactions: bobva
1 - 20 of 22 Posts
Top