Dodge Cummins NV4500 to G56 - DONE!
- Thread starter Route55
- Start date
Route55
Adventurer
Sorry for the delay guys. I had some other stuff I needed to do and I was waiting on the driveshaft.
First, I checked out whether or not the seal is different between 2 and 4 wheel drive. It appears to be. The 241 case I had bolted up takes an approximately 2 inch inside diameter seal, where the 2wd yoke takes one that is approximately 2 7/8.
I also had to modify the crossmember. To have the trans yoke in the right spot the mount needed to come rearward about 2 inches, and down 1.
So I cut out the offending area and reworked it.
And probably didn't need to, but braced it from underneath for insurance.
First, I checked out whether or not the seal is different between 2 and 4 wheel drive. It appears to be. The 241 case I had bolted up takes an approximately 2 inch inside diameter seal, where the 2wd yoke takes one that is approximately 2 7/8.
I also had to modify the crossmember. To have the trans yoke in the right spot the mount needed to come rearward about 2 inches, and down 1.
So I cut out the offending area and reworked it.
And probably didn't need to, but braced it from underneath for insurance.
Route55
Adventurer
The new driveshaft from CCI in Ira Township, Michigan. They made a new front and rebuilt the rear. It has a new center bearing and all new spicer U-joints. For my 2wd extended cab truck I needed the driveshaft to be 46 1/2 inches from the face of the flange to the center of the mid-bearing.
Route55
Adventurer
Unfortnately the 2011 boot is for a console and too short. The stock boot works but is just about stretched to it's limit. After my next run I'll probably build some sort of console to use 2011 boot.
The G56 shift knob is a weird one. To get it off you pop out the indicator tab, and unbolt a 15mm bolt. Then you still have to unscrew it from the shaft. So don't go trying to just twist one of these off like the old ones!
The G56 shift knob is a weird one. To get it off you pop out the indicator tab, and unbolt a 15mm bolt. Then you still have to unscrew it from the shaft. So don't go trying to just twist one of these off like the old ones!
Route55
Adventurer
Filled up trans with Syncromesh. Even though the G56 calls for ATF, Southbend and others reccomend Snyncomesh due to its thicker viscosity and cooling properties.
Then I got to work on the Reverse light switch. Problem there is the plug is unique to the G56, I don't have it, and it is unavailable via both aftermarket and dealer as of now.
Finding a yard willing to cut off the plug from a good harness wouldn't be easy (or timely) so I put some very small female spade connecters on some wire and pressed them in.
Since the spades are so close to eachother (less than half a mm) I filled the cavity with silicone to keep them in place and protected. The G56 reverse light switch sits about two feet rearward of where the 4500 one was, so some extensions with spades were necessary. I plugged it all in and it worked great!
Then I got to work on the Reverse light switch. Problem there is the plug is unique to the G56, I don't have it, and it is unavailable via both aftermarket and dealer as of now.
Finding a yard willing to cut off the plug from a good harness wouldn't be easy (or timely) so I put some very small female spade connecters on some wire and pressed them in.
Since the spades are so close to eachother (less than half a mm) I filled the cavity with silicone to keep them in place and protected. The G56 reverse light switch sits about two feet rearward of where the 4500 one was, so some extensions with spades were necessary. I plugged it all in and it worked great!
Route55
Adventurer
Last thing was to get the Speedometer working. G56 trannys do not have a speed sensor. Dodge started taking the speed off the rear axle in 98. My truck is a 97, but does have an ABS sensor in the rear axle.
It was not my idea, but saw it in a couple of writeups. The idea is to use a Dakota Digital (the company, not the truck) SGI-5 interface unit to pick up the rear axle signal. Currently Dakota does not list this as an application, but I figured it was worth a try.
The writeups use a four wire hookup. Power, Ground, Input, and output.
For input, I picked up the ABS signal from the back of the OBD2 port under the dash. The wire to tap into is red with a purple tracer.
For output to the speedo the writeups say to tap into the white wire with an orange tracer at the bundle under the dash next to the parking brake. I was unable to find the wire there, so I pulled out the cluster and found it easily to the right there. I tapped into it and tried driving truck......nothing.
Long story short is that the writeups did not say that the white wire with orange tracer needs to be cut completely, not tapped into. Once a wire is run from the back of the speedo (still the white with orange tracer one) directly to port 3 it works great. Switch 1 and 2 are left down, 3 and 4 up.
I mounted the unit to the brace under the panel at bottom of the dash. It is accessable while driving with panel off for fine tuning. Push and hold the buttons down for adjustment. I tuned mine in a few seconds with my GPS. Cool thing is I can easily retune with a push of a button for different tires or a gear swap.
Only thing I noticed with this setup is it runs 1-2 MPH fast under 25 mph. After that it is dead nuts accurate.
It was not my idea, but saw it in a couple of writeups. The idea is to use a Dakota Digital (the company, not the truck) SGI-5 interface unit to pick up the rear axle signal. Currently Dakota does not list this as an application, but I figured it was worth a try.
The writeups use a four wire hookup. Power, Ground, Input, and output.
For input, I picked up the ABS signal from the back of the OBD2 port under the dash. The wire to tap into is red with a purple tracer.
For output to the speedo the writeups say to tap into the white wire with an orange tracer at the bundle under the dash next to the parking brake. I was unable to find the wire there, so I pulled out the cluster and found it easily to the right there. I tapped into it and tried driving truck......nothing.
Long story short is that the writeups did not say that the white wire with orange tracer needs to be cut completely, not tapped into. Once a wire is run from the back of the speedo (still the white with orange tracer one) directly to port 3 it works great. Switch 1 and 2 are left down, 3 and 4 up.
I mounted the unit to the brace under the panel at bottom of the dash. It is accessable while driving with panel off for fine tuning. Push and hold the buttons down for adjustment. I tuned mine in a few seconds with my GPS. Cool thing is I can easily retune with a push of a button for different tires or a gear swap.
Only thing I noticed with this setup is it runs 1-2 MPH fast under 25 mph. After that it is dead nuts accurate.
Route55
Adventurer
And it is done!
I took truck on an 80 mile shakedown and it is awesome. The Southbend clutch is oh so smooth and the extra gear greatly helps keep it in the RPM band.
For those who would like to know, here is a breakdown of costs:
17,000 mile G56a trans - $2750
Southbend Clutch w Flywheel -$989
Driveshaft Re-work - $479
Fluids, various small stuff - $100
Dakota SGI-5 unit - $85
Sub Total $4,403
Sale of old trans. +$600
Total project cost $3,803
Final notes:
Get shifter and wiring plug for reverse light switch with trans. They are not yet available aftermarket.
If possible, get front yoke with bolts off driveshaft to avoid having to buy them.
Get short (G56) slave rod with trans, it is the one you need.
I will give an update once I get some miles on this. So far so good!
I took truck on an 80 mile shakedown and it is awesome. The Southbend clutch is oh so smooth and the extra gear greatly helps keep it in the RPM band.
For those who would like to know, here is a breakdown of costs:
17,000 mile G56a trans - $2750
Southbend Clutch w Flywheel -$989
Driveshaft Re-work - $479
Fluids, various small stuff - $100
Dakota SGI-5 unit - $85
Sub Total $4,403
Sale of old trans. +$600
Total project cost $3,803
Final notes:
Get shifter and wiring plug for reverse light switch with trans. They are not yet available aftermarket.
If possible, get front yoke with bolts off driveshaft to avoid having to buy them.
Get short (G56) slave rod with trans, it is the one you need.
I will give an update once I get some miles on this. So far so good!
Last edited:
Route55
Adventurer
Not a problem! If anyone has additional questions they can post them up here and I'll do my best to answer them.
Heavy44TRT
New member
Glad it is done and you are back driving it. Thanks for all the work documenting and taking pictures. I am hopefully looking to do the same conversion within the year. This will help myself and others looking to go to a 6 speed.
Route55
Adventurer
I just completed a 9,000 mile torture test of the G56 combo in the truck over 3 weeks. I took off from Michigan with my loaded 42 foot trailer, went down to South Carolina, down to Florida, over to California, up to Montana, and back home. All in all this truck saw lots of miles in the Rocky Mountains and Smoky Mountains, it saw both the Atlantic and Pacific, Both the Canadian and Mexican Borders, and crossed the Mohave Desert and several others. It climbed a private road with a loaded trailer 3 miles up a mountain with a 18 degree grade! It saw 113 degrees in Houston, and lots of traffic, hills, etc. I even hit an overnight severe sand storm north of Reno that covered the truck in a few inches of sand, and it almost tipped the whole thing over!
I am very very pleased with the truck and the combo. The extra gear made all the difference in the world. I can't even see ever towing with a five speed again. Downshifting is so much easier, and the Southbend Clutch is great. I have no complaints whatsoever. I'll continue to keep you all updated through the life of this truck and trans, but so far am a huge fan of the G56.
I am very very pleased with the truck and the combo. The extra gear made all the difference in the world. I can't even see ever towing with a five speed again. Downshifting is so much easier, and the Southbend Clutch is great. I have no complaints whatsoever. I'll continue to keep you all updated through the life of this truck and trans, but so far am a huge fan of the G56.
Rostirolla_ben
New member
Hi route55
Hows the g56a going after running it for over a year?
And also of the top of you head can you remember what the measurement from the bellhousing to where the. Shifter comes out is. Looking at using a 6.7 and g56a for a conversion.
Cheers Benny.
Hows the g56a going after running it for over a year?
And also of the top of you head can you remember what the measurement from the bellhousing to where the. Shifter comes out is. Looking at using a 6.7 and g56a for a conversion.
Cheers Benny.