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The mythical CUCV 4L80E swap

Keith_J

Well-known member
3,657
1,323
113
Location
Schertz TX
A bone stock 6X is perfect. I want original shift mechanism, probably with a new index in the dash as the detents are in the transmission. To the casual observer, it will be a nearly stock M1031.

My only worries are on the non-stock first (2.97) gear set. Any weakness should have showed up by now, I have not found a complaint yet still there is a bug in the back of my mind. Since the torque converter lockup isn't possible in first gear, diesel engine torsional vibrations should be damped out.
 

Glockfan

Member
274
14
18
Location
Brigham City, Utah
Did you finish the swap yet?
No, it is still on the rack. I’m doing several things at once. I will post up pics when I’m done. I was originally going to do just the ORD 203/205 doubler. Then I decided to add the TH400 to 4L80 conversion. Along the way, I had to source other parts for the 4L80 swap such as the throttle position sensor (using a factory AC Delco which will replace the old vacuum TPS on the injector pump), I eliminated the mechanical speedometer and replacedU it with with an ORD VSS kit. Both of these steps were required for the transmission controller that I chose to use. I would suggest that anyone considering the swap go with US Shift for the controller. I will be using the “Quick 4”.

While my truck is “down”, I decided to pull the runflats and switch to Trailworthy Fab PVC beadlock adapters and use 10 ounces of ballast media in the tires. That was work!

Maybe the finial step for me will be a Detroit Locker up front. Maybe an ARB. Updated pics will be posted soon. I still have to get the driveshafts made but other than that, we are getting close.
 

Abbylind

Member
284
14
18
Location
Palm Harbor FL & NM
"While my truck is “down”, I decided to pull the runflats and switch to Trailworthy Fab PVC beadlock adapters and use 10 ounces of ballast media in the tires. That was work!"

AGREED! Try removing the PVC inserts when the tire is bad....its even more work!

 

Abbylind

Member
284
14
18
Location
Palm Harbor FL & NM
I ended up using a bottle jack and turned the PVC insert into an oval. Used some WD 40 to lube the edges....when it got too tough I cut the sidewall on the old tire and pulled the insert out.
 

Matt S

Active member
Steel Soldiers Supporter
142
35
28
Location
Los Angeles, CA
No, it is still on the rack. I’m doing several things at once. I will post up pics when I’m done. I was originally going to do just the ORD 203/205 doubler. Then I decided to add the TH400 to 4L80 conversion. Along the way, I had to source other parts for the 4L80 swap such as the throttle position sensor (using a factory AC Delco which will replace the old vacuum TPS on the injector pump), I eliminated the mechanical speedometer and replacedU it with with an ORD VSS kit. Both of these steps were required for the transmission controller that I chose to use. I would suggest that anyone considering the swap go with US Shift for the controller. I will be using the “Quick 4”.

While my truck is “down”, I decided to pull the runflats and switch to Trailworthy Fab PVC beadlock adapters and use 10 ounces of ballast media in the tires. That was work!

Maybe the finial step for me will be a Detroit Locker up front. Maybe an ARB. Updated pics will be posted soon. I still have to get the driveshafts made but other than that, we are getting close.
Nice. I'm looking to see what you need to swap the 4L80 with the NP205.
 

Matt S

Active member
Steel Soldiers Supporter
142
35
28
Location
Los Angeles, CA
What exact are you looking for to see?
I have purchased a m1008 with the 4l80e conserion and a np205. I can make some pictures.

Ow, and it drives fantastic!
I was looking to see if the 2wd version works. Does the current NP205 mount bolt up? What other little parts that you don't think about are required to make the transmission operational. How does the controller work?

That's what I'm hoping for. The original poster has a NP208 transfer case and required a different mount to the transfer case that stock.
 

True Knight

Active member
673
179
43
Location
San Pedro, CA
I was looking to see if the 2wd version works. Does the current NP205 mount bolt up? What other little parts that you don't think about are required to make the transmission operational. How does the controller work?

That's what I'm hoping for. The original poster has a NP208 transfer case and required a different mount to the transfer case that stock.

I used the stock 4L80E mount with the NP208. I just had to make the ‘pedestal’ to go in between the 4L80E mount and the CUCV crossmember.

I could’ve also used the stock TH400 to NP208 mount if I clearanced the lip on the mount slightly to fit in the rear of the 4L80E.

Not sure if that’s what you were concerned about but I hope that helps.
 

Glockfan

Member
274
14
18
Location
Brigham City, Utah
Nice. I'm looking to see what you need to swap the 4L80 with the NP205.
Mine is going to throw a slight monkey wrench into the works. While converting from a TH400 to the 4L80E, I decided to do the ORD 203/205 "doubler". My measurements are going to be off a bit because I have an NP203 wedged in between the 4L80 and the NP205. Actually, the ORD doubler kit uses only the range box from the NP203, the rest of the case went into the scrap barrel.

If I could source a flexplate cover and a dipstick and tube, I would be in good shape. We are getting close.
 

Matt S

Active member
Steel Soldiers Supporter
142
35
28
Location
Los Angeles, CA
Mine is going to throw a slight monkey wrench into the works. While converting from a TH400 to the 4L80E, I decided to do the ORD 203/205 "doubler". My measurements are going to be off a bit because I have an NP203 wedged in between the 4L80 and the NP205. Actually, the ORD doubler kit uses only the range box from the NP203, the rest of the case went into the scrap barrel.

If I could source a flexplate cover and a dipstick and tube, I would be in good shape. We are getting close.
I'm still interested in what worked and what was required. Other than the length, is it different for just the NP205 in the way it mounts to the support and how the electronics are used?
 

hotcorner216

New member
18
0
1
Location
Southern California
Awesome write up, I did most of my 4l80e swap off of this information.

I have been having issues with the transfercase, prior to the swap I had no issues with it, popped it in after and not getting 4LO, it like neutral. Took off the linkage and manually shifted it, same thing. Any advice appreciated!
 

True Knight

Active member
673
179
43
Location
San Pedro, CA
Awesome write up, I did most of my 4l80e swap off of this information.

I have been having issues with the transfercase, prior to the swap I had no issues with it, popped it in after and not getting 4LO, it like neutral. Took off the linkage and manually shifted it, same thing. Any advice appreciated!
I had the transfer case rebuilt when I did the trans swap. Only issue I’ve had was it would pop out of 4 Hi into neutral. There are plastic wear tabs on the shift fork that once worn out will cause this. But I don’t think it’ll cause it not go into 4 Lo.
 

NWM1008

New member
7
10
3
Location
WA
I had the transfer case rebuilt when I did the trans swap. Only issue I’ve had was it would pop out of 4 Hi into neutral. There are plastic wear tabs on the shift fork that once worn out will cause this. But I don’t think it’ll cause it not go into 4 Lo.
Mine started popping into neutral after the swap (didn't before swap). It ended up being the linkage out of adjustment.
 

Keith_J

Well-known member
3,657
1,323
113
Location
Schertz TX
For my upcoming 4l80 swap, I bought the adapter from Advance Adapter for 205 transfer case. It's a 356 T6 aluminum casting with the larger index ring machined into the front. Its also relieved for the oil pan. Dakota Digital tach module and AC Delco TPS round out the sensor suite. Transmission already has the output speed sensor.
Moving the engine forward to accommodate the increased length.
 
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True Knight

Active member
673
179
43
Location
San Pedro, CA
You’re moving the engine forward? That’ll be a lot more work that moving the trans mount back. Plus there’s not a whole lot of room in front of the engine. But it sounds like you might have a plan figured out already. You changing to electric fans?
 

Keith_J

Well-known member
3,657
1,323
113
Location
Schertz TX
You’re moving the engine forward? That’ll be a lot more work that moving the trans mount back. Plus there’s not a whole lot of room in front of the engine. But it sounds like you might have a plan figured out already. You changing to electric fans?
This is a 205 TC M1031 SECM. PTO generator is one of the plus features I really use. Three drive shafts plus the TC shifter and PTO interlock. There is plenty room, GM positioned the engine as far back for center of gravity issues, the engine bay was designed to accommodate the 250/292 inline six engine so there is plenty room to move it forward. Doing so will put the fan into the shroud completely which will make the fan more efficient. Sure, changing belts will be a bit more involved but the fan can still be pulled from the water pump.
 

chevymike

Well-known member
597
463
63
Location
San Diego, CA
Doing so will put the fan into the shroud completely which will make the fan more efficient.
Ummm... not sure where you got this info but the correct fan to shroud placement is to have 1/2 to 3/4 of the fan outside of the edge of the shroud. If in too far, it will actually block airflow and cause it to run hotter. You might want to do some research before you consider the fan location as you have listed.
 
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