5th Gen G56 Swap

[Gen3Moe]

Hey Guys, any idea on the electronic side of things when converting a 2021 5th gen from 68rfe to g56? I just toasted the 68 and buying a 4th gen with a g56 is not an option unfortunately. I know how to mount everything mechanical. Wiring and tuning is what concerns me. Is it do-able? You know anyone that ever did it besides the dually on youtube that’s done by FSD?

 

[Topzide]

@Gen3Moe, Still is a 4th Gen as no body redesign has been done yet. You're going to need all the computers and possibly wiring. At least you're over seas and don't have to deal with all the crap we have to. What year is the donor truck? The closer the years, the easier the swap. See, you turned it up to much for the 68RFE to handle!

 

[bcbender]

They no longer offer a manual transmission in the new trucks, ( I cant remember the last year but I think it was 2018) and none of the 4th gens that had the manual were rated for the HP/TQ output of the Auto trucks. I am a bit confused thou as you state buying a 4th gen is too expensive? A donor truck or whole truck? Did you toast the trans in a 4th gen (21') or third gen trans? If you bought a 4th gen manual that was running, why swap it? Filling out the truck signature will help members avoid confusion when discussing options.

If it is a 2021 SO Auto truck with the 68RFE, IMHO it would be the least cost option to rebuild / replace that trans and correct whatever it was that caused the failure, the 68RFE is a tough transmission, not that many fail under normal usage.

 

[Topzide]

@bcbender, he's got it tweaked and tuned with high output! Search his post and you'll see.

 

[Ozymandias]

Why tune an engine and leave Trans stock? Doesn't make sense to me.
Upgrade Trans to match engine output would be the smart move in my opinion.

 

[Gen3Moe]

@Gen3Moe, Still is a 4th Gen as no body redesign has been done yet. You're going to need all the computers and possibly wiring. At least you're over seas and don't have to deal with all the crap we have to. What year is the donor truck? The closer the years, the easier the swap. See, you turned it up to much for the 68RFE to handle!

Yeah I guess the 68rfe couldn’t handle the power, although i got the hp and torque locked on 420hp-800lb/ft.. at least that’s what my iDash shows.. I’ll be using parts from a 2017-2018.. I know for sure the transfer case and the bell housing bolts without any problems. Then we have the floor console, shifter, pedal and clutch master cylinder, they also bolt right up as the cab itself is the same with previous models.. wiring is the only problem. From what I heard and saw, no g56 truck came with a push button start. Thats one of the challenges… we’ll see how things turn out. If it can’t be done then I’ll get a built 68 from a reputable shop.

 

[Gen3Moe]

Why tune an engine and leave Trans stock? Doesn't make sense to me.
Upgrade Trans to match engine output would be the smart move in my opinion.

I was planning on getting an upgrade for the transmission. Tune was also done to be compatible with the stock trans as all I did was delete the emissions system. I also don’t do WOTs and boost launches. I don’t even tow heavy loads.. I’ll get a better idea of the damage when I remove the 68

 

[Gen3Moe]

They no longer offer a manual transmission in the new trucks, ( I cant remember the last year but I think it was 2018) and none of the 4th gens that had the manual were rated for the HP/TQ output of the Auto trucks. I am a bit confused thou as you state buying a 4th gen is too expensive? A donor truck or whole truck? Did you toast the trans in a 4th gen (21') or third gen trans? If you bought a 4th gen manual that was running, why swap it? Filling out the truck signature will help members avoid confusion when discussing options.

If it is a 2021 SO Auto truck with the 68RFE, IMHO it would be the least cost option to rebuild / replace that trans and correct whatever it was that caused the failure, the 68RFE is a tough transmission, not that many fail under normal usage.

I meant expensive as a whole truck. I toasted the trans of my 2021.. I will be looking at the rebuild cost for my 68rfe.. swapping it for a g56 from a 2017-2018 was an option

 

[Ozymandias]

I was planning on getting an upgrade for the transmission. Tune was also done to be compatible with the stock trans as all I did was delete the emissions system. I also don’t do WOTs and boost launches. I don’t even tow heavy loads.. I’ll get a better idea of the damage when I remove the 68

As soon as you tune you exceed the Trans capacity, it's the torque that destroys em. Especially the removal of the torque management which almost all tuners do is crucial for the longevity of the stock trans.
Get a full built Trans that supercedes the numbers your engine puts out.

 

[Ozymandias]

By the way, the G56 isn't bullet proof at all. That's why all manual trucks came from factory with in comparison small hp/to numbers. Put behind a tuned engine you're going to break them too.

 

[Diesel85]

By the way, the G56 isn't bullet proof at all. That's why all manual trucks came from factory with in comparison small hp/to numbers. Put behind a tuned engine you're going to break them too.

Exactly. I love standard transmissions, but to derate an engine just to drive stick always bothered me.

Reminds me of the same problem with the 97-03 F150s with the M5OD behind the modular V8 and folks adding a supercharger. Transmission just couldn't handle it.

 

[bcbender]

Exactly. I love standard transmissions, but to derate an engine just to drive stick always bothered me.

Reminds me of the same problem with the 97-03 F150s with the M5OD behind the modular V8 and folks adding a supercharger. Transmission just couldn't handle it.

Nope... and on top of that you now have to row your way down the road w/less power.

Neither the G56 nor the NV5600 are rated for that much power continuous. I for one do not miss shifting at all, not one bit. New truck has 2x the TQ and a lot more power with a warranty.. Simply do not understand how that's not enough... If I wanted to make big power and twist parts to death, etc... Id go back to a 3rd gen or 2cnd gen where parts are cheaper, and so are repairs. But alas my younger brothers still like to beat things to death, they haven't figured it out yet. Best of luck on the swap, challenge might be the ability to start while in gear... historically that's why manual trucks did not have remote start, IDK if the G56 has a neutral sw, but the NV5600 did not.

JM2C.. its not my money.....

 

[AH64ID]

Yeah I guess the 68rfe couldn’t handle the power, although i got the hp and torque locked on 420hp-800lb/ft.. at least that’s what my iDash shows.. I’ll be using parts from a 2017-2018.. I know for sure the transfer case and the bell housing bolts without any problems. Then we have the floor console, shifter, pedal and clutch master cylinder, they also bolt right up as the cab itself is the same with previous models.. wiring is the only problem. From what I heard and saw, no g56 truck came with a push button start. Thats one of the challenges… we’ll see how things turn out. If it can’t be done then I’ll get a built 68 from a reputable shop.

No gen 4.5 truck came with a manual transmission, so there isn't a manual transmission file you can write over your SO tune. So you'll need an ECM from a 17-18 truck, but then there are wiring harness differences.

You may also into issues mounting a clutch pedal and slave cylinder, as the aux PDC appears to be in the way.

Stock was'21 SO is 370/850, so you're running a lower torque but higher hp tune?

 

[Gen3Moe]

No gen 4.5 truck came with a manual transmission, so there isn't a manual transmission file you can write over your SO tune. So you'll need an ECM from a 17-18 truck, but then there are wiring harness differences.

You may also into issues mounting a clutch pedal and slave cylinder, as the aux PDC appears to be in the way.

Stock was'21 SO is 370/850, so you're running a lower torque but higher hp tune?

Yes I know the 2019+ models didn’t come with a manual but I’ve seen a couple of em done with a g56 conversion.. They all managed to make it work with the factory 2450b ecm, problem is they show everything bolted on and working but they don’t share the specifics of wiring..

About my tune, yes I was running a lower torque tune, but after checking the datalog I noticed that prior to the 68rfe failure the torque graph reached 900+ lb/ft which indicates a malfunction in the tune

 

[Gen3Moe]

By the way, the G56 isn't bullet proof at all. That's why all manual trucks came from factory with in comparison small hp/to numbers. Put behind a tuned engine you're going to break them too.

From what I have heard and seen, the lower hp/tq rate is because of the factory clutch.. a friend of mine has a g56 truck making well over 600rwhp and it’s holding just fine with an aftermarket flywheel and dual disc clutch

 

[Gen3Moe]

Nope... and on top of that you now have to row your way down the road w/less power.

Neither the G56 nor the NV5600 are rated for that much power continuous. I for one do not miss shifting at all, not one bit. New truck has 2x the TQ and a lot more power with a warranty.. Simply do not understand how that's not enough... If I wanted to make big power and twist parts to death, etc... Id go back to a 3rd gen or 2cnd gen where parts are cheaper, and so are repairs. But alas my younger brothers still like to beat things to death, they haven't figured it out yet. Best of luck on the swap, challenge might be the ability to start while in gear... historically that's why manual trucks did not have remote start, IDK if the G56 has a neutral sw, but the NV5600 did not.

JM2C.. its not my money.....

Problem is I miss shifting my own gears.. and I am doing a heavy research on the matter. Only time and trial will determine whether i go with the swap or build the 68rfe

 

[BigPapa]

Sorry, but I can’t deal with the bold italic font in your posts. Something wrong with the standard font?

 

[AH64ID]

Sorry, but I can’t deal with the bold italic font in your posts. Something wrong with the standard font?

Beat me to it. Really annoying.