4l80 swap question

[Retoxtony]

This might be a bit of a dumb question but I’m unsure of the answer. It came up in conversation with a friend when I was saying how i was having a problem finding a 2wd donor truck to do a LS swap. 4wd trucks are everywhere ( I actually own a 1500hd I could use) but 2wd trucks are like hens teeth in my area.

Can a 4wd transmission be swapped straight into a 2wd square without any modification? I realize the proper way would be to tear into the trans, get rid of the transfer case and swap on the proper tailpiece. But could a guy just swap in the 4L80 as it sits with the transfer case and just run it in 2wd?

 

[Tank6x2]

This might be a bit of a dumb question but I’m unsure of the answer. It came up in conversation with a friend when I was saying how i was having a problem finding a 2wd donor truck to do a LS swap. 4wd trucks are everywhere ( I actually own a 1500hd I could use) but 2wd trucks are like hens teeth in my area.

Can a 4wd transmission be swapped straight into a 2wd square without any modification? I realize the proper way would be to tear into the trans, get rid of the transfer case and swap on the proper tailpiece. But could a guy just swap in the 4L80 as it sits with the transfer case and just run it in 2wd?

Sure you could do that - could just remove the transfer case portion - but no reason you couldn’t do that

 

[Matt69olds]

Pretty sure the output shafts are different lengths. I’m not a 4x4/transfer case expert, but I’m almost positive the shafts are different.

Another headache, and one I’m all too familiar with is the lack of the tone wheel for the rear speed sensor. I assume GM decided not to put the tone wheel on the rear carrier on 4x4s as a cost cutting move. Since the speed sensor in in the transfer case on 4x4s, hole in the trans case is blocked off with a plastic plug and the tone wheel eliminated. No tone wheel, no speed sensor input, lots of drivability issues and codes stored in the computer.

I ran into this very issue on one of my first 4L80 builds. Guy bought a 4x4 core, I bought the output shaft and extension housing to convert to 2wd. The trans was all assembled, painted, ready to go after I put the speed sensors in. It was at that moment I noticed no tone wheel. I had to take it back apart to install the correct parts.

 

[Frankenchevy]

Pretty sure the output shafts are different lengths. I’m not a 4x4/transfer case expert, but I’m almost positive the shafts are different.

Another headache, and one I’m all too familiar with is the lack of the tone wheel for the rear speed sensor. I assume GM decided not to put the tone wheel on the rear carrier on 4x4s as a cost cutting move. Since the speed sensor in in the transfer case on 4x4s, hole in the trans case is blocked off with a plastic plug and the tone wheel eliminated. No tone wheel, no speed sensor input, lots of drivability issues and codes stored in the computer.

I ran into this very issue on one of my first 4L80 builds. Guy bought a 4x4 core, I bought the output shaft and extension housing to convert to 2wd. The trans was all assembled, painted, ready to go after I put the speed sensors in. It was at that moment I noticed no tone wheel. I had to take it back apart to install the correct parts.

I may be wrong, but I believe the 96 and older 4L80e has the rear tone ring. I’m not certain though, just from “research” I’ve done…

 

[Matt69olds]

Here is the tone wheel. GM calls it a reluctor wheel.

I have 2 4L80s torn apart right now, both are 2002ish center lube models, one 2wd, the other 4x4. The 4WD does not have the pickup for the rear speed sensor. Maybe GM felt generous on certain day?

 

[Retoxtony]

Thanks for the helpful answers guys. I guess the quick answer is to just save myself the headaches and find a trans out of a 2wd truck (which is what i kinda assumed). I’m not in a big hurry to do a swap so I’ll just keep looking till the right donor shows up. My plan is to have things lined up and ready to go for next winter, so I have plenty of time.

 

[idahovette]

@Retoxtony I don't believe there is such a thing as "plenty of time".........time seems to get away from all of us................ask me how I know

 

[Big Ray]

lot of truth right there ^^^^

 

[Ricko1966]

I am about positive you could take the transmission, transfer case,crossmember and do your swap.You will have to make or find a rear drive shaft the correct length. I've gone to boneyard before with a tape measure and measured drive shift after drive shift before until I found something the right length. My k had been running who knows how long before I got it,no front drives shaft,its been awhile now that I think about it it may have been no rear drive shift. Anyways it was being driven with 1 driveshaft.

 

[Hunter79764]

Are you asking if a 4WD can be converted to 2WD? If so, the answer is definitely yes, but basically requires a full teardown to replace the output shaft etc as Matt pointed out.
Or are you asking if you can install it with the transfer case as a money saver, not hook up anything to the front output, and drive it as-is? If so, I believe the answer is also yes as Rick pointed out. It would not be much if any different than a 4WD running in 2WD its entire life, and as a West Texas native, I can attest that many of them do just that. Might not be the healthiest thing, I think GM recommends putting it in 4WD every so often, but probably not a killer.
Note, if it was an AWD, that would not be the case. Those need a front driveshaft as well, otherwise you will likely burn them up. I don't think there was an AWD application for 4L80e, just the 4L65e's in Escalades and Denalis, but just wanted to add that

 

[Matt69olds]

Quick google search shows 5 different output shafts. The 4x4 shaft is several inches shorter, meaning even if the spline count is the same, there is no way to put a yoke on it once the extension housing is installed.

 

[Matt69olds]

It just dawn on me you want to bolt the 4x4 trans and transfer case into a 2wd truck and not use the front driveshaft? I suppose you could, but if you’re wanting the LS engine for the added powere, why handicap the truck with a couple hundred pounds of extra weight?

If you have a known good 4x4, and are reasonably mechanically skilled, it’s not terribly difficult to swap output shafts. The parts would probably be 100-150 bucks, and since you wouldn’t be rebuilding the transmission, it’s fairly simple remove and replace components. It will require complete transmission tear down, but that gives you an opportunity to inspect the clutches and install a good shift kit.

Another option, have a transmission shop swap the parts for you.

 

[Ricko1966]

Another option use the transfer case for gear multiplication like like running a 2 speed rear-end. I've thought of doing exactly that,more than once,stump puller,heavy trailer puller,stoplight to stoplight killer in low highway cruiser in high.