4L80e in place of 700R4

[Darty03]

I have a bbc in an 83 k10 short bed with a 700r4 and an np208 behind it. The 700r4 isnt holding up to the big block and I was thinking about swapping in a 4l80e. Im confused about matting the transfercase to the back of the 4l80 though.

What adapter does it take to mount a np208 to a 4l80?

I do have an np205 with a slip yoke output shaft on it from a parts truck, it had a th350 in it. I know it is a stronger case so if its easier to adapt Ill use it instead.

What do I do about a speedo signal for the transmission controller? Am I going to have to pull the trans apart to have a reluctor installed? I plan to use a TCI transmission controller.

[Irish_Alley]

The 4l80 needs a electric speedo your 208 is 27 splines you would need a 208 or whatever as long as it has 32 splines. Th400 and the newer sm465. There's a lot more but I'm on my phone right now

[Darty03]

Hmm, by the time I find a transfercase with the correct spline and buy an adapter and a 4l80, it might be worth just building the 700r4 to take the power.

The motor is a 454 bored to a 468. I bought it thinking it was a stock 454 but its turns its a 468 ATK crate motor, its rated at 415hp 497tq. The 700r4 has a fresh rebuild but isnt holding up to the horse power.

[LTZ C20]

700r4 will hold up to the power. They just have to be built to handle it. The second gen 700s (30 spline/4L60) are better than the first gen 700s (27 spline). My 89 700 (4L60) was capable of about 500hp after it was built. In total I've only spent about 2500-2800 on it and that's with 2 rebuilds, but not including labor.

[Irish_Alley]

its not just the power it has to hold up too but the weight of the truck. it can be pretty pricey for the 4l80e tcu adapter and t case. i lucked out and found a 91 crew cab the first year for the 4l80e and the last year for the 205. theres adapters out there you can buy but they will prob cost 500 easy unless you find a 4l80e/205 which will be very hard. think it will be cheaper and easier to get a nv4500 bolted to a 205. if i had to find the trans knowing what i know now thats the way i would of went. think it can be done for about 1k. if you can get a round pattern 205 it should be 32 splines and if its the long shaft 205 you need a spacer but besides that it will bolt right up to the gm nv4500

[Darty03]

This truck is ran hard so Im afraid even a built 700 wont hold up for more than a year or 2. I actually just twisted both axle tubes in the 12 bolt rear a few days ago.
 I have considered putting a nv4500 in it. Id rather keep it auto but Ill swap one in if I can find one. All Ive been able to find is dodge versions so far though. I have been looking for transfer cases and cant seem to find any in driving distance with the correct splines. Seems like my issue with going with anything other than a built 700r4 is finding the stinking parts. I thought it would be easier with how many of these trucks are out there.

[Irish_Alley]

700 can be foud in a lot of chevys the 4l80e only came out in 91 so theres only one year for that trans. most times you find the correct stuff but it takes a while to put it together.

[hatzie]

Hmm, by the time I find a transfercase with the correct spline and buy an adapter and a 4l80, it might be worth just building the 700r4 to take the power.

The motor is a 454 bored to a 468. I bought it thinking it was a stock 454 but its turns its a 468 ATK crate motor, its rated at 415hp 497tq. The 700r4 has a fresh rebuild but isnt holding up to the horse power.

The NP208 & NP241 can be had with the 32 spline input fairly easily and the 32 spline NP205 is not a Unicorn. 
You should look for the 1991 - 1996 transmissions.  They have VSS in the transmission whether it's a 2wd or 4wd.

You can use the stand alone GM TCM from an early 90's T400 chassis,  express Van, or the T42 TCM from some of the H1 Hummers.   

700 can be foud in a lot of chevys the 4l80e only came out in 91 so there's only one year for that trans. most times you find the correct stuff but it takes a while to put it together.

The 4L80E was used from 1991-2013 but I'd lean toward 1996 and earlier.  You can use any year unit but the connector pinouts are different.

[LTZ C20]

700 can be foud in a lot of chevys the 4l80e only came out in 91 so theres only one year for that trans. most times you find the correct stuff but it takes a while to put it together.

As Hatzie stated, the 4L80E was used from 1991-2013. It's replaced now by the 8L90E.

[Darty03]

I didn't know earlier 4l80s had a vss! Thats good to know. Ive been looking but cant seem to find squat. Im finding 2wd and a few newer 4x4 4l80s but nothing in that range yet.

Ive decided Ill just swap out the input shafts on one of the transfer cases I have. I cant find anything cases within 100 miles of me so i think this would be the easiest option. Ill just order an input shaft that will work.


Okay so looks like all I need are
4l80e from a 4x4 preferably 96 or earlier
Either a gm TCM or a TCI to control it
32 spline input shaft for my 208 or 205
Adapter to bolt either transfer case to the 4l80

The rest is just driveshaft lengths, linkage lengths, and a crossmember.

[Irish_Alley]

meant 91 is the only year for that trans/transfer case combo and you cant just use a th400/205 adapter fot the 4l80e. the trans does have speed sensors but it doesnt have an output speed sensor which is either on the tailshaft or the transfer case. or have i been understanding this all wrong

[Irish_Alley]

found this,
http://www.trucktransdiag.com/downloads/4l80e-tech-info.pdf
but whats the speed sensor on my 205 for? is that for when it gets put in 4L?

[Darty03]

I have converted my np208 to an electric speed sensor to work with my aftermarket gauges. So the speed sensor on my np208 wouldn't run the transmission controller? If that's the case then I would think any 4x4 4l80 would work if I use that transfer case.

Thats actually some really good info Irish_Alley, I saved it in case I need it later.

[hatzie]

meant 91 is the only year for that trans/transfer case combo and you cant just use a th400/205 adapter fot the 4l80e. the trans does have speed sensors but it doesnt have an output speed sensor which is either on the tailshaft or the transfer case. or have i been understanding this all wrong

The 83 needs a speedometer cable not a VSS.
Transfer case runs the speedometer cable with a gear. 
Early 4L80E VSS is for the TCM only.  It is an output signal but it's not suitable for an electronic speed head on a 4wd rig.





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[Irish_Alley]

Maybe you could help me with mine. I'll start a new thread if it too in-depth for just more than one response. But my speed hasn't worked on the 4l80e/205 since the cummins swap. I have the dracs box and ecm and wires. The ecm isn't hooked up. But how do I get the signal to my speedo for it to work again