1984 4L80E conversion what parts?

I started a project but not sure how to proceed with transmission and parts. Its an 1984 K1500 High Sierra 3.08/33" tires with 305 and 700r4 that leaks fluid like crazy. I've purchased a blueprint crate 350 2 bolt from Summit (2 bolt cause it was $2k less than 4 bolt options) and now would like to install a 4L80 so I dont have to worry about setting up TV cable or extra hp from new motor. I've seen 1/2 tons with the 4L80 conversion but what will I need to swap if I plan to change out the axles with 3/4 or 1 ton?

This is my first squarebody so any help or ideas would be greatly appreciated, thanks!

Just bolt your new motor in and adjust the TV cable, done.

4L80 will require a transmission controller, probably need to shorten rear drive shaft & lengthen the front, need to move the crossmember, and may need an adapter to mount the transfer case.

I know nothing about transfer cases, so I can’t help there. A 700 and a 4L60E are the same length. To the best of my knowledge, all the 4x4 output shafts have the same spline. I don’t know for a fact if there are different length shafts for different transfer cases. I do know corvettes use a unique shaft and extension housing.

If the 700 worked, get a seal kit for it. As long as your not rebuilding the transmission, changing the gaskets isn’t that hard.

Fastduramax said:

Casey would that be the case with the 4L60E also ? Thats what I want to run and was under the impression the 60 was the same dimensions as the R4... US Shift makes a banging sweet controller...

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The 4l60 is a straight swap for a 700r4 except you need a controller

Fastduramax said:

Casey would that be the case with the 4L60E also ? Thats what I want to run and was under the impression the 60 was the same dimensions as the R4... US Shift makes a banging sweet controller...

Click to expand...

I just did a 700/60E swap & had to move the crossmember slightly, it's possible the crossmember wasn't in exactly the right spot for the 700 anyway. Moving the crossmember is like a 15 minute job, super simple since you will already have everything apart.

Front and rear shaft lengths stayed the same.

NP-208 TC bolted right up with no adapter.

Only real difficult thing was adding a 40 tooth reluctor wheel and VSS to the output of the TC:

There are adapters that will get a signal from between the Trans and TC which is an option but if will shift way to aggressively when in 4x4 low range.

The TC from a late model 90-91 blazer or suburban (IIRC) is already set up this way but they are getting hard to find.

I added the VSS & reluctor from a NP-241 into my 208 tail housing using scrap parts for no cost, the downfall of this is I can not run a mechanical speedo any longer because the VSS is in its place. Easy for me because I had already decided on Dakota Digital gauges.

Fastduramax said:

Thanks guys that's what I thought, mine is the stock original R4 and no one within reasonable driving distance can build it to handle my motor, it dynoed @ 675hp/715tq... R4 and 60E are very close in cost for a 700/800hp build from most of the big name builders, downfall is the US Shift Quick 4 controller is pretty pricey... I wanted street manners from the start of this project, My spunky but not stupid aggressive roller cam choice, Sniper injection and a 60E should accomplish this...

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Damn dog... With that level of build the 4L80 may be in order

Fastduramax said:

Thanks guys that's what I thought, mine is the stock original R4 and no one within reasonable driving distance can build it to handle my motor, it dynoed @ 675hp/715tq... R4 and 60E are very close in cost for a 700/800hp build from most of the big name builders, downfall is the US Shift Quick 4 controller is pretty pricey... I wanted street manners from the start of this project, My spunky but not stupid aggressive roller cam choice, Sniper injection and a 60E should accomplish this...

Click to expand...

Ok, the 675hp/715 torque numbers change things, I’ll revise my statement!!

With that kind of power, but once, cry once, put a 4L80 in it. For the money it’s going to cost to build a 4L60 to handle that power you could use a 4L80 and have money left over.

You can supposedly build a 700 to handle that power, but it will be expensive and a maintenance item. A 4L80 will handle that with ease.

Fastduramax said:

Thanks guys that's what I thought, mine is the stock original R4 and no one within reasonable driving distance can build it to handle my motor, it dynoed @ 675hp/715tq... R4 and 60E are very close in cost for a 700/800hp build from most of the big name builders, downfall is the US Shift Quick 4 controller is pretty pricey... I wanted street manners from the start of this project, My spunky but not stupid aggressive roller cam choice, Sniper injection and a 60E should accomplish this...

Click to expand...

Yeah, the 700R4/4L60 is gonna have a hard time with that. Also the quick shift controller is not very good. You'd be better of going to a junkyard and get a used 4L80e, wiring harness, and ECU since you are running a sniper anyways. Pick off the TPS signal from the sniper and the tach signal from the HEI and you will have a 4L80 that drives just like from the factory. You can have someone rebuild the 4l80(or do it yourself) for a reasonable amount since all the hard parts are sufficient to handle 700hp stock. You would just want a basic rebuild kit(I paid $700 for a comprehensive one for my build with all new everything), do a dual feed mod, and a basic trans go shift kit and the thing would probably outlast the engine. Call a reputable torque converter company and have them build you a converter for the trans and specific engine specs.

Have you heard of these guys?
LINK:
Gearvendors
Video
There's link called factory tour and at the top of the page there's a guy in a hat. Click on his face and a very informative video will play. You might be able to save some time and money by calling them and asking a few questions, before you buy an electronic transmission.

My recent experiance with rebuilt Automatics has not been very good. I am not convinced electronic controllers are my friend. I ordered a 700R4 without a TV cable and the builder ignored me and sent one with it anyways. My 700R4 transmission is dead.

You can use an ECM from the same vehicle the 4L80E came with and a tach wire for signal from the HEI dizzy, but you'll need to make a harness from the ECM to the transmission. If you buy an OBD2 Van ECM from a 2000-2001, you can even hack it and program your shift points and modify it to run a base-map program your roller cam, if you ever needed it to for EFI. It would be cheaper than buying the $600-$800 stand alone controller, if you can crimp and rewire your self. The ECM is $175 on ebay from TX, and the guy is an OEM supplier. You'll need to find a set of pig tails and buy a pin out diagram from GMT-400 forum.
Let me know if you want his contact info or the youtube videos for the ECM mod/hack, if you decide to go that rout.

I watch a lot of this guy Richard's videos. He goes into minute detail regarding the cryogenic hard parts and HP Mods, in several of these rebuild/tear downs. I highly recommend a few days of binge watching this guy at work.
LINK: Precision Transmissions Youtube Channel
Richard often opens up other guys work and shows how people ended up getting ripped off. A lot of people get ripped off... even when they are told they are getting a high HP unit. Quality HARD Parts are hard to come by.



Hope these links and videos are informative while you select your build.

Welcome to the Forum!