TH400 Needs Overdrive... 4L80E swap? Bolt on OD?

[SasquatchOnDeck]

Looking for some experience and advice. Bought a 89 ECLB last year, It's got a 454/TH400, 4x4, a SRW Dana (60/70?) with 4.10 gears, a questionable dually conversion, and finally, as all TH400s, no overdrive. Coming from a 88 with a 350/700R4, and seeing as i don't own stock in Exxon-Mobil, it's damn miserable.
LSS, i'd love to daily this truck, but that's going to involve putting in overdrive, the cheaper the better. I'm leaning away from the gear vendors at the 2,000$ price point because i'd still only have 3 gears, but if there's a cheaper alternative, i could happily avoid freeways and stick to 60MPH two-lanes.
I'm pondering a 4L80 swap, could it be done without the E on the end? I'm going to delete TBI to remove electronics, i'm trying to not add more, but i don't know that there's any other option there. Would a 4L80E pop right in where the TH400 was? I don't now what transfer case is in there, or if it even matters, and to complicate things, I'm on deployment and can't exactly look at/under the truck for a couple months.
Has anybody done anything similar? What other bolt-on O/Ds are out there? TIA

 

[454cid]

...i don't own stock in Exxon-Mobil, it's damn miserable.

...I'm going to delete TBI to remove electronics

I don't think your mileage will go up after removing the fuel injection.

I think you can use a manual valve body in the 4L80E, but you would have to shift it like a manual. It would be more of a drag racing type thing. There are aftermarket controllers but I have no experience with them. My truck is basically stock.

This truck is never going to be great on gas.

 

[Frank Enstein]

I would do the 4L80E swap in a heartbeat.

Although the Gear Vendor's overdrive unit is bombproof, the 4L80E's .75:1 O.D. is better than the GV's .78:1 ratio.

And you would be giving up on the locked torque converter. Locking the converter feels like 5th gear and reduces the fluid temp greatly.

In O.D. the final drive is 3.08:1. Lock the converter and it feels like 2.73:1!

 

[SasquatchOnDeck]

That's the way i was starting to lean. I know a trustable transmission guy, i could probably find a core, have him rebuild/install, and any other necessary controller, for the price of buying a gear vendor unit. Plus, i'm handy, but i don't play with transmissions. i don't trust myself.

I just wish there was a way to do it without electronics, they've only ever caused me problems. I've got a whole 88 sitting in my yard back home, simply because "electronics". If it was 4x4, i'd consider swapping it's 350/700R4 into this truck, it would still suit my needs fine, i'm not going to be hauling houses up mountain trails THAT often.

 

[Frank Enstein]

Looking for some experience and advice. Bought a 89 ECLB last year, It's got a 454/TH400, 4x4, a SRW Dana (60/70?) with 4.10 gears, a questionable dually conversion, and finally, as all TH400s, no overdrive. Coming from a 88 with a 350/700R4, and seeing as i don't own stock in Exxon-Mobil, it's damn miserable.
LSS, i'd love to daily this truck, but that's going to involve putting in overdrive, the cheaper the better. I'm leaning away from the gear vendors at the 2,000$ price point because i'd still only have 3 gears, but if there's a cheaper alternative, i could happily avoid freeways and stick to 60MPH two-lanes.
I'm pondering a 4L80 swap, could it be done without the E on the end? I'm going to delete TBI to remove electronics, i'm trying to not add more, but i don't know that there's any other option there. Would a 4L80E pop right in where the TH400 was? I don't now what transfer case is in there, or if it even matters, and to complicate things, I'm on deployment and can't exactly look at/under the truck for a couple months.
Has anybody done anything similar? What other bolt-on O/Ds are out there? TIA

Leave the EFI. I've been tuning carburetors for over 40 years. I can make a carb sing and dance. What I CAN'T do is tune one 200 times a second. EFI wins that one every time. In my experience over 95% of problems with EFI are bad grounds and bad connections.

This is my go to controller and has been for years.

TCI Auto 302820 TCI EZ-TCU Automatic Transmission Controllers | Summit Racing

Free Shipping - TCI EZ-TCU Automatic Transmission Controllers with qualifying orders of $109. Shop Automatic Transmission Controllers at Summit Racing.

www.summitracing.com

 

[stutaeng]

Nice truck! Are you out honestly going to daily driving it?

Gear vendors is $2k??? Have you priced out a 4L80e recently? Around here, guys are asking $1200 or more for part out units! A manual valve body is going to set you back at least $600, plus labor! Will probably need driveshaft elongation/shortening...so add that as well.

How much mpg savings are you looking for? These are just heavy, brute work trucks. You will never get anywhere the gas mpg vs you 1500...

I'd say just run it. You could run a stock ECU/harness from a '94-95 TBI 454/4L80e, I think if you want to keep it stock.

Edit: No, your 700R4 is not up the task of lugging this heavy beast around reliably.

 

[Nad_Yvalhosert]

Let's say you did go the Gear Vendors route. You have a 4x4. That means you'll need to lose the 4x4 tranny and the t-case. You cant throw it into Overdrive and use 4x4 if its installed after the t-case

You'll need to install a 2wd TH400.
Then the Over/Under unit, hopefully it bolts to the tranny, if not a custom short driveshaft.

Then a divorced t-case.
Then another custom short driveshaft.

And a shift lever for the G.V.
And shift lever modification for the divorced case.
Then two more custom driveshafts
Add in a couple crossmembers while you're at it too.
Hope the extra drivetrain length doesn't interfere with the fuel tank...
So now that you've added an additional 1000lbs to the truck, you just lost any gains in MPG you might have saved.

Of course throwing in a 4 speed tranny will necessitate two new driveshafts too, but they're likely available in a junkyard.

If its $ you're worried about, dont change any of the current parts. Leave it "as equipped". Instead, change what you drive or how you drive.

 

[letitsnow]

Realistically - what kind of mpg difference would we be talking about from a th400 to gv or 4l80e? 8-9mpg vs 11-12mpg?

It would take many years to recover the costs of that change.

 

[SasquatchOnDeck]

Yeah, sounds like a whole rat's nest i can't afford. i'll revisit the idea if the transmission grenades, or if the engine goes, id even consider swapping my old 350 into it.
I've never actually drove it enough to even get a ballpark estimate of MPG, i bought it, made two pick and pull runs, and then went on deployment. We'll find out next year i guess. Thanks for the sense, saved me some dollars.

 

[MrPink]

Gear Vendors, Divorced T-Case, and a 2wd Th400.