3rd Gen: Swapping MT gears into an AT?

Has anyone swapped the 4.3's from a MT truck into an AT in place of the factory 3.9's?
If so how does the truck seem now? Do the rpms sit too high cruising? Is the hunting calmed down or even worse? Is it even noticeable?

 

Are you just talking about doing a regearing? What size tires are you running? Of course your RPM's are going to be higher without adjustment.

I've heard the hunting is solved with some regearing in the automatics, but I've only driven manual.

 

Stock setup(suspension, tires, gearing), I'm just curious if anyone has done this swap to see if the feel is better. I understand rpms will increase, but questioning if it would be that relevant or noticeable as far as exhaust sound and responsiveness. I assume even MT guys regear and probably have stock gears hanging around, so this could be a cheaper solution to the AT's that aren't going to crazy build lengths and a way for MT's to offload their stock parts and recoup some $$ (unless they're feeling generous) haha

 

My take on it is if you don't care about gas mileage and you're going to do regearing, go to 4.56, 4.88, or 5.29 and slap some funboy tires on there. You're only going to want to regear once. My manual has a 4.3 in it and it is nice, but I'm sure if I went beyond 33'' and had a bunch of extra weight, I'd want to go higher.

If you can get some freebie 4.3's, then by all means regear away. It's a process, but if you don't mind doing stuff yourself. But if you're paying for it, I'd go a higher ratio. Just my two cents, so I hope that helps!

 

On a bone stock truck...It would increase acceleration at the expense of fuel economy.

 

Regearing the AT's is common for larger size tires, I'm also aware many people dislike the gear hunting the AT does. This is just a question posed to see if anyone has tried the 4.3's as a hopefully cheaper second hand alternative to buying a full regear for larger tires/heavier weight. If AT's can gain a favorable advantage in the gear hunting/response department by using MT factory parts they got secondhand I could see it being a new market for MT's who regeared. If this isn't beneficial though I guess it's a moot point. Really looking for anyone who has actually attempted this out of frustration (or for broscience), appreciate your input though.

 

There are a few things that you need to do:

-- First is to see if you are actually getting into 5th and 6th gear. With none, partial, and full TC lock up, what folks think are shifts might just be the TC dancing around. Some stock AT folks have said that they rarely see 6th and it never stays there for long. So here, a regear might net you some MPGs. Monitor your gears with an OBD tool like Torque, OBD Fusion, or other apps.

-- The other thing is to research what the gearing change will actually do. I really like this site:
http://www.grimmjeeper.com/gears.html

Be sure to hit the Save button at the top if you are going to be checking some different ratios. The 3rd Gen gears are linked in my signature.

-- And yes. Some MT folks have regeared, so 4.30s are available every once in a while.

-- Lastly, ATs with 5.29s and stock everywhere else are very slightly lower geared than a stock MT. That said, my stock MT is running at about 20mpg overall. 265/70R17 Wildpeaks seem to have stolen only about 0.5mpg with a 5% correction factor compared to GPS, the Softopper definitely has a bit of aero drag at highway speeds, and because of the ST, I am carrying a more weight in the bed due to some storage. That said, OVT gave me about a 2mph boost, which means that I am about the same as stock overall.

 

I don’t know why you’d install 4.33 gears if you are paying to have both stock diffs Opened up and installing the Toyota 4.33 stock gears vs some aftermarket 4.88+. If you are going to pull open your diffs and rear gear ..install something that will work better.

however , If you mean get some junk yard 4.33 rear axle and the front 4.33 diff, and swap that in your AT then that makes sense . You could do this “bolt on” swap yourself and if the junk yard isn’t stingy you can probably get both diffs or even whole rear end (if you dont already have a 8.75” or elocker) for 1k or less

 

I agree. That's what I basically said in my post too.
If you're going to go through with the work, just kind of go big or go home.
And just make sure you know what you want and where your truck will end up so you don't do double work.
There's always the "what if" situations, and trying to future proof your vehicle is endless.
I just hope you come to a decision that works for you after all is said and installed!