Swapping 4spd auto for 6spd auto?

Has anyone tried swapping the 4spd auto that is mated to the 2.7 for the third gen 6 spd auto (mated to the same engine)? If not, does anyone know what it would theoretically take to do this? Highway speeds + hills + the 2.7/4spd does not make for a happy me... No I don't want to buy a v6 or a manual. I want my truck, it is paid off and was my grandfathers.

 

I can’t answer your question.

But you’d probably be better off with regearing. I’d bet swapping in a manual 5spd. would be easier then an Auto 6.

I vote regear. And if you really want more power? (SC / Turbo)

 

I'm more discontent with the gear hunting it does on the highway, not the get up and go. Not sure how re-gearing it would help?

 

Adding more gears usually doesn’t help “hunting”.

Regearing will bring the engine RPM up.
When your truck hunts for gears. It usually drops to a lower gear. Thus your engine RPM is higher.

These trucks don’t make optimum power at cruising speeds. The power is further up in the rpm.

One of the main reasons a lot of 3rd Gen guys went with 5.29 gears, is exactly for the same reason you are having.

I don’t think 6 gears is going to help your particular issue. Unless you lock out some of the gears. As in stay in 4th.

 

For clarity, when I say regear.
I mean the gears in the rear differential.

 

Gotcha. I don't pretend to know much. That's why I ask questions. I have a 5 lug, so my gear options are a little limited. Would you say going from stock 3.58 (i think) to something like a 4.10 would help my issue?

 

I don’t have a lot of real word experience with the 4spd 2.7 trucks.

I’d venture to say, Yes. It should help a good bit.

@whatstcp will probably know more.
I think he has a 2.7 and is regeared?

 

I don't know specifically all the answers to your questions, but I did swap between a 4sp auto to a 5sp manual. I'll guess that you'll need to swap the transmission (obviously) and the engine ECM.

The transmission should bolt up no problem. You might need to shorten your driveshaft...I'm guessing the 6sp auto is longer than the 4sp auto. But any driveline shop can do it for about $100. Might need to adjust the support cross member and mount, but that's not a big hurtle either.

The engine ECM controls the transmission. I'm guessing it's the same setup in the 3rd gen. But since the transmission is difference you'll need the 3rd gen engine ECM to control the transmission. The 3rd gen 2.7 is dual VVT-I, while all 2nd gens before 2015 are single VVT-i. I'm not sure how that plays into the engine control ECM interchangeability.

 

What about switching to a 2nd Gen 5-speed auto? The 6-speed has a double overdrive and unless you really want that 2nd overdrive, I'm wondering if it would be simpler in any way to use a 2nd gen trans. If the stock 3rd Gen ECM tuning also includes how the trans shifted, you're not going to like how the 3rd Gen's shifted. If you thought gear hunting was bad in the 2nd gens....

But I'm pretty ignorant on all of this, so just putting my thoughts out.