What does it take to modify a 4L60E to a 4L70E ?
 

I have a 2006 Rainier 5.3 with a 4L60E at 70K miles it has cratered. I am looking at rebuilding it and beefing it up to 4L70E specs. It will not be hotrodded but will do some towing. I'm new to this forum, but heard there
are some knowlegeable transmission people here.

Thanks Richard:)

Welcome!

Lots of good people here with real world solutions.

What parts failed on your trans? 4L70 trans specs are not massive difference in basic parts of the 4L60 series trans.

5 pinion planets in 4l65 & 70E trans. Servo upgrade (small change), heat treating of input shaft, one extra 3-4 friction.

Changes and up grades on the 4L60 are simple and common.

Unless you broke a shaft or the planets broke apart, a proper rebuild is all that is needed along with common upgrades folks do

Thanks for the response, Crosley, I don't have the trans out yet, but I did pull the pan, I found a bunch of curved metal pieces and one needle bearing laying in the bottom. I believe the rear planetary has self-destructed. :(

If you need to buy planetarys for this unit, then you could purchase 5 pinion planets like the 4L65 - 70 E have.

IF you move forward on the project, Do NOT purchase import 5 pinion planets. Only purchase genuine GM 5 pinion planets.

What other mods would you recommend?

How to Convert a GM 4L60E Transmission to a 4L65E - Car Craft Magazine

There're better options for the 3-4 clutch pack than the Z-pack in Article above, depending on how much HP/TQ you're gonna throw at it. Best = Raybestos Blue Plate Specials, Better = Ray. Stage 1's or Alto Red Eagles, next High Energy's .

More >> GM's Stronger 4L65-E Transmission-Super Chevy Magazine
65E's Output Shaft is also an upgrade.