haftrek

I am wondering how difficult it would be to swap out a 4 speed automatic with a 6 speed automatic...with a little reflashing of the ECM wouldnt the dimentions of the 4 speed be the same as the 6 speed? And could it be handled with just a new valve body?

no_6_oh_no

Nope, not gonna be that easy. The 68RFE is fully electronic which means all its functions are now controlled by a computer. The ECU or maybe a PCU again, will contain all the programming needed to run the trans based on engine and speed inputs. This conversion will require a standalone computer to function correctly.

Since the program to run the trans as designed are not exactly public domain, it will mean lots of R&D to develop it from scratch and mate the needed inputs to it. It can be done but will take some significant resources to accomplish.

Barrett_Fodder

sigh... sounds like this probably won't happen any time soon. I would love it if ATS or someone would come out with a 6 speed automatic trans as a swap for my 4 speed auto. I think that would stretch the fuel out a bit more on those long road trips and should keep the engine in its power band a little better in town driving too.

soulezoo

you can try Suncoast to get the Allison swap... $10k +

t-boe

The cheapest route to accomplish the same exact thing is adding an external overdrive. If you add a Gear Vendors or US Gear you would end up with an 8 speed, the ability to split each gear and lower cruising rpm. All that and at a fraction of the cost of an Allison conversion.

DevilzTower

I have high hopes that in a few years a 68RFE swap will be possible for the 3rd gen trucks. I found this site while digging around the other day, they offer fully programmable stand alone computers. I also noticed that they have a 47RE controller that's "[supported by ATS diesel]" so there's hope, we're just going to have to wait.

http://www.powertraincontrolsolution...content-4.html

SSminnow

There is ALWAYS hope. And one day, it probaly will be a common swap. Today, teh 6 speed auto is too new, notenough time for people to study it, and do the swap yet.

You can swap in ANY trans behind the CTD, just takes the right knowledge/people and of course how big your wallet is.

Dieseljunkie

Honestly, I think if I had an auto, I would save my $$ and have suncoast swap an allison into it.. Now THAT is a combo.. my dream combo.. cummins with an allison behind it
Scott

SSminnow

Yep, me too. I brought that up about 2 year ago.....dreaming about an Allison swap

Sevir

the allison is JUNK, a completely built 48RE from any of the top companies will out preform the allison. and you are paying 1/3 the price of the allison swap.

The allison in the chevys is the lowest quality tranny they make.

Raspy

The reason so many of us want to switch to something else is to get more gears. Not just to handle more power. So saying that a built 48 will outperform an Allison is not the case. A built 48 still has 4 speeds, and that's the problem. The 48 is not very good for towing because of the gearing.

Adding a OD behind the 48 adds more stuff and reduces efficiency compared to a 6 speed tranny. You can't just keep gearing higher and higher in search of greater efficiency. A 4.10 gear set and an OD would be OK but mainly for gear splitting. Best is a 6 speed tranny to begin with.

The Allison sounds nice because it has 6 speeds and a nice low first gear, but it is a difficult and expensive conversion and the tranny controller is not widely available yet as far as I know.

I keep hoping the Aisin becomes available or the 68 proves itself and becomes available for retrofitting.

John

SSminnow

Out of all the STOCK trannies, teh Allsion is teh best made, period. The STOCK Allison will handle more power reliably than a STOCK 48re, easily.