Later 5.9 or 6.7 with 6 speed auto in a 2nd gen

[DHayden]

Is it possible? Have been looking to do the 6 speed auto swap (have a NV5600) I just called around again and peaple do the allison with stand alone computer but still nothing really for the 6 speed dodge auto.

So I got to wondering, if I did a late 5. 9 or 6. 7 and 6 speed auto it would get rid of the need for a stand alone, I could use the exhaust brake and everything but will it fit? will it work? Anyone have names of places that do this? I called D-stroked and they mainly deal with ford/chevy conversions to cummins.

 

[RustyJC]

Unless someone modifies it completely, I don't know how the 68RFE could operate without a computer of some sort since the FE in the model designation stands for Full Electronic. Besides controlling shifting in both the normal and tow/haul modes, the computer also controls the 2 stage transmission fluid pump based on fluid temperature, modulates line pressures if it senses slippage, etc.



Rusty

 

[DHayden]

Thats why I'm wondering if a whole late model engine/trans assembly can be swapped, then I wouldnt need anything.

 

[HBarlow]

IMO the days of making conversions like that are a part of the past. The new engnies, tranmissions, and even body/cab electronics are too complex and too interrelated. That's not ever considering the difficulty of finding a complete take out engine, transmission, or both and the cost of either or both.

It would be cheaper and you'd have a better end result to just buy a newer truck.

 

[HBarlow]

Very few of us have the talent to make the conversion that Andres reports above and most of us could not (or would not) afford the price tag to pay a professional to do the work.

Andres did it the smart way. He purchased an entire vehicle with a complete engine and drivetrain including all the related computers, harnesses, etc.

I admire anyone who has that kind of talent.

 

[AClayton]

I've been thinking about putting an Allison in my 01'. The auto in my truck could really benefit from a lower 1st gear ratio. I know a 4. 10 gearset would be much better in getting the load off the line but I really like my cruising rpm at 65mph with the 3. 55's. I just don't think 4 spds is enough for these trucks..... loaded or even unloaded!! Once I get my 5th wheel moving to above 25mph, I can easily accelerate to highway spd from there. This where a modern 5 or 6spd auto trans could benefit the versatility of the second gen trucks.

 

[RustyJC]

I know a 4. 10 gearset would be much better in getting the load off the line but I really like my cruising rpm at 65mph with the 3. 55's.

That's one thing that surprised me the first time I took the new truck (see signature) out on the highway. My previous 2002 Ram with the NV5600 6-speed and 4. 10 gears ran almost 2000 RPM at 60 MPH - it was a pleasant shock when the new 68RFE truck with 4. 10s was running along at 1600 RPM at 60 MPH - less than my 2002 would have run with 3. 54s. Of course the 68RFE is a double overdrive (4th is 1:1 with a 0. 61 6th gear ratio) while the NV5600 is a single overdrive (5th is direct with a 0. 72 [IIRC] 6th gear ratio).



I haven't towed with it yet, so I guess we'll see how that tall 6th gear affects the towing performance, but Dodge rates this truck with the 4. 10s at 24,500 lbs GCWR (vs 21,000 lbs for the 3. 73s).....



Rusty