Ford Power Stroke Nation banner

ZF6 or 6R140 for 08 Superduty 6.7 Cummins swap ?

34K views 45 replies 22 participants last post by  navistar45 
#1 ·
I'm swapping a 6.7L Cummins into an 08 4x4 F350 Superduty.

I need to make a decision about the transmission.

I'll be tuning the engine with EFI live. I hoping for 900 ftlbs and 400-450 HP. I pull a 35 foot 5th wheel that weights about 13,500lbs loaded. I use the truck for towing only. No racing.

I have narrowed it down to 2 choices:

1) ZF6, ie the Ford manual transmission in pre 2011 Superduties.

2) 6R140, ie the Ford automatic transmission used in post 2010 Superduteies.

I am hoping that both of these transmissions will handle the power of the 6.7 without any modifications.

I am eliminating the Allison and 68RE transmissions because I feel it would need extensive mods to handle the 6.7 output.

I am eliminating the FSO6406 and FSO8406 because it would be difficult to mate the transfer case to them and they are expensive and they don't shift as nicely as the ZF6.

I am really torn about whether to chose the ZF6 or the 6R140. I want great fuel economy, both towing and empty and I want longevity. I don't want any incidents of roadside breakdowns.

The 6R140 has better gear ratios. 0.67:1 for cruising and 0.89:1 for towing. The ZF6 has 0.72:1 for both. A little too fast for optimal pulling (ie engine is lugging at 1600 RPM @ 60) and a little too slow for cruising, though not bad for that.

My truck is a King Ranch and I'm cringing at the thought of cutting a hole in the transmission tunnel and carpet and sticking a gear shift in it. Though I do like driving a stick.

I'm driving the truck right now with the 6.4 and 5R110. I hate how the engine revs up every time you want to accelerate. The fuel economy is dreadful, though I suspect that is more because of the engine than the transmission.

I have also been thinking about playing around with an air shifted ZF6, ie no gearshift in the cab.

?????????????
 
See less See more
#2 ·
What happend to your 99? Did you get rid of it after the dick head tried to steal it? That was a very nice truck!:psn:
 
#4 ·
Thanks ! Its sitting in my garage while I wait for a settlement with insurance.

In the mean time, I bought an 08 CC LB 4x4 King Ranch. And a Cummins 6.7.
 
#3 ·
I personally like auto's when towing but that's just me. The With the amount of work and money your about to do and spend why not just purchase a used Dodge? Now obviously I don't know your personal finances or reasoning behind a cummins swap other than you love your Ford and its need a new motor or like me perhaps your on the larger side and don't fit into a dodge cab very well.
 
#5 ·
I personally like auto's when towing but that's just me. The With the amount of work and money your about to do and spend why not just purchase a used Dodge?
Spend some time in an 08 King Ranch and you'll understand.

I looked at Megacabs. They were generally more expensive and I didn't like the interior as much. And there was no way I could live with the short box, so I would have had to cut the frame and lengthen things. It boiled down to me wanting another Ford versus a Dodge.

Now obviously I don't know your personal finances or reasoning behind a cummins swap other than you love your Ford and its need a new motor or like me perhaps your on the larger side and don't fit into a dodge cab very well.
Contrary to popular belief, it doesn't cost a lot to swap in a Cummins. The engine cost is a wash if the 6.4 is good and you sell it as a running engine. I've got two buyers lined up now.
 
#6 ·
I know nothing about auto transmissions. My 08 has a 5R110 and I think it slips way too much.

I need to learn. Why do you like autos better when towing ?
 
#7 ·
Does anyone have input on putting 8-900 ftlbs through a ZF6 at 1600 RPM for hours on end ?

Articles like this make me VERY leery of the Allison.
http://www.kennedydiesel.com/dmax_ats_tranmission.html

At least the 6R140 was designed from the ground up for 800 ftlbs. And the 5R110 seems to have done well behind tuned 6.4s.

What other options do I have ?
 
#8 ·
Personally I would do the 48RE with a PCS controller
 
#9 ·
I think the 5r110 is pretty bulletproof but thats just my opinion. Stick with an auto, you do not want to be towing around the country with a zf6, Unless you still love shifting after 5hours of stop and go traffic between 0 and 30mph. Automatics are 10x better.
 
#11 ·
I'm the resident MPG nut and a bit of a Cheap Charlie about repairs and I come down firmly behind the ZF6. It's good for +2 MPG over any automatic made. I've got 280,000 miles on my factory clutch.

There's way less to go wrong on a ZF6 than any automatic. Clutch, throwout bearing and input shaft bearing is about it, and those should be hundreds of thousands of miles away.

If you are pulling enough load to wreck a ZF6, you need to unload the pickup and get a real tractor. A ZF6 is a German deuce-and-a half tranny.

Have a long talk with a clutch pro. There are some outstanding clutches available these days.
 
#14 ·
#15 ·
The 6.4L in my truck seems fine. As does the 5R110. The truck has a clean OASIS report.
 
#19 ·
How would you control a 6R140? I don't believe PCS has a controller yet & if they do I haven't heard anyone ply with it. The people I talked to that did a 5r110 behind a cummins said it was a PITA & still didn't hit perfectly.
 
#20 ·
The 6R140 has a dedicated transmission control module. It uses the CAN bus to communicate with the ECM and its its own ODBII device.

My plan was to install a CAN bus sniffer on an '11 and watch the messages go back and forth to the transmission. My dad has an '11 with the 6R140.

The 2008+ Dodge 6.7s use the CAN bus as well. I was going to sniff its network to see what goes back and forth as well. My friend has a 2009 Dodge with the 6.7.

I was also going to sniff the CAN Bus on my 08 to see what goes back and forth between the 6.4 and the 5R110.

Between all this, I was hoping that I could write a CAN bus bridge to take the info from the 6.7 and feed it to the 6R140. The number of messages and content shouldn't be that great, only simple things like torque requested, throttle position, speed, etc.

I've read a number of posts on the 6R140 having issues. I don't think I am going to pursue using it.
 
#21 ·
I have had two 7.3 SuperDuty's with the ZF6, and one with the 4r100.

I have had more trouble than most do out of both.

My current 2002 ZF6 is on clutch #4 at 130k. My 2002 4R100 went through 3 complete transmissions in 109k miles.

The truck with a 4R100 was on 37" tires and made a lot of power. I was also not easy on it at all. That was pretty much my fault there.

The current ZF6 problems, however, are not/have not been my fault.

The original clutch got replaced around 50k miles. The input bearing on the trans went out and damaged the input shaft as well. I thought since the transmission was out it would be a good idea to have a new clutch put in while I was at it. I knew it wasn't needed, but it seemed like a good idea at the time. Looking back it definately wasn't.

I had a very reputable trans shop do the work. Turns out they did the involved part (trans repair) but farmed out the simple job (clutch) to another place. I wanted an OEM replacement clutch and was told that was what I got.

About 10k miles later the clutch started slipping under normal driving. The truck at this point was not lifted, was on factory size tires, and didn't even have a chip.

Come to find out the clutch that went in was inferior and the original pressure plate was reused as well.

I didn't want any more problems so I did my research the next time and put a dual friction SouthBend clutch, flywheel, pressure plate, and Kevlar input bearing.

The pedal action wasn't quite as smooth as the OEM clutch but that was to be expected and things were great for another 60k or so.

Fast forward to sometime last year. I was towing my 12k pound 5th wheel and heard a noise that sounded a lot like several thousand dollars. I downshifted to pass someone, went to shift back into OD and got nothing but grinding.

Turns out one of the springs on the clutch disc broke and the clutch grenaded. I was in the middle of BFE several hours from home and the logical choice at the time was to have the truck repaired at the local Ford dealer. They insisted on using Ford parts and after this incident I had no reason to request otherwise. The oversize SouthBend flywheel was able to be re-used but a new clutch and pressure plate were bolted up and I was on the way. Only thing I regret is not insisting the Kevlar input bearing be reused.


With all of that being said, I still prefer the ZF6. All of the above was on my 2002. The 1999 I had was problem-free but I only had it for 80k miles. I have had a series of unfortunate events but I think they have been (for the most part) freak occurrences. The trans itself is very strong and as long as it is well taken care of will provide a lifetime of service.

My advice: Go with the ZF6 and insist on a Kevlar input bearing. Choose a clutch you feel confident in, but from my experience the OEM is tough to beat for anything shy of excessive power levels.
 
#23 ·
My advice: Go with the ZF6 and insist on a Kevlar input bearing. Choose a clutch you feel confident in, but from my experience the OEM is tough to beat for anything shy of excessive power levels.
I have a South Bend clutch and a Kevlar input shaft bearing on my '99 with a 3rd gen and ZF6. No issues whatsoever.

I've all but decided to go with ZF6 from behind a 6.4.
 
#25 ·
The 6R140 uses its own stand alone controller. It should be possible to get it working in the same manner that the Allison uses its own controller.

The Ford controller might need a few messages from the high or low speed CAN buses. It would take some doing to get it to work, but it could probably be done.
 
#26 ·
By stand alone you mean that it is not integrated in the same "box" as the PCM. It's not stand alone in the sense that it can be used as a universal controller in any vehicle. IT could be possible to use it that way with a engine that used CAN, but it would require the CAN message "bridge" as you said in your earlier post. I would expect it would require quite a few inputs on the bus for it to work right, and some of the Ford sensors but it would be fun to try- as long as a guy didn't burn or break up a trans in the process :)
 
#27 ·
I'm not sure how stand alone it is or isn't. Apparently Ford went with a special SAE bolt pattern for bellhousing on the 6R140. And the TCS has its own OBDII compliant controller.

I'm thinking that Ford looked over the fence at how well the Allison does in a number of different non GM applications and took a step in that direction. How big that step is needs to be investigated.
 
#28 ·
Bro, make it easy on yourself and run the 68rfe that was behind it in the first place. Use all the factory crap from the 6.7 to the 68rfe TCM and it will all drive/shift/work like factory. For towing on long hauls, you just want it to work right so you can lay back and just focus on the road.
 
#29 ·
The 68rfe blows IMO with anything over stock HP levels.

I'm just curious about why do you want to do the swap? Why not DPF delete the 6.4 and get a good tow tune in it and go towing? Can easily make a reliable 450 out of a 6.4 and get decent mileage as well.
 
#30 ·
I've decided that my truck will get an air shifted (ie automated) ZF6.
 
#37 ·
The zf6 is a much better, and stronger manual transmission then any of the dodge manual trans. when compared.

Like you said, the G56 has had its share of failures mostly attributed to the aluminum case, the nv4500 has that stupid 5th gear nut.

I'd say the only down fall to the zf 6 is the stupid hydraulics for releasing the clutch, which is an external problem so its tolerable.

For the record, I bought a 6R140 last week.

Its going to take me a while to get it running.
I thought you were going with a zf6? :confused:
 
#32 ·
If you look deeper, the Dodge 6 speeds, both of them, are problematic.

There are many threads in the Dodge 6.7 forums at cumminsforum.com about blown G56s. The ZF6 is a way tougher transmission, especially the ZF6-750 variety.
 
#40 ·
The ZF6 is a way tougher transmission, especially the ZF6-750 variety.
Going to have to disagree with you there. I've owned both and still own the ZF6 750 right now.

The NV5600 could take a way bigger beating than the ZF. But that's not the main reason i dislike the ZF.

All the ZF's shift the same. They're notchy, chunky and clunky shifting. It drives me nuts.

NV4500/5600's shift like butter.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top