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Discussion Starter #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.

?????????????
 

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Canadian Stroker
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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:
 

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C10H20
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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.
 

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Discussion Starter #4
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:
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.
 

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Discussion Starter #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.
 

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Discussion Starter #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 ?
 

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Discussion Starter #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 ?
 

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Personally I would do the 48RE with a PCS controller
 

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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.
 

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C10H20
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Spend some time in an 08 King Ranch and you'll understand.

I understand about the KR, I was dead set on buying a '10 but the dealership would not move on the price so I bought my Lariat.

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.




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.
That's cool, so i'm guessing your 6.4 engine is in good shape?
 

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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.
 

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Agreed. I love my damn ZF6, won't buy a truck without one now.
 

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C10H20
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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.
280k on a stock clutch!? My hat is off to you sir.
 

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Discussion Starter #14

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Discussion Starter #15
The 6.4L in my truck seems fine. As does the 5R110. The truck has a clean OASIS report.
 

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C10H20
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The 6.4L in my truck seems fine. As does the 5R110. The truck has a clean OASIS report.

How much you asking for it? Have a project that could use a newer engine.
 

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I can't see how you'd go wrong with a ZF6.
 

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OBS junkie
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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.
 

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Discussion Starter #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.
 
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