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Discussion Starter · #1 ·
Completed C6 to 6R80 swap in my 1972 F-250. 6 gears is a totally different driving experience than 3 speed C6.
6R80 1st gear is 4.17, almost 2x that of C6, and 2 ODs with 6th being 0.69. Cruise 50 mph at 1200 rpm. Lockup converter also helps MPG.
The 6R80 with engine adapter and transfer case adapter is the same length as a long tail c6. Mount moves but driveshafts don't need modification.
Total cost around $5000.

E4OD + converter gets expensive when you need it to hold higher power. 6R is stronger stock and plentiful in the junk yards, for now.

Controller:
US Shift quick 6 is the only option at this time. $1200

Transmission:
Must use a 6R80 with external wiring and controller. Round plug on back right side. Not all 6R80 are like this, for example anything behind a mod motor won't work (4.6, 5.4..)
Most common is a F150 or mustang. F150 can be had in 4x4 flavor although case is the same, maybe output shaft (31 spline) too.
5.0 and 6.2 use mod bell housing. 3.7 TT is different bell/case. These trans are on ebay with mileage from 50k to 300k, for $500 to $1500, torque converter included
I ended up with a trans out of a 2013 F150 5.0 4x4 with 86k for $1200 delivered.

Engine Adapter
2 options, I went with speed gem, and a 5.0 trans. PA had long lead time.
1) Speed Gems $1900, 2" thick, 460 style starter included. Mod bell only
2) Performance automatic PA68508, $700, some modifications needed. 3.7 bell only

Transfer case adapter:
Advanced adapters has a 6R to atlas adapters, $500. 6R80 TO ATLAS ADAPTER
Atlas is same 6 bolt pattern as many other transfer cases, NP20x, dana 300, BW15xx.
I have a ford NP205 with 31 spline input so no spud shaft needed.

Cooling:
PBH dual o-ring to AN8 adapter. Must use 1/2 lines and decent cooler. I used 26 row plate style OEM Ford 6.0 PSD cooler.

Misc:
Trans has 7 positions, but controller can use 5,6, or 7 position shifter. OEM was a cable, but you can make your own mechanical linkage.
Remote Dipstick, B&M 22200, $250. PA also make one, not as good, not in stock. B&M 22200 B&M Locking Automatic Transmission Dipstick & Tube - Billet Aluminum/Stainless Steel Braided

Adapters


TC adapter need machining for use with NP205


TC uses same 2" spacer. Original 460 flex plate.


Mock-up


Size wise the 6R is similar and should fit with minimal modifications where a C6 was. 6r pan is long and narrow as opposed to the wide pan on C6, hence the C6's need for a long TC adapter for a double cardan style front driveshaft. 6R is slightly heavier than C6 with long iron TC adapter.
 

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Outstanding!! I picked up a kit at Speed Gems in person and had a nice conversation with the owner.The guy is a genius.He has a vision and just makes it happen.On the transfer case adapter...was the machining just for bolt clearance on the 205 or is anything else involved?
 

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Discussion Starter · #4 ·
The NP205 being gear driven puts the shift rails in tight to the adapter. Had to clearance the following:
1) Rear axle shift rail
2) idler shaft cover and nut
3) 4 bolts and the 3 nubs on input shaft retainer





I cut this bolt down and welded nut to shifter sleeve.
 

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Discussion Starter · #5 ·
For a chain driven transfer cases the machining of the adapter is likely not needed. Also the trans adapter is dry and needs no gasket/sealer on either side.

The needed machining for 205 could be done with simple hand tools with some patience.
 

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Discussion Starter · #6 ·
Getting some miles on the new trans. Dialing in shift points with shiftware, can set any gear change to any RPM, firmness, converter lockup and so on.
Engine RPM is significantly lower in all conditions (if you want it to be) and should improve fuel consumption, increase effective range, which is a big deal at 5 MPG.
 

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You want mileage buy a Prius 😂😂😂

Overall the swap looks pretty straight forward, not inexpensive but sometimes you gotta pay to play.

If I had a crystal ball it would be interesting to see a side by side with a 6R80 vs a C6 with a gear vendors.
 

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Just the gearing (low and high) and lockup converter would put the C6 substantially behind. For me, the E-trans configuration ability through programming to tweak to the vehicle and my preferences is as important as the other advantages. If you don't like these settings, want something different, or just try something out - do it. Revert with a click. :cool:
 

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Discussion Starter · #9 · (Edited)
You want mileage buy a Prius 😂😂😂
Can't be seen driving one of those.🤮
..and a Prius can't tow a horse trailer or haul a dirt bike. I need a truck to do truck stuff and fuel consumption is what it is.

The problem is range. 26-28 gallons is all you can fill into the 31 gallon tank before sucking air (matching factory pick-up in tank). So effective range is only 150-200 miles and simply not enough to drive way out of town and then try to get lost wheelin' out in the desert. Don't want to carry Jerry cans.

1-2 MPG increase from 5-9 is actually a big percentage (20%). Hope to get 6-7 in town and 9-11 on the highway, which brings range up to 180-300.
 

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Ah, sucky MPG. I already had overdrive in there, and after trying chipping and emulators on my truck's factory '91 ECM (which helped a bit), I decided to try one of the new-fangled aftermarket DIY-type ECMs. That was the original MegaSquirt v1.01 using a TBI and home-made WBO2. I was floored a couple weeks in when I finally achieved not only better power, but max economy with a 38% improvement over stock. 🎉

About 9 mpg up to 12-13, and it was a combination of a bad knock sensor and the emissions tuning that year that killed the engine so badly. I could still switch tunes and pass emissions. :sneaky: The system cost about $450 all-in, and was saving about $900 each year in fuel, over 20 years ago. I was hooked, and never looked back. Sometimes improvements are in nibbles, and other times in nice, juicy chunks! Best of luck to you in your nibble or chunk. :cool:
 

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Discussion Starter · #12 ·
Well 'finished' is a theoretical state I never seem to achieve on a project vehicle. but yes the trans swap is done.

Been tweaking one shift point at a time and getting behavior as I want. Most important and frequently used are idle, 10% and 20% shift settings. Above that not so picky.

With some miles on it up to temp and able to learn, pushing it progressively harder to WOT. WOT launch in 1st lifts the chassis so much the front end hits limit straps which unloads the chassis, and causes tires to spin. Hope to address this with lowering front of traction bar to effectively moving instant center down and forward.
Gear spacing is much more suitable for coming out of 90* turn at intersection, can just mash pedal and it pulls to 5500 in 2nd. Can feel the converter lock up and shift is firm. Moves well for a 6000# truck on 40s and 4.10 gears.

Price went up with his modification :)
 
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Discussion Starter · #13 ·
Hard to capture fitment in tunnel


Even stock the 6R80 will handle BBF on nitrous


6 speed makes truck so much quicker and more fun to drive. Highway is much quieter, 75 MPH is 1750 RPM instead of 3000
 
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