Help me decide, 4R70 or 6R80

[73azbronco]

Hi all, finally getting close to getting the barn queen driving again. My winter project, Currently, very nice NV4500 behind a 347 SBF out of an explorer. Carbed. Stock D44, 1.5 SL, 2 inch BL. Explorer serp and stock radiator which has tranny cooling ports.

Been reading a lot in the tech forum, my decision is the the 6R80 still seems unrefined compared to the 4R70 swap. I really want the 6 gears, but not if it means months of fab work. I know, some of you would have it done in a day but thats not my life these days, nor my facilities to work in. I really want to buy it all, bolt it up, and install, with little fab besides exhaust, maybe new driveshafts.

Things that are similar between the two: both need a controller, both need driveshaft checks or new ones., floor shifter, possibly twinstick modification for stock D20. Exhaust change, probable removal of torque tamer along driver side inner frame rail to rear end.

Differences:

4R70, more plug and play, fits better. Cheaper, but not by much.

6R80, probably front driveshaft fitment issue. Definite lift issues, some kits noting 2.5 inch suspension lift needed, not really understanding why, other than tranny pan to driveshaft problems. Odd adapters to get modular tranny to SBF.

Lastly, long term goal, install EFI. Should I do that before attempting a shift controller, or can that be changed from carb to EFI without cost?

I am leaning 4R70. Prove me wrong, or right

Love the NV4500, but wife has some knee issue, and don't want a one driver vehicle.

Thanks

 

[904Bronco]

I think you have answered your own question... You want extra gears, but you do not have abundant time/facilities to make substantial modifications. You haven't said what your driving is like; Asphalt queen, on road, some off road, significant trail use, rock crawling. Do you really need those two extra gears? US Shift controller is a nice unit, but they are getting near $1000. In my mind, that money would be better spent on an explorer EFI conversion if you think that is a future desire. You are looking at AA kit for the 2wd/4wd 4R70 to attach the D20, that will move the D20 back 1.5". If the 4wd 4R70 AA kit is even still available, that would be 3" back. Front Driveshaft will need a 2" tube for pan clearance.

I think the 4R70 will give you the two driver vehicle, with minimal headaches. Happy Wife, Happy Life as they say...

 

[Broncobowsher]

There is still front driveshaft clearances with the 4R70W. I dealt with that when I wrote the article in the tech section 20+ years ago.

The 4R70W was latest and greatest 20 years ago. Pretty much all of them were brand new, just the vehicles were wrecked. Huge improvment over the C4 and AOD options that existed before.

Today the 6R80 has a lot going for it. Pretty much back to what the 4R70W had 20 years ago. You can get a good used one that doesn't need a rebuild. Looking at a 4R70W today, quarter million miles and needing a rebuild is pretty much what will be expected. That would be a low mile one (25 years at 10k a year is a quarter million)

The 6R80 also has so much more in the gearing. A low 1st gear that you don't need doublers to get crazy crawl ratio.

Now I am not saying that the 6R80 is the only choice now. If you find a good running/driving Explorer package, use it. 5.0, with good intake and accessory drive already mated to a 4R70W and all the electronics to match. Makes a great complete package swap. Just put a real transfer case on it and off you go. But if sourcing parts for just a trans swap, I would be shopping for a good 6R80 to start with. And seeing you are coming from an NV4500 wide ratio transmission, the 6R80 would keep things closer to what you already know.

Right now I want to think that the 6R80 should typically be cheaper than the 4R70W given you can have a better chance at finding a good low mileage transmission that doesn't need to be opened up. Adaptors are expensive, having work done inside the transmission is also expensive. I would rather spend the money on adaptors and get the better gearing in the end.

 

[73azbronco]

Yes, daily to fun time driver. It's days of going into level 4 are over. I will have everything needed to swap to nv4500 when done for sale for all the hovering vultures

I have to be honest, my current jeep Rubi JL is a lemon, going through process to return it, and If I turn it into a 392 jeep, well, the whole shebang goes... Ok just kidding.

Blueprint has a SBF 347 and 40r70 all ready to go. $20,000 not including shipping. LOL, on the floor...

Hughes has pretty toughly rebuilt 4r70 or 6r80 for around $3,000

Ebay used parts, 6r80 out of ford f150 4x4 2011-14, $850

Is this the version I would be looking for? https://www.ebay.com/itm/1266030508...d=link&campid=5335857059&toolid=20001&mkevt=1

for 4x4 6r80, I would need d20 adapter, but, this one from WH references the coyote, not SBF, not seeing how a d20 adapter cares whats in front of tranny.

https://www.wildhorses4x4.com/early-bronco-ford-6r80-dana-20-transfer-case-adapter-coyote

I need an engine to 6r80 adapter, best looks lo be again, from WH which looks far better:

https://www.wildhorses4x4.com/ford-...k6vqaB3PBkLlvfK3sJ9ldfca1fWHfdnhoCgj0QAvD_BwE

Lastly, what to use for tranny to frame mount, the coyote version and modify it?

Broncobowsher, I hear ya, I was leading edge on rebuilding the C4, to have that overcome by the NV4500 push. Now it's a dinosaur So 6r80 may be the ticket over the 4r70, which places me back into c4 technology and rebuild ability.

904bronco, yeah, still flip flopping.


anyone know why the 6r80 notes a 2.5 inch SL? I have 1.5 SL, 2"BL.


Currently adding up parts, using junkyard tranny, about $5,500 all in...

 

[DirtDonk]

I don’t remember ever hearing this discussed, but can he run the Explorer computer right now, just to control the transmission?
Hooking up the Efi later and already having what he needs except for the rest of the wiring harness?
Or maybe even having the wiring harness, if the bulk of it can be kept out of the way!

 

[Boss Hugg]

The transmission requires the TPS input from the throttle body, and probably something else that I can't think of right now. Then I'm pretty sure he'd need the pcm flashed for such a special configuration (and I don't think anyone will do that anymore , re:EFI GUY) so you're limited to finding stuff to DIY, and it gets really complicated really quick. Even if it's doable, I think the money is better spent on an EFI setup with transmission controls.

 

[Broncobowsher]

Run a 4R70W with an Explorer EFI without actually using the EFI. Interesting idea.
It might actually work. The computer will be all pissed trying to run a running engine with few signals.

what I think it would need:
TPS, see what load you are commanding
Tach signal, so it has some idea if a shift needs to happen, or at least verify the engine is running.
All the normal transmission connections (MLPS, OSS, ATF temp, solenoids)

I remember being school and taking a 90s EFI and unplugging almost everything. MAF, O2, TPS, ECT, any other plug I could find. I left the tach signal and it would start, run, and (lazally) take throttle. It was very adaptive to missing signals.
If the ECM sees a TPS (even without a MAF) it can figure a load fairly well. It would need a tach signal as well. I don't think any Ford EFI will run without a tach signal. How else would it know if the engine was even running?
So it can't control spark, no injectors plugged it so nothing for it to control there either. No MAF, it is guessing airflow which doesn't matter since it isn't controlling fuel or spark. Im not sure the shift points would be perfect, I suspect they will be off actually. But I think it would shift.

Just thinking, Explorer takes a crank position sensor, not a tach signal. As long as you run the Explorer front dress, just plug it in.

It's bench racing, but I think it will do it.

 

[73azbronco]

I just looked at quick shift 6 wiring diagram, for carbed use, it only uses battery voltage, rpm signal, and throttle position sensor.

Could use this:

https://www.speedwaymotors.com/B-M-...JeJQab69sr5VqIeAUFXJxtOGatP5byGhoCwFUQAvD_BwE

 

[73azbronco]

Any issues fitment with D20 after using adapter, and use of JB Fab twinsticks?

 

[bigmuddy]

Run a 4R70W with an Explorer EFI without actually using the EFI. Interesting idea.
It might actually work. The computer will be all pissed trying to run a running engine with few signals.

what I think it would need:
TPS, see what load you are commanding
Tach signal, so it has some idea if a shift needs to happen, or at least verify the engine is running.
All the normal transmission connections (MLPS, OSS, ATF temp, solenoids)

I remember being school and taking a 90s EFI and unplugging almost everything. MAF, O2, TPS, ECT, any other plug I could find. I left the tach signal and it would start, run, and (lazally) take throttle. It was very adaptive to missing signals.
If the ECM sees a TPS (even without a MAF) it can figure a load fairly well. It would need a tach signal as well. I don't think any Ford EFI will run without a tach signal. How else would it know if the engine was even running?
So it can't control spark, no injectors plugged it so nothing for it to control there either. No MAF, it is guessing airflow which doesn't matter since it isn't controlling fuel or spark. Im not sure the shift points would be perfect, I suspect they will be off actually. But I think it would shift.

Just thinking, Explorer takes a crank position sensor, not a tach signal. As long as you run the Explorer front dress, just plug it in.

It's bench racing, but I think it will do it.

BBowsher what did you end up with for a diameter on the front driveshaft?

 

[73azbronco]

JB fab says I can reuse my nv4500 mount with twinstick and use shorter bolts to case.

 

[Broncobowsher]

BBowsher what did you end up with for a diameter on the front driveshaft?

That was 20 years ago. I want to say 2½" is normal diameter and I had to drop to 2" to clear. With attention to making sure the weights were not in the wrong spot as well,

 

[bigmuddy]

Thanks man!

 

[fishinman78]

I've done both conversions and for a driver I would do the 4r70w. The 6r80 was more work, time and more money. The adapters are a pain and take you away from stock parts.

With the 6r80 you get the lower first gear and two overdrives, and if you want to bump shift it you would have to come up with a shifter that would do so (this is where the 6r80 shines in my opinion). Some guys may like the low first gear for rock crawling, etc but I never really did like it. Around town, It felt like when you started from a stop, you would just get going in first and it would hit second so quickly, so I tuned the first gear start out of the 6r80 and went 2-6, which I liked a lot better for cruising and since I hardly ever drove fast enough to use 6th I was primarily using 2-5 (4 speeds).

I also like the fact that it is really easy to convert the factory column to shift the 4r70w with an inexpensive lokar kit. Maybe that can be done with the 6r80, but I did a floor shifter and a console with mine.

I still have a 6r80 in the shop as well as a 4r70w. I plan to swap the 4r70w into my 76 this winter. My 76 is a driver and the 4r70w is well suited for this application.

Ultimately, I don't think you can go wrong with either choice!

 

[Johnnyb]

Found this while wasting time on YouTube today, talk alot about 6r80:

 

[73azbronco]

I've done both conversions and for a driver I would do the 4r70w. The 6r80 was more work, time and more money. The adapters are a pain and take you away from stock parts.

With the 6r80 you get the lower first gear and two overdrives, and if you want to bump shift it you would have to come up with a shifter that would do so (this is where the 6r80 shines in my opinion). Some guys may like the low first gear for rock crawling, etc but I never really did like it. Around town, It felt like when you started from a stop, you would just get going in first and it would hit second so quickly, so I tuned the first gear start out of the 6r80 and went 2-6, which I liked a lot better for cruising and since I hardly ever drove fast enough to use 6th I was primarily using 2-5 (4 speeds).

I also like the fact that it is really easy to convert the factory column to shift the 4r70w with an inexpensive lokar kit. Maybe that can be done with the 6r80, but I did a floor shifter and a console with mine.

I still have a 6r80 in the shop as well as a 4r70w. I plan to swap the 4r70w into my 76 this winter. My 76 is a driver and the 4r70w is well suited for this application.

Ultimately, I don't think you can go wrong with either choice!

excellent points.

 

[73azbronco]

Found this while wasting time on YouTube today, talk alot about 6r80:

WH kit eliminates the speed gem and other guys adapter kit.

 

[73azbronco]

Leaning back into 4r70 choice vice 6r80.

What source of 4r70 am I looking for, f150 4x4?

Simpler.

 

[lars]

Leaning back into 4r70 choice vice 6r80.

What source of 4r70 am I looking for, f150 4x4?

Simpler.

For what it's worth I just finished a 4R70W swap. I used a 1998 Explorer 5.0 AWD transmission with a 3:1 Atlas transfer case so I didnt need any adapters. I designed and fabbed my own crossmember with help from @ntsqd that allowed me to use the awd tail housing and trans mount. Had the transmission gone through by a local shop. It's controlled by a reflashed Explorer PCM that also runs the 408. Built the harness myself. JB Fab cable shifters for the t-case, Winters shifter for the transmission, 2" diameter front driveshaft.

Big switch for me coming likewise from an NV4500 and 4.3:1 Atlas. So far I'm very happy with the new combo. Extremely, actually, but I've never had an automatic in a hobby vehicle. Running on 35" tires, 4.56 axle gears the gearing is about perfect around town and on the highway. I will continue to use it as a street/backcountry trail and camping rig, I don't foresee missing the ultralow gears that I never used, or wishing for the lower 1st of the 6R let alone the taller 6th.. But I'm not doing hardcore crawling and the torque of the 408 kind of warps things.

Anyway. My 2 cents, take it for what you paid...

 

[Broncobowsher]

The best swap into a Bronco 4R70W is the '98 to '01 Explorer 5.0 version.
4x4 takes a simple adaptor to mate the D20. 2WD will require a rebuild to put the right adaptor parts in it.
F150 you need to watch what you get it from. Any of the overhead cam V8s are wrong. The 5.0 V8 from the old body style '96 and older will work, but that trans doesn't have the best parts inside. The 4.2 V6 has the updated parts inside, but one less clutch in one of the packs. If doing a rebuild, this is a good choice as the clutch upgrade is easy if not free. With a 347 I would have the V8 clutch pack.