Help me decide, 4R70 or 6R80

[73azbronco]

I rebuilt my D20, how deep to go to make adapter work?

So the v8 explorer 98-01 then for a 4r70w?

 

[lars]

I rebuilt my D20, how deep to go to make adapter work?

So the v8 explorer 98-01 then for a 4r70w?

Yes for that transmission.

I'm no expert (I have an Atlas, duh) but IIRC if you have an awd version you dont have to change the tailshaft housing. AA used to sell an option (I dont think they show it anymore) that used the ZF adapter ring with the correct spud shaft plus a seal carrier, simpler than changing to the custom AA tailshaft housing. And i don't believe any D20 disassembly is required.

 

[904Bronco]

Yes for that transmission.

I'm no expert (I have an Atlas, duh) but IIRC if you have an awd version you dont have to change the tailshaft housing. AA used to sell an option (I dont think they show it anymore) that used the ZF adapter ring with the correct spud shaft plus a seal carrier, simpler than changing to the custom AA tailshaft housing. And i don't believe any D20 disassembly is required.

I believe that you will need the automatic spud shaft, rather than the manual one you have now in the d20. But the collar, seal bearing should be the same...

I don't believe the 4WD AA kit is still available, they will push you toward the 2wd kit. Best call and ask them.

 

[73azbronco]

going to start doing this during winter.

 

[73azbronco]

sorry, last item, shifter.

Lokar floor like this https://www.speedwaymotors.com/Loka...4dv9biwky_FCSAZxpDfS4xL9usHIuLgUaAscwEALw_wcB? It would cost more to put an auto steering column in than the most expensive lokar.

Can or has anyone used a 6r80 type lokar floor shifter with digital display and manual shift modes. ie, my jeep is an auto, but move shift lever inboard, it is a manual-ish shifter.

 

[76YETI]

Found a 4R70W out of an 99 explorer....Rebuild & Convertor was just over $2K....FYI

 

[bigmuddy]

By the way, I would always advocate installing new parts over junkyard. However, I have it on good authority that these trannies are really quite hardy and know plenty of guys installing and running them with 150K or more without issue. If your sticking it behind a stroker and racing like Lars does is one thing. Behind a 5.0 going for ice cream is whole other thing.

 

[73azbronco]

Yeah my tranny place on Washington by 44th that I have been using since the 70's can rebuild one no core OTD about $1,800. Just talked an he already knew it needed the v8 4x4 valve body.

 

[nvrstuk]

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

You read my extensive write on the 6r install?

The 6r is a lot taller that's why a small body lift or tunnel mod is needed.

I have several in the shop. If you want me to measure it from the cross member to the top of the bell housing area or from the bottom of the oil pan to the top of the bell housing area, let me know.

 

[nvrstuk]

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

That adapter is what I ended up with designing after building quite a few of the early style that needed a bit of alum bellhousing removed because a stock starter was used.

Jim & I were talking & I was working on some stuff & but I need to retire.

The adapter WH now carries (since the middle of August) I highly recommend.

I was working on a complete "bolt in" kit. Like anything on an Early Bronco is bolt in LOL

One of the things that you will notice instantly is the 6r's has a very low first gear and ir really pulls you out of the hole.

Just like these, the 700 R4 had a lower first gear than many other 3 & 4 speeds back in the day. And it seemed like an anemic V6 had more power than your old V8 because of that first gear.. Well, the 6r is that on steroids.

I've asked dozens of people now what their opinion is of the 6r compared to the 4r or any other automatic for an early bronco, because of our weight and all the other issues it has for street ability and the one word most of them come back with is "game changer."

I am not ranking the 4r and saying it is not a good transmission. Do not get me wrong!!!! I loved mine. Like Lars, I went from always running a stick & I had the ZF/203/Atlas.

4r is an amazing trans. Stack it up against a 5 speed manual for what we do (wide gear splits in truck trannys especially that see large torque loads) and it's a gamechanger too.


I ran a 4r for 6-7 yrs. It is an amazing tranny.

Just like the difference between the C4 and a 4R. That's kind of what we're talking.

I might be a bit biased now but because i've run them both in the same Bronco, same gear ratios, same tires, same engine, I have a pretty good apples to apples comparison and the 6r in (edit) my opinion is a Gamechanger & you'll never look back.

Your call tho.

 

[Jaybr]

I bought a 97 Mountaineer off Craigslist for $600 and sold everything but the tranny and front dress brackets. made a little $ and got a free 4r70w. Had a Bronco shop rebuild the tranny with the AA adapters, and purchased a US shift controller. I think I'm all in for around $2500.

Not on the road yet so can't comment on the performance.

 

[73azbronco]

You read my extensive write on the 6r install?

The 6r is a lot taller that's why a small body lift or tunnel mod is needed.

I have several in the shop. If you want me to measure it from the cross member to the top of the bell housing area or from the bottom of the oil pan to the top of the bell housing area, let me know.

I'm good i have the nv4500 in there with a 2 BL thanks

 

[EFI Guy]

By the way, I would always advocate installing new parts over junkyard. However, I have it on good authority that these trannies are really quite hardy and know plenty of guys installing and running them with 150K or more without issue. If your sticking it behind a stroker and racing like Lars does is one thing. Behind a 5.0 going for ice cream is whole other thing.

Agreed. Part of the reason they last so long in factory form is in the programming. There is a feature in the factory programming for torque reduction. What it does is it cuts timing to the engine for a split second while the clutches engage to reduce wear on them. It's hardly noticeable but prolongs the life of the trans greatly. The drag racing guys will shut it off but I think its a great feature for just about any other kind of use.

 

[73azbronco]

Sooooo, going 4r70w for the near term. I am also turning my lemon JL into a 392, so that gets me 8 gears....

 

[Broncobowsher]

Agreed. Part of the reason they last so long in factory form is in the programming. There is a feature in the factory programming for torque reduction. What it does is it cuts timing to the engine for a split second while the clutches engage to reduce wear on them. It's hardly noticeable but prolongs the life of the trans greatly. The drag racing guys will shut it off but I think its a great feature for just about any other kind of use.

The tuning that goes into that is good stuff. For the most part, shifts are super quick. Not like the old C4/C6 days where the clutch pack will slowly engage for a smooth shift. Since the engine torque never changes during the shift, but the general public wants smooth shifts, the clutches take a beating. And often why those old transmissions needed a rebuild at 60k. The RV/Tow shift kit took that smoothness out and made a quick shift. Since the clutches only have a small window of slipping while engaging they don't take as much of a beating. While at it, the overdrive transmissions that got a bad reputation for burning up when towing, "always turn the overdrive off while towing". That was the clutches taking a beating as the trans hunted in and out of overdrive, generally at full engine torque. Gear high for economy and it has to hunt while towing. The shifting is what fried the overdrive transmissions during towing, not the actual towing. Get into the "don't fear the gear" and be able to pull most grades without downshifting, transmissions will be happy. Even towing in overdrive.
I've encountered late model 7-speed automatics that if you hunt through too many gear shifts in too short of a time, the computer calculates the clutch temp and figures they need a break. The computer will lock the trans in a gear to keep it from hunting and give the clutches a chance to cool down. Don't know if that is in the factory Ford programming or not.
The engine torque drop during the shift is tuned. The trans does a quick shift, pretty much a bang shift. But since the torque is killed at that moment, it doesn't bang. The clutches hit hard, but with the engine killed off for that moment, some careful programming and it is nice and smooth.

The 6R80 has a lot of torque managment in the shifts. The ones I drive you can tell. It can't shift that fast and be that smooth without torque managment. The 4R70W is the last hold out of minimal torque managment. The basic design came from old school transmission design. The shifts are just 2 somenoids.
Back in the late 80s Chrysler came out with the A604 transmission. Computer controlled 4-speed automatic. The control system is actually closely related to the 6R80. Each clutch pack has it's own solenoid. The computer learns the clutch apply delays and rates and tunes itself. The A 604 was known to drive a little funky the first week you owned it as it self taught, then would run perfect all the way to the point it didn't run at all. This was 80s tech. The computers got better, but the same basic control that is in the 6R80.

The 4R70W is more of the old school mechanical valve body shifts. Instead of looking at line pressure, governor pressure, and flopping valves to control shifts, it is done with solenoids. There is no learned shift in the system. A single PWM contols the line pressure, but the shifts are simple dumb commands. Flip a switch, next gear. How hard does it shift into that next gear, what line pressure is commanded? The 4R70W is still great in the shift points are controlled so much better with a computer. A hydraulic computer brain can only do so much, and is very limited once you get beyond 3 gears.

 

[nvrstuk]

What bowsher said is why I didn't want a manual valve body in my 4r.

The shifting I needed under full load was quite different than going to get ice cream with my wife.

You have one choice with the manual VB as you set that line pressure and that's what you get. Bang!

US Controller allows different shidt tunes and you still get full "manual" Control which is the absolute best of all worlds. Least for my needs.

 

[73azbronco]

Nah full auto mode for me in this thing, no need for lock out and such.

 

[nvrstuk]

Nah full auto mode for me in this thing, no need for lock out and such.

Yeah, you'll like it. I probably run mine 90% of the time in full auto mode.

 

[rocknhorse76]

Yeah, you'll like it. I probably run mine 90% of the time in full auto mode.

I run my 4R in auto on the pavement and and smooth gravel roads, and in manual for wheeling. Pretty hard to beat.

 

[fordguy]

Yeah my tranny place on Washington by 44th that I have been using since the 70's can rebuild one no core OTD about $1,800. Just talked an he already knew it needed the v8 4x4 valve body.

Which trans are you referencing?