Swapping to 4R70?

[dhendriksen]

I’m thinking about transmission options. I have all my new interior stuff sitting here and I’m debating if I want to cut a huge hole in the carpet to accommodate the existing floor shifter or if I want to take the plunge to an automatic which is what I think I ultimately want.

I’m looking at the 4R70 and looks like I can get a solid rebuild from any of the reliable transmission sellers for <$2,000. Can anyone share any tales of woe or success around doing? Anything I should be aware of or look out for?

It appears the Dana20 bolts up to it fine. What other customizations will I need to factor in that I’m not thinking of?

 

[tasker]

You will need an adapter to use the Dana 20....if you are going 4R70w and not just an AOD you will need a transmission controller as well

 

[pcf_mark]

As Tasker pointed out you will need an adapter to use a D20 and it requires transmission disassembly. I was too cheap to go that route and bought a used $250 Explorer 5.0 transmission and tossed the electronic transfer case. I bought a NP205 (big ugly, heavy mutha) which bolts to the 4R70W by only grinding a nub off the outside of the case.

Then you need this:
1) Make or buy a transmission mount crossmember. This was surprisingly easy but you need cut and weld skills.
2) New driveshafts. I shortened my rear and then bought a junk yard explorer front shaft. Swapped the yoke on front of NP205 for about $100 to get one that fit the Explorer u joint. Had the front Explorer d-shaft shortened.
3) You need a transmission controller there are a few options depends on your skills but some are out of the box simple.
4) Transmission cooler - if your radiator does not have provisions you can change radiators or get a large cooler and put in front of radiator. I recommend getting a radiator with provisions this will insure long life. The warm water in winter helps the trans warm up too. You can buy the lines or make them.
5) Shifter. I had a floor shifter and hated it plus no back up light provisions built in. I ended up getting an A/T column it is so much cleaner.

In the end it cost more than I expected but was worth it. I went cheap at every corner and still spent close $1k.

Trans $250
T-case $150
Driveshaft work $300
Yokes and seal $100
Microsquirt controller $350
Lines <$50
Mount <$100
Resealed NP205 <$100

I put a lot of hours into wiring harness, transmission tune set up, trans mount this it was not a bolt in and go. Spend more money it takes less time. After disc brakes and EFI this has been my best modification. So much more pleasant to drive. Depending on what set up you have now you may also need to add a TPS and MAP sensor to provide info to the trans controller. Not a trivial task if your engine is carbureted.

 

[Broncobowsher]

4R70W bolts tot he engine just fine. Adapter needed for the transfer case. Crossmember needs relocation/modification/just fab a new one. Driveshafts change lengths. Hole for the transfer case shifter moves a little bit.

What tires and axle gearing are you running? You probably need to regear so the overdrive will be useful.

These days I would be looking at a 6R80 over the 4R70W. You can get a good used take out that doesn't need a rebuild.

 

[doran4x]

Dana 20 will need an adapter. You do not need to disassemble transmission if you get a 4x4 unit. I used ZF adapter with ZF crossmember. Shaved 3/4” off of trans output shaft. Baumann controller. Great upgrade. I’m running 5:13 gears and 35” tires.


Sent from my iPhone using Tapatalk

 

[JSBX]

Check out the Bronco tech section and Google, type in 4R70W Classic Broncos. and you will see post on the subject. There is also some You Tube videos on the swap.

 

[gnpenning]

Not sure what your plans are for your EB, this is another option. I have never used them so maybe someone else might have feedback.

COLOSSUS CASES

Creators of the Dana 300 and NP205 Billet Aluminum Colossus transfer case, the Borg Warner Electric to Manual conversion kit and the Strongbox underdrive series.

behemothdrivetrain.com

Oh yeah, be sitting down

 

[73azbronco]

If planning to go 4r70, might want to consider 6r80. Basically same size, controller to work it, adapters. Modern. Not that a 4r70 cant be built tough.

I plan the 6r80 unless a sniper like failing occur with the controllers out there, you test pilots you (nvrstuk).

 

[Jamie Chriss]

I love my 6R80, you can drive in sport mode around town, very dependable transmission. You will need to find one out of a 4x4 F150..

 

[73azbronco]

What year again? And thats a 5.0 coyote vs 5.0 windsor?

 

[Broncobowsher]

If planning to go 4r70, might want to consider 6r80. Basically same size, controller to work it, adapters. Modern. Not that a 4r70 cant be built tough.

I plan the 6r80 unless a sniper like failing occur with the controllers out there, you test pilots you (nvrstuk).

I'm the onw who wrote the 4R70W article, that was 20 years ago. today I would do the 6R80.

The only reason I would do a 4R70W swap today is if I found an Explorer and took the powertrain package and it was already attached.
Not that the 4R70W is bad, but the 6R80 is better. You can get a 6R80 that doesn't need a rebuild and run that for less than the $2k you are looking at for a built up 4R70W. You never stated the motor, so probably something stockish? That doesn't need a built transmission. Both of these have pretty good parts right out of the factory.

 

[73azbronco]

What year ford f150 4x4? And recommendation is to keep the NV mounted to it, ditch the d20?

 

[Quick & Dirty]

keep the NV mounted to it, ditch the d20?

Chain drive cases are too wide for the Bronco frame. Gear drive cases are narrower, so options include the Dana 20 of course. NP205 is tight, but fits. The Atlas is based on the Dana 300 and also fits.

 

[dhendriksen]

Thanks for the info. I have the stock carb'd 302.