4R70 - np205 question

[Stock 77]

I am building a 77 bronco back stock and am considering using the 98 explorer I have for a donor for the engine and transmission. Someone had told me the NP205 transfer case will bolt right up to the 4r70. I will have to find a 205 if I go this route and I want to make sure I get the right one. This route sure seams like it would be simpler, more cost effective and yield a shorter drive train than using the adaptors and D20. Since this will be a stock daily driver with 4WD only used on the road during snowy winters, I'm not real worried about losing the lower low range of the D20.

Also i was wondering if I could use a NP208 transfer case.

I appreciate any advise or information you can provide.

 

[Boss Hugg]

People have used the ZF adapter with the 4wd tail housing. I paid around 600 for the d20 adapter which comes with a 27 spline output shaft, so the tranny HAD to be rebuilt, which I was doing anyway.

For a stock DD, I wouldn't spend the time of putting a 205 in it. The 4r70w/d20 setup only adds an inch or two and the 205 will add more than you think.

The 205 will require a mount to be built off the drivers side frame rail to support the extra weight. The 208 sticks out too far to the left so the transmission has be moved over which might affect things under the hood.

I haven't looked into the ZF/d20 adapter too much. It works tho. There's info here somewhere, but you may have to use Google to find it. Type in site:www.classicbroncos.com, space, and then type in what your search and it'll search only CB for the results.

 

[fordguy]

i was going that route, but changed back to dana 20. I have a 205 that could be bought.

 

[randbjorn]

I went the atlas route. If I ever get this dam thing together ill tell you if it was worth the $$$

 

[Apogee]

I'm stuck on the "...building a 77 Bronco back stock...", and then talking about Explorer 5.0/4R70W/NP205 drivetrain options. If you wan to restore the rig to original, then that would be I6 or 302 with C4 or 3-speed manual transmission and D20. If you're going to resto-mod it, then the Explorer drivetrain would be the easy choice. Since you don't have an NP205 laying around, nor do you need the added strength IMO, I would just adapt the original D20. Anytime you swap something, there are always additional costs to deal with in my experience.

 

[Stock 77]

Maybe the word stock has different meanings to different folks. My use was relative to the look and height of the truck, not the drive train.

As far as the use of the D20 goes, I was looking at avoiding the $500 + cost of the adapter and possibly find a case that would bolt right up to the 4r70. A plus with a more modern case than the D20 is I would hope it wouldn't leak.

 

[Boss Hugg]

with the proper sealant the D20 won't leak. also check the vent to make sure it's breathing. If it's plugged, heat will cause pressure and leaks.

and the 205 is basically the same design, so wouldn't it leak too? IDK.

 

[Stock 77]

I have owned a couple of the np 208 cases and never seen a leak of any kind, but I may have just been lucky. As far as the np 205 goes, I haven't owned any of those, so they may in fact be leak prone like the D20. I may just be unlucky but I have owned a half dozen of the D20s and they all leaked. I have successfully sealed them up for a while but ultimately they all ended up leaking again eventually. I hate to bolt a leaking TC to a engine and tranny that don't leak.... I would like to be able to park this truck in my garage when its finished and not have oil on the floor!

 

[nvrstuk]

I don't understand the leaking D20 problem???

I had one in my Bronco since I bought it in 76 and it never leaked a drop! Seriously never.

We put over a quarter of 1,000,000 miles on them, abused the heck out of them, broke four of them and they never leaked between replacements...

Where are you having problems with them leaking?

 

[Stock 77]

I seem to have trouble keeping the four gasketed areas from leaking. At least one of the four and sometimes a couple seem to seep a little.
Also I don't want to pay $600 for the adapter. I am thinking of using the np208 since it is light weight and should bolt right up to the 4r70. I am thinking it would hold up ok for street driving. I'm just not sure the np208 will fit ok in between the early bronco frame without modifying the frame.

 

[bronconut73]

208 is too big.

205 is narrower and it "barely" fits....

You do not want a 208 Bud.

 

[nvrstuk]

1/8" X 1/8" line of blk silicone on either side of the gasket, no more and zero leaks... I know, the Motorcraft gasket should seal but they don't always...

 

[Stock 77]

Thanks for all the help. Thats what I needed to know, so a 205 is going to be the way for me to go.

 

[bronconut73]

Lots of examples of the 205 here on CB.
Good photos.

BC has a cross member for it I think....