NP208 Range Box (Doubler)

[ncjeepers]

I need a doubler. Has anybody used the planetaries from a 208 to make a range box? I'd be willing to bet that is basically what a Klune-V Goliath is. I just wonder if there is a way to do it without the $1800 price tag.

[shadowjeep]

you can do a 203/205 for around $900.00 but i dont know how you could use a 208 the way your wanting without a bunch of machine work.

[ncjeepers]

The 203/205 is certainly an option.
I'm also considering a 3:1 Lo-Max for the 205 for around $1100.
Just looking for something new.

[incommando]

Swap in a t18/d20 for about 1/2 the money?

[Chevelleguy]

There is a 231 kit. http://www.pirate4x4.com/articles/productreviews/mad_rooster

[orangecherokee]

The 203/205 is certainly an option.
I'm also considering a 3:1 Lo-Max for the 205 for around $1100.
Just looking for something new.

i don't think that's worth the money. You can put the doubler together for less and have 4:1.

[ncjeepers]

The T-18/D20 has been an awesome combo in my CJ, especially with the 2.5 low range swap, but I'm going with a slush box this time.

Yeah... 3:1 doesn't get me too excited either.

The 203/205 is tried-and-true but I have some issues with it in my app... I already have a TH400/NP205 (round pattern) combo. From what I can gather, I would need a relatively scarce 32-spline 203 (or buy an input gear), then I would need to change the input gear on my 205 to the short style... so I'd probably end up with $1100-1200 in it.

I really like the planetary/NP205 idea because you get 4 ratios to choose from and a lower low... 1, 2, 2.7, and 5.4

So far I've heard about Mad Rooster and D&D Machine, but details are sketchy and I'm concerned that a 231 isn't strong enough. 208's are strong, plentiful, and cheap.

I just found that Northwest Fab has a planetary box for $1600 that they claim is superior to the Klune. I'd still like to find a way to cut a 208 in half and slap an adapter plate and output shaft in it for $500 or less.

[rustywagoneers_com]

I am going to quote myself from a thread on a different board...

Well... The only pictures I have right now are these....

http://i169.photobucket.com/albums/u213/myspareparts/HPIM1042.jpg
http://i169.photobucket.com/albums/u213/myspareparts/HPIM1046.jpg
http://i169.photobucket.com/albums/u213/myspareparts/HPIM1048.jpg
http://i169.photobucket.com/albums/u213/myspareparts/HPIM1049.jpg

What you are seeing is a GM NP208 case (pass drop) cut and plated.
I have this case assembled right now with the stock GM output shaft, which will be shortened (by simply cutting off the end) I cannot remember the amount right now... but like maybe 3 inches??
Anyway, I have to make (or significantly re-work) the output tail housing to go between the 4-bolt round face that you see (back half of case) and a stock Ford NP205 (6 bolt round mount face). The Ford case has a GM 32 spline input swapped in (big bearings swap straight across).
With a simply shortened Gm output, you will have ABOUT a foot between the back of the 208 case half and the front of the NP205.
Incidentally, SOME Ford NP208's use a 31-spline slip-yoke rear output, and a stock Ford 31 spline NP205 slides right on the back of those... But the slip yoke Ford NP208's are only in a few years (mid/late 80's F250's only - F150's and Bronco's are fixed).
Also... The XJ/MJ/S10 NP231's (and NP207's) are a 27 spline output which matches the 27 spline INPUT on an S10 NP231 or on a 208/241 from behind a TH350 or TH700... (see here) http://www.Pirate4x4.com/forum/showthread.php?t=383730&highlight=doubler


As far as strength.... The 208 (or whatever front case) in a doubler is hardly ever the problem... Life is toughest for the rear case... and if you are running a big bearing NP205, with a 31 or 32 spline input... Don't get much stronger than that...
peace
Dave

Hope that can be of some use. I suppose some of the NP205 discussion won't apply here, but, maybe it will....

I think there is more, I will post it, if so.

[ncjeepers]

That's what I'm talkin' bout. I like it.
I hear tell that D&D has a block off plate and short output shaft for ~$500 that uses just the front half of a chopped 241 case. I called but never heard back from him.
Here's a nice cutaway of the Northwest Fabs "Black Box". Pretty simple set-up really.
http://northwestfab.com/images/Product%20Pics/DSC02350.JPG

[elbastardo]

Im running/sitting the 203/205, and I "think" im under 1K. I picked up 2 ford married 205s for 150$. 2 203/28 splines for 25$. My 205 came with figure 8 pattern, It cost me 150$ to have the case punched out to the "big bearing" 32 spline input.

I dont remember what i paid Elliott for the 208/465 adapter.


The next call was to SUMMNER machine/John. And that adapter was 650$.

Theres gas involved and other problems that i ran into (like accidently switching to a 32 spline input 465).

With this said, With help from some members on THIS site I was able to do ALL the work (minus the machine work) Myself, including upgrading my 465 to the 32 spline output.

Give John Summner a call, the last time i talked to him he was working on a 231/D20 doubler. Maby hes onto the 208s by now?

[JeepinPete]

Actually, it is pretty easy, at least with a NP241. You will need a lathe, a mill, and a welder. I believe your TH400/NP205 is a 32 spline coupling. If so:

* Find a 32 spline 241 (from a 4L80E, NV3500, or NV4500).
* 1/2" plate aluminum (12" x 18" will be enough)
* Disassemble the 241, discard everything other than the front case, planetaries, main shaft and shift fork
* Cut front case as you see fit
* Transfer bolt holes to the 1/2" plate.
* Mill index hole into 1/2" plate. I did this by gutting the front case and bolting it up to the plate. Then I indicated the bearing bore in the case in the mill, and drilled a hole in the plate. Removed the case, and bored the hole to match the bearing retainer on the transfer case.
* Face the case and plate. Bolt the plate back to the case, and set it up so that you can machine the cut surface of the case and the plate to the same plane. This will allow you to make a plate to cover the opening, and not have to deal with welding in a fill plate.
* Index the new range box to your transfer case, and transfer the 6 bolt pattern to the plate.
* Cut the mainshaft. The output that originally went to the rear driveshaft slip yoke is 32 splines, the same as any GM 32 spline transfer case input. You are going to keep both ends of the mainshaft, and remove the center.
* Bore the front half of the mainshaft, and turn down the back end of the mainshaft so that you can press to two together. I used a 1/2" dia journal for this.
* Weld the two pieces back together. The shaft is 8620 steel, which is case hardened. A company called Weld Mold make a welding wire specific for this application, namely 920. It requires pre and post heating, which can be done in a bbq grill.

See, easy!

PS. I have done everything up to welding the shaft back together.

[rustywagoneers_com]

Good Post!

<runs off to find that welding wire>

[JeepinPete]

Ya, finding the wire is the trick. I tried to buy it directly from Weld Mold. 30# spool, $11/lb. Need to get 30 people who want to weld up these shafts and split the spool :lol: I am looking for another alternative.

[ncjeepers]

Now we're gettin' somewhere. Killer idea on that mainshaft... never thought of that.

[JeepinPete]

Here are a couple pictures of the 241 range box:

http://usera.ImageCave.com/pdatcuk/02-20-09_0755_resize.jpg

http://usera.ImageCave.com/pdatcuk/02-20-09_0753_resize.jpg

http://usera.ImageCave.com/pdatcuk/02-20-09_0758_resize.jpg

The one thing I forgot to mention is the shift rail needs to be cut shorter, and attached to the new back plate. I drilled and tapped the end of the rail, and used a socket head cap screw to bolt it to the plate.

Another thing not shown is the side plate. In the commercial kits, this is welded to the housing. Instead of doing that, I made up a plate that bolts to the edge of the new back plate and covers the opening in the front housing. I plan on running a bead of perma-tex around it to take care of sealing it.

To trim the back plate to the front housing, I scribed the outline of the front case onto the back plate. I then did a rough trim on the bandsaw. Finally, I set up a flush trim bit in the router table, mated the plate to the front case, and used the case as the template for the trim bit to follow. Works great.