I'm looking to build a 203-205 doubler and am looking for some advice. I want to mount it divorced, and I understand the 203 was also used divorced. Also a low ratio kit for one off them would be good, it reduces the versatilaty having both be 2-1.

So, who's done it? What am I going to run into?

Good parts sorces? I need to find the transfer cases to use, hardest to find is probably the 203 divorced. Also I haven't yet seen any low range kits for either case, Suggestions?

 

I use this:
NorthWest FabWorks - Products - Transfer Cases - NP203 / NP205 Adaptor
I like this adapter because it used blind tapped fasteners, so no leaks, and the clocking ring is externally mounted so changing stuff around was easy.
I too am in the process of eliminating the "married" 203 case, and will be using a "divorced" 203 as my range box. I will move the entire package slightly, and eliminate the stress on the transmission adapter. This thing is heavy, and while I did make two x-mamber for this, it still appears to be awkward.
The divorced package wil also allow me to use equal length driveshafts so I will only have to carry one spare.

Lo-max has 3:1 kits for the pass side drop 205's but not for driver side drop.
I am not aware of any at all for fords.

While 3:1 would be fantastic, the 4:1 is cool. Although it does kill some wheel speed, and the 3:1 might be just right and still maintain a reasonable low range. HAving the doubler with a 3:1 option would provide us with 1:1, 2:1, 3:1, and 6:1 options.
I would give up 4:1 to get 3:1 and 6:1 anyday.
I have considered making some gears, but this got way out of control, and was crazy expensive. Too much for me to experiment with.
I will settle for 2:1, and 4:1 for now.
I have even thought about running a chevy drop upside down, but was concerned about oiling the bearings this way, and having the shift rails so low.
I guess patience is the key here.

 

Thanks good info.

I am not a 205 expert but have been told two things that I would like some clarification on. One, that the 205 can be built for both left and right drop with the same case by reversing/mirroring all the guts and outputs. Two, that when set up for twin stick it functions like the atlas alowing independent engagement of the front and back. That if one wanted to they could have the rear in high and the front in low.

I also am after the divorced largely so I can move it back, getting me equal length drivelines, my truck is very long. Also I don't want to deal with mating to the transmission along me to change my mind more easily. Third I can install a driveline brake between the transmission and transfer case helping to stop the truck in low range.

 

Two part question:
First the mirror image is not 100% correct because the gears are helical cut and not straight cut. They would be noisy then. This means the the gears actally have a pair, and have to be installed on the same side, and not all of the gears can be turned around to accomodate a partner gear on the other side.
Difficult to type this explaination, but my lo-max 3:1 gears required too much work to install in my ford box.

Twin stick for the 205. if performed properly will not allow the function of low range and high range from either end at the same time. This would destroy the case in a hurry.
There is a shuttle pin that eliminates this posibility, (actually two) and as long as the long shift rail is left alone, and you do not take too much material away from the range rail (short rail) it cant and wont allow the front to be in low, and the rea to be in hi, or the opposite.
This modification only really takes about 20 minutes when the case is on the bench.
The only thing that has to be modified is the range rail, (short rail), and this is the only one that has to be removed.
Here is an image:
Image of 205 modified shift rail - Photobucket - Video and Image Hosting

 

But if I really wanted to and romoved the shuttle pins, it could be done. And I beleive this woldn't actually seize the transfer case like it would a transmission. That if the tires were off the ground you could have the front and rear in a differant range.

 

You actually dont have to remove the shuttle pins, you can just remove more material from the shift rails, to prevent the saftey detent from being struck.
This could permit the use of either e front or rear low range while the opposite output is in the opposite range.If you do not believe that this will blow up a t-case, you should think again.
This would not be any different than running different differential gears. This is a sure method to busting a case in half. This has been done, and if the shuttle pins are not used for thier saftey to prevent this, it will happen again. Just take a few pics for us when it does.
Any reason to believe why it would not? I am curious....

 

Well, if you were running on sheet ice it would probably hold up just fine.
I am with 75F350, I think that it would grenade faster than you could let out the clutch. Basic mechanical engineering would prove that this won't work with this T-case.

 

Don't misundertand me I agree it's a bad idea. I am just thinking about some other drivetrain options that are to complicated to get into here.

 

Too complicated? Now I am more than interested, I am intrigued.
Please share. I am not the sharpest knife in the drawer, and I am always looking to learn something new.........

 

OK I'll throw this out there. I'm looking to use a 205 as an attachment point for a hybrid drivetrain. This will allow seperate gear selection and disengagement. While being strong enough, simple, and cost effective.

 

OK, I actually anticipated that. If you use this as a third output option, what happens to the other two? You have only two outputs, the front and the rear. If you still use this vehicle as a 4wd, the only two outputs are already consumed by the front and rear axles.
Perhaps this is not actually a truck or off-road application. In this case, you should use a chebby t-case, and use the lo-max kit.
Third options are available by the PTO output, and the output selection has nothing to do with this, since both outputs would have to be in neutral anyway. No reason to have either output in a different range.
By the way, if you actually use a "doubler", you will have two PTO options. This means you could have two "Hybrid" drivetrains.
I actually attempted a front and rear PTO, and a doubler for a pair of winches, and there was simply not enough room under the truck. Cool idea on paper, but not reasonable.
What is a hybrid drivetrain? Are you considering some sort of electric generator?
I am not being a "wise guy" I am really trying to understand the concept.
If you are attempting some sort of electric generation, then you will have to use the PTO, as this would be a 1:1 ratio. Underdriving the output would only spin the generator slowly, and defeat the purpose.
I moght have misunderstood what you meant. Maybe you were taking a jab at me, who knows.......

 

No jab, This will be a 2nd transfer case I'm thinking I'll end up with it going transmission, then first 205 with right side output for hybrid, then 203/205 doubler to transmit power to the axles. I need my hybrid system to turn much slower then the driveline at highway speeds. 3 to 1 in a chebby box sounds good. This aragement will give me lots of gear selection options for both the engine and the hybrid seperately.

With what would normaly be the rear drive powering the 203/205 in high and the front drive powered by the hybrid in low this will alow my system to turn slow in relation to the rest of the drivetrain, and give me lots of gear options including putting the first 205 in rear low to get me a super low 12 to 1

I guess now that I've thought about it some more I don't really need the doubler two 205's would do just fine and save some money 6-1 is plenty.

 

You need an atlas case, and not a huge amount of cast iron pigs hanging around under the rig. Even in a long bed truck this would be crowded, and that rear driveshaft would be rather tiny.
You can obtain a crazy low ratio to the axles, by other methods.
Two 205 cases in series makes shifting a real task because of the long shift rails.
I supose if a third output was required, and the PTO option was no longer an option, this could be achieved.

 

An Atlas would be wasted money I can get 205's at $75 a pop. I am after the extra input and the versatility. Using a PTO isn't strong enough. I got alot of room it's a crew-cab long box. I would use a cable shifter set up like this one NorthWest FabWorks - Products - Transfer Case Parts

It's looking like the LoMax 3 to 1 requires there case, to much money. Any other ideas there?

 

I have just been following this, and I have to say that I have toyed with the idea of a pass side drop divorce mounted case for a doubler if I ever seriously looked into a dana 60F/47s combo. I do agree though, that a divorce doubler behind a married case might make for a really long drivetrain combo.

No matter what, post up pics of it when you are building it.