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2 rear output np205 ?

sweetk30

sweetk30

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Got a friend who is planning a 6x6 build and wants to use a 205 and have 2 rear outputs .

Anyone got good pics / writeups / links to the buildup of one ?

I know behemoth has made a shaft for this swap . I have seen pics only of the shaft .

Also thinking 2 cases as he has the frame length . 1 in normal and a divorced in backwards to use single rear as input and then front & original input as outputs .

This will be a road driven and used on highway truck . So we need this to be reliable .

Thanks for any help .
 
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There is one on pirate that shows pretty good details about how to do it. I think it was Mikel and his M715 6x6 built. I think Adamsoffroad or whatever the mega truck guy had some pretty good details about it. I haven’t been back to pirate since they ruined it.

If he wants the easy expensive route, the hero transfer case can be ordered with the second rear output. Try to stay away from behemoth. Your chance of getting your order is about 1%.
 
Interesting idea but how would the second d/s be routed past the first axle? Isn't that why the trucks use top load axles?
 
510583d1269470905-how-question-dual-rear-output-np205-6x6.jpg
 
yep like this for the most part .

lots of guys say these np200 t-cases are good for low speed but heat up BAD on highway at todays speeds . some think its the TALL axle gears making the case spin so fast . but we are trying not to use one of these if we can help it .
 
I agree on Np200 is old school with some not desireable traits for modern road speeds. Just thought I'd post up layout for awareness.
Yes, np205 more desireable.

There is also a setup that uses two transfer cases. I think Ford Marmon-Herrington style from WW2 6x6.
 
na this guy is going BIGGER . . . ford f550 front and 2 rears . making a med duty 6x6 truck and stuffing it under a OLD truck body with heavy body mods .
 
more i think it over if we go 2 cases and flip the rear case for twin output and twin stick that case we can get a true 2wd / 4wd / 6wd selecting combo out of this setup .

oh and i forgot to say he wants to do a doubler setup on this :eek: . . so since i have a hard to find ford DIVORCED 203 range box we can do this via 1 married ford 205 with ord doubler kit and then a extra divorced case spun backwards feeding in the rear output and then sending power to both rear axles . and if twin sticked we can make it select front or rear axle .
 
Sounds like a cool project. Always thought those trucks were cool but would be hard to drive on a regular basis with the length to get around and find parking.
 
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sweetk30 said:
Got a friend who is planning a 6x6 build and wants to use a 205 and have 2 rear outputs .

Anyone got good pics / writeups / links to the buildup of one ?

I know behemoth has made a shaft for this swap . I have seen pics only of the shaft .

Also thinking 2 cases as he has the frame length . 1 in normal and a divorced in backwards to use single rear as input and then front & original input as outputs .

This will be a road driven and used on highway truck . So we need this to be reliable .

Thanks for any help .
Click to expand...
I'm working on a design for this. It combines a married NP203 and an NP205. It uses the 203 range box as a doubler and the 203 differential to split between the two rear drive axles. The 205 upper set of gears from a divorced transfer case gets moved to the lower position. The gear teeth will be removed from the front output and an area to fully slide the shift collar will be machined in.

The rest of the lower shafts and gears remain the same as original. This will require two shift collars. One will be in the original location and engage the rear gear for the forward rear drive axle with the center section offset to the passenger side. The second one will be in front of that one and engage the front axle. This will create a direct connection and shouldn't be used on the highway.

The intermediate shaft will get modified by narrowing the front gear to be the same as the undesirable shift on the fly 205 with automatic hubs. It will have about 3/8" removed to make clearance for the lower forward shift collar.

Now for the complicated part. The original lower front gear will be moved to the top shaft. The doubler output shaft will be machined to accept a splined shift collar inner piece. The gear will probably get roller bearings installed between it and the shaft because it will be turning twice the speed of the shaft.

The next part is adapting the 203 differential section too the rear of the 205 case. There will be room for an adapter because it needs to be spaced back so that the large 205 gear will line up. This gear can have the inside splined too be locked on to the forward output that original drove the chain in a 203.

The gear will need to be turned around backwards so that it's shifter engagement teeth are to the rear to make room for the connection shaft that will be custom made. The connection shaft is splined onto the center drive of the 203 differential on the rear and has shift collar engagement teeth on the front.

Shift shafts will need modifications but I am not going to extend this post to explain it.

Operation in single axle drive is done by having the lower shaft gears in neutral engaging the upper shaft with the differential and engaging the differential lock.

Operation in on road double rear axle drive is done by engaging the rear gear of the lower shaft and disengage the differential lock. This allows the rear axles to be like almost all semi truck rear drive. If you get in a position off road where you are having tire slippage just engage the differential lock. To engage the front axle just engage the lower shaft front drive.

Low range can be accomplished with either the doubler or engagement of the front upper gear. The rest of the drive is the same as high range. Put both the doubler and transfer case in low for the 4:1 gear reduction.

The differential and the bearings on the front upper drive gear are what gives this setup its longevity and lack of overheating. There is also an oil pump in the 203 differential section that feeds oil through the center of the shaft to oil the bearings. I was going to see if a 208 oil pump could be retrofit to this as it is a better pump.

So in conclusion 4 gears and 2 or 3 shafts have to be modified along with the shift rails except the top one.

I have a shift on the fly 205 transfer case and am going to be getting a 4 speed and 203 transfer case soon. I already have the divorced input shaft and I have a standard divorced transfer case as well.

If anyone is interested in working on this project with me call or text 360-536-1441
 
highway101 said:
I'm working on a design for this. It combines a married NP203 and an NP205. It uses the 203 range box as a doubler and the 203 differential to split between the two rear drive axles. The 205 upper set of gears from a divorced transfer case gets moved to the lower position. The gear teeth will be removed from the front output and an area to fully slide the shift collar will be machined in.

The rest of the lower shafts and gears remain the same as original. This will require two shift collars. One will be in the original location and engage the rear gear for the forward rear drive axle with the center section offset to the passenger side. The second one will be in front of that one and engage the front axle. This will create a direct connection and shouldn't be used on the highway.

The intermediate shaft will get modified by narrowing the front gear to be the same as the undesirable shift on the fly 205 with automatic hubs. It will have about 3/8" removed to make clearance for the lower forward shift collar.

Now for the complicated part. The original lower front gear will be moved to the top shaft. The doubler output shaft will be machined to accept a splined shift collar inner piece. The gear will probably get roller bearings installed between it and the shaft because it will be turning twice the speed of the shaft.

The next part is adapting the 203 differential section too the rear of the 205 case. There will be room for an adapter because it needs to be spaced back so that the large 205 gear will line up. This gear can have the inside splined too be locked on to the forward output that original drove the chain in a 203.

The gear will need to be turned around backwards so that it's shifter engagement teeth are to the rear to make room for the connection shaft that will be custom made. The connection shaft is splined onto the center drive of the 203 differential on the rear and has shift collar engagement teeth on the front.

Shift shafts will need modifications but I am not going to extend this post to explain it.

Operation in single axle drive is done by having the lower shaft gears in neutral engaging the upper shaft with the differential and engaging the differential lock.

Operation in on road double rear axle drive is done by engaging the rear gear of the lower shaft and disengage the differential lock. This allows the rear axles to be like almost all semi truck rear drive. If you get in a position off road where you are having tire slippage just engage the differential lock. To engage the front axle just engage the lower shaft front drive.

Low range can be accomplished with either the doubler or engagement of the front upper gear. The rest of the drive is the same as high range. Put both the doubler and transfer case in low for the 4:1 gear reduction.

The differential and the bearings on the front upper drive gear are what gives this setup its longevity and lack of overheating. There is also an oil pump in the 203 differential section that feeds oil through the center of the shaft to oil the bearings. I was going to see if a 208 oil pump could be retrofit to this as it is a better pump.

So in conclusion 4 gears and 2 or 3 shafts have to be modified along with the shift rails except the top one.

I have a shift on the fly 205 transfer case and am going to be getting a 4 speed and 203 transfer case soon. I already have the divorced input shaft and I have a standard divorced transfer case as well.

If anyone is interested in working on this project with me call or text 360-536-1441
Click to expand...
I have most of the parts now and am doing the preliminary design and drawings for the 203/205 dual rear output transfer case. It will take 2 custom shafts, two adapters and some modifications to the shift rails.
 
That sounds like a lot in order to get two rear drive shafts and be able to differentiate between tandem drive axles. I saw this setup a while back but it would leave both axles driven like having your power divider locked in a semi all the time.
received_631666627385670.jpegreceived_586446735306617.jpegreceived_612489429478447.jpeg
 
Behemoth sells a shaft that goes all the way through so you have 2 wheel drive or 6x6. The shaft would become driven by the rear axle and would be spinning the front drive shaft all the time which is not really what a person would want.
 
It would be nice if there was a small enough medium duty tandem axle setup but there's not that i know of.
 
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