CUCV with NP205 transfer cases

[richingalveston]

So far the Magnum box has given me no problems. I use it before I switch to low in the t-case. It is 2.5 to 1 reduction Which is a little better than the 2.1 in the 205. I have two 208 t-cases if any one needs one.
I have not been able to use it much and only in some mud and not really climbing anything. I just used it to exercise it a little bit, it was not needed. I hope for it to get its first test in a couple of weeks at the College Station off road park.
I considered a lomax but for just a little more I could get the magnum and have a really nice and compact doubler. The magnum and 205 is almost the same length as a 208

At the time of my build I found 4l80e adaptors to the 205 t-case to be expensive, So I went ahead and spent 3X that and got the magnum. Does not really make sense but makes me feel better when I think of it that way.

I really like the truck, how it drives and handles has been a pleasant surprise. I did not think it was going to be as good as it is with this set up. I have a 2014 GMC truck loaded and I would rather drive the blazer.

 

[Drunkle Scuzzy]

So with the magnum box in an m1010 would you need to do any drive line work if its almost the same length as an np208?

 

[Bunkerbuilder]

Since the box in question makes the transmission transfer case assembly longer and I would assume you are planning a upgrade from the np208 to the np205.
The only reason I would assume and or suggest this is if your spending almost 2000.00 on a ord magnum box or anyone elses doubler I wouldnt think you would run a weakn & cheezy np208 for a t case.

So with the magnum box in an m1010 would you need to do any drive line work if its almost the same length as an np208?

 

[Drunkle Scuzzy]

That wasn't a very well thought out question on my part, Bunkerbuiler. What I was wondering is how much drive line work would it take to mount a Magnum box behind the stock TH400 in an M1010 with an np205 transfer case. I wouldn't want the weaker combo indeed. Curious what the total cost of parts and what all it would entail. This is all a hypothetical for me at this point. The M1010 I am looking to buy on Sunday has 3.73 gears and I was thinking this would be an ideal way to keep the highway gears and get back the low range, despite the fact that it would cost possibly as much as the truck is selling for. If my calculations are correct it would create a crawl ratio of approximately 99:1 in the lowest transfer gear (5.33:1) for crawling, around 51:1 in the 3rd transfer gear(2.72:1) for trail riding, and around 37:1 2nd transfer gear (2:1) for mud type situations where you want more speed. An inquiring mind would like to know if anyone is willing to take the time to answer. Thanks for obliging my curiosity. Certainly not trying to waste anyone's time nor hijack the thread.

 

[Bunkerbuilder]

Its ok I consider myself the king of thread hijacking so you would have to do alot better than this to best me in that respect.

as to cost that would depend on what You have presently....as I understand it the 84 - 87 cucv has a small trans to tc bolt pattern so IMHO you would need the late T400 trans / the doubler $2000.00 / a round pattern np205 $1000.00 - $1500.00 and driveline work

 

[muddobber40]

THe 400's in the CUCV's can be mated to either 205 adapter. The doubler conversion kit is middle 700's from 2 reputable places. THey build kits for both the figure 8 and round pattern 205's. Also, if you have a round pattern 205 (85-91) you will need to switch to the short output like in the 77(maybe earlier)-84 205's. The input on the round pattern is longer than that of the figure 8. So unless you have a later 205, might as well buy an older one. They seem to go cheaper since most people know that the later 205 is what is needed to bolt to the NV4500. The 203 t-case can be had for about $150 around here, or one place that sells the doubler ,sells the range box as well.



Just for a side note to richingalveston,

the 205 and 208 adapters can be machined to fit the 4l80E. I have done so to both and several times.

 

[richingalveston]

yes the adapters can be machined but I did not have one to start with. A pre-built adapter from 4l80e to fig8 205, when I was shopping, was over $500. I started with a figure 8 - 27 spline not sure what it was off of. I had the main bearing hole enlarged and purchased the fat shaft from ord along with modified shift rails. I rebuilt the t-case myself. I had planned on a doubler anyway in the future but decided I did not want to waste the energy and time to do it twice so I went with the magnum and I am glad I did.

Building a 203/205 or a 205/241 doubler is not that easy and when finished you have a very heavy t-case that almost always requires two cross members and the front one takes some work to build because it has to go over the front drive shaft. And you will spend over a $1000 for sure to do it (unless you are extremely thrifty and can get the parts for free).

Why would I spend 500 now to connect the 4l80e to the 205 to later take it apart and put a $1000 plus t-case in and throw the adapter away. Then I have to build the t-case and two cross members. I would have $2k in my doubler and way to much time.

The magnum box is the adapter, it is light, relatively easy to install, and because of my situation and my starting point (the parts I had on had) It made more sense to spend the extra $500 now and do it once. The magnum205 with cv style fixed yoke outputs is shorter than a 208 with slip yoke. only slightly longer than 208 fixed yoke.

My cost of the: ORD magnum, shifters, fat shaft, 205 rebuild kit, 205 t-case used, correct output flanges, and cross member cost me about $3000.00
The 4l80E with two computers and a two rebuilds cost me $2800, should have only cost about $1800 but I made the mistake and bought the TCI controller which ruined the first rebuild. you can read my other threads on this for more detail.

I recommend the magnum if you want a doubler. however you must decide what you want to do with your truck (how far do you want to take it). I have 2 to 3 times more money in the drive train than the truck is worth. 4l80e, optishift controller, magnum205, 1 ton axles with lockers front and rear, 4 inch lift, cross over steering with hydro assist. And I am ok with that because I am building the truck for me, not for resale.

I do not know if it is for sale yet but Trail Worthy Fab was building t-case's that were really awesome. Two speed built in and looked like a little bit larger 205. all aluminum case. I think it was going to cost about $3500 but it was nice. They may have it on the market by now.

If you have a blazer and do not do the axle upgrades, lockers and such then don't waste your money on a doubler. Until you get the rest of the driveline to a 1 ton rating. You will never use the capabilities of a doubler on 10 bolt axles.

 

[Skinny]

Man you just gave me sticker shock on gearing. I really want to get into an NV4500 at some point but I have the figure 8 pattern NP205 which I think creates issues. I was thinking an NP241/205 doubler to solve that problem on the cheap and get the extra gearing. I'm thinking that could be done for under $3k. Amazing how the cost of transmission and tcase upgrades go beyond the value of the truck!

 

[richingalveston]

I am not familiar with NV4500 options. I would never go back to a standard for an off road vehicle. I have a jeep that is a 5 speed and when you get into technical off road it is a workout. A lot of people like the clutch but I am not a fan of it. I can gas and brake at the same time with an auto and spend more time concentrating on the steering and the trail than worrying about gears and a clutch.

For a highway runner, it is not a bad thing. I live in Houston and the traffic is terrible and miserable with a 5 speed.

You can do a 4l80e for less than 2k, prob. close to 1k if you have the knowledge and a cheap core. I think a nv4500 will cost about the same and is a lot more work to install.

I like the magnum with the fig 8 pattern better than the round. Using the magnum on a round pattern 205 to me is a weaker set up. Only 6 bolts hold it together. With the figure 8 you get a large foot at the bottom of the magnum that has 5 more bolts in addition to the 6 and three are very large. Since you do not need a second cross member, I though six bolts was asking for trouble.

A 700r4 is ok but to build it right it is not cheap. Only a few hundred cheaper than a 4l80e of course your level of knowledge, parts gathering and wrench turning ability can change this price dramatically in each direction.

I have not built it yet but plan to have a back up manual shift controller (made from switches) to carry in my rig for long off road trips. If the controller fails, you can still shift it with a simple set of switches. The 4l80e controlers also offer a paddle shift option so you can control what gear you stay in a lot better than a 700r4.

When my truck is in crawl mode, both transfer case in low. Gives the truck a 5.1 to 1 reduction. I can use second and third gear in the tranny allowing the torque converter to lock and thus significantly reduce the amount of heat build up in the tranny. For long steep hill climbs in rocky terrain I have no fear of overheating my tranny. I believe you can get the 700r4 to lock up in 3rd but not second (I could be wrong on this). locking the torque converter is a good thing.

I believe the 4l80e with a magnum and fig 8 205 is the best of all the options out there.

The 205 t-case is extremely heavy. When you put a 203 front half on it, it makes it even heavier. The 241 is a lighter add on but from what I have read it takes some welding to put these together. What you end up with on this style of doubler is a very large and heavy t-case. Then you have to put two cross members under it. And the clocking options are not that great with the finished project.
Also when you use this style of doubler, you have to use the 205 gears first then the 203/241 or you risk breaking the intermediate shaft. With the ORD magnum, take a look at the fat shaft, you will not break this and thus I can use the 2.5 to one reduction in the magnum before the 1.9 in the 205.

I studied things for a while and chose the 4l80e,magnum, and 205 because it appeared to be the best of everything. Cost is a factor sometimes but I believe I only spent 1k more getting the magnum than I would using a 203/241 to 205 doubler. It installed a lot easier and I had to do very little cross member work.

 

[skysix]

I think that regardless of year of manufacture, the parts list used in assembly was what was available when they bid/won the contract ie 1984