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Discussion Starter #1
Awhile back I saw a thread on diffs rated for strength. I have some strong opinions on them and those opinions pretty much match the consensus.

But on transfer cases I don't have strong opinions. I would appreciate the well versed to rate them.
 

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Search. There are lists on the Internet with them listed per the manufacturer's torque ratings. Though I would say that I believe the early cases, like the NP205, are rated a bit conservatively compared to modern cases.
 

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Samurai/Track/Kick
NP231
D20
D300
NP241
NP205
Atlas.

There. There is my list. 241 not much further ahead of the D300 only because the weak factory outputs. Based of the case itself I would say 300 is stronger.
 

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Discussion Starter #4
Search. There are lists on the Internet with them listed per the manufacturer's torque ratings. Though I would say that I believe the early cases, like the NP205, are rated a bit conservatively compared to modern cases.
Torque ratings is one factor. Real world experince is another. I believe a Ford 8.8 has a higher torque rating than a Dana 44, but I do not consider a 8.8 to be "stronger" than a D44 overall. I would assume the same could be true for T-cases.

Also, like you said, they could rate them conservative. (Or overrate) I have a friend that loves to show his pics of his 205 split in half. Lol. (I'm sure he was beating on it bad)
 

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Torque ratings is one factor. Real world experince is another. I believe a Ford 8.8 has a higher torque rating than a Dana 44, but I do not consider a 8.8 to be "stronger" than a D44 overall. I would assume the same could be true for T-cases.
The axle thread was a complete cluster with a lot of stupid shit being spewed as well as some good tech. The problem is no one has done any controlled testing to properly determine strength and there is little available data from manufacturers. Therefore we must rely on what we can observe as well as design priciples, which is far from definitive in most cases.

That said, a 31 spline 8.8 is stronger than a 44 in every way. Gears, shafts, and housing are all stronger. The only demerit for the 8.8 vs. the 44 is the C-clip design, but that has to do with failure mode rather than strength.

NP tranfercases are easily comparable since manufacturer torque ratings are readily available, but as to where the Dana, Borg Warner, and other cases fall is a lot of speculation.
 

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NP271 probably is about as strong or stronger than NP205, but NP205 certainly can take abuse, likely because of all gears and cast iron housing, however.

The list I posted was with cases I’ve had experience with.

I feel any iron gear driven box beats it’s chain driven cast ally counterpart.

Now weight does become an issue to consider as well. Building a light buggy with day Toy axles and a Jeep drivetrain, (just to piss off the Yota guys :laughing:) I would opt for the 231 over the 300.

One ton Jeep where weight isn’t such a factor the 300 is the obvious choice. And the 205 is an even better option, with the trade off of being a little bigger.
 

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I run 650hp through a np205. I don't rebuilt it, I think it has a little oil in its water lubrication system.


If I had an atlas race case it would be rebuilt yearly or more often.

If I had a penny for every atlas I have seen take someone out of commission I'd need a wheel borrow. If I had a penny for every np205 that ended someones day I would have no penny's.

I'd run an atlas if I thought it made sense. At this point I don't think it does.
 

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Discussion Starter #9
That said, a 31 spline 8.8 is stronger than a 44 in every way. Gears, shafts, and housing are all stronger. The only demerit for the 8.8 vs. the 44 is the C-clip design, but that has to do with failure mode rather than strength.
Gears and shafts maybe. The housing if you don't count the tubes. (The tubes are paper thin) Also the connection between the tube and the pumpkin sucks. I've never personally had an issue with the C-clips, but I've heard stories. The big design flaw I hate is the outer wheel bearings riding on the axle. I don't think I've ever pulled an axle that didn't have brinelling on it.

I have a lot of experince with a D-44 on 35's. (Scout II) I have lots of experince with an 8.8 on 35's also. (Bronco) I had zero problems with the 44 and I've had to put over a grand in upgrades on the 8.8 (now I'm running 38's, but had 35's at first and nothing but trouble)
 

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I broke the output on my 205 bouncing around on backdoor back in 2011. Changed to an Atlas 3.8 and it is holding strong in my rock buggy today.

But anecdotal crap aside, the 205 is slightly stronger than an Atlas II; but, the Atlas gives fantastic gearing options, mounting options, yoke options, output options, clocking options, etc. And it shaves 50# of weight off the buggy. So IMO, it is a better case even if it does give up a little robustness to the 205.

I went through a couple of 231s on my TJs, which seemed to break relatively easy.

I think anything can be broken.
 

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i chose to run a NV271 in my rig over the 203/205 that i also had to chose from. the 271 is a big heavy bitch for sure as about the same length as the doubler but like the 2.73-1 low over the 1.98 of the 205. mine is out of a first gen superduty so 31 spline outputs and stock with flange yokes ect. have been beating on it behind my BBF and other then not having front dig im very happy with it over the 205.
 

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The list I posted was with cases I’ve had experience with.

I feel any iron gear driven box beats it’s chain driven cast ally counterpart.

Now weight does become an issue to consider as well. Building a light buggy with day Toy axles and a Jeep drivetrain, (just to piss off the Yota guys :laughing:) I would opt for the 231 over the 300.

One ton Jeep where weight isn’t such a factor the 300 is the obvious choice. And the 205 is an even better option, with the trade off of being a little bigger.
I can guarantee you a NV271 will handle more torque than a NP205 will. Are you suggesting that modern trucks with 3X the torque of any truck that came with a NP205, significantly more weight (as well as higher payload and tow ratings), and bigger tires have weaker transfer cases? Have you seen an NV271? They're massive. I cant find it now, but I remember seeing a max input torque rating for the NP205 of somewhere around 6,000FtLbs. compared to the NV271's 7,000FtLbs.+. I do however agree with TrailTamerXJ, the cast iron construction of the NP205 should hold up better to impacts with rocks and such. Neither are weak cases by any measure, but we have made progress in the last 30+ years.

Gears and shafts maybe. The housing if you don't count the tubes. (The tubes are paper thin) Also the connection between the tube and the pumpkin sucks. I've never personally had an issue with the C-clips, but I've heard stories. The big design flaw I hate is the outer wheel bearings riding on the axle. I don't think I've ever pulled an axle that didn't have brinelling on it.

I have a lot of experince with a D-44 on 35's. (Scout II) I have lots of experince with an 8.8 on 35's also. (Bronco) I had zero problems with the 44 and I've had to put over a grand in upgrades on the 8.8 (now I'm running 38's, but had 35's at first and nothing but trouble)
First, both the Dana 44 and Ford 8.8 have cast iron center sections with tubes pressed in and plug welded, so I am not sure how you conclude this is a weak point on the 8.8, but not the 44. Now there are several variations of both Dana 44s and Ford 8.8s, but the torque capacity doesn't really change between models, just the housing specs.

Since you mentioned a Scout and Bronco, lets compare the tubes on those. From what I could find with a quick search, Scouts have 2.75" OD .25" wall tubes. I don't know of any factory 1st gen Dana 44 rear with tubes larger than 3" OD. The Bronco has 3.25" OD .25" wall tubes. Some 8.8s have .1875" wall tubes, but I think those were limited to some Explorers and lower GAWR applications. For the sake of argument, lets say the Bronco has .1875" wall tubes.

The Bronco axle tubes (assuming .1875" wall thickness) have a moment of inertia of 2.1228256786 in4, and the Scout axle has a moment of inertia of 1.5493205958 in4. The cross-sectional moment of inertia is directly proportional to the bending strength of the tube. Therefore, even with .1875" wall tubing, the 8.8 is ~37% stronger than the Scout Dana 44 in bending.

Now let's say you have a Dana 44 with 3" tubes and an 8.8 with .25" wall tubes. The 8.8" with .25" wall tubes has a moment of inertia of 2.6691265709 in4 (~72% stronger than the Scout Dana 44 in the previous example). The 3" tube Dana 44 would need a wall thickness of .375" to slightly edge out the 8.8 in bending strength. When it comes to bending, OD plays a bigger role than wall thickness.

The max input torque rating I found for a 31 spline 8.8 is 6,500LbFt vs. 5,000LbFt for a rear Dana 44. A quick search also reveals a GAWR of 3,800 Lbs. for the 8.8 and 3,500 Lbs. for the dana 44. This indicates that the 8.8 has a stronger housing and can take more torque than a Dana 44.

What exactly have you upgraded on your 8.8? Also what have you broken? Anecdotally, I have personally seen more broken Dana 44s than 8.8s. I personally am running a stock shaft Explorer 8.8 with 37" Pitbulls, a locker, and a crawl ratio of 125:1 and haven't broke anything besides the locker yet (Knock on wood).
 

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I can guarantee you a NV271 will handle more torque than a NP205 will. Are you suggesting that modern trucks with 3X the torque of any truck that came with a NP205, significantly more weight (as well as higher payload and tow ratings), and bigger tires have weaker transfer cases? Have you seen an NV271? They're massive. I cant find it now, but I remember seeing a max input torque rating for the NP205 of somewhere around 6,000FtLbs. compared to the NV271's 7,000FtLbs.+. I do however agree with TrailTamerXJ, the cast iron construction of the NP205 should hold up better to impacts with rocks and such. Neither are weak cases by any measure, but we have made progress in the last 30+ years.
Yeah. They are fucking huge.

So packing one into a crawler that is already limited on space is moot. Is it stronger, yes. Is it a viable option for what we’d use it for? No, not really.
 

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Discussion Starter #16
What exactly have you upgraded on your 8.8? Also what have you broken? Anecdotally, I have personally seen more broken Dana 44s than 8.8s. I personally am running a stock shaft Explorer 8.8 with 37" Pitbulls, a locker, and a crawl ratio of 125:1 and haven't broke anything besides the locker yet (Knock on wood).
As far as the tubes, pressed and plug welded, I've heard of many people twisting the tubes out. (It has never happened to me.) I've never heard of the D44 doing this. Maybe they have better welding process. I don't really know what fails when they "twist out". I was not aware of .250" wall tubes. I have an old Bronco 8.8 in the corner of the shop. (Bent) I'm going to measure for fun.

As far as upgrades, As mentioned, I bent mine and now have a truss welded on.

The biggest PITA has been the wheel bearings. It wouldn't be so bad if they had a complete bearing. But the design has no inner race. So when the bearing gets stressed, it wrecks the shaft. When you pull a shaft and it has brinelling, you install a "repair bearing". This is a bearing that rides a little further out on the shaft. Once it wrecks it there, you must replace the shaft. If you don't, the shaft will break right there and you lose the wheel.

I have owned a Bronco since 92'. I use to replace shafts all the time. That was with 35's. (I'm running 38's now) Now I have a "full float" kit on mine. It solves the problem, but I had to do some other reinforcing to make the kit work. I now have a pretty good axle, but if I was to do it again, Sterling and be done with it.

If your running 37's, I would check your axles. There's not really any warning when your axle breaks.
 

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Yeah. They are fucking huge.

So packing one into a crawler that is already limited on space is moot. Is it stronger, yes. Is it a viable option for what we’d use it for? No, not really.
I am not saying a NV271 is the answer for everyone, but definitely an option for the fullsize crowd or many people running a 205 or 203/205 setup. Snowracer who posted right before me said he put one in his rig and is happy with it, so your claim that it is not a viable option is untrue.

As far as the tubes, pressed and plug welded, I've heard of many people twisting the tubes out. (It has never happened to me.) I've never heard of the D44 doing this. Maybe they have better welding process. I don't really know what fails when they "twist out". I was not aware of .250" wall tubes. I have an old Bronco 8.8 in the corner of the shop. (Bent) I'm going to measure for fun.

As far as upgrades, As mentioned, I bent mine and now have a truss welded on.

The biggest PITA has been the wheel bearings. It wouldn't be so bad if they had a complete bearing. But the design has no inner race. So when the bearing gets stressed, it wrecks the shaft. When you pull a shaft and it has brinelling, you install a "repair bearing". This is a bearing that rides a little further out on the shaft. Once it wrecks it there, you must replace the shaft. If you don't, the shaft will break right there and you lose the wheel.

I have owned a Bronco since 92'. I use to replace shafts all the time. That was with 35's. (I'm running 38's now) Now I have a "full float" kit on mine. It solves the problem, but I had to do some other reinforcing to make the kit work. I now have a pretty good axle, but if I was to do it again, Sterling and be done with it.

If your running 37's, I would check your axles. There's not really any warning when your axle breaks.
I have actually seen axles twist tubes, and it is not an 8.8 problem, it is a cast center section with plug welded tubes problem that any axle of that type is susceptible to. I believe that you bent your 8.8. I am not claiming that 8.8s are unbendable or even particularly hard to bend. My point is solely that an 8.8 is no easier to bend than a Dana 44 and in fact more resilient to this kind of abuse.

I agree that a semi-float pressed taper-bearing design (as the 44 is) is preferable to the C-clip design of the 8.8 that lets the axle slide in and out on the bearing surface, but I have not had issues with wheel bearings or bearing surfaces on the axle shafts of my 8.8 (and yes I had the shafts out when I put new bearings in after pulling it from a junkyard and when rebuilding my locker fairly recently). I believe a big part of the difference between our experiences lies in the weights of our rigs. My rig has 1,790Lbs. on the rear axle ready to hit the trail without me in it, and I would assume your Bronco weighs a good bit more.

Sorry for the thread Hi-jack, I'll leave the axle discussion at that.
 

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Samurai/Track/Kick
NP231
D20
D300
NP241
NP205
Atlas.

There. There is my list. 241 not much further ahead of the D300 only because the weak factory outputs. Based of the case itself I would say 300 is stronger.
swap spots between 241/300 and atlas/205 and i would agree
 
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