NP 208 transfer case brace

The FLU farm · Jun 16, 2017

Skinny said:
Just want to point out again that I have yet to see something built in the last 20 years have anything remotely close to a torque rod on the tcase, never seen one on a Japanese import truck, nor anyone adding one aftermarket.

As you probably already knew, early Jeeps had a simple setup that worked in the correct plane for counteracting torque.
Okay, it was likely more of a transfer case support than anything else, considering the whopping 105 lb.-ft. that the Go Devil engine produced.

rustystud · Jun 17, 2017

The FLU farm said:
So where we differ is that you say that the rod provides support vertically while I feel that it adds strength in the fore/aft direction. Well, mostly when under tension.
To me, and using your body analogy, that would be like holding a weight with your arm stretched out, versus pulling (or pushing) on that stretched out arm.
Also, the fact that the rod is just that, a rod, used as a strut, makes it strong only under tension. There's obviously some strength in it under compression, but only until it starts bending, which doesn't take much.

It seems to me that it's the wrong material for vertical support, even if the rod would be mounted differently in the engine end. As it is, the single fastener at the engine is basically a hinge. So yes, I am failing to see this the way you do.
Maybe we're just talking past each other somehow, but my take is that the rod prevents the right side of transfer case from moving rearwards, through triangulation.
And if I understand you correctly, you say that the rod supports the transfer case vertically, and helps with rotational forces.
At least it seems like we're talking about the same rod.

I don't think we are talking about the same rod. Yes it is in the same place but the factory rod I remember is a solid forged round bar that works pulling and pushing. It is not some "tweaky" little rod. It is also not mounted horizontally, but at an angle. Mounted high on the transmission and going down to the transfer-case.
As far as "skinny's" comments, he totally doesn't understand my comments about GM even adding this rod. No vehicle company adds anything they don't need. That is just not cost wise. So since the transfer-cases are now made from aluminum and not cast-iron they don't add it anymore. Doesn't mean it will not help though. Also neither you "Flu farm" nor "skinny" even commented on that "fact" about GM using that rod. Why is that ? I guess it is hard to argue against facts. I agree cucvrus, this discussion has degenerated into a forum for arguments. Not facts anymore.

fitz · Jun 17, 2017

This subject got me thinking back to when aa member here (Ithink it was Cucvrus) replaced some motor mounts on a CUCV. It seemed odd to me that they said they had to use the ones from a gas 350 and not a 6.2 diesel. Now I'm wondering if this has something to to with the lack of a strut rod plate under the motor mount on a CUCV. Maybe the gas job motor mount compensated for that extra space?

cucvrus · Jun 17, 2017

No I don't think so. I think they just specked out the CUCV back in the early 80's and someone high up accepted the prototype they built and said "Yes we want 75,000 units built just like that one" and being it was a different model year that is the motor mounts they were using at the time. just like the grilles and windshield washer system did not change from 1984-1987 CUCV's but did on civilian general production stock models. I am glad they did not OPT for the dimmer switch on the floor like the 1983 models had. 1984 was the first year in the truck models to have the stalk mounted wipers/dimmer switch and cruise control all in 1 lever. But that plate is on the back of the engine block pockets of the CUCV. Just not equipped with the holes for the rods. It is a spacer on the CUCV to take up that room that the rod plates take up. Make any sense from that?

The FLU farm · Jun 17, 2017

rustystud said:
I don't think we are talking about the same rod. Yes it is in the same place but the factory rod I remember is a solid forged round bar that works pulling and pushing. It is not some "tweaky" little rod. It is also not mounted horizontally, but at an angle. Mounted high on the transmission and going down to the transfer-case.

No, apparently we aren't talking about the same one. I was referring to the rod shown in posts number 31 and 32, which appears to be basic bar stock and a mere 5/8" in diameter.
And with the bend in it right before the two bolt holes for the transfer case, it really doesn't lend itself to any compression loads.

Also, as mentioned earlier, I think that GM used that rod to triangulate the engine/trans/'case setup, preventing the transfer case from being "peeled off" if hit while the vehicle is moving forward.
Either way, also mentioned earlier, my 3/4-ton Suburban has that rod, and an aluminum transfer case.

Hasdrubal · Jun 17, 2017

The FLU farm said:
preventing the transfer case from being "peeled off" if hit while the vehicle is moving forward.

Really..Thats the most ridiculous thing you've posted in this thread. Just stop.

ken · Jun 17, 2017

I read a few years back this rod is there because when the front suspension bottoms out, the slip yoke on the front drive shaft also bottoms out. This pushes the transfer case to the rear and breaks the transfer case to transmission adaptor. This is not the case on all GM trucks and so some came without it. All NP203's from the 1970's had them.

The FLU farm · Jun 17, 2017

ken said:
I read a few years back this rod is there because when the front suspension bottoms out, the slip yoke on the front drive shaft also bottoms out. This pushes the transfer case to the rear and breaks the transfer case to transmission adaptor. This is not the case on all GM trucks and so some came without it. All NP203's from the 1970's had them.

Please. You shouldn't have posted that, Ken! Now there's two of us for them to hate.

Skinny · Jun 17, 2017

The fact is that if some vehicles have it and some don't means it isn't really a mission critical item that is going to cause catastrophic damage regardless of the cost to install. Some of the cases I've seen have a mounting boss cast into the housing with no threaded holes so at some point New Process gave up on it. Again, if it actually did something everyone else using NP and NV tcases like GM, Ford, Dodge, Jeep would all have them out of necessity.

rustystud · Jun 18, 2017

Skinny said:
The fact is that if some vehicles have it and some don't means it isn't really a mission critical item that is going to cause catastrophic damage regardless of the cost to install. Some of the cases I've seen have a mounting boss cast into the housing with no threaded holes so at some point New Process gave up on it. Again, if it actually did something everyone else using NP and NV tcases like GM, Ford, Dodge, Jeep would all have them out of necessity.

We where not talking "mission critical" here but is that rod helpful. The answer is "yes" that rod and the two on the lower housing are extremely helpful.
And again no one will answer the question I posted. If this rod is so "useless" then why did GM even have it ? Come on guys, if you cannot answer with facts then just stop posting stupid theory's.

The FLU farm · Jun 18, 2017

rustystud said:
If this rod is so "useless" then why did GM even have it ?

Not a single post refers to it as "useless". The debate seems to be about how useful it is, and for what.

Okay, so here's one theory for why that rod exists.
On civilian vehicles it serves to keep the big chunks from ending up on the highway when the chain in the 208 breaks the case in half.
In military applications it would not be good to leave a trail of smaller parts, such as needle bearings, so a catch pan (often referred to as a skid plate) was installed instead.

rustystud · Jun 19, 2017

The FLU farm said:
Not a single post refers to it as "useless". The debate seems to be about how useful it is, and for what.

Okay, so here's one theory for why that rod exists.
On civilian vehicles it serves to keep the big chunks from ending up on the highway when the chain in the 208 breaks the case in half.
In military applications it would not be good to leave a trail of smaller parts, such as needle bearings, so a catch pan (often referred to as a skid plate) was installed instead.

OK, come on now. I said to stop the stupid theory thing. For one they pretty much stopped using this rod after they dropped (stopped using) the NP205 transfer-case. So the NP208 never really had the support rod. I know a few did, but they are extremely rare. For another thing the case doesn't break apart when the chain goes. It can severely damage it, but I have never seen a case break apart due to a chain going bad. I think at this point your just messing with everyone here and don't really have anything constructive to say. So on that point I'm saying "enough" . So unless anyone can prove me wrong (with real facts) the support rods and side torque rods do provide a significant improvement to the durability of our trucks no matter the transfer-case used.

The FLU farm · Jun 19, 2017

rustystud said:
So unless anyone can prove me wrong (with real facts) the support rods and side torque rods do provide a significant improvement to the durability of our trucks no matter the transfer-case used.

Are you hoping that someone will post that they don't help strengthen anything, or that they can make things worse?

I'm hesitant to write this, for obvious reasons. but I have one 208 (and have had a few) with the rod. I have also seen split cases as a result of the chain wadding up. Sorry.

scottladdy · Jun 19, 2017

The FLU farm said:
A I have also seen split cases as a result of the chain wadding up. Sorry.

I've been looking all over the interwebs and cannot find a single instance of a 208 case splitting due to a catastrophic chain failure. I'm sure that it can happen, just finding nothing out there.

A couple of examples:

https://ck5.com/forums/threads/np208-whos-broken-one.285111/

https://www.google.com/search?q=np2...iMvUAhVUVWMKHQsOBCsQ_AUIBygC&biw=1584&bih=807

In fact, most of the failures reported are due to abuse. Low fluid or running dry, hitting hard at speed, driving the front driveshaft into the case without the support rod in place, etc.

So, hoping you can help the community out and post some pics of the failures you have seen? I am a big fan of facts!

All the best!

The FLU farm · Jun 19, 2017

Unfortunately, there's no way I can look through a few thousand proof sheets (negatives for B&W photos) or about the same number of color slides. Yes, lots and lots of photos from the 80s and 90s. I don't even remember what shops those broken cases were in.

And yes, it obviously takes something out of the ordinary to experience catastrophic chain failure.

I, too, poked around a bit to find a photo for you, but the closest I saw was this post in a forum:

" Can somebody tell me how my transfercase literally broke in 2 pieces? Half of it is on the truck and is still drivable in 2wd but the other half fell onto the street. Anybody know how in the **** I could have done this?

It's an 85 Chevy on 35's "

Okay, that it's on the internet doesn't make it a fact, but I doubt that the guy posted that just because he could. And if it is true, I'm not the only one who has seen a 208 broken in half.

scottladdy · Jun 19, 2017

The FLU farm said:
Unfortunately, there's no way I can look through a few thousand proof sheets (negatives for B&W photos) or about the same number of color slides. Yes, lots and lots of photos from the 80s and 90s. I don't even remember what shops those broken cases were in.

And yes, it obviously takes something out of the ordinary to experience catastrophic chain failure.

I, too, poked around a bit to find a photo for you, but the closest I saw was this post in a forum:

" Can somebody tell me how my transfercase literally broke in 2 pieces? Half of it is on the truck and is still drivable in 2wd but the other half fell onto the street. Anybody know how in the **** I could have done this?

It's an 85 Chevy on 35's "

Okay, that it's on the internet doesn't make it a fact, but I doubt that the guy posted that just because he could. And if it is true, I'm not the only one who has seen a 208 broken in half.

https://www.pavementsucks.com/threads/np208.130677/

Sounds like the type of catastrophic damage that is caused when a front driveshaft is jammed back into the t-case. Snapping the t-case in half along a line parallel to front/back in a somewhat vertical plane, keeping the left half of the case relatively intact and therefore drive-able. Unfortunately this is not chain failure. Could be many root causes, but not chain failure.

Now, I wonder whether or not that crazy bar that attaches to the transmission and reaches all the way back to those strange mounting holes on the right side of the t-case would have helped disperse the stress and maybe just maybe have helped prevent this failure?

Here's an NP205 case that broke in a similar fashion.

Wait, there's no chain in these t-case's AND they are the STRONGEST cases made? Here's the link:
http://www.offroaddesign.com/catalog/doubler.htm

Now I gotta believe they (New Process) spent that extra money tapping those holes in the side of the t-case for a real reason. Gotta think it's to help prevent breakage like this.

Now, for those of us with a real engineering background, you can see how the 205 cracked along the plane made by the stress risers induced from the drilled and tapped mounting holes. Stress induced by either a sudden shock load OR gradual over time. In either case, that right hand bar really does seem to fulfill a purpose.

OK, this should be enough said on this topic. The bars are included to reduce the dynamic loading on the transmission/t-case assembly and together increase the resistance to stress induced failures of the assembly. The "torque" being induced is NOT rotational around driveshaft rotation as has been posited (incorrectly), but instead being imparted from a rearward thrust that even marginally exceeds the range of motion of the driveshaft assembly, whether the full design limit or some dynamically induced (wear, corrosion, impact) limit. This induces a rotational moment in the t-case with the axis of rotation roughly vertical. Hence GM's term.

I am calling ELMO (Enough, Let's Move On). Please do not make me model this in CAD and perform a stress analysis on this. It is not necessary and is obvious to anyone with mechanical engineering skills what the intentions of these rods are.

All the best!

Skinny · Jun 20, 2017

I've lost so much sleep about my missing torque rods...wait...no I haven't. Carry on!

cucvrus · Jun 20, 2017

Skinny said:
I've lost so much sleep about my missing torque rods...wait...no I haven't. Carry on!

https://youtu.be/AHRkvH8HRVw

cucvrus · Jun 27, 2017

I decided to install the torque / strut rod on Terminus M1009. If for nothing else to keep the trails clean and free of transfer case debris. It is a 5 minute install. About 1/2 hour cleaning the bolt holes. I used a .99 cent battery brush and cleaned them out. the threads were clean enough to thread the bolts by hand. I loose fit the bar and painted it. Rosey pinkish / purple seemed good. Actually I left a few friends pick the color.

It matters not the color. But the effectiveness of the heavy stout steel rod that adds great strength, support and durability to my tank like Terminus M1009 mobile fortress of power and off road capability. It's my truck. I like it. keep the highways of America beautiful. Add your torque/strut rod today. Available where all quality truck parts are sold. By Romco.

Rustyshackelford · Jun 27, 2017

Does anybody know the official name of this thing so we could search the web for them if we desired to install one?

NP 208 transfer case brace

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