Engineers? - Passenger side tcase brace function

[BadDog]

I have a question for the engineering types. Not looking for "GM engineered it, leave it alone", I can figure that out on my own, and that's basically where I am pending review. I'm hoping for real answers to what and why.

First off, exactly what forces is it meant to handle. By it's design, it would seem well suited only to be managing only linear tensile loads along its length. Like suspension compression shortening the drive shaft. To a lesser extent, compression loads like lengthening the drive shaft. And almost nothing in any other direction.

The reason for asking is that it's proving very tight in there to get my exhaust routed between the shackle hanger and that bar. Life would get a WHOLE lot easier if I modify that bar so that for most it's length it runs more parallel to the transmission center line with a kick out to connect to the case. Even with gusseting that's obviously going to hurt it's ability to manage the linear loads since it will introduce a substantially larger force vector trying to bend the rod where the gusset ends. But is it likely to matter?

 

[Bent77]

I have a question for the engineering types. Not looking for "GM engineered it, leave it alone", I can figure that out on my own, and that's basically where I am pending review. I'm hoping for real answers to what and why.

First off, exactly what forces is it meant to handle. By it's design, it would seem well suited only to be managing only linear tensile loads along its length. Like suspension compression shortening the drive shaft. To a lesser extent, compression loads like lengthening the drive shaft. And almost nothing in any other direction.

The reason for asking is that it's proving very tight in there to get my exhaust routed between the shackle hanger and that bar. Life would get a WHOLE lot easier if I modify that bar so that for most it's length it runs more parallel to the transmission center line with a kick out to connect to the case. Even with gusseting that's obviously going to hurt it's ability to manage the linear loads since it will introduce a substantially larger force vector trying to bend the rod where the gusset ends. But is it likely to matter?

I’m presuming you mean the 205 brace?
If so, the latter trucks didn’t have them. That alone tells me a bunch

 

[sweetk30]

@Stephen at ORD told me and i have read others say make sure all the bushings / motor mounts point in the same direction if possible . so the WHOLE combo flexes as a unit and wont bind up .

and the most proken adapters and transmissions are from frame flex and drive line flex and binding against others .

 

[Bent77]

Here's some fun old reading. I remember asking this same question at some point in the dark ages. I replaced the bushing and reinstalled the one on the 72 K5 465/205. THe 77 465/205 did not have one

https://ck5.com/forums/threads/how-many-have-a-transfer-case-brace.139806/page-6

 

[Capt Ron]

I’m presuming you mean the 205 brace?
If so, the latter trucks didn’t have them. That alone tells me a bunch

I'm assuming he means the brace like what is used up to and including 241s. Either way I am hoping to get @Tnsejed opinion on this.

 

[BadDog]

Sorry, my bad, I was rushing to get it posted before company arrived. Yes, it's a 241 brace.

 

[obijuank5]

You're talking about this one from the case to the bellhousing right? This is on my 91 4l80e 205.
I think it's there to help take the front to back load off the case like from the driveshaft compressing and extending. There is still a measurable load placed on the case by the shaft and as time goes on, it only gets worse from poor maintenance by the owner. Three trucks now I've bought have had shafts so bad that they wouldnt compress enough to remove them. I had to flex it out to get the shaft out of the front yoke. I'm sure that would eventually fatigue the case.

That's my thought.

 

[BadDog]

Yes, basically the same thing on 241. That pic shows one with an offset like I want to introduce to mine. Though rather than a bend, I want to cut it at that same spot (a few inches in front of the tcase mount), and offset it about twice that much toward the transmission with a few inches of gussets each side.

Right now I have a 3" turbo down pipe trying to fit between the upper shackle bolt head and that brace. That leaves maybe 3/8" on each side (to be generous) as it stands. I think it will work as long as everything is still pristine and new (mainly talking motor/trans mounts), but any thing off perfect and it's going to hit/vibrate. I've decided I need to tweak it anyway by reclocking one joint to get more clearance from the bottom of my AC box, and would like to get a minimum of 1/2-1" clearance on the pipe going back. I'm also already thinking of moving that upper shackle hanger forward a bit, but because of the relationship/angle, that's only going to give me an extra 1/2" or so total (plus larger bushing/bolt and better shackle angle with lift spring dynamics).

I could also add a sort of helix corkscrew to that (now) straight section of pipe, so that's not off the table either.

 

[BadDog]

Everyone loves pics, here's what I'm dealing with.

 

[rampage]

Here’s my take. It does very little to support the weight being on the side. It also doesn’t do anything for torsional rotation. The bar can flex somewhat during compression. My best guess is that it’s related to the front driveshaft since it’s on that side. Maybe during testing the engineers saw the t-case moving rearward slightly under load in 4WD (putting that rod under tension) and this was their quick and cheap fix.

 

[BadDog]

Exactly my thoughts as well. Question is, can it still do the necessary job if I create an offset?

 

[rampage]

I don’t see why not. What I’d do is cut the bracket where it meets the t-case and move it in as much as you need. Then make a bracket that has two 90s in it that are well gusseted at each bend.

 

[K85 Octane]

Can you bend it at the flat section where it bolts to the T-case? Then move the bell housing mount up one bolt if that moves it away from the exhaust. If it doesn’t reach, but looks to be out of the way, I would sleeve the rod to make it longer.

This way the rod stays straight. Even if this won’t work, any rod, bent or straight, is better than nothing. (Especially on an aluminum T-case)

 

[BadDog]

Again, my thoughts exactly. In my mind the offset be just forward enough to clear the tcase and would gusset basically rigidly to the tcase mount side, then have a tapered parabolic gusset to the front over 6" or so.

 

[K85 Octane]

Also, did anyone notice the jangkie T-case drop before seeing the support rod? Lol

That’s your next project ASAP.

 

[BadDog]

I had to go look before responding to going higher. But as I suspected, it doesn't really offer an improvement in horizontal clearance, plus it would hit the floor unless curved substantially. If it's got to bend, I prefer to offset to the driver's side to gain a lot more clearance. I'm just not sure if doing so will still provide the added stability needed by that aluminum case (poor boy doubler 700/241) stack.

I should also add that I'm pretty much done with rock crawling. This is more an expedition rig, what they now call "overland", but with a bit more capacity for really bad roads than the typical overlanding crowd.

 

[BadDog]

Also, did anyone notice the jangkie T-case drop before seeing the support rod? Lol

That’s your next project ASAP.

LOL! Yes, you are correct. I wanted to button it up on the frame rail, but the drive shaft clearance is pretty close. The current "janky ass" drop is for testing, assuming I ever get it together enough to try out anything. That's not the only thing so far in "unfinished form". You can include the craptastic shackles (including angle as with all bolt on lifts), the horrible upper bushings, and on and on...

 

[BadDog]

Oh, and dropping it down (expeditiously) also provided for the pipe to fit at all as it is. Without that space, there would be no space without putting the pipe nearly on the floor boards.

 

[Tnsejed]

@Capt Ron There's a great thread on here from a long time ago about this. I do think a broken case was involved but I think it was not enough plunge that it ended up being. This must have been a decade ago or more. If I remember the discussion correctly.

There are trucks with it and without it. Definitely a driveshaft plunge type of brace but I always wondered about the reasoning why some have it and some don't. All Transfer case mounting rules apply, You want to keep the bushings relatively inline with the center shaft, and let the motor mounts do the torque resistance. Or you put to much force on the case and transmission trying to resist the forces. This thing doesn't apply here. I ran my truck without it for years.

I always wondered to if it was some sort of accident protection deal as well. Or abuse prevention method to keep the case intact.

For whats it worth though the bolts break off at the bellhousing. Like what @obijuank5 said, the shafts that don't get greased get bound up pretty good.

 

[K85 Octane]

No worries about the drop, it’s just the spacers are no good. But temporarily for “testing purposes only” is ok

My T-case is clocked and the rod is up one bolt hole. I also have a 1/4” thick plate bolted to the T-case, then the rod is bolted 2” higher up on the new 1/4” plate. That was all because the clocking. I run a single exhaust though.