NP205 Brace

[marsk5]

I tried searching all over the web but couldnt find the right answer, I have a 86 k5 that I swap a sm465/205 and I was wondering do you really need a brace for the tcase??? Ill mostly be using it for mud and street since there is not alot of rocks here in the Midwest.

 

[JDNobodi]

My old 73 had the brace, but my brothers old 77 did not. In fact his transfer-case didn't have the holes on the side of the case drilled and tapped. I'ved seen pictures on the Internet of broken adapters, so having the brace wouldn't be a bad idea.

 

[diesel4me]

The 80's trucks had a truss rod from the t-case to a bellhousing stud I'm pretty sure,at least I know the automatics did..some years in the 70's with a Sm465 had none,and the t-case wasn't even drilled or tapped--but GM decided "none" was not a good idea,after some breakage occoured--the truss rod is better than nothing...

I always wondered why GM never used the a transmission tailshaft mount that is just sitting there unused ,instead of having a brace to the frame or the truss rod...

 

[Fordum]

My '89 F250 came with a Borg Warner 1356, aluminum T-case. I needed the PTO, so I swapped in a 205.
Since that truck came standard with that a couple of years before, I grabbed a brace from the junkyard.
Then, discovered that along with going with the lighter weigh case, Ford also re-purposed the brace mounting holes in the frame.
That was where they mounted the high pressure pump for the fuel injection.

Since I kinda figured I was going to need that, I left the brace off. I noticed a lot of shifter movement when I was hitting bumps.
Then, I mounted a small cast iron PTO gearbox, and a huge hydraulic pump to the side of the already heavy 205 case.

I found myself cringing whenever I hit a hard bump. Finally, I got some 1/2 inch steel, some grade 8 bolts and some rubber bushings, and fabbed a brace which hooked to a different part of the frame.

That eliminated a large amount of shifter movement. Also, while I was working, I noticed that I could take up some slack on the bolts holding the aluminum adapter on.
It looked like the washers had gotten pressed into the housing a little..

So, if you have the places to mount one, and can find one, its probably better safe than sorry.

Those cast iron monsters are heavy!

 

[marsk5]

That was my fear about the adapter cracking from the tcase brace not letting it torque with the trans.

 

[Hogback Fabrication]

The early trucks had a brace from the t-case to the frame, they got rid of it in the mid 70's. I think it over-constrains the system and it's part of the reason you see so many cracked adapters.

The strut rod that runs from the t-case to the bellhousing is a good idea all around, however.

 

[Fordum]

Well, if it ever quits raining I may slide under and take a pic of the one I built. If the T-case is braced to the transmission housing, I would think there should be no problem, since you do not want any movement between the two.

Mine, however was braced to the frame. I thought about the fact that both the engine and transmission were flex mounted, so I did the same with my build.

I bolted a flat plate to the frame, which extended over to just before the side of of the case.
Bolted another plate to the side of the case, sticking down at right angles to the first.
Then, I put a floor jack under the case, and jacked it up until I figured I had about the weight of the case on the jack.
Laid a couple of thick rubber bushings on the plate from the frame, laid another plate on top of them and slid the end over until it touched the plate on the case.

Put a clamp on the plates and compressed the bushings slightly. Then I tacked the end of the top plate to the side plate on the case with a welder.
Removed the clamp, and unbolted the now two pieces from the case. Finished welding them into one "L" shaped piece.

Removed all the pieces, laid the two parallel flat plates, the one from the frame, and the bottom of the L from the side piece together, one on top of the other.
Clamped and drilled two holes. Then drilled the holes in the side piece a little larger.
Bolted the two pieces back on. Placed the two bushings between the two parallel plates, placed two more bushings on top with thick washers, and put two bolts down through the sandwich.

Tightened with lock nuts until the bushings were clamped. Now, the piece bolted to the case is clamped between bushings top and bottom, and can even move from side to side slightly due to the larger holes.

Now all the weight of the case is supported by that piece of 1/2 inch plate steel bolted to the frame, but the case can torque both ways by compressing the rubber bushings, or can slide from side to side by sliding between the rubber.

25 years and over 300K of darn hard miles with no cracks yet. When I replaced the engine a few years back, and put on new motor mounts and transmission mounts, I replaced the bushings also.

 

[Fordum]

Chris, you posted while I was writing mine......

The bracket that came with my old Ford, and that I tried to put on my new one, was like a version of a transmission mount.
It bolted to the frame, and had rubber bushings to let the case flex.
Were the GM ones solid? Sounds like it.

 

[diesel4me]

The frame brace for the NP-205 in my '72 K5 and 77 GMC I put one in from a '72, had rubber biscuits between the frame and the brace,only about 3/4" thick and maybe 1-1/4" in diameter...

I think since frames flex a lot on GM trucks you'd want some "give" ,otherwise the adapter or tranny tail would be much more likely to crack when the frame flexes going over off road obstacles..you wont want the brace bolted solid,when the rest of the drive train is rubber mounted ..

 

[xenomarine]

Now that I have a working welder, I'm planning on building a support that ties the brace holes in the transfer case and the tcase adapter holes together. I think that would be a better way. Either that or a skid plate with poly bushings mounting to both the brace holes and adapter feet. I'll need to play around with it, though.

 

[diesel4me]

Stock one looks like this...

 

[marsk5]

So you think it would be a good idea to get a brace for the tcase????? What do you guys think about the diy4x brace???