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Going Postal
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Discussion Starter · #1 ·
I've cracked two auto tranny's now in four years. Not too bad considering the situation but I think it can be addressed better then just getting the mounts into sync.

Anyway, the break occurs at the tail on the top right next to where the transfer case adapter attaches. Also on the top is a boss with a hole in it. I was thinking of making a brace that attaches to the two top bolts and across to this boss on the tranny and giving the tailshaft area some more grunt.

Anybody see anything like this?

I'll post up some pics in a bit.....



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Sandman said:
I've cracked two auto tranny's now in four years. Not too bad considering the situation but I think it can be addressed better then just getting the mounts into sync.

Anyway, the break occurs at the tail on the top right next to where the transfer case adapter attaches. Also on the top is a boss with a hole in it. I was thinking of making a brace that attaches to the two top bolts and across to this boss on the tranny and giving the tailshaft area some more grunt.

Anybody see anything like this?

I'll post up some pics in a bit.....
The more attachment points the better at distributing the load. I had a detailed discussion with the folks on Pirate about this a while ago and I am still running the hard mount at the tranny and the bushings at the frame. Hope that I dont bust the tranny though.


http://www.pirate4x4.com/forum/showthread.php?t=404437
 

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Wrench Wench
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The early 205's used a side mount to the frame in addition to the trans mount. Without it, I break housings, with it, I don't. But I have found that transmissions that can't withstand the rotational torque loads break the bell housings, not usually the rear of the case.

In my experience rebuilding GM trans, when the rear of the case brakes, it seems to be caused from front to back movement of the trans, specifically the leverage the front driveshaft places on it. All the aluminum cases and 203's came with a strut rod that went from the side of the trans up to the bell housing bolts. This is a crucial part and yet is often thrown away.:shame:

If I were you, I would first put a strut rod from the two bolts at the side of the tcase and up to two bolts on the bell housing. Make 2 3/16" plates to bolt on, then use 5/8" rod welded on the connect them. Then if you decide that later you need a side mount, you can fab one. Just be careful and realize the the tcase still needs to move around back there a little with frame flex and such, so stiff mounts and urethane shouldn't be used for the side mount. I can take a pic of my factory one if you would like.



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semi-pro hack
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This failure is also common when you mix rubber mounts with poly mounts
I broke a case in my truck I believe because I had rubber motor mounts and poly tranny mounts. I have beat my current rig harder than my truck and no prolblems yet since I went to poly on both.
 

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Going Postal
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Discussion Starter · #5 ·
Thanks for the reply's! :thumb:

I had rubber mounts all around and I do have the older style factory bracket that goes from the side of the 205 over to the frame. Before I installed that, I used to kill transfercase adapters all the time.

I think this last go around was the failure of the motor mounts as the transfercase is held down pretty tight. I cannot use the rod that Chris reffered to as the exhaust is in the way. I now have poly mounts in the front with stock rubber mounts on the adapter with the bracket from the side of the transfercase to the frame. I think this should be better then the last setup (which did last about 4 years) but I'm looking for some better insurance.

So in comes the idea of a support over the top. After looking at it again, I dont think it would be too bad to build something that uses the three top bosses on the transmission, goes back and bolts to the rear of the tailhousing and then continues to the transfer case. In a way, tying the whole thing together in several points.

Here is a pic of my idea. The blue would be along the lines of a brace and the red is where some of the crack is..



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Wrench Wench
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One more thing to consider doing. If the engine and tranny are "free" to twist due to the engine mounts flexing during high torque loads and the transfercase is basically held in place by a bracket running under the adapter and the side mount to the 205 then there is a lot of stress built up just where you marked it. I would suggest using a "motor plate". These usually mount to the front of the engine between the block and the water pump and then to the frame. There are also rear plates available. Summit sells these as does Jegs for around $90 to $100.

Or...if money is an issue or you have space restrictions (like I do in the Dawg) then you can build a bracket that attaches to one of the spare hole on the front of the block and tie it to the frame for a solid mount. I have seen high torque engines without some sort of torque twist limiter actually tear off the motor mount on the driver side during a race...not pretty.
 

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Here is a picture of the two piece design of the motor plates. They also make a one piece. This one is built by Competition Engineering.



 

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This is a picture of a mid-mount plate that I believe goes between the block and the bell housing.
 

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Going Postal
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Discussion Starter · #11 · (Edited)
Well, here is what I ended up doing in the end. It lasted about 4 years before this happened so this cant hurt any I think. I need to paint it so its looks pretty. I'm thinking Blue. :smokin:

What I did was cut a length of 2" angle and then bent in the ends as the back of the adapter is not very flat. Then I bolted in a piece to the top of the tranny using a bolt that fit tight in the hole. I had to grind down a nut so it would fit under it. Tightened all the bolts up and then welded it. I was think about preloading it before I welded it but decided not to.



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