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DIY4X 205 T Case Mounting Kit

Where did the case break?

Also, how is everything mounted?
 
I always kind of thought that mounting the Tcase TOO solid would cause trans breakage... Because motor mounts flex enough, and there's only the 2. But then you get back to the Tcase and it's all mounted up sort of solid, the trans case is taking all the twist.

:dunno:

Just the way it seems in my mind
 
It broke at the tail piece.(Apparently a weak spot on the TH400 case) I have it braced in the OEM spots on the adapter between the Trans & TC and on the side to the frame. My trans guy had a nice talk to the guys at Reid Racing who make a aluminum billet case for 4x4 race trucks because I was going to use one and they said that even theirs could break the same if I did not add another brace. Their Case alone is $1700 so Ya I really don't want to chance it
 
Hmmm :thinking:....sounds like a case, about a broken case?!? :yikes::confused:! Lol! I think we need Dick Tracy on the case!!! Lol! Good ol’ Cock Tracy as his criminal foes know him as, will Pound the ASSphalt looking for clues, as to WHY the cases have become a problem creating the case we have here. Which is unknown in this case still! OMG! What a F’ing Hell of a case! But Dick Will Get this case, in the End! The case that is! Get you mind out of the freakin gutter ya sicko! Lol! :haha::haha::D. I never said it was going to be a good joke lol!
 
Since you're always doing the high speed, jumping stuff I'm guess there's little chance of the front driveshaft length being wrong and bottoming out?

What about going with a rear mount on the 205 that supports weight but does not control rotational movement? NWF and (cringe) Behemoth Drivetrain offer them.

http://www.northwestfab.com/Transfer-Case-Supports_c_913.html
 
Check out the TMR NP205 mount as well, it supports the rear output keeping the mounts inline with each other.
 
if i recall @Stephen told me and i have read it before its best to have all your engine / trans / t-case mounts all in line . so if they flex its all in the same direction . if you do engine front/back bolts then trans/tcase sideways or 90* off of the engine it will bind up a lot more and not flex as a unit as much . so keep this in mind and maybe ask stephen or others if my thinking is correct .
 
If it's the factory side mount to the 205, that's why it broke. Lots of debate on the subject of that mount but there is a reason gm stopped using it on later 205's in the squarebody trucks. Hell my 75 didn't have the side mount used, but the holes on the side of the 205 were drilled and tapped.

Just think about this way. As the engine twists from torque that side of the t-case is going to rotate up. Stopping the t-case from rotaing puts the aluminum trans housing into a tug-o-war with the engine. The engine rotates under load, t-case won't with that mount and eventually the housing cracks on the transmission.
 
ZooMad75 said:
If it's the factory side mount to the 205, that's why it broke. Lots of debate on the subject of that mount but there is a reason gm stopped using it on later 205's in the squarebody trucks. Hell my 75 didn't have the side mount used, but the holes on the side of the 205 were drilled and tapped.

Just think about this way. As the engine twists from torque that side of the t-case is going to rotate up. Stopping the t-case from rotaing puts the aluminum trans housing into a tug-o-war with the engine. The engine rotates under load, t-case won't with that mount and eventually the housing cracks on the transmission.
Click to expand...

Don't forget to add some frame twist into that equation.
 
side brace to frame more times than not break the trans tail .

th400 = weak rear tail design to begin with . gm should have gave them more meat back there .

yes our old frames FLEX a lot compared to what people think .
 
ZooMad75 said:
If it's the factory side mount to the 205, that's why it broke. Lots of debate on the subject of that mount but there is a reason gm stopped using it on later 205's in the squarebody trucks. Hell my 75 didn't have the side mount used, but the holes on the side of the 205 were drilled and tapped.

Just think about this way. As the engine twists from torque that side of the t-case is going to rotate up. Stopping the t-case from rotaing puts the aluminum trans housing into a tug-o-war with the engine. The engine rotates under load, t-case won't with that mount and eventually the housing cracks on the transmission.
Click to expand...

So on your 75 did it have a center mount or just the factory one at the adapter?
 
sponsoredbydad said:
So on your 75 did it have a center mount or just the factory one at the adapter?
Click to expand...
Just the center mount. Nothing on the side. Mine was an original 465/205 truck. There were no mounts unused on the frame either.

By only having the center mount only the t-case can rotate with the drivetrain rather than stopping it.
 
Yeah, this topic has come up many times over the years around the forum world. In our Workhorse days, Rob and I used to work with a retired GM truck engineer who knew this topic well. Right from the horses mouth, he said GM engineering removed the side mount from production about the time the new truck came out in 1973 because it was known to break automatic transmission tail shafts and 465 trans to t-case adapters due to torsional stress. Many of the 70’s 205’s didn’t even have holes tapped in the side boss.

If you think about it, it makes total sense as your engine naturally wants to twist and by tying down the transfercase to the frame something in between will eventually break. Sure, there are still plenty of 69-72 4x4’s running around with them that haven’t ever broke anything when they are driven nicely but once they are used hard the chances of breakage drastically increases and even more so with worn/broken engine mounts with a heavy foot/quick clutch foot. To make it worse, GM truck engine mounts prior to 1973 were terrible and split in two quite easily which allowed the engine to lift up and twist with a kaboom of the trans adapter or tailshaft and if you're really unlucky the throttle can stick wide open. GM even had a recall back in the day on vehicles with those old crappy mounts equipped with a throttle rod (instead of cable, basically prior to 1971) to add a tie down cable from the drivers side exhaust manifold to the frame in order to hold the engine down when the engine mount failed to prevent the throttle rod from getting stuck holding the throttle wide open.

Back to a tranfercase mount, adding a transfercase mount that moves at the same frequency as the engine and trans is fine, which is why they later went from a tcase to bellhousing strut.

A 78 K20 without any holes in the side mount boss
5319826357_cb9d597bf8_b.jpg
 
Ok so I guess I'll remove my side mount on my 70 before it tares the th350 puney bolts out, even though the frames are said to be stiffer than later square bodies... More n more I wish I just built a full tube frame k5 n put the 70 tub on it... :popcorn:
 
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