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Transfer case custom mount

73K5BlazerSS

73K5BlazerSS

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I need to fabricate a transfer case mounting bracket. What should I be looking at as far as support for my transfer case? Obviously I'll support it from below so the weight is taken care of (starting with the stock crossmember). What else should I be planning for? Left, right, up, down movement ? will it want to twist under load?
It's bolted up to a 6L80 so I don't want to break the rear of the trans, there's not much strength at the mounting point.

Are the 2x4s sufficient? I can glue them and paint them black.

20220908_162616.jpg

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That mounting point is what’s stock. Why do you think it’s not enough? It’s what I’m using for my 4l80e//np208 and what my th350//np208 used.
 
TJ1978 said:
203?
Click to expand...

It looks like it but I've never seen a tail cone like that.

As far as the mount goes, it looks like you have a short adapter mount on a tall adapter crossmember. Switching to a short adapter crossmember ('85+) may fix the problem.
 
To be technically correct, just put on an 85-91 and bolt it on. To use your 84 and older crossmember, just build a NOT WOODEN spacer to bring that up a bit. If I remember right, it’s 2.5”.
 
nvrenuf said:
It looks like it but I've never seen a tail cone like that.

As far as the mount goes, it looks like you have a short adapter mount on a tall adapter crossmember. Switching to a short adapter crossmember ('85+) may fix the problem.
Click to expand...
The shifter portion looks like a 203 and the fill screw. But the tail throws me off as well.
 
Yes it's a 203. The TH350 that the truck came with had a bracket right near the trans that held the weight of the transfer case. I had to lose that setup when I put a 6L80 in.

I gotta check out the 85-91 mounts. Or I was going to weld some kind of bracket with a rubber mount for vibration. I just didn't know if it could be flat brace, I have no idea how much a transfer case moves under acceleration.
 
Digging deep in the vault isn’t that just like a 73 only iron housing?
 
I see the rubber or poly transfer case mounts for sale online. So the transfer case just sits on top of those? No bolts or any mechanical connection? I don't know if the tail of the 6L80 can handle that.
 
No. The mount bolts to the adapter housing and then also bolts to the crossmember. In the second picture you posted you can see the holes where the bolts go.

F2DF0AD4-672D-45D8-A174-B0F298A2ABE8.png
 
If I were you, I would use 73-84 trans mounts like your truck came with and then a 2.5” square tube spacer that will bolt to the bottom of the adapter and sit on top of the factory rubber mounts with a bolt through the lower rubber mounts.
 
centexk5 said:
No. The mount bolts to the adapter housing and then also bolts to the crossmember. In the second picture you posted you can see the holes where the bolts go.
Click to expand...
That's the stock GM 6L80 mount for the trans in the 2nd pic. I can add a square tube hollow block in there to make up the difference.

I need to support the case towards the back. I guess I can make a steel hoop that bolts together around the tail housing and bolt it to the rear cross member.
 
73K5BlazerSS said:
I need to support the case towards the back. I guess I can make a steel hoop that bolts together around the tail housing and bolt it to the rear cross member.
Click to expand...
No, you really don’t. But if you choose to, put a single bushing directly under the rear output shaft centerline to act as a pivot mount. Don’t go adding all this mess to the sides and over mounting it. A too firm mounted tcase will definitely break that trans case.
 
73K5BlazerSS said:
That's the stock GM 6L80 mount for the trans in the 2nd pic. I can add a square tube hollow block in there to make up the difference.

I need to support the case towards the back. I guess I can make a steel hoop that bolts together around the tail housing and bolt it to the rear cross member.
Click to expand...
Correct. That’s the mount point. There isn’t a separate one for the transfer case.
 
I don't understand, you want another support just for the Tcase alone?

They never had one as far as I'm aware. The support to the Tcase is on the cross member to adapter from transmission to the Tcase.

I left the crossmember attached when I pulled it

19DADD98-981F-4349-B908-77CF32AEB8F7.jpeg
 
I was concerned with mounting the transfer case which is about 200lbs off the back of the trans. If you could see the casting from the inside it's hollow. It looks beefy in this pic but it's only about as thick as the horizontal webs that run front to back.

Am I overthinking this with an extra mount at the back of the transfer case? Thanks for all your help!

16626820155844546113005744894432.jpg
 
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