72 frame twist issue

[72bigred]

396 700r4 swap into my 72. Am I crazy to believe that the transfer case and engine cross member give this frame all its rigidity? Just mocking things up with the members loose and I get over a 1" drop from my right frame rail. I took the engine weight off and the frame perked up, tightened the engine cross member and now only 1/2" drop. Leads me to believe I need to take the weight off the tranny member and tighten her up and then tighten up the engine member before putting any engine or tranny weight on it at all.

Any insight would be great, I have been playing with this mock up for a couple of days, starting to go a lil nuts over thinking things..

[kwmech]

Bolts in the cross members should be upgraded to 7/16 with lock nuts and gr8 flat washers with the big block. Wouldn't hurt to pull the cross member forward to the next bolt hole also with the big block. The front cross member should be tight before installation.

After thinking about this, what kind of shape are the springs in? bushings? front cross member rivets? Spring mount rivets?

[72bigred]

Took your advice on the bolt upgrade, no dice on curing the drop but I see the need. I did move the engine forward 2" and the TC back 1.5.. I used the adapter for the 205 to 700 as I had the tranny rebuilt already.. The rivets are all solid, I went with the ORD 2" springs so they are new.. Everything tight as a tick and I am still getting 1/2-1" drop on my right frame rail up front..

I have read that many drop the side bracket for the TC off the frame and let it float on the cross member without problems.. Maybe the weight of the BB/700/205 is just to much and causing a drop although I do not see how.. Still playing with things..

[72bigred]

So no one has any ideas?

New body bushings, new suspension etc..

Without any weight my frame is perfect up front, when i drop the engine weight on the cross member the right side drops 1"..

Either the right side is dropping or the left side for some reason is not giving under the weight.. Yet it appears based on the drop of the right side of the truck the frame is just unable to handle the weight of the 402..

Measurements tell me that from Position 1 body mount on the right side I begin to drop and the drop totals 1" from that position to the tip of the horn.. from position 1 back everything is exactly the same as the left side. Frame is pristine, no accidents in its lifetime..

I could of course shim the difference, I have shimmed upwards of 1/2" in the past but this seems extreme. Would cause some issue with front bumper mounting.. No issues with the sbc I removed.. This makes me wonder if some kind of frame reinforcement is possible to keep the drop from happening..

[72bigred]

NM got it figured out..

[72gmguy]

What did you find? Just curious.

[SeventyOne]

Originally Posted by 72gmguy

What did you find? Just curious.

same...