'74 Ambassador - rear sagging?

[adamgraves]

so new to AS community and just got a 74 ambassador and am starting to redo it. I noticed some separation where the back bumper meets the body and can see subfloor peeking out. I find i can actually lift the back bumper and push the subfloor up and bumper closer to the body. I've read about this issue a little on the forum but am wondering what the best fix is for this. the subfloor and interior is in good shape so im wondering about a fix from the exterior/bottom? any ideas?

[DanielB]

Center bath or rear bath?
You can't fix it until you know what the problem is.
The rear end will naturally sag if it is not attached to the shell/floor.
It could be that only, or a problem with your chassis, which you will need to remove at least part of the underbelly to take a peek at.

[wasagachris]

It sounds very claerly like rear end seperation. There is no quick fix. To fix it properly you must remove the inner skins or walls to access the bolts holding the shell to the frame and as Daniel said the belly must be dropped to get at the bottom of the bolts and inspect the frame for damage.
Temporary repairs nicknamed "elephant ears" because of the patches to the shell do not work long term. It requires cutting open the shell and bolting the shell to the frame and then patching the holes in the shell but like I said it doesn't work and the shell will seperate again.

[adamgraves]

so sounds like step one is remove the underbelly and see what i can see... thanks guys. any tricks to the underbelly or is it pretty straight forward?

[wasagachris]

Originally Posted by adamgraves

so sounds like step one is remove the underbelly and see what i can see... thanks guys. any tricks to the underbelly or is it pretty straight forward?

It is relatively straight forward to remove the belly pan. The center section is riveted to the frame main rails and to the crossmembers. Drill out the rivets far enough forward from the rear to expose the area you need to work on. Once the pan is free you can roll up that portion of the rear section so you can work under there. You don't need to remove the entire rear section of the center belly pan only to repair the rear end seperation problem.
Next would be to remove the lower beltline trim which goes around the bottom edge of the shell. Start at the center of the rear where the two sides meet. Drill out the pop rivets holding this molding to the shell. Remove the molding, this will expose the rivets holding the banana wraps and the side sections of the belly pan to the shell. Drill out these rivets and remove the banana wraps and the side sections of the belly pan.
I'm afraid you probably won't like what you find under there. The insulation will be water logged and infested with mouse poop. You will also be able to inspect more of the frame crossmembers, outriggers and main frame rails for rusting out. You will also be able to see the condition of the floor. More times than not the floor actually rots out from below due to the insulation trapping water against the bottom of the floor.
Is your unit a rear or center bath?
Once you get into it post some pics and tell us what you find. We then can advise further what need sto be done. Like I said before to fix this properly the interior skins need to be removed to get at the bolts inside the walls.