Sliding 2X3 rect tubing into rear frame rail.

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Valiant63

Valiant63

Early A-body Valiants
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I'm in the process of putting 2x3 x .125 rectangular steel tubing between the front sub frame and rear sub frame and I'm installing it vertically and sliding it into the rear frame rail. My question is, since it is not a tight fit inside the rear frame rail, are you guys shimming it with Steel stock or something to make it a tight fit before welding it in place? It doesn't seem like it would be that strong of a frame connector if it is only secured solidly on one side. What is the correct way to weld it to make it as rigid as possible? I already have it going back to the spring mounts and I have drilled holes on the inside of the rear frame rail against the frame connector. I just have not welded it in yet. Advise appreciated, please.
 
I put mine into the rails on both ends. what I did is drill the bottom of the rail 3/8 holes( can't remember exactly how many) to do rosette/plug welds. Trimmed the very front lip of the factory rail back so the connecter would sit flush. I peeled a section of the floor up and made a plate the width of the rail. Plug welded it to the frame connecter and welded to both sides of the rail. Plenty strong I can pick up any rail and that whole end raises up.
Disturbed Duster
Post 8 in my build thread first pic shows the rear, not very clear, but enough to get the idea
 
I already have the 2x3 rectangular tube slid vertically inside the frame rail. It's going to get welded on the inside one way or another. Floor is already cut, too.
 
Mine fit tight around the outside of the rear frame rails and the last owner on my previous car already had it done before I bought it, so I've never seen that issue, but I've never seen someone trying to weld them inside the rear rails either. Why did you decide to do it that way when it is so much easier to slide them around the rear rails and then weld?
 
If you're set on doing it that way, you can measure the gap, cut some plate of that thickness and weld it to it prior to sliding it into the rear rail.
 
I did it that way for strength. The frame rails of the car don't lie horizontally they stand vertically. Also, I can weld more floor into the frame rail this way. I saw pictures on here of other guys doing it that way but it never said specifically how it was welded inside the frame rail. It is just such a sloppy fit side to side when standing it up inside the rear frame rail. I don't have any steel plate material to cut and put in there at home. I will just have to use what I can find and weld it to the outside of the frame connector before putting it in and plug welding it in place unless somebody else chimes in of a better way.
 
Brad4406 said:
Mine fit tight around the outside of the rear frame rails and the last owner on my previous car already had it done before I bought it, so I've never seen that issue, but I've never seen someone trying to weld them inside the rear rails either. Why did you decide to do it that way when it is so much easier to slide them around the rear rails and then weld?
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I did mine that way because the complete floor was out and I wanted to stub them in on both ends. In the front I went through the torsion crossmember into the front rails, and did a bunch of extra welding throughout the torque box area and bar mounts being it might get an o/d at some point and the hump would get cut and I could fab a mount easily.
 
I have used flat washers around the holes inside the frame rail to take up slack then welded.
 
Valiant63 said:
I did it that way for strength. The frame rails of the car don't lie horizontally they stand vertically. Also, I can weld more floor into the frame rail this way. I saw pictures on here of other guys doing it that way but it never said specifically how it was welded inside the frame rail. It is just such a sloppy fit side to side when standing it up inside the rear frame rail. I don't have any steel plate material to cut and put in there at home. I will just have to use what I can find and weld it to the outside of the frame connector before putting it in and plug welding it in place unless somebody else chimes in of a better way.
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find a metal supplier near you . You can usually get dropoffs of 1/8 for couple of bucks
 
Well, if you have any of the rectangle tubing left over, and if your gap is .125", you could cut pieces to slip between.
 
If you want to run the 2x3 vertically, I'd cut it to end right at the front of the rear frame rail, then cut another piece to use horizontally and "cup" the outside of the rear frame rail. Then just join the two with with a 3" x 4" piece of 1/8" plate.

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I ended up welding some pieces of leaf spring to the sides of the frame connectors to get them to fit in there tightly. I had a busted leaf spring on one of the cars and it was the right thickness so it worked.
 
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