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Discussion Starter #1
What is the consensus on strengthening the hollow inner floor frame support? Installing new frame rail and floor frame support. I’m thinking of welding in either square tube or angle stock to make those supports more rigid.
 

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Not sure what inner frame support you're referring to, but most add subframe connectors and some, me included, have added convertible inner rockers to stiffen up these cars.
 

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Discussion Starter #3
Not sure what inner frame support you're referring to, but most add subframe connectors and some, me included, have added convertible inner rockers to stiffen up these cars.
Not sure what inner frame support you're referring to, but most add subframe connectors and some, me included, have added convertible inner rockers to stiffen up these cars.
This inner floor frame support that the frame rail sits in.
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Never seen anyone try to add support to that area, but there are subframe connectors that slide into the end of the floor support, but only about 4-6" or so. Add some convertible inner rockers while you're in that deep, also add the torque boxes if yours is earlier than a 68.
 
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Discussion Starter #5 (Edited)
Never seen anyone try to add support to that area, but there are subframe connectors that slide into the end of the floor support, but only about 4-6" or so. Add some convertible inner rockers while you're in that deep, also add the torque boxes if yours is earlier than a 68.
Definitely going with new torque boxes. If I go with convertible inner rockers, would that require the more narrow convertible floor pan? And if I have to custom fit the floor pan for convertible width, that sounds like a real PIA.
 

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What is the consensus on strengthening the hollow inner floor frame support? Installing new frame rail and floor frame support. I’m thinking of welding in either square tube or angle stock to make those supports more rigid.
I have a 67 vert & as someone else posted it you want it stiff look at adding vert inner rockers & torque boxes . I also have a 66 coupe I have not fooled with in about 25 years & I remember the coupe was no where as rigid as my vert.
If you use the vert inner rockers you'll have to use carpet for a vert I'm pretty sure .
 

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There is a convertible style seat support for coupe/FB if you choose to not install the inner rockers. I am adding that to the 67 coupe, but not the conv inners. The one piece riser ties the sides together nicely and adds a large amount of rigidity.
 
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After seeing the inner rockers in my 67 vert ( they looked like they might be 16 ga )when I replaced the carpet & how they were welded in, they look like they would be better than subframe connectors to me.
 

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No real advantage to doing so as it's adequate for its purpose, which is supporting the front floor. Front end loads are transmitted to the cowl then outward to the rockers and up the windshield pillars to the roof. Extending the floor supports to the rear using "subframe connectors" will lend some rigidity to the floor making the area under the seat feel stiffer. If you want to add TORSIONAL rigidity the answer is front torque boxes, convertible inner rockers and convertible seat riser.
 

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The best sub-frame connectors I've seen are a design on the Daze Cars web site. Fellow VMF member buckeyedemon fabricated something similar for his '69 Mach 1 and they are amazing. I wish I had welded those into my car when I was building it.

 

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Discussion Starter #13
The best sub-frame connectors I've seen are a design on the Daze Cars web site. Fellow VMF member buckeyedemon fabricated something similar for his '69 Mach 1 and they are amazing. I wish I had welded those into my car when I was building it.

The entire Dazecars website is great.
 

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Discussion Starter #14
Going to research vert rockers and the one piece seat risers. At the least, putting in torque boxes. Thank you all for your input.
 

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No real advantage to doing so as it's adequate for its purpose, which is supporting the front floor. Front end loads are transmitted to the cowl then outward to the rockers and up the windshield pillars to the roof. Extending the floor supports to the rear using "subframe connectors" will lend some rigidity to the floor making the area under the seat feel stiffer. If you want to add TORSIONAL rigidity the answer is front torque boxes, convertible inner rockers and convertible seat riser.
Thought so . I guess if you have a high hp low torque motor it don't matter . Haveing fooled with a lot of old school cars as a teenager my buddies & I figured out power is ok but that torque is what breaks stuff.
 

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The best sub-frame connectors I've seen are a design on the Daze Cars web site. Fellow VMF member buckeyedemon fabricated something similar for his '69 Mach 1 and they are amazing. I wish I had welded those into my car when I was building it.

I went by his measurments & made a set of sub frame connectors for my 69 Coupe.
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