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The pic's you posted are very nice and it confirms what I said. The back connection is only about 1 1/4 tall. The rest of the factory frame is above it and not connected to anything. If you are going to take the time to add the connector you mite as well go the full height and add some real support so the car won't twist. Height is strength when it come's to frame's

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, but nobody's listening.

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Fabbing from 1/4" steel box is rediculous! and I wont be cutting through the floors!

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2x2 .083-ish will work just fine if you dont't want to cut the floor. It will go up against the floor from about the seat area back to the rail end.

I don't get paying these outfits hundreds of dollars for 10-20 bucks worth of tubing.

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I don't get paying these outfits hundreds of dollars for 10-20 bucks worth of tubing.

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'69 RR, boxed subframe connectors, welded in correctly....

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I think that the difference between the "fit to floor" and full square tube is so small in the big picture, that it really makes no difference. Sounds good on paper to argue about but the diff is so small it really doesnt matter.

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Exactly. Also it seems like 90% of the time when this subject comes up the guy fretting about ultimate design and strength of subframe connectors has a street car driver that likely 60 foots in the 2 second range.

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Boy this topic has been beat to death on this board...do a search and you'll hear the same argument over and over again....:)

This is the way I look at it..... yes the square tube has some more strength, since compared to the "fit to floor" ones, one wall will be thicker. Thats about it.

Take alook at the rest of your frame.....its a U-channel spot welded to the floor....take a look at your rear crossmember...its a U-channel tying the two frames together....take a look at your trans crossmember...its s U-channel too.....

My point is that having a big beefy square tube in the middle doesnt change that much. The rest of the frame still has lots of places to flex. Having one section of square tube in an otherwise "U-channel ladder frame" isnt a huge improvement.

Take some 2x4 and make a big rectangle....put jack stands under 3 corners and then put a weigh on the unsupported corner... the frame will twist and that corner will drop ALOT. The bottom line is that SFC dont add much torsional stiffness... they add alot to front to rear sag and bend....but not torsional.

If you want torsional stiffness you need to add alot of triangulation too....like torque boxes and other braces, that triangulate the "corners" of the "box" that the frame makes up.

Dont get me wrong....SFC are well worth it... and they do help quite a bit in a uni-body car.....but dont fool yourself into thinking they make the car super rigid. If you dont believe me, take a look at a real "frame design" book by race car builders etc etc. My Herb Adams book has great pix of just how much torsional stiffness is added (or not added) by common types of frame designs and "reinforcements".

I think that the difference between the "fit to floor" and full square tube is so small in the big picture, that it really makes no difference. Sounds good on paper to argue about but the diff is so small it really doesnt matter. Its one of those topics where it seems intuitive....full box is stronger....but put it into context of the whole car and its really doesnt translate..... do the math...look at the physics of the whole car.....

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Well this will be for the second time I will ask for/suggest one of these horse beaten subframe connector posts be at least archived, silly me, that will never happen.

Besides, OP, just switch over to other unlawful sub frame conncetor post that has declared that the new connector of the month is better then sliced bread.

Monkey see, Monkey do