frame connectors

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Jim Irving

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looking for the guy that makes the frame connectors for A body cars. I have a 72 duster I want to put some on.
 
Or do a search and build your own and save some cash.

X2. I referenced a few posts here at FABO and managed to fabricate a set for $36. Bought some 1.5"×3" tubing. Used a circular saw w metal cutting blade, a lot a measuring, trimming and test fitting. But mangaged to get them fabbed and welded in on an afternoon. Note: I have minimal experience fabbing metal pieces.

Pat
 
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Years ago i used 2, 1" o.d. steel pipes welded to 2, 1/4" plates and bolted thru torsion frame and to back leaf mounts. For both sides.
cost about $50. Been on car for 25 years now. Food for thought.

Dave
 
I just bought material to make mine, 2x3 steel tubing...slips right over rear frame rails.
$30
 
Yup, did the same with the 2X3s, but I got mine by the pound out of the scrap barrel. I think it was $18. slip fit over rear channels with a few holes for plug welds as well as perimeter bead (My welder is suspect for adequate penetration heat) and a butt weld to flange and another bead around that at the torsion bar cross member. Jack car up on level jackstands and make sure the door shuts properly before doing the final weld on the slip fit rear because if you weld it up with the unibody sagging, youll have door alignment issues.
 
Don't hold you breathe.

Oh I know, it's not gonna happen and that was my point. And I really don't want to start the tubular vs. weld-to-floor subframe connector pissing match again either, it's been beaten to death over and over again. Truly, until someone builds at least 3 or 4 A-bodies that are identical in every way except for the type of subframe connectors and donates them for destructive testing and analysis the question won't get even get a good preliminary answer. Because really you'd need dozens of cars and multiple tests to come up with a definitive answer (just like the safety testing done on modern cars now). Even a full 3D solid modeling analysis would only be a start, you could always argue about how all the different welds were modeled, what assumptions were made etc.

And since none of that will ever happen, we'll continue to see people make assertions on which type is better without having any facts or evidence on which to base their assumptions. There are too many variables in play to guess at which is "best" or "strongest". And given the complexity of the problem it would probably come down to application anyway, because which type is "better" would likely go back and forth between different tests. One kind might do better for torsional rigidity, the other might do better in pure bending, all of it would depend on where the loads were placed etc. Heck it might even be different by bodystyle, 111" wb vs 108". And at some point you would find that it doesn't matter how stiff the subframe connectors are because the bending would just happen somewhere else instead, there's a limit. At some point the chassis would stop improving even as the strength of the subframe connector was increased, because a subframe connector can only do so much.

So, install whatever type of subframe connector you can. The contoured, weld-to-floor kind are much easier to install on a car that's already been fully stripped, blasted etc, and put on a rotisserie. If the entire car isn't being blown apart and taken to bare metal the tubular kind are much easier, and even someone with fairly limited fabrication skills can make them at home if costs are an issue. Both kinds make a noticeable difference in the kind of anecdotal things we can "test" ourselves, things like how much the body gaps change when jacking the car, the sound the doors make when they're closed, how many squeaks and rattles the car makes on the road, and on the higher horsepower cars whether or not cracks start to develop (or re-develop) in the paint at the quarter seams and other problem areas where flexing occurs. Those are all legitimate ways to tell something changed, but none of them are a good way to compare one kind of subframe connector to another, the difference is too small between the different kinds and the results are too subjective.
 
Oh I know, it's not gonna happen and that was my point. And I really don't want to start the tubular vs. weld-to-floor subframe connector pissing match again either, it's been beaten to death over and over again. Truly, until someone builds at least 3 or 4 A-bodies that are identical in every way except for the type of subframe connectors and donates them for destructive testing and analysis the question won't get even get a good preliminary answer. Because really you'd need dozens of cars and multiple tests to come up with a definitive answer (just like the safety testing done on modern cars now). Even a full 3D solid modeling analysis would only be a start, you could always argue about how all the different welds were modeled, what assumptions were made etc.

And since none of that will ever happen, we'll continue to see people make assertions on which type is better without having any facts or evidence on which to base their assumptions. There are too many variables in play to guess at which is "best" or "strongest". And given the complexity of the problem it would probably come down to application anyway, because which type is "better" would likely go back and forth between different tests. One kind might do better for torsional rigidity, the other might do better in pure bending, all of it would depend on where the loads were placed etc. Heck it might even be different by bodystyle, 111" wb vs 108". And at some point you would find that it doesn't matter how stiff the subframe connectors are because the bending would just happen somewhere else instead, there's a limit. At some point the chassis would stop improving even as the strength of the subframe connector was increased, because a subframe connector can only do so much.

So, install whatever type of subframe connector you can. The contoured, weld-to-floor kind are much easier to install on a car that's already been fully stripped, blasted etc, and put on a rotisserie. If the entire car isn't being blown apart and taken to bare metal the tubular kind are much easier, and even someone with fairly limited fabrication skills can make them at home if costs are an issue. Both kinds make a noticeable difference in the kind of anecdotal things we can "test" ourselves, things like how much the body gaps change when jacking the car, the sound the doors make when they're closed, how many squeaks and rattles the car makes on the road, and on the higher horsepower cars whether or not cracks start to develop (or re-develop) in the paint at the quarter seams and other problem areas where flexing occurs. Those are all legitimate ways to tell something changed, but none of them are a good way to compare one kind of subframe connector to another, the difference is too small between the different kinds and the results are too subjective.

No worries blu, we all have different opinions. you guys are like family here on FABO and just like relatives we disagree sometimes but the pasion remains the same. if your budget permits then by all means go with what works for you and can afford. the tube type are strong i just believe attaching them to the floor pan makes more sense. Im flying three NASA scientists and two Boeing engineers in next weekend to do a stress test.
 
That's a shame, that looks like a pretty nice car to destroy. I wouldn't give a Boeing engineer anything that nice to test, they break stuff.

 
Its all personal taste or what the wallet allows. I installed the US Car Tool connectors to because I liked the way they looked. And I'm sure they are just as good as anything out there.
Jeff
 
I like to weld in 2x2 square tubing connectors first and when thats done install the US Car tools on top of the them, that way nobody can tell me I'm wrong.
 
If you have a convertible A body these connectors are a must, especially with a big block installed. BUT, the Convertible A's have torque boxes, the rear boxes make the frame connectors not install the same as a hard top. I guess this would also apply to the Big Block A bodies as they too have the torque boxes. Custom are in order here or US Car Tool...
 
If you have a convertible A body these connectors are a must, especially with a big block installed. BUT, the Convertible A's have torque boxes, the rear boxes make the frame connectors not install the same as a hard top. I guess this would also apply to the Big Block A bodies as they too have the torque boxes. Custom are in order here or US Car Tool...
no way can a 3 sided, (body thickness piece of metal) welded to the underside of the floor, be as strong as a 4 sided-1/8 wall, 2" square tube stuck in side the rear frame-and cut up into the floor area-and welded the full length of the floor cut-and then welded to the trans cross member. think about it.
 
Its all personal taste or what the wallet allows. I installed the US Car Tool connectors to because I liked the way they looked. And I'm sure they are just as good as anything out there.
Jeff

agreed, i have US CAR TOOL on my 66 dart, they fit great, super easy to install. also torque boxes are another good upgrade while you are under there.
 
no way can a 3 sided, (body thickness piece of metal) welded to the underside of the floor, be as strong as a 4 sided-1/8 wall, 2" square tube stuck in side the rear frame-and cut up into the floor area-and welded the full length of the floor cut-and then welded to the trans cross member. think about it.

You're ignoring how much stiffer it makes the floor pan, and how much these unibody cars base their torsional rigidity on the floor pan. Even the torque boxes make a big difference, and what do they do? just reinforce the corners of the "box" between the rockers, frame and floors. Even the frame rails on these cars aren't much thicker than the floor pan. 16 gauge. That's it. The floor is what, 18 gauge? For the weld-to-floor, contoured style connectors you have to look at the entire structure, which is how the uni-body was made to begin with. Plus for a lot of the torsional calculations the cross sectional area is a more important factor than the wall thickness (same idea as a tubular sway bar), and the contoured style connectors have some areas where the cross section is larger than a 2x2" square tube.

Like I said earlier, neither type of subframe connector is clearly better than the other. You'd need a whole lot of high level, scientific testing to prove one way or another which style was "best", and that's never going to happen. Truly, I think the limit with these chassis' is not the type of connector, but how much the chassis as a whole can be improved by adding any kind of connector. There's a point where it doesn't matter what you do for frame connectors, you could weld in railroad track if you wanted, the chassis wouldn't get better (it would just bend somewhere else). And with these unibody's I think the limit for improvement of the chassis is more important than the construction of the frame connectors. Either style of connector will probably get you pretty close to the maximum amount of improvement you can get out of the chassis by adding a frame connector.
 
The three sided units use the floor pan as a sheer plane/plate. They work very well.

Pick your poison here, round, square, weld to pan are all better than the factory set up!
 
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