Front/Rear subframe connectors. Best that DON'T require welding to floorpans? I'm WELDING mine in!!

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  1. biomedtechguy

    biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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    So my best friend brought to my attention that the U.S. Car Tools subframe connectors require welding to the floorpans (which I knew, but wasn't thinking about). Before I began to see my car in the reference of trying to make less "invasive" performance modifications, I was all set to use the U.S. Car Tools frame connectors....
    My Assassin traction bars are shipping next week, and I'm ordering my Calvert split mono leaf springs and sliders as well. So while the car is having the front and rear suspension system replaced, I may as well tie the front and rear frames together.
    What brand of subframe connectors do the best job without having to weld them to the floorpans, and how drastic of a compromise is that vs the U.S. Car Tools pieces and technique?
    Thanks to all of you. I want to make the order by next week, so please let me know what you think!
     
  2. flypaper

    flypaper Well-Known Member

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    weld them..
    bolt in doesn't do the job half as good..
    I wouldn't even bother with bolt in
     
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    • Aarons Air

      Aarons Air Well-Known Member

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      I bought Hotchkis leaf springs. Their sub frame connectors are next on my list. They are made of 2x2 steel. They weld in on front and back, but not to the floor boards
       
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      • snakeoil24

        snakeoil24 FBBO Gold Member FBBO Gold Member

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        Do not weld to floor pan. buy your self 2 inch square stock and make yourself. Should not be welded to floor. You also can get from a company ion mass that makes them.. safe t cap is their trade mark
        https://www.autorust.com/safe-t-cap-kits/
         
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        • 70chall440

          70chall440 Well-Known Member

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          I guess I could understand your reluctance to weld them, but then why even bother with SBC's; if you don't weld them to the floor you are getting little benefit from them. The US car tool ones when installed look like the frame extends front to back and looks very good. The ones that weld to the rear and to the front are not offering a lot of support, I suppose you could make some brackets and bolt them to the floor which would be better than not attaching them at all to the floor.
           
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          • biomedtechguy

            biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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            I sent them an email. I didn't see B body subframe connectors.
            Thanks.
            To those who reply, I may wind up with the weld in U.S. Car Tools, but I would rather accomplish enough of an improvement in overall frame rigidity and support without having to weld to the floorpans.
            What about welding the ends of the U.S. Car Tools units, and using a powerful adhesive for the joints along the floorpan? Anyone do or have knowledge of that and was it successful?
            Thanks again!
             
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            • biomedtechguy

              biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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              And that may be fine!
              @vintage chromoly , what say you? being as you are my auxiliary "conscious" where modding my V-code is concerned, and I am being serious, I respect your opinion. (Although I reserve the right to do other than what you suggest)
               
            • vintage chromoly

              vintage chromoly FBBO Gold Member FBBO Gold Member

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              That’s a tough one Bio.
              Fully welded is definitely the best way to go structurally.

              I’d probably just bite the bullet and weld them in along the entire way. They could be removed and the pans reconstructed in the future if someone wanted to remove them.

              The flip side of not welding them in and really having them strengthen the unibody, is that you may do worse damage to the car (twist it, tweak it in some fashion) by trying to minimize the install.

              These are the things you wrestle with when trying to modify a classic and still be a good steward to it.
               
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              • biomedtechguy

                biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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                Thanks VC! Stay with me my new found friend, and I will honor and respect your opinions, even if I may do something that you may not, I appreciate it!
                So I am of the mindset, if it's worth doing, it's worth doing right.
                Looks like U.S. Car Tools may well be the way to go.
                I'm still open to advice!
                :popcorn2::popcorn2::usflag:
                 
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                • bearman

                  bearman FBBO Gold Member FBBO Gold Member

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                  Bio, with the big boy engine going into your ride I would weld them in. Others have done it themselves and some buy the us tool kit. Welded in also makes it look complete. Good luck
                   
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                  • 70chall440

                    70chall440 Well-Known Member

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                    They really do look good when installed correctly (I say correctly because they do require some fitting to get them to sit up against the pan). In fact, I would say that once installed, it looks like it should have been this way from the beginning.
                     
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                    • CoronetDarter

                      CoronetDarter Well-Known Member

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                      Mopar Muscle did an article on that very subject a while back. They used 3M adhesive under the floor pan and welded the ends. Their subject car had a full interior and they didn't want to strip it down to fully weld in the SFC.
                      BTW, I welded US Cartool SFC's in the Coronet. One thing to keep in mind prior to installing: the E-brake cable has to run through the driver's side connector so measure entry and exit point and drill an elongated hole on each side.
                       
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                      • conv67bdere

                        conv67bdere Super Moderator Staff Member FBBO Gold Member

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                        I was not sure which way to go on the frame connectors either, as I was not a very good welder when I started this project . . . but after my research on the topic, I came to the realization that if they are not welded into the car, building a "torque box", then you're sacrificing the strength and gain that they are being installed to address . . .

                        I've got just about every option for frame stiffening in my car, all purchased for US CarTools - they have been amazing to work with and have provided me with outstanding customer support. They also redesigned and re-cut new parts for me because my measurements showed the holes in the parts off by 3/8" . . . they custom made new parts for me to match my measurements.

                        Not only that, really like the end results . . .

                        sm_bedliner09-jpg.jpg
                         
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                        • dvw

                          dvw Well-Known Member

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                          Why do you say not to weld them to the floor pan? That's where it all ties together creating a strong platform. In this case we have a real V code car that's about to go into no mans land. Part racecar, part street car, and a car that is probably worth good money in stock condition. Ah what to do what to do, that is the question.
                          Doug
                           
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                          • theman440

                            theman440 Well-Known Member

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                            The old Mopar Perf ones are great, they are bolt-in but just weld 'em in. That's what I did.
                             
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                            • BIGSHCLUNK

                              BIGSHCLUNK FBBO Gold Member FBBO Gold Member

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                              I also made my own. 1X3 tubbing welded front and back. The reason these dint get welded to the floor is cause I had no way to do it. But I will say the more point's welded the stronger things will be. I will also say what I did definitely helps!
                               
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                              • biomedtechguy

                                biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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                                Well Doug, it's like this...
                                I bought it to enjoy! 70 Roadrunner was one of a few body styles I was looking for, having originally started with 68/69/70 Super Bee, then 70 Roadrunner, possibly 69 Roadrunner...
                                Any of the above would have been fine.
                                My reminiscent mind then took me back to my best friend's 70 Roadrunner, my parents 69 Roadrunner, and for those of you who are familiar with these next 2 cars, the interior is basically identical: the 71 Charger and 70 Coronet Super Bee or R/T.
                                Now once I had the Roadrunner, the whole host of FUN, especially cruising in crowds of people or doing the car show circuit, and how the Roadrunner has the Warner Bros cartoon characters that I've incorporated into my show props, and even at the race track, all of that has BROAD ranging appeal.
                                Back on track: while it is a real V-code Roadrunner, and that "V" in the VIN will ALWAYS ADD VALUE, it is not numbers matching and THAT gives me extra latitude to do what I want since it is basically impossible to make it a high end STOCK V-code because the original engine probably got scattered somewhere. So ULTIMATELY I am going to do what I want to so I can enjoy ALL of the benefits of ownership, mindful that the farther away and deeper into modifying it in ways that "permanently alter" it, the more those changes may have a negative impact on the added value of the "V-code" value that it has. What that means is that there are "resto-mods" that bring more money that unrestored original (________) fill in the blank cars.
                                So what I will do is be mindful of the inherent value of "the V" and not unnecessary molest the aspects that maintain that value, but the MOST IMPORTANT THING is that I ENJOY my car, while being responsible for my stewardship of a valuable V-code,
                                but my enjoyment of it in whatever "form" that requires is ultimately going to determine what I do.
                                I have decided, it's going to be welded in U.S. Car Tools frame connectors.
                                Once again, all of you, THANKS!
                                :thumbsup: :lowdown::lowdown: :luvplace: :thankyou:
                                 
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                                • flypaper

                                  flypaper Well-Known Member

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                                  I have decided, it's going to be welded in U.S. Car Tools frame connectors.

                                  best choice :thumbsup:
                                   
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                                  • conv67bdere

                                    conv67bdere Super Moderator Staff Member FBBO Gold Member

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                                    I like your choice . . . very well done ! ! !

                                    ( And yes . . . I love this place too for great advice on topics related to cars . . . . )
                                     
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                                    • dvw

                                      dvw Well-Known Member

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                                      I've never been afraid to modify anything. To many worry about what happens "IF" they sell. Not what they really want. Build what you want. Don't build by committee.
                                      Doug
                                       
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