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Tubed front end

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  • Tubed front end

    So I've had my s13 for about a decade. I bought it when I was a dorifto teen and have been in a wreck or two with it. I have since grown up a bit (a small bit) and have built the car purely around the driving quality leaving cosmetics to wait. Chassis wise my car is solid. Core support...well thats another story. It is currently tweaked in 5 different directions.

    Since finding a new s13 core support is next to impossible and every junk yard one is worse off than my own, I feel as if the best solution to make my body panels and headlights point in the same direction is to tube the core support. I would try to engineer it to be no stronger than the factory support so as to not cause chassis damage in the event of another mishap. What do SCCA rules and most HPDE events have to say about slightly tubed fronts if anything at all?

    Last edited by mischief; 08-09-2016, 05:36 AM.
    - '93 S13 (the long awaited fun machine)
    - '05 E46 (the S13 fund evaporator)

  • #2
    Racing classes might have an issue with it by "not being allowed explicitly," but no issues with HPDEs around here.

    I almost did this on mine to get some more space up front, but I made mine removeable via 2x M6 bolts. It's not like it needs to do much more than hold the top of the radiator in place. Some of the upper core supports I've seen made with 1.75" OD x 1/8" WT tubing is ridiculous for what it's doing.

    I'd personally terminate the stock stuff into a 1/8" thick plate just in front of the strut towers up top, and at the end of the frame rails (just past tension rod bracket upper bolts) on the bottom, with a few welded nuts and maybe a dowel pin, then build off that.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!

    DefSport Koni Sleeve and Spring Perch Buy!!!


    • #3
      It would be illegal for pretty much anything in SCCA club racing below GT3. And there's all kinds of other safety and engine prep items that would keep you out of GT3.
      For auto X, it's going to put you in Mod class I would think.

      Safety-wise, they'll let you into a PDX or something. you just can't race the thing because the modifications are illegal for just about every class other than the ones that allow tube frames.
      Originally posted by SoSideways
      I don't care what color they are as long as they are LONG AND HARD.
      '04 G35 Sedan 6MT- The DD
      '96 240SX- The Track Toy


      • #4
        For NASA classing, you can do it in the ST/TTU-3 classes I think, but you end up taking the modification factor of a tube frame car when calculating your power to weight ratio.

        Personally I want to tie my strut towers to my A pillar bars on the cage to eliminate my biggest source of chassis flex, but I don't like stripping the car down far enough to do it.
        '95 240sx