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  1. #1
    GrandSportC3
    Guest

    Default Who make a 5-point Roll Bar for a C3 Convertible?

    I'm thinking in swapping my engine this summer/fall and I'll definetely need a Roll Bar (5-point) for my '68 Convertible..(new engine should catapult my '68 into low to mid 10's)

    I need a roll bar that still allows normal operation of the convertible top and no cutting of the deck... Does anybody know who fabricates a NHRA/IHRA legal Roll Bar that matches those requirements??

  2. #2
    Member
    Join Date
    Nov 2000
    Location
    usa
    Posts
    255

    Default

    GrandSportC3
    The url below has some pictures and info about roll bars for Corvettes. I looked into this a bit when I was restoring an 68 Corvette IMSA racecar, but decided to have a complete cage built with NASCAR style door bars in it.

    http://www.ioportracing.com/rollbar.htm
    You probably need to really check the rulebook to make sure whatever you purchase will meet those requirements. I'm doubtful that you can make one that will allow the convertible top to work and also not cut the decklid.

    To miss the side-irons of the convert top, the roll bar will have to be bent so that it won't meet the requirements of protecting you in a roll over. Your head would be outside of the rollbar's protection. Likewise with the angle support bars. They have to be within so many inches of the top of the roll bar, and I believe there is an angle specified in the rule books too. To meet those specs, that down brace will most likely require cutting of the deck lid. If you drive with the seat forward, then the placement of the roll bar might allow you to have a downbrace that minimizes the cutting of the decklid though.

    I'm contemplating putting a roll-bar in my daughter's 72 LT-1 Convertible that will allow the top to function, but I'm pretty sure that the decklid will have to be cut some. Since it's only for protection and not for racing, it doesn't have to meet specs.

    It seems to me that either Morrison or Autopower would do a custom roll bar if you give them the specs you want built.

    You can see a little of the roll cage and how it fits in the attached picture. Notice how far back the rear angle support bar goes down into the decklid.
    http://www.knology.net/~corvettes/Alspaugh-68Racer
    Good luck
    Ol Blue

  3. #3
    Member
    Join Date
    Aug 2002
    Location
    Gig Harbor, WA
    Posts
    85
    Corvette(s)
    1970 convertible

    Default

    I had an NHRA rulebook laying around a while back and based on the specs, I saw no way to build a legal bar that doesn't go through the decklid. I'll see if I can find it and post some specs.
    Jeff
    1970 convertible
    LS1 and T56 powered

  4. #4
    GrandSportC3
    Guest

    Default

    Quote Originally Posted by 70 LS1
    I had an NHRA rulebook laying around a while back and based on the specs, I saw no way to build a legal bar that doesn't go through the decklid. I'll see if I can find it and post some specs.
    If it has to be cut a little bit - it would be still ok.. but I don't want to cut big pieces out of the deck...

  5. #5
    Member
    Join Date
    Nov 2000
    Location
    usa
    Posts
    255

    Default

    GrandSportC3

    The 2001 SCCA rule book has this to say about Roll Bars.

    The main hoop (behind the driver) shall be the full width of the cockpit. (Ol Blue comment; this may be where the design to miss the convert top arms may render your roll bar unacceptable) The main hoop shall be as near to the roof as possible on closed automobiles and not less than two inches above the drivers helmet on open automobiles with the driver seated normally and restrained by seat belt/shoulder harness. (Ol Blue comment; Corvettes with the hardtop installed seem to meet the closed auto criteria)

    Main Hoop Bracing (same thickness and diameter as approved roll bar)
    Main hoops shall have two braces extending to the rear, attaching to the frame or chassis. Braces shall be attached as near as possible to the top of the main hoop (not more than six inches below the top) and at an included angle of at least 30 degrees. (Ol Blue comment; this is where I thought you might not be able to get away from some cutting of the deck lid, but it may only be a bit of trimming, not cutting as much as I did on the racecar. I went right to the top of the roll bar.)

    Sorry to not have NHRA specs, but this might not be too far off. Oh, you need to have the acceptable specs on diameter and wall thickness too. I went beyond requirements with 1.75" diameter and .125 wall on Military Spec Chrome moly
    There is more info on side protection, but I don't know if that's required for Drag Racing

    Regards
    Ol Blue
    BTW nice looking car you have there, and FASSSSST!


    .

  6. #6
    Member
    Join Date
    Nov 2003
    Location
    Sunshine State
    Posts
    108
    Corvette(s)
    1969 coupe

    Default

    You might also check S&W, they just list Corvette application without specifying coupe or convertable. http://www.swracecars.com/

  7. #7
    GrandSportC3
    Guest

    Default

    Quote Originally Posted by Ol Blue
    GrandSportC3

    The 2001 SCCA rule book has this to say about Roll Bars.

    The main hoop (behind the driver) shall be the full width of the cockpit. (Ol Blue comment; this may be where the design to miss the convert top arms may render your roll bar unacceptable) The main hoop shall be as near to the roof as possible on closed automobiles and not less than two inches above the drivers helmet on open automobiles with the driver seated normally and restrained by seat belt/shoulder harness. (Ol Blue comment; Corvettes with the hardtop installed seem to meet the closed auto criteria)

    Main Hoop Bracing (same thickness and diameter as approved roll bar)
    Main hoops shall have two braces extending to the rear, attaching to the frame or chassis. Braces shall be attached as near as possible to the top of the main hoop (not more than six inches below the top) and at an included angle of at least 30 degrees. (Ol Blue comment; this is where I thought you might not be able to get away from some cutting of the deck lid, but it may only be a bit of trimming, not cutting as much as I did on the racecar. I went right to the top of the roll bar.)

    Sorry to not have NHRA specs, but this might not be too far off. Oh, you need to have the acceptable specs on diameter and wall thickness too. I went beyond requirements with 1.75" diameter and .125 wall on Military Spec Chrome moly
    There is more info on side protection, but I don't know if that's required for Drag Racing

    Regards
    Ol Blue
    BTW nice looking car you have there, and FASSSSST!


    .
    I might check locally to see if somebody can build something to my specs.
    A friend of mine has a 2-point rollbar which makes his convertible (with hardtop) legal to 11.50. He always gets past NHRA inspection with his rollbar. His bar clears the convertible top without any problems (even though his bar does not go over the full width of his car. His rollbar clears the convertible top frame by an inch or so each side.. If I used exactly his main hoop setup - I'll just have to make sure that the rear 2 points will clear the rest of the convertible top assembly.. The rear 2 points may be 5 inches below the top of the bar which helps to reduce cutting to the deck..
    I'll ask around locally during the next couple of days and see...

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