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  1. #1
    Join Date
    Sep 2020
    Posts
    10

    Default Metric a frame location help

    we are building a new chassis, imca stock car, we are allowed to fabricate the upper a frame mount and relocate it. We must use stock lowers, stock spindles and imca upper a frames. My question is, what types of things should I measure to get the optimum placement.

  2. #2
    Join Date
    Nov 2007
    Posts
    163

    Default

    You are kinda limited by the required upper a-frame. The a arms will get into the tires before you can move them far enough to eliminate caster change. You can change roll centers some by using ball joints with longer stems, but choices are limited by the a arm.
    Then, you need to consider pro or anti dive.
    Moving them to get camber and caster needed can sometimes make bump steer problems.
    Even on the modifieds, some chassis builders have opted to stay with the stock mounts to keep stock geometry.

  3. #3
    Join Date
    May 2007
    Location
    in a van down by the river
    Posts
    1,768

    Default

    I assume you are building a Metric Chassis?
    May look at the square body Caprice (gen 3 77-90), or the Gen4 91-96
    I know the 3rd gen stuff the spindles are taller, and share parts with Camaros/Firebirds.
    you will also have a better chance of getting better Geometry with them.

    Not messed with any 4th gens, but i hear you can use those lower a arms on the metric, (are 3/4" longer) so they must be similar
    I think there should be lifeguards in the genepool.

  4. #4
    Join Date
    Apr 2009
    Location
    Marengo IN
    Posts
    246

    Default

    Your best option is to build some small tabs that you can cut and tack in place. Use a bump steer gauge setup and cycle it. watch your caster and camber gains/changes. Try many different locations until you get it where you want it. Like at 10 different mod chassis with chevelle or metric clips and you will find 10 different setups. Most of them work. Once you find the sweet spot you want fabricate your mounts to match.

  5. #5
    Join Date
    May 2007
    Location
    in a van down by the river
    Posts
    1,768

    Default mount it

    Quote Originally Posted by racer69 View Post
    Your best option is to build some small tabs that you can cut and tack in place. Use a bump steer gauge setup and cycle it. watch your caster and camber gains/changes. Try many different locations until you get it where you want it. Like at 10 different mod chassis with chevelle or metric clips and you will find 10 different setups. Most of them work. Once you find the sweet spot you want fabricate your mounts to match.
    best advise right there
    I think there should be lifeguards in the genepool.

  6. #6
    Join Date
    Jul 2007
    Posts
    3,148

    Default

    Quote Originally Posted by JustAddDirt View Post
    I assume you are building a Metric Chassis?
    May look at the square body Caprice (gen 3 77-90), or the Gen4 91-96
    I know the 3rd gen stuff the spindles are taller, and share parts with Camaros/Firebirds.
    you will also have a better chance of getting better Geometry with them.

    Not messed with any 4th gens, but i hear you can use those lower a arms on the metric, (are 3/4" longer) so they must be similar
    Why do you reply to these posts when you have no idea wtf your talking about.

    The original poster said IMCA stock car..... THEY can not use any of what you said nothing, nada.

    I come back here very seldom and yet almost every time your on here posting about stuff you know zero about. I know Ive told you this many times the rules are at IMCA.com.....


    What do you gain from making posts on here? Why not go find a yahoo chat and talk about something you do know?
    My ignore list... copy pasted. Which means if your on here I DONT see your posts.

    ALLDIRT a1driver a25rjr balljoint balljoint_ calverton carowner73 CIRF Clayton_Wetter decrate61 dirtdobber45 dirtman007 frontrunner gator 49 LITE--OUT Raceready

  7. #7
    Join Date
    Jul 2007
    Posts
    3,148

    Default

    remove anti dive
    move arms for less shims but leave on stock location axis
    My ignore list... copy pasted. Which means if your on here I DONT see your posts.

    ALLDIRT a1driver a25rjr balljoint balljoint_ calverton carowner73 CIRF Clayton_Wetter decrate61 dirtdobber45 dirtman007 frontrunner gator 49 LITE--OUT Raceready

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