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Thread: j-bar

  1. #1
    Join Date
    Sep 2006
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    LaFollette, Tennesse
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    153

    Default j-bar

    If you raise the jbar up on the pinion what efect does it have? and if i raise it on the pinion do you have to raise it on the frame at the sametime?

  2. #2
    Join Date
    Jun 2006
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    kansas
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    Default

    Raising it on the frame or lowering it on the pinion increases the rake in the j-bar and will tighten the car up to a point, sometimes going over a certain point of rake can loosen the car thru the center by keeping it up and steering.

    Generally lowering it on the pinion is a bigger adjustment then moving the same amount up on the frame.

    Moving both up or down is like raising or lowering the Rear COG of the car, basically you are moving the rollcenter in relation to the COG. So moving the whole bar up evenly is like lowering the COG.

  3. #3
    Join Date
    Sep 2006
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    LaFollette, Tennesse
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    Default

    Moving both up or down is like raising or lowering the Rear COG of the car, basically you are moving the rollcenter in relation to the COG. So moving the whole bar up evenly is like lowering the COG.





    when would you us this adjustment?
    when would you raise of lower the whole bar evenly and what type of track would you do this on?

  4. #4
    Join Date
    Sep 2006
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    Port St. Lucie, FL
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    384

    Default

    You would raise the bar on a fast track. Probably high banks. Too low when you have too much corner speed makes the car hike up too much and roll over too much.

  5. #5
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    Sep 2006
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    LaFollette, Tennesse
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    Default

    So you would raise the the Jbar (pinion and frame) when you run a fast high bank and lower it (pinion and frame) on a dry slick flat track if I have it right. That was what i was thinking (But keep the same amount of rake).

  6. #6
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    kansas
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    For me I almost never move the whole bar up or down. The most common adjustment is to add rake or reduce rake.


    MasterSbilt_Racer is correct if your going to move the whole bar up or down. However I disagree with a high banked track, should be fast or slow.

  7. #7
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    Sep 2006
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    Port St. Lucie, FL
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    Yeah, that was poorly worded. I was equating high bank to fast, but that is not always true. I also agree about moving on the pinion. A move of 1" will kill your car. If you can move .5", I have found that to be useful at times. I usually just adjust on the frame as Billet does.

  8. #8
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    Jun 2006
    Location
    kansas
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    I figured you just misworded.

    Explaination for others not following:

    When you get to a certain amount of banking (picture 90 degrees of banking) the centrifical force is pushing straight down on the car into the surface so it isn't rolling to the right but pushing down on the left and right sides. So more banking can actually hinder the left side rolling up and you may need more j-bar to lift the left side up going in and to the middle of the corner.
    Last edited by billetbirdcage; 08-07-2007 at 03:04 PM. Reason: wording - go figure! LOL

  9. #9
    Join Date
    Oct 2006
    Posts
    177

    Default

    So you guys are saying if you take angle out this will loosen the car on entry move down on chassis . Move up on chassis add angle to tighten. I do know on my pinion mount hole to hole is 1 1/4. The way i take it when you raise on chassis you lower roll center when you lower on chassis you raise. How much drop of rake or added rake where you could see a differce. thanks

  10. #10
    Join Date
    Sep 2006
    Location
    LaFollette, Tennesse
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    153

    Default

    you guys have lost me

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