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Thread: Importance of front sway bar angle?

  1. #1
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    Importance of front sway bar angle?

    Installed the front swaybar last night. FFR instructions state that the sway bar should be horizontal or hang down up to 20deg (See picture). I didn't have a protractor at the time, but estimated ours was approximately 30deg. The car is on the frame dolly and the suspension is not loaded. Won't the sway bar move up towards horizontal when the finished car is on the ground and the suspension is loaded? What is the potential issue if the sway bar hangs more than 20 degrees?

    I'd like to avoid trimming the rod ends again.

    swaybar.JPG
    MK IV Roadster-Delivered Nov '18
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  2. #2
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    Brian76,

    As you load the suspension (drop it on the ground to ride height) the sway bar will follow the lower control arm. So yes it will become more parallel to ground.

    The sway bar should have one end-link attached after ride height is set. The bar shouldn't introduce any tension when the suspension is at it's normal position/height.

    Jim

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    The end of the bar moves through an arc, as the tire moves up and down. The end goes down on the inside of the turn, and up on outside of the turn (in relation to the frame). As the end of the bar moves further away from the 90* horizontal mark, it becomes less effective, and imparts less control over movement. If the bar is significantly up or down at rest, then you'll get different effects in a right turn than you would in a left turn. Keeping the end of the bar at 90* will keep the car balanced and predictable through both left and right turns.
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    Thanks Jim & Bob. Looks like the sway bar should be parallel to the frame for optimal performance. Do you recommend I leave the front sway bar as-is and wait until the go cart stage to determine if the rod ends need trimmed more? With the car on the dolly and the front suspension and a-arms hanging down, I'm not sure how parallel the sway bar needs to be to the frame. As you mentioned, it will follow an arc (towards parallel) as the suspension is compressed.
    MK IV Roadster-Delivered Nov '18
    Complete Kit, Gen2 Coyote, TKO 600, 2015 IRS, FFR brakes, FFR power steering, Full length headers

  5. #5
    Senior Member rich grsc's Avatar
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    Quote Originally Posted by Brian76 View Post
    Thanks Jim & Bob. Looks like the sway bar should be parallel to the frame for optimal performance. Do you recommend I leave the front sway bar as-is and wait until the go cart stage to determine if the rod ends need trimmed more? With the car on the dolly and the front suspension and a-arms hanging down, I'm not sure how parallel the sway bar needs to be to the frame. As you mentioned, it will follow an arc (towards parallel) as the suspension is compressed.
    Jack up the front suspension till the controller arms are parallel to the ground, then you'll know.

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    Quote Originally Posted by rich grsc View Post
    Jack up the front suspension till the controller arms are parallel to the ground, then you'll know.
    This ^

    When I was installing the front and rear sway bars, they looked all wrong to me and I was sure I needed to tweak stuff because something wasn't right. But if you back off the spring seat on the shocks and jack up the suspension until the control arms are parallel you'll have a much better sense for what things will look like when in use and everything makes a lot more sense (at least it did to me).
    MkIV Roadster build: Coyote, IRS, TKO600. Ordered 10/24/18. Delivered 1/29/19. Build thread here.

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    Quote Originally Posted by JohnK View Post
    This ^

    When I was installing the front and rear sway bars, they looked all wrong to me and I was sure I needed to tweak stuff because something wasn't right. But if you back off the spring seat on the shocks and jack up the suspension until the control arms are parallel you'll have a much better sense for what things will look like when in use and everything makes a lot more sense (at least it did to me).
    Thanks!
    MK IV Roadster-Delivered Nov '18
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  8. #8

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    Set the frame at ride height, about 4.5" in the front. Then look at the sway bar ends. The A-arms may not be exactly horizontal at ride height.
    .boB "Iron Man"
    NASA Rocky Mountain, TTU #42
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    Quote Originally Posted by Bob Cowan View Post
    Set the frame at ride height, about 4.5" in the front. Then look at the sway bar ends. The A-arms may not be exactly horizontal at ride height.
    I don't have tires & wheels yet. I suppose I could estimate radius of tire and wheel then jack up the front suspension accordingly.
    MK IV Roadster-Delivered Nov '18
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  10. #10

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    I would wait until you have some wheels and tires mounted. You can get it in the ball park by resting the rotors on some wood blocks. But it won't be quite right, and you'll have to revisit that task again later.

    Once you have tires mounted, set them down on a folded plastic trash bag so they will move easily.
    .boB "Iron Man"
    NASA Rocky Mountain, TTU #42
    FFR MII: Dart 427W, Momar 8 stack EFI, Tremeac TKO, IRS, Red with Ghost Flames, 600'ish HP.
    -- Gone, but never forgotten
    BDR 1642: Coyote, 6 Speed Auto, Edelbrock Supercharger
    www.RacingTheExocet.com

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