Road racing setup help

Discussion in 'Mazdaspeed 3 General Discussion' started by gotovato, Jun 4, 2018.

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  1. Mauro_Penguin

    Mauro_Penguin Punk in Drublic Gold Member

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    I got Mattyhawks old setup last month. It's Focus ST inner tie rods and a bumpsteer/outer tie rod kit from Steeda. (Spacer required for the inner toe rod)

    @phate I've watched your video, love all your stuff. I just didn't want to the math because at first I wasn't sure if I was going to notice any change. (Originally thought I had a sway bar issue). I couldn't measure anything well the way I had it, because the camber change at compression and rebound was throwing off my control height laser marking. Your way looks better and is what I will use when I revisit it in a few weeks. Hence why I just eyeballed it in the end.
     
    Mauro_Penguin, via a mobile device, Jun 12, 2018
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  2. phate

    phate Motorhead

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    The problem with projecting onto a wall or on the ground is that it doesn't account for change in track width (scrub) through the vertical range of the wheel assembly. Using the laser line and mirror trick eliminates that issue :)
    --- Double Post Merged, Jun 12, 2018 ---
    Bump steer is purely a function of the suspension geometry. If you look at the top view plane of the suspension steering geometry with a specific steering angle, you'll see that it's just a 4 bar linkage like most everything else in the suspension. subframe, LCA, knuckle, and tie rod. The lengths of the subframe and knuckle are static in the top view - the LCA and tie rod are not. The horizontal length of both the tie rod and LCA change throughout vertical motion of the wheel assembly - and that change relative to each other is what causes the knuckle to rotate.

    Remember that everything travels in arcs - you cannot eliminate bump steer unless you redesign the entire front suspension. What you can do is move the unwanted behavior to a different part of the range. Alternatively, you opt to not operate in the "bad" part of the range.
     
    Last edited: Jun 12, 2018
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  3. AYOUSTIN

    AYOUSTIN Silver Member

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    QFT
     
  4. gotovato

    gotovato Greenie Member

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    thanks all for the wealth of knowledge. i guess first step is to try and get that whiteline kit installed, then play with alignment. im fortunate to have access to a shop thatll align my car however i want and can make tweaks and adjustments along the way till i find what works best for my car
     
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