Help me correct my understeer!

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  • JJ1
    Advanced Member
    • Oct 2009
    • 176

    #1

    Help me correct my understeer!

    I have a 90' 325is with GC 375f/475r springs and billy sports. Tires are 215/45 16 Ecsta XS's on all four corners. Im looking for the easiest way to correct my under steer. I would like my car better balanced or to have a little over steer. Any good advice based on experience would be greatly appreciated.
  • jlevie
    R3V OG
    • Nov 2006
    • 13530

    #2
    Understeer results from a lack of grip on the front wheels relative to the rear wheels. The grip of the front wheels can be increased by shifting weight forward and.or increasing front camber. With coilovers the weight shift can be accomplished by raising the rear springs and lowering the fronts. When adjustable sways are fitted softening the fronts and stiffening the rears will also shift weight to the front wheels when cornering.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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    • gearheadE30
      No R3VLimiter
      • Jun 2007
      • 3734

      #3
      I'd assume you're still on stock sways? Adding a 14.5mm rear bar from an ix/M3 helps, but for me it just took grip away at the rear while making it more neutral. I was quicker managing the understeer with my driving than with just the rear bar.

      Adding a 21mm bar to the front (mine's from a 325ic) actually made more of a difference, and I got all of my grip back. In effect, what this does is limit the body roll, especially at the front. Strut suspensions have rather lacking camber curves, so the less roll at the front, the more perpendicular the tires will be with the road. Obviously, the next step is camber plates, which make the biggest difference but kill tires on the street.

      Project M42 Turbo

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      • JJ1
        Advanced Member
        • Oct 2009
        • 176

        #4
        1) Thank you guys, those were both awsome answers!

        2) I should have been more specific in my opening statement. In the near future I think I am going to do the GC Koni setup with shortened strut housing and camber plates. With that in mind I was looking for an easy/ cheap way to get rid of the oversteer with my current set up.

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        • JJ1
          Advanced Member
          • Oct 2009
          • 176

          #5
          Originally posted by gearheadE30
          I'd assume you're still on stock sways? Adding a 14.5mm rear bar from an ix/M3 helps, but for me it just took grip away at the rear while making it more neutral. I was quicker managing the understeer with my driving than with just the rear bar.

          Adding a 21mm bar to the front (mine's from a 325ic) actually made more of a difference, and I got all of my grip back. In effect, what this does is limit the body roll, especially at the front. Strut suspensions have rather lacking camber curves, so the less roll at the front, the more perpendicular the tires will be with the road. Obviously, the next step is camber plates, which make the biggest difference but kill tires on the street.
          I was thinking about pulling an "ic" rear bar from the junk yard. So if I get the front and rear that should be a little more balanced without losing too much grip?

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