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Adjusting Alignment

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  • Adjusting Alignment

    So I've been throwing this around in my head for the past few weeks.
    What is the better way to get your alignment sorted out?
    - Adjusting via Moving the Pivot Points
    (i.e. Camber Bolts, Eccentric Bushings, etc.)
    - Adjusting via Arm Length

    Reason I ask is because say you adjust your alignment via Arm length. Now our chassis are old and beat and have twisted/deformed and all that Jazz over the how many years and we only add to it when pushing it out on the Track. Now adjusting via Arm length you may have = Static alignment from left to right, but if the arms are off it would intern meaning that your geometry would change in relation from left to right.

    If that didn't make sense hows this:

    Adjust Rear Camber via adjustable RUCA's
    You dial in -1.5* Left and Right Static.
    But arm length is ~.75" difference in length. (Example)
    How would this affect Handling/Transitions?

    Can anybody shed some light on the Pro's and Con's of each? I'm no Suspension/alignment/Geometry expert but always willing to learn and always looking to get the most for me mula...

  • #2
    I would say if there is a 3/4" difference something is bent or the centric bolts are in different spots when starting, assuming you set the lengths of the arms the same.


    • #3
      As you've surmised, changing the arm length can change things like bumpster and camber curves.. exactly how much? I dunno.

      that's why I took all my adjustable crap off and stuck sphericals in the stock arms and put them back on the car using stock alignment bolts. I can't tell a difference in handling at all, but I dropped several pounds of unsprung weight by going back to the stock arms over thick 1" DOM tubing to make all the others. I wish I'd have weighed them.

      If that didn't provide enough adjustment to get things where I wanted them, then I would suggest maxing out the factory adjustments before adjusting the arms.

      That said, if you have a REAL race shop that knows what they're doing work on the car and set it up, then by all means have them tweak on everything.
      Of course a race chassis setup is very subjective and will be different for each person's preference, track type, and driving style. I had a local race shop set my car up and he dialed in some rear toe-in and I hate how it caused it to slow corner entry rotation. It has, however, allowed me to trail-brake deeper into a corner so I think the car may be faster overall.

      but things like that are where rear bump steer (traction rod length) come into play, as well as each person's individual camber/caster/toe settings. I don't think there's any one right answer/perfect setup/ golden alignment spec that anyone can quote you.
      Last edited by Matt93SE; 02-24-2011, 10:51 AM.
      Originally posted by SoSideways
      I don't care what color they are as long as they are LONG AND HARD.
      '04 G35 Sedan 6MT- The DD
      '96 240SX- The Track Toy


      • #4
        The arm length isn't that different, and stock arm lengths aren't necessarily optimal for a lowered car. Bumpsteer isn't that hard to measure.
        '18 Chevrolet Volt - Electric fun hatch for DD duty!

        DefSport Koni Sleeve and Spring Perch Buy!!!


        • #5
          If the arms differ that much from side to side, you probably should pick up another chassis. Some frame dragging ricer will buy the old one without much worries.

          Epstein already did some great subframe measurements for us; enough to get in the ballpark.


          • #6
            Ok .75" difference was a horrible example. Let's say .125" or 1/8th of an inch. Sound more acceptable right? Will the difference affect the handling much from side to side. I believe someone did a bumpsteer graph with 1/8th inch increments and the changes/difference was pretty noticeable on paper. What about on the track.

            I'm probably WAY over thinking this huh? Lmao


            • #7
              Probably way over thinking it. You really think the rear sub frame points would flex and move to make this a thing to worry about?
              SM 63 KA-t 470hp 480tq G30-660 A2W IC


              • #8
                You are def splitting hairs!
                "the kid" -- "wrenching and racing" -- "will race for food!" -- '90 Nissan 240sx ITA #5
                Kessler Engineering in Berlin, CT - dyno, engines, cages, etc.
                Driving Impressions Racing safety equipment, motorsports shop and more!
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                • #9
                  I'm not sure I'd just ignore the variance,

                  I prefer to set the factory adjusters (cam bolts) to the center of travel both sides, then adjust alignment with arms. T
                  his allows you to have some "dial in/dial out" room with the factory cam bolts without having to get into adjusting arm lengths for minor changes.

                  For a slightly more developed setup I would remove the factory cam bolt and enlarge the hole to 1/2" so I could use shoulder-bolts to locate the spherical bearings in the arms.
                  I am SKULLWORKS