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New S14 bumpsteer graphs

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  • #91
    Originally posted by Full-Race Geoff View Post
    can you share some more info, maybe post a pic of your setup? did you do the front end also
    Just to clarify on the readings in my last post; the bump values are toe in & droop is toe out, values are in inches (thousand of an inch) I am running 17x9 25 offset in rear, tires are 255/40-17, Nismo subframe bushings

    the static ride height (center of hub to edge of fender is 33cm.) the right side pic with wheel on, is static ride height & the last pic is at ride height as well

    Yes, i bumped the front already, i have a thread in the Alingnment section of the forum, i will update that thread with pics & the final values just as soon as i get the rear done.

    Hey Geoff what combo did you come up with in the rear?

    Hey Jason M, i read your thread (great work) i noticed how adding length to traction arm lowers the tie rod pickup point at knuckle, can you verify your arm lengths? I'll keep trying to figure this out this weekend.









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    • #92
      what an a$$ where'd you get all that baller machine shop garb?
      I am SKULLWORKS

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      • #93
        Be carefull using the marks on the plate for measuring the height change, the spindle rolls as it goes up and down. Although you will get repeatable reference numbers to go off of, it does not reflect actuall wheel travel. IIRC, my spindle rolled about 3 degrees/inch of wheel travel.

        I just read your front bumpsteer thread, can't beleive I did not notice it before. It's good to see others looking into bumpsteer. I'll be keeping a close eye on your progress.

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        • #94
          Originally posted by Tower240sx View Post
          what an a$$ where'd you get all that baller machine shop garb?
          Perhaps, lol

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          • #95
            Originally posted by Jason M View Post
            Be carefull using the marks on the plate for measuring the height change, the spindle rolls as it goes up and down. Although you will get repeatable reference numbers to go off of, it does not reflect actuall wheel travel. IIRC, my spindle rolled about 3 degrees/inch of wheel travel.

            I just read your front bumpsteer thread, can't beleive I did not notice it before. It's good to see others looking into bumpsteer. I'll be keeping a close eye on your progress.
            I agree, i noticed every time i moved the arm lengths the plate rotates & then i have to reset my centerhub, to fender edge distance & then re-level the plate to reference dial indicator, the fun part about this is after the desired bumpsteer readings are attained veh. has to be realigned & then bump rechecked in the rear since these seem to be drastic adjustments.

            Thanks

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            • #96
              hurrdurrr

              http://www.enjukuracing.com/products...t-for-S13.html
              http://www.enjukuracing.com/products...t-for-S14.html

              But srsly, incredible thread, great info.... You guys make my head hurt.

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              • #97
                hi cheeky, thanks for posting the photos - i do not understand how you are able to measure toe change with only one dial indicator (perhaps i am reading this wrong? )

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                • #98
                  Originally posted by Full-Race Geoff View Post
                  hi cheeky, thanks for posting the photos - i do not understand how you are able to measure toe change with only one dial indicator (perhaps i am reading this wrong? )
                  I was just thinking about that the other day. How do you account for camber change? Do you measure both sides of the plate at different times? Most setups use two dial indicators and you have to compare the difference of the two, or have 1 indiactor, a follower, & a hinged setup (to compensate for camber change) like my LongAcre setup.

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                  • #99
                    I am just measuring the one side of the plate, I see your point about the hinged set up? i guess back to square one with the whole deal.

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                    • Ya, camber change in the rear probably effected your numbers quite a bit. I know that on the S13 subframe it has a linear 1.3*/inch camber gain, througout the entire suspension travel range. The front camber gain might be 0 to .3*/inch depending on your SAI, and roll center correction.

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                      • My data was taken with the Maximum Motorsports single dial / hinged setup.

                        Yeah, the hub/knuckle rolls forward pretty good as you sweep it up through the range. Even more if you're running a short traction arm. I'm wondering what that roll equates to. If you projected a line forward, swept the assembly up and down, and watched where it converged... would this point be... the instant center?
                        She's built like a Steakhouse, but she handles like a Bistro.

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                        • I have not plotted the rear spindle fore & aft movement, but I have plotted the spindle roll angle on the s13 subframe. It is right around 3*/inch & very linear. I believe the roll may be accelerated on the s13 subframe due to the higher amount of antisqaut. I would be interested in seeing the spindle roll angle rate on an s14 subframe.


                          I believe that the higher amounts of antisquat may attribute to higher amounts of "roll steer", or fore & aft movement of the spindle. The roll steer that I'am refering to is the wheel base change during body roll.

                          Something else that we have not discussed is the setback amount of the toe rods outer pickup point vs the inner pickup point. As the spindle rolls forward under bump, the toe rod pick up points align. This setting/adjustment is similar to moving a steering rack forward or rearwards in a chassis to change the bumpsteer curve. It can be changed with lca's that have inner rod ends, and by modifiying the spindles toe rod pickup point. If the spindle roll rate is different on the s14 subframe, it would produce a different curve if the toe arms pickup point setback was left the same.

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                          • Just messaged Epstein for the excel file anyone happen to have it? thanks!

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