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  • Alignment analysis

    So took the car in for an alignment (should have done this sooner)
    here is what we got...

    before alignment

    front left toe -0.04"
    front right toe -0.05"

    front left camber -4.39
    front right camber -4.35

    rear left toe -0.13"
    rear right toe -0.26"

    rear left camber -2.36
    rear right camber -2.16

    looks like the rear had way to much rear toe out..what would that do to the car? could that be my understeering issue?

    anyway I took Krispy's suggested settings and this is after the alignment..and got the rear toe into some toe in now

    camber left all the same...since rear is maxed out in its stock settings and front should be ok with -4.3

    after alignment

    front left toe -0.06"
    front right toe -0.05"


    rear left toe +0.02"
    rear right toe +0.01"


    comments....suggestions?


    Adam
    Former CCC member, and shit disturber

    winner of a bunch of different classes over many years

    breaker of parts, burner of engines

    CREATOR OF "ULTIMATE DOOM 570SX"


  • #2
    Re: Alignment analysis

    Hmm, I've always used toe-out in the front to aid turn-in and toe-out in the back to help rotation. This is on an AWD so maybe RWD is different.

    It may also depend on how your toe changes with compression/rebound and camber change where you want to set the static values.
    www.spda-online.ca
    sigpic

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    • #3
      Re: Alignment analysis

      I do have toe out in the front now...and toe in the rear
      Former CCC member, and shit disturber

      winner of a bunch of different classes over many years

      breaker of parts, burner of engines

      CREATOR OF "ULTIMATE DOOM 570SX"

      Comment


      • #4
        Re: Alignment analysis

        Toe out in the rear would induce poweron oversteer, so that is definitely not your understeer problem. The new settings sound good.
        Arek Wojciechowski
        8legs Racing, SPC #77
        http://www.8legsRacing.com

        Comment


        • #5
          Re: Alignment analysis

          Originally posted by Tashko View Post
          Hmm, I've always used toe-out in the front to aid turn-in and toe-out in the back to help rotation. This is on an AWD so maybe RWD is different.
          Makes perfect sense.

          Originally posted by ADAM View Post
          I do have toe out in the front now...and toe in the rear
          No you don't, and no you don't ...

          ... unless you're doing "double negative" math? "+" toe is toe-out. "-" toe is toe-in.

          So according to all of your figures, you HAD and still HAVE toe-in in the front, while you did change the back from being toe-in before, to toe-out now.

          Originally posted by ADAM View Post
          before alignment

          front left toe -0.04"
          front right toe -0.05"

          rear left toe -0.13"
          rear right toe -0.26"

          after alignment

          front left toe -0.06"
          front right toe -0.05"

          rear left toe +0.02"
          rear right toe +0.01"
          The toe-out in the rear should, like Tashko said, help the rear end rotate. It's not a lot of toe-out, so to what extent? Guess you'll find out. But in the front, you actually gave yourself and additional .02" of total toe-in (-.06" + -.05" = -.11", which is not far from -.125", which is -1/8"). If you want toe-out, you'd be looking for +.xx".
          OMSC
          Current: 2011 Corvette Z06
          Previous: '06 Z06, '10 Corvette, '93 & '02 Camaro Z28's

          Comment


          • #6
            Re: Alignment analysis

            no they actually reverse what common sense would be on the alignment machines printouts... they consider a - to be toe out ...and a + to be toe in


            I asked the tech guy at the shop 3 times to make sure..that he in fact was adding toe out to the front which shows as - , and adding toe in on the rear which shows as +

            not sure why they do this maybe they consider it an adjustment to the back of the wheel which in that case they are adding or subtracting from dead straight?

            anyone know why they do that with alignment?
            Former CCC member, and shit disturber

            winner of a bunch of different classes over many years

            breaker of parts, burner of engines

            CREATOR OF "ULTIMATE DOOM 570SX"

            Comment


            • #7
              Re: Alignment analysis

              Just check it with a couple of boards and 2 tape measures to be sure.

              I'm not sure about othe RWD cars, but on a BMW, having rear toe-out basically makes the car undrivable. You just NEVER want rear toe-out.
              Last edited by ScotcH; 07-08-2008, 03:17 PM.
              Arek Wojciechowski
              8legs Racing, SPC #77
              http://www.8legsRacing.com

              Comment


              • #8
                Re: Alignment analysis

                not even on the front?

                I can 100% see why not on the rear
                Former CCC member, and shit disturber

                winner of a bunch of different classes over many years

                breaker of parts, burner of engines

                CREATOR OF "ULTIMATE DOOM 570SX"

                Comment


                • #9
                  Re: Alignment analysis

                  Originally posted by ADAM View Post
                  not even on the front?

                  I can 100% see why not on the rear
                  Sorry ... I meant on the rear. Yes, you can have some tow out in front to help turn in. Too much might give you mid-corner push though.
                  Arek Wojciechowski
                  8legs Racing, SPC #77
                  http://www.8legsRacing.com

                  Comment


                  • #10
                    Re: Alignment analysis

                    Originally posted by ADAM View Post
                    no they actually reverse what common sense would be on the alignment machines printouts... they consider a - to be toe out ...and a + to be toe in


                    I asked the tech guy at the shop 3 times to make sure..that he in fact was adding toe out to the front which shows as - , and adding toe in on the rear which shows as +
                    Ok then ... so it's like I said ... "double negative" .

                    Basically, their machine is telling you how much toe-in you have. Anything greater than 0 is toe-in (+) and anything less than 0 is toe-out (-).

                    So -.06" of toe-in is +.06" of toe-out!! ..... weird, but if that's how it is, then that's how it is!!!

                    Then you can ignore the part where I said you don't have toe-out!!

                    (FWIW, the alignment shop I went to, the computer displayed toe-in as "-" and toe-out as "+", and everywhere I've seen it discussed, that's the way it's been).
                    OMSC
                    Current: 2011 Corvette Z06
                    Previous: '06 Z06, '10 Corvette, '93 & '02 Camaro Z28's

                    Comment


                    • #11
                      Re: Alignment analysis

                      Hmm! Man Adam, with settings like those, I would have thought that thing would have turned like crazy with some trail braking, especially from mid-corner onwards. Is it unstable under braking? What hot pressures do you use front to rear?

                      Perhaps with those wide wheels, you might need to dial back more on Front Camber still to get more tire on the ground for cornering. Tire temperatures or wear should tell you that.

                      For autoslalom I like a little toe out up front. 2/16" or ~0.13" Total (0.065 a side). But for the track, I prefer the confidence and predictability of 0.0 toe. If the car pushes from the apex onwards I add up to 2/16" toe out in the rear for rotation. Some folks like more than that.

                      You're using 10kg front, 8kg rear, with McPherson struts front and rear, right? Your weight balance was near 50/50, front to rear, wasn't it? Perhaps some more rear spring?
                      sigpic

                      Stephen, SPDA VP, OTA Director, CCC Member
                      OTA: SGT1 ! -=- CSCS: SSA #842

                      Comment


                      • #12
                        Re: Alignment analysis

                        Originally posted by ScotcH View Post
                        You just NEVER want rear toe-out.
                        unless you are Zanardi at the end of a race!

                        Comment


                        • #13
                          Re: Alignment analysis

                          According to Millikan (Race Car Vehicle Dynamics), a typical radial tire produces a side force due to camber approximately equal to the side force due to steer at 1/10th the camber angle. This tells me that negative camber is stabilizing for the same reason that toe in is stabilizing, and that toe out (in degrees) equal to 1/10th of negative camber angle should not cause instability issues. This means that at -2.5 negative camber, 0.25 of toe out (which coincidentally corresponds to about 0.25" of total toe out on a typical tire) is not unreasonable. I have tried more without serious consequences. The same thinking may be applicable rear toe, but conventional wisdom says that toe out at the rear will cause instability (oversteer) at track speeds so I haven't experimented with this.

                          Most references are very reluctant to suggest toe out, and Millikan is the only author I have seen to point out the camber/steer relationship. Perhaps they are paranoid about liability. In any case, only experimentation will yield the definitive answer for your situation.

                          I suggest much more front toe out. With -4 degrees front camber, try up to 0.4" total toe out (0.2" per side).
                          James Mewett
                          CCC Lurker

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                          • #14
                            Re: Alignment analysis

                            hnmmm even more toe out..

                            well somethings gotta change cause the nose is just plowing..


                            maybe the front splitter will be the answer..will see
                            Former CCC member, and shit disturber

                            winner of a bunch of different classes over many years

                            breaker of parts, burner of engines

                            CREATOR OF "ULTIMATE DOOM 570SX"

                            Comment


                            • #15
                              Re: Alignment analysis

                              What kind of tire temperatures are you running?

                              I am not surprised you induced more understeer with your new alignment settings. however, this probably makes it more consistent. The virtually 0 toe in the back is a good start.

                              But, recently, you have gone from a large aftermarket rear bar to either no rear bar to a small OE one. This would shift the balance of roll stiffness towards the front. Now, you have taken a fair amount of rear toe out away from the car, making the car less loose.

                              Why are you averse to changing spring rates?

                              Where in the corner is your car understeering?
                              Pete Mills
                              Cheap, fast, reliable. Choose 2.

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