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97 M3/4/5 running in STU

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  • #31
    Re: 97 M3/4/5 running in STU

    Mmmm steak
    -Sean Martin
    2009 Pontiac G8 GT

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    • #32
      Re: 97 M3/4/5 running in STU

      I'll take all the steak you'll feed me...


      ... But it's not gonna do anything to diminish the advantage I have! HAH!
      Chris
      97 M3/4 - STU
      06 Evo - SM
      00 S2000 - STR

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      • #33
        Re: 97 M3/4/5 running in STU

        Let's put the toothpaste back in the tube...

        How will running no rear bar and a huge front bar help with rotation?

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        • #34
          Re: 97 M3/4/5 running in STU

          Originally posted by 97M3 View Post
          How will running no rear bar and a huge front bar help with rotation?
          It won't... At least in my experience. A bigger front bar *will* help front grip to a point, but once you get the roll under control, swaybar tuning in an M3 is just like any other car - A stiffer front bar increases understeer, a stiffer rear bar increases oversteer.
          Chris
          97 M3/4 - STU
          06 Evo - SM
          00 S2000 - STR

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          • #35
            Re: 97 M3/4/5 running in STU

            Originally posted by 97M3 View Post
            Let's put the toothpaste back in the tube...

            How will running no rear bar and a huge front bar help with rotation?
            Like Chris said, it won't help rotation but should help put power down on corner exit. We kind of did this on our open diff E30, by running a big H&R front bar and the stock (tiny!) rear bar - along with some custom shocks.

            On the E36 and E46 M cars I actually like the turn in, transition abilities, mid corner "feel" and rotation with using bigger (adjustable) bars front and rear, and running 5-6x the spring rate of stock. These cars are VERY softly sprung from the factory. Not everyone agrees as some folks like a car the "moves around a lot" (more roll, dive, pitch), as it transmits more inputs to the driver. I think the stiffer setup is faster, especially at ever higher speeds (esp. road courses).
            Terry Fair - www.vorshlag.com
            2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
            EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

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            • #36
              Re: 97 M3/4/5 running in STU

              I have no rear bar on my '97 328is, and a 28mm H&R fsb connected to the control arms. It works really well with the 650F 750R rates. I am going to try running stiffer rear springs eventually, but for now, the setup is quite well balanced. Was able to put 70 runs on the car on a small test and tune course to get it dialed in with the shocks. I am not a believer in running a rear bar on a rwd car if avoidable.

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              • #37
                Re: 97 M3/4/5 running in STU

                Someone shot some photos of the car on Saturday. The 245's (Dunlops) on a 17in Koseis are still rolling over at the 32-35psi range, will increase pressures next event. As we learn the car we're picking the insde front tire up under acceleration. Suggestions?

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                • #38
                  Re: 97 M3/4/5 running in STU

                  How much camber do you have? I started the season with -2.8F and -1.8R, and am now at -3.8F and -2.8R and I am longer rolling over the edges. I run 34 psi all around on starspecs.

                  My car lifts wheels sometimes:
                  http://www.briangt.com/gallery/328is/2_wheelin
                  Last edited by BrianGT; 04-05-2009, 07:10 PM.

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                  • #39
                    Re: 97 M3/4/5 running in STU

                    -3.5 front, -2.5 rear. What size tire and wheels?

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                    • #40
                      Re: 97 M3/4/5 running in STU

                      17x9 with 255/40-17 StarSpecs

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                      • #41
                        Re: 97 M3/4/5 running in STU

                        Ran a BMWCCA event at 36F/32R and rolled the sidewalls again. Had at least a 1/2 of deflection. Don't know how your keeping the sidewalls stiff?

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                        • #42
                          Re: 97 M3/4/5 running in STU

                          I run 255x40x17s on a 17x9. Front pressures 35 and rears 30. No rolling over. Ever.

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                          • #43
                            Re: 97 M3/4/5 running in STU

                            _DSC1338.jpg

                            Pick it apart. 36F/32R. Feels very sloppy. I do plan on loosening up the front bar before the next event.

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                            • #44
                              Re: 97 M3/4/5 running in STU

                              Originally posted by 97M3 View Post
                              ...installed a TCK SA setup with 550/540 springs and plates.

                              ...

                              Pick it apart. 36F/32R. Feels very sloppy. I do plan on loosening up the front bar before the next event.
                              I doubt the issue is really about tire pressure at all, but spring rate. Rear spring rates too low (relative to the front) + front roll stiffness looks too high (relative to the rear). Front tire in air under corner exit is The Tell. Honestly I see more E36's setup this way, than not.



                              That picture above is our E36 M3 with 600F/750R springs, AST4200s, big (adjustable) swaybars at both ends, -4° of static front camber. This picture was shot mid corner on clean concrete, rolling into max forward acceleration @ Wide Open Throttle in 2nd gear, laterally loaded at about 1.25g on 255/40/17 AD07s. As you can see the tires are loaded up hard relative to the wheels. Inside front tire looks "light" but is still contributing some work. Rear of the chassis isn't squatting or heeled over - just getting it done and hauling tail out of that corner.

                              edit: Bridgestone RE01Rs are always going to feel sloppy on 2800+ pound cars. They are no Yokohama. You can improve the RE01R's feel only by shaving the tread under 4/32", stretching the tires onto much wider wheels than you think necessary, and upping tire pressures.
                              Terry Fair - www.vorshlag.com
                              2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                              EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

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                              • #45
                                Re: 97 M3/4/5 running in STU

                                Oops! No proofreading skills.

                                The spring rates are 450F/500R. These are the crappy Dunlops. Loosened the bar already. What spring rates does everyone recommend?

                                Thanks,

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