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  • Automatic?????

    Looking at building a rally cross car, better to have an automatic or standard in a rally car?
    Thank-you for helping a new guy.
    Joe

  • #2
    Everything here is just my opinion.

    If you are truly new then you shouldn't be "building" a rallycross car. You should just be coming out and running what ever you have to learn car control and what it takes to be fast on dirt/gravel/snow etc. Based on you avatar image you may already know something about that. Starting off with an automatic "may" be helpful initially because it's one less thing to focus on while you try to learn things, but most events you don't wind up shifting once you're in second gear. You want to wind up with a standard shift eventually because the gearings will be better and when it's really messy you can short shift to help limit wheel spin. Also, if you're looking to compete with an AWD car typically automatic AWD cars are really FWD until the computer tells it not to be while stick shift cars usually are always driving to both front and rear axles. This makes a difference in how the cars handle coming in and out of corners.

    Keith

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    • #3
      My thought on Auto vs Manual. I think either can work and I have seen both work. I have only had a manual. The thoughts I have are

      1. Weight is important and an automatic typically weight more.
      2. Gearing is also a big deal. Automatic typically have a longer first gear which can be good.
      3. I would probably stay in L2 and not let it go into 3rd, 4th or 5th ..... on its own.
      4. Automatic will shift when it want. Manual you can control when you shift.
      5. You never miss a shift in an automatic.
      6. Some cars don't have auto options - Not sure what you are building but with some cars it seems they come in only manual or auto.

      Mark
      Mark Macoubrie
      RXB
      Kansas City Region
      2005 STI 41 PA

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      • #4
        Automatics are superior. There are only two real downsides. If you have a front-driver and you want to run outside of Stock, it is extremely difficult to find any kind of limited slip or torque biasing diff. (Quaife makes one for certain GMs, at least, but then you have to have a midsize GM)

        They are also generally RPM limited to 7000-8000rpm because of torque converter issues. But on the other hand, if you make power with a turbo instead of RPM, then you can size the converter correctly (legal mod in Prepared) and goodbye turbo lag, power is instantaneous.
        Last edited by Pete; 01-11-2017, 07:08 AM.

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        • #5
          If you have a turbo, running an auto may be a problem. Driving one even with an '05 WRX clone (Saab 9-2x) with an auto and a 2.0 turbo on a course with tight low speed corner, between the turbo lag and waiting for the auto to kick in was excruciating.

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          • #6
            You need to tell that to the to Ed and Jon Trudeau. They're driving their automatic WRX's waaay too fast.
            Charles
            RXB
            RX Rule Committee chairman
            MR 1986 Mazda RX-7
            SA 2000 Subaru Impreza 2.5RS

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            • #7
              Originally posted by slowautoxr View Post
              You need to tell that to the to Ed and Jon Trudeau. They're driving their automatic WRX's waaay too fast.
              Ed let me drive his yellow WRX at a couple events the past couple years. The automatic is way better than the manual. Better gearing for rallycross and a better center diff setup. Plus you know it won't shatter like the glass 5-speed will.

              In my opinion if you can't get an STI, get an automatic WRX. Or an '09 2.5GT, a real unicorn that I keep my eyes peeled for. The '08 WRX and '09 2.5GT were the only way to get the modern chassis with a turbo automatic.


              .

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              • #8
                I agree an automatic in a WRX is a better gear set. The first and second gears are longer and have higher top speeds. I am not sure that is true for all cars. I have also heard with some cars that the downshift can be inconsistent when left in auto which can mess with the car balance as it shifts in inopportune times.

                Mark Macoubrie
                RXB
                Kansas City Region
                2005 STI 41 PA

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                • #9
                  That's the thing - a proper automatic will only shift when you want it to. This generally means manual control.

                  There isn't much you can do about that in Stock, but in Prepared, engine controls are implicitly free ("piggybacked but not replaced" is a loophole you can fly a 777 through) so you can alter electronically controlled transmissions easily, either by editing the stock PCM or piggybacking one.

                  For example, the Aisin-Warner 5-speed in my PF car has a hack available that allows you to control the trans 100% manually with the stock controller via piggyback modification - literally piggyback in this case, soldering wires directly to the controller board. I have not done this because it is not necessary, the OE trans algorithms are exquisite and manage to put the car in whatever gear I would have wanted it to be in anyway.

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                  • #10
                    GTI with DSG?

                    09+ Lancer Ralliart with the TC-SST was okay, but both that and the EVO X needed big power braking to launch with any authority. And from an instructor's perspective, the EVO X when left in the base automatic non-sport setting gets confused by quickly changing course grip conditions. Manual control with the paddles would definitelybe the way to go.

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