Autocross speed

Discussion in 'Autocross' started by mrminimmel, Mar 25, 2011.

  1. mrminimmel

    mrminimmel New Member

    Dec 5, 2010
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    So I just finished my 4th race this past weekend. So between those races and a one day driver's school I've put in maybe 50 laps around a race course. My question at this point is whether it's better to slow the overall speed down so that less is lost to corner or should harder braking occur prior to cornering? I have an automatic trany, I use the sport mode and I've been trying the manual shift ability of the car to change gears in order to increase acceleration out of the corners.Tires are squealing but this last race I didn't really seem to be pushing that much. Feedback?? Thanks, Pete. BTW this stuff is addictive
     
  2. BThayer23

    BThayer23 Well-Known Member

    Jun 12, 2009
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    Harder braking. There's a maximum velocity for every corner, and the goal is to hit that speed on each corner. Sometimes you won't have enough engine to make it up to that speed, and sometimes you'll need to brake long and hard to get down to that speed, but the ideal lap will keep your minimum speed as high as possible.

    There isn't much shifting on an autox course, but on the track, think about downshifting during the last 1/3 of your braking zone so the engine's ready to accelerate out of the turn. Make sure the brakes are doing all the braking, not the engine, and wait until you've slowed the car and the engine down enough to raise the revs in a lower gear and not hit redline. Especially with a peaky four cylinder engine, focus on keeping the revs up all the way around the course.
     
  3. rigidjunkie

    rigidjunkie New Member

    Dec 23, 2009
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    I will argue the alternative to BT23, but would like to point out both arguements are valid. When I was starting out I tried and tried to get my braking points as late as possible to hold momentum (I was in a Cooper.) What I learned is it is more important to have a high exit speed rather than a high entrance speed. I always focus on getting as much power to the ground as possible and many times it is faster to enter a turn slower so you do not push and then miss the apex.

    Another thing to play with when AutoX'ing is the force of your brakes. Smooth inputs give smooth results, but some times it is easier to get the car to rotate a little if you are harsh with your brakes. The Mini is very open to brake oversteer so if you come in hot and brake just as the car is turning you can get the rear to come around which can help get around some tight corners. This is something that is very helpful to learn at AutoX because in an emergency you are likely to encounter brake oversteer and it is really helpfull to know how to react when it happens.
     
  4. mrminimmel

    mrminimmel New Member

    Dec 5, 2010
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    thanks

    Those ideas are going to be considered in the next race , thanks. One more piece of info to consider. I recently put in a 19mm rear sway bar. It is currently in the softest position. Should I adjust one side up a notch, both sides up a notch?? Pete
     
  5. Crashton

    Crashton Club Coordinator

    Jun 4, 2009
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    Both, doing one side at a time will make handling for left & right turns different.
     
  6. GreyLens

    GreyLens New Member
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  7. PGT

    PGT Wheel Whore

    May 4, 2009
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    one thing I found from autocrossing mine is that you have to go slow to go fast. setting peak speed hold on my Garmin, the times I hit 40mph on one course were longer ET than if I only peaked at 36-37mph. Consistency and maintaining momentum are key.

    Also...there are different lines to take on a course....momentum line or a power line. Here's an example from some of the guys in the local group I autocrossed with....Noble M400 (V6TT and RWD) and six different drivers with six different lines.

    [ame=http://www.youtube.com/watch?v=V9vCaAR2u1w]YouTube - Virtual Race CDC Autocross July 5-6 2008[/ame]
     
  8. PGT

    PGT Wheel Whore

    May 4, 2009
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    and, here's my car being driven by a buddy who's more experienced than me. He owns a supercharged Miata and a bunch of turbo Subaru's (i.e. nothing FWD). His first time around the course in the video was 1-2 seconds quicker than my best time that day. He was not overdriving the car....this was on Falken RT615s, thus the noisy tires

    [ame=http://www.youtube.com/watch?v=HvSy_DUCffs]YouTube - CDC Frederick 7/6 MINI Cooper S[/ame]
     
  9. rigidjunkie

    rigidjunkie New Member

    Dec 23, 2009
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    That is another misconception squealing tires are not always overworked tires. Most tires squeal before they lose traction.
     
  10. BThayer23

    BThayer23 Well-Known Member

    Jun 12, 2009
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    Not true, as the bar isn't fixed in the middle. Hole 1 on the left and hole 2 on the right would give you a rate somewhere in the middle. And it's the same rate whether you're turning right or left. Imagine a bolt with a nut on the other side that you're trying to tighten, and the bolt can spin freely in the hole. It doesn't matter if you hold the bolt side and turn the nut side or hold the nut side and turn the bolt side - the amount of twisting force is the same. So the sway bar doesn't care which arm is shorter or longer, it's the cumulative effect because it's free to rotate.

    That said, the difference between hole 1 and "hole 1.5" is so small you probably won't feel anything, so move both up at the same time (or move one side from 1 to 3).
     
  11. Crashton

    Crashton Club Coordinator

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    Interesting, my thought was that the preload on the bar would be different on each side causing a difference. Never too old to learn.
     
  12. BThayer23

    BThayer23 Well-Known Member

    Jun 12, 2009
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    Sorry, I was nitpicking, but my statics professor would be happy to know that I didn't sleep through all his classes. :D
     
  13. Crashton

    Crashton Club Coordinator

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    That is OK. Sharing knowledge is a good thing. :sleep:
     
  14. PGT

    PGT Wheel Whore

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    well, they squealed a lot because they sucked. RE-01R' were much more predictable and were very progressive at the limit (oversteer became fun)
     
  15. ScottinBend

    ScottinBend Space Cowboy
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    There is no preload on the sway bar UNLESS the endlinks are of a different length. This would add some twist to the bar, whereas the holes simply change the lever length.
     

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