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Thread: Only had money for two slick tires...

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    Default Only had money for two slick tires...

    I was at a local Porsche parts dismantler lately picking up a new window regulator when I spotted a 997 with heavy rear-end damage. Seemed totally normal considering this place was a Porsche graveyard...

    Then I noticed that the rear tires were all-seasons... and the fronts were racing slicks.

    I suppose if your car is struggling with understeer, that's one way to change things up.

    Last edited by Bongo; 07-05-2016 at 07:17 PM.
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    Administrator ucfbrett's Avatar
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    I didn't think 911s suffered from understeer.

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    The 911 does suffer from snap understeer. It is so quick and violent that the front of the car attempts to do a U turn and the rear end winds up passing the front.

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    Quote Originally Posted by ucfbrett View Post
    I didn't think 911s suffered from understeer.
    They are tuned for understeer from the factory to combat the inherent imbalance. The newer generations use electronics to do a lot of the stability control near the limits of adhesion. The 911 has always required a keener awareness of weight transfer than in other platforms.
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    Quote Originally Posted by emilio700 View Post
    The 911 has always required a keener awareness of weight transfer than in other platforms.
    This is also what makes it such a pleasure to drive at the limit. It's got VERY pronounced forward-transfer oversteer, and conversely, rear-transfer understeer. Really great for high-speed corners and kinks -- off-throttle behavior really becomes an additional steering input.
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    Quote Originally Posted by emilio700 View Post
    They are tuned for understeer from the factory to combat the inherent imbalance. The newer generations use electronics to do a lot of the stability control near the limits of adhesion. The 911 has always required a keener awareness of weight transfer than in other platforms.
    Imbalance? I suppose you think 50/50 is the proper ratio. I'll take a rear-engined car over a front-engined car any day.

    Also, all modern expensive performance cars have nannies to save idiot street car drivers from themselves.
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    Quote Originally Posted by winders View Post
    Imbalance? I suppose you think 50/50 is the proper ratio. I'll take a rear-engined car over a front-engined car any day.

    Also, all modern expensive performance cars have nannies to save idiot street car drivers from themselves.
    You are comparing rear-engine Porsche to entirely front engine car like an Audi? Personally I prefer the engine in the middle like a Corvette or a Ferrari 458.
    Yes hanging the engine off the back is inherently unbalanced. Porsche has tried to move forward from the 911 without success. You diehards believe in the platform despite its inherent imbalance and just keep buying them. Please don't cite race victories as proof that the platform is somehow superior to mid engine.
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    Now you are just making stuff up. I never said rear engined was better than mid-engined. Oh, the Corvette does not have the engine in the middle just because most of the mass is behind the front wheels. No one in their right mind would say a Corvette C7 had it's engine in the middle. The best place is the engine in front of the rear wheels and behind the driver. A 40/60 front/rear weight distribution is near ideal. The problem the 911 has is its polar moment. Front engined cars have other problems that are harder to get around. That's why the 911 has been such a success on the race tracks. It excels at getting the power down AND is notoriously great at braking.

    I would prefer to have the engine just behind me....but I would rather have the engine all the way in the back versus in front of me.
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    Quote Originally Posted by winders View Post
    Now you are just making stuff up. I never said rear engined was better than mid-engined. Oh, the Corvette does not have the engine in the middle just because most of the mass is behind the front wheels. No one in their right mind would say a Corvette C7 had it's engine in the middle. The best place is the engine in front of the rear wheels and behind the driver. A 40/60 front/rear weight distribution is near ideal. The problem the 911 has is its polar moment. Front engined cars have other problems that are harder to get around. That's why the 911 has been such a success on the race tracks. It excels at getting the power down AND is notoriously great at braking.

    I would prefer to have the engine just behind me....but I would rather have the engine all the way in the back versus in front of me.
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    Quote Originally Posted by Bongo View Post
    a 997 with heavy rear-end damage... <snip> ...Then I noticed that the rear tires were all-seasons... and the fronts were racing slicks.
    I'm surprised no one suggested yet that the front slicks might be the very reason the rear end is heavily damaged.
    I can certainly see this being the case.

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    Quote Originally Posted by Blackbird View Post
    I'm surprised no one suggested yet that the front slicks might be the very reason the rear end is heavily damaged.
    I can certainly see this being the case.

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    Quote Originally Posted by emilio700 View Post
    Tasty koolaid
    Like your flavor is any better than mine!
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    Quote Originally Posted by Blackbird View Post
    I'm surprised no one suggested yet that the front slicks might be the very reason the rear end is heavily damaged.
    I can certainly see this being the case.
    Isn't it obvious? The rear was heavily damaged and the front end had slicks. The rear had slicks too but those wheels didn't survive the crash. Those wheels and tires are elsewhere.....they just threw on a different pair of rest wheels that just happened to have all-season tires on them to make the car easier to move and sell.
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    Quote Originally Posted by winders View Post
    Like your flavor is any better than mine!
    Oh but it is.

    Engine within the wheelbase FTW
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    Weight distribution is what matters most, making the exact location of the motor almost irrelevant but for packaging concerns. That said, you arent going to see a 40/60 distribution with the motor in front of the driver. In any case, front engine platforms still manage to be competitive, so apparently its all academic within the current rule set.
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    That inaccurate, PMOI can bite you pretty hard even if static weight dist seems okay.

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    Quote Originally Posted by SDSUsnowboards View Post
    Weight distribution is what matters most, making the exact location of the motor almost irrelevant but for packaging concerns. That said, you arent going to see a 40/60 distribution with the motor in front of the driver. In any case, front engine platforms still manage to be competitive, so apparently its all academic within the current rule set.
    Dirt cars can hit 40/60 with the engine up front.

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    Quote Originally Posted by Blackbird View Post
    That inaccurate, PMOI can bite you pretty hard even if static weight dist seems okay.
    What is inaccurate?

    Practical experiment. Go to the grocery store and observe the shopping kart. Everything you load in that cart is between the wheels, resulting in excellent PMOI in theory. Now, grab two or three 12-packs of soda and stack them in the front. They are right behind the front wheels. This is your "front-mid engine" car like a St00K or Vette. Grab the front of the car and pull it around, and feel how it steers. Now, put those sodas in the rear. They should be right in front of the rear wheels. This is your NSX, or your Elise. Grab the front of the car and steer it around. Then tell me weight distribution is not the most important thing.

    Quote Originally Posted by robburgoon View Post
    Dirt cars can hit 40/60 with the engine up front.
    Interesting, and I stand corrected. Any examples I can look at? I'd like to see how they are packaged.
    Last edited by SDSUsnowboards; 07-08-2016 at 04:16 PM.
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    Your grocery example isn't quite right, you need all four wheels on casters or none of them on casters, then retest pushing sideways from front and rear.

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