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Re: What chassis are you running ?
Posted by 'davidmc' on 29 Mar 2011 @ 11:06

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davidmcJoined: April 2003
Total Posts: 2
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Itpro,

1) Read what is written, not what you think is written. At no stage have I stated that a kart is steered through the duration of the corner. I've driven long enough and even managed to win a couple of tin pots to know that. All I have stated is that for an infinitely stiff kart, the inside rear can only lift whilst there is steering lock applied.

2) I discussed flex as it is the natural progression from the infinitely stiff kart, that must have steering lock applied for the inside rear to lift, to what we have now, where the steering lock induces the lift, and the flex maintains it. When the steering is returned to the dead ahead position and the inside rear sets down too early, the kart understeers all the way to the exit.

3) Whilst turning (not the wheel but the kart), there is nothing like an even distribution of load across all four wheels. Load is predominantly on the two outside tyres. Yes, the tyres have a slip angle (they have to, since that's the way all tyres generate cornering force) but again, when the steering is returned to dead ahead, if the inside rear sets down too soon, you understeer all the way to the exit. Flex, especially at the waist of the chassis, maintains this lightened inside rear.

4) All of the quick guys, when grip levels come up, will have their seats scraping the circuit at many points. They are already as low as they can go. Again, read what is being written. It is quite possible, especially in cadets but other classes also, to get to the point where you cannot go any wider, any lower, drive any better, lose any more weight, alter anything else etc etc, to deal with the extra grip effectively. What do you do then?

5)The axle doesn't have to flex much to maintain grip. Again, read what is written. By allowing the axle to flex more, the grip of the outside rear is INCREASED and the kart stops hopping. All the drivers walk around saying the grip has DECREASED because the hop has gone away but the opposite has happened. Why is the grip increased? Because it only has to flex enough to maintain the contact patch at the outside rear a little better. Much of the angle seen when hopping is caused by momentum of the system. The outside rear had broken away long before that angle was reached.

6) Further, I'm not sure you do understand what I'm saying about a rotating axle being similar to a mass, spring, damper system. The frequency of the system does not change (it is defined by rear axle speed (revolutions)). Take the mass, spring, damper system and fix the frequency of the oscillations (rear wheel revolutions), the mass (load on the outside rear), the spring constant (Youngs Modulus of steel) and the only thing left to alter is the damper (the axle "stiffness"). Increase the damping enough and the amplitude of the oscillations (flex) decreases.

7) When you get to the front of the grid everybody has already done all those things that make a bigger difference. All the drivers can drive, all the drivers are physically fit, all the drivers are mentally prepared, all the karts are well setup, all the carbs and engines are at optimum. It's then the tiniest things that can and do make a difference.

Whilst many of the quick guys may make up pseudo-scientific reasons for things being quicker (axles, seats etc), generally speaking, they've gone through the process of testing and those things have made them quicker, regardless of the reasoning behind it. It may be less than half a tenth, but half a tenth over 20 laps is enough to win by 1 second; a margin not uncommon in karting.

Message Thread:

Hard or soft axle? by 'SteveAW' (28 Mar 2011 @ 18:06)

What chassis are you running ? by 'ScoobyScene' (28 Mar 2011 @ 18:23)

Re: What chassis are you running ? by 'SteveAW' (28 Mar 2011 @ 18:33)

Re: What chassis are you running ? by 'MikeMcMahon' (28 Mar 2011 @ 23:11)

Re: What chassis are you running ? by 'itpro' (28 Mar 2011 @ 23:35)

Re: What chassis are you running ? by 'davidmc' (29 Mar 2011 @ 0:06)

Re: What chassis are you running ? by 'itpro' (29 Mar 2011 @ 0:29)

Re: What chassis are you running ? by 'davidmc' (29 Mar 2011 @ 8:39)

Re: What chassis are you running ? by 'itpro' (29 Mar 2011 @ 10:19)

Re: What chassis are you running ? by 'davidmc' << You are here!

Re: What chassis are you running ? by 'itpro' (29 Mar 2011 @ 11:54)

Re: What chassis are you running ? by 'davidmc' (29 Mar 2011 @ 12:42)

Re: What chassis are you running ? by 'Rafe005' (29 Mar 2011 @ 7:55)

Re: What chassis are you running ? by 'NJB' (29 Mar 2011 @ 9:34)

Re: What chassis are you running ? by 'SteveAW' (29 Mar 2011 @ 10:05)

Re: What chassis are you running ? by 'davidmc' (29 Mar 2011 @ 10:14)

Re: What chassis are you running ? by 'chriskasch' (29 Mar 2011 @ 10:21)

Re: What chassis are you running ? by 'itpro' (29 Mar 2011 @ 10:35)

Re: What chassis are you running ? by 'BanzaiBoy' (29 Mar 2011 @ 11:00)

Re: What chassis are you running ? by 'davidmc' (29 Mar 2011 @ 11:18)

Re: What chassis are you running ? by 'QuickOldTimer' (29 Mar 2011 @ 13:10)

Rafe by 'itpro' (29 Mar 2011 @ 10:28)

Re: Rafe by 'davidmc' (29 Mar 2011 @ 11:14)

Re: Rafe by 'itpro' (29 Mar 2011 @ 12:22)

Re: Rafe by 'PaulMRotax' (29 Mar 2011 @ 12:53)

Re: Rafe by 'davidmc' (29 Mar 2011 @ 13:04)

Re: Rafe by 'PaulMRotax' (29 Mar 2011 @ 13:25)

Re: Rafe by 'davidmc' (29 Mar 2011 @ 13:38)

Re: Rafe by 'PaulMRotax' (29 Mar 2011 @ 13:44)

Re: Rafe by 'davidmc' (29 Mar 2011 @ 13:54)

Re: Rafe by 'davidmc' (29 Mar 2011 @ 12:56)

Re: Rafe by 'itpro' (29 Mar 2011 @ 13:14)

Re: Rafe by 'davidmc' (29 Mar 2011 @ 13:32)

Re: Rafe by 'itpro' (29 Mar 2011 @ 14:20)

continued.... by 'itpro' (29 Mar 2011 @ 14:24)

Re: continued.... by 'itpro' (29 Mar 2011 @ 14:41)

Re: Grip continued.... by 'John' (29 Mar 2011 @ 14:59)

Re: Grip continued.... by 'itpro' (29 Mar 2011 @ 16:13)

data! by 'BanzaiBoy' (29 Mar 2011 @ 18:40)

Re: Grip continued.... by 'John' (29 Mar 2011 @ 18:46)

Re: Grip continued.... by 'Traxtar' (29 Mar 2011 @ 18:48)

Re: Grip continued.... by 'John' (29 Mar 2011 @ 22:28)

Re: Grip continued.... by 'itpro' (30 Mar 2011 @ 10:28)

Re: Grip continued.... by 'John' (30 Mar 2011 @ 12:07)

Re: Grip continued.... by 'davidmc' (30 Mar 2011 @ 12:15)

Re: Ian ----- Grip continued.... by 'John' (30 Mar 2011 @ 15:35)

Re: Ian ----- Grip continued.... by 'Bod' (30 Mar 2011 @ 15:40)

Re: Ian ----- Grip continued.... by 'DavidMH' (31 Mar 2011 @ 13:30)

Re: Grip continued.... by 'itpro' (31 Mar 2011 @ 2:38)

Re: Grip continued.... by 'itpro' (30 Mar 2011 @ 15:44)

Re: Grip continued.... by 'John' (30 Mar 2011 @ 16:15)

Re: Grip continued.... by 'itpro' (30 Mar 2011 @ 17:34)

Re: Grip continued.... by 'John' (30 Mar 2011 @ 22:03)

Re: Grip continued.... by 'QuickOldTimer' (30 Mar 2011 @ 22:22)

Re: Grip continued.... by 'John' (30 Mar 2011 @ 23:33)

Re: Grip continued.... by 'QuickOldTimer' (30 Mar 2011 @ 23:55)

John... by 'itpro' (31 Mar 2011 @ 2:22)

Re: Ian... by 'John' (31 Mar 2011 @ 5:31)

Re: John... by 'itpro' (31 Mar 2011 @ 11:11)

Re: Ian... by 'John' (01 Apr 2011 @ 0:32)

Re: John... by 'itpro' (01 Apr 2011 @ 1:19)

Re: continued.... by 'PaulMRotax' (29 Mar 2011 @ 15:42)

So what about tyre graining? by 'SteveAW' (29 Mar 2011 @ 17:48)

Re: So what about tyre graining? by 'itpro' (29 Mar 2011 @ 18:21)

Re: So what about tyre graining? by 'PaulMRotax' (29 Mar 2011 @ 18:22)

Hopping by 'NJB' (29 Mar 2011 @ 18:48)

NJB by 'Traxtar' (29 Mar 2011 @ 19:14)

Re: Hopping by 'Inter61' (29 Mar 2011 @ 19:17)

Re: Hopping....PFI by 'NJB' (30 Mar 2011 @ 11:49)

Re: Hopping....PFI by 'davidmc' (30 Mar 2011 @ 12:27)

Re: Hopping....PFI by 'itpro' (31 Mar 2011 @ 2:32)

Re: Hopping....PFI by 'NJB' (31 Mar 2011 @ 15:54)

Re: Hopping....PFI by 'itpro' (31 Mar 2011 @ 17:18)

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