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Old 02-17-2003, 08:57 PM   #1
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Default Which Kick-up transfers more weight?

I got confuse with the two books i've read, hope somebody can clear things up. When u say positive kick-up, is that the front block is higher than rear block? During off throttle will there be more weight transfer or not?

Like Surikarn's setup in S. Africa, he uses negative kickup, is that to limit weight transfer or to have more weight transfer during off throttle?
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Old 02-17-2003, 09:13 PM   #2
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i think kickup is the opposite of antidive on the front end. on the rear, it's referred to as anti/pro squat. it is the angle of the hingpins relative to the ground. negative kickup would be positive antidive or the pins should be lower at the front of the arm. this, i believe, is to minimize diving durring deccelleration . i think the weight should transfer quicker, but the magnitude should remain unaffected and the car won't pitch as much.
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Old 02-17-2003, 09:52 PM   #3
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Old 02-17-2003, 11:32 PM   #4
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Default Which Kick-up transfers more weight?

Front Kick-up and Anti-Dive are one and the same. It is when the Front of the hinge pins are higher than the back (for the same pins).
In the back of the Car/Truck, it is the Rear of the pins that is adjusted giving Anti-Squat.
Did I make any sense ??
For more rear bite (traction), remove Anti-Squat in the Rear of the Car/Truck. I cannot say if Anti-Dive in the Front will effect Rear bite. Maybe someone else will know.
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Old 02-18-2003, 12:00 AM   #5
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Default Re: Which Kick-up transfers more weight?

Quote:
Originally posted by Wilfred
I got confuse with the two books i've read, hope somebody can clear things up. When u say positive kick-up, is that the front block is higher than rear block? During off throttle will there be more weight transfer or not?

Like Surikarn's setup in S. Africa, he uses negative kickup, is that to limit weight transfer or to have more weight transfer during off throttle?
You are correct to say that kick-up has the forward block higher than the rear block of the front hinge pins. When you are off throttle, the car's momentum will continue forward, but since you are off power the weight that was transfered to the rear will now transfer forward causing your front suspension to load as you dive into a corner. Kickup, which is the same as anti-dive, places a counter force against the weight transfer to the front, in effect trying to keep more weight at the rear as you are off power. Also keep in mind the amount of weight transfer is dependent on the spring rates of the front and rear shocks. Try not to confuse the degrees in the kickup from the degrees in the caster. In Surikarn's car with negative kickup, the forward blocks are lower than the rear blocks on the front hinge pins. This promotes alot more weight transfer to the front while off power.
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Old 02-18-2003, 12:38 AM   #6
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how about -2degree rear kickup and 0 degree front kickup?
what would the effect be??
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Old 02-18-2003, 05:41 AM   #7
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Kick-up(anti-squat) in the rear will affect the car on acceleration. The more you have the less weight will be transfered to the rear tires. So if on power you have a push coming out of turns adding some kick up in the rear will limit the amount of wieght transfer and take away some of the push.

In the front it will affect it on off-power turn in. If you are oversteering when entering a corner adding some kick-up to the front will limt the weight transfer to the front tires, taking away off-power steering. If you need more off power steering you can take away some kick-up(negative) to gain steering when entering a corner.

I use these as a fine tuning aid to get the car dialed. TTYL.


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Old 02-18-2003, 08:41 AM   #8
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I aggree with seaball. The amount of forward or rearward weight transfer is unnaffected by kickup or antisquat. The speed of front to rear weight transfer is affected. If the suspension is made stiffer the forward or rearward weight transfer is quicker.

Kickup (front of front pins higher) makes the front suspension stiffer on power. This increases lateral weight transfer at the front while cornering. This creates on power push. Great for high grip tracks where you want to free up the front on power. This might make the car go through bumps better, but I have not noticed this improvement.

Negative kickup or antidive (front of front pins lower). Makes the front suspension softer on power. This gives slightly more front cornering traction on power.

Antisquat (front of rear pins higher) makes the rear suspension stiffer on power. This increases the lateral weight transfer at the rear while cornering. This makes our touring cars loose (more oversteer) on power. (It has a different effect on full size cars with live axles). Again use it when you have too much traction. The axle may unload off power and make the rear end loose.

Prosquat (front of rear pins lower) makes the rear suspension act softer on power. This tightens the rear end (less oversteer) on power and may create a push.

If you get the springs and shocks right you may find that you don't need to add kickup or antisquat unless you are on a very high traction surface. Try not to be off-power.

Last edited by John Stranahan; 02-18-2003 at 08:54 AM.
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Old 02-21-2003, 06:03 PM   #9
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Rcinfinity, Gary F. Seaball, John S.

Isnt it if during off or on throttle, there is more weight transfer if it dives or squat?

In negative kickup, during off throttle or braking, if it limit or stops your front end to dive, how can weight be transferred? Do i make sense?
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Old 02-21-2003, 06:57 PM   #10
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Wilfred.

If you add antidive you stiffen the front off-power. The car will pitch forward less, the front will be stiffer, weight transfer will be faster, but the amount of weight transfer to the front will be the same as without the antidive. More explanation below.

When a car pitches (dives or squats) The ammount of forward or backward weight transfer is affected by several things: the higher the g forces generated accelerating or decelerating, the more weight transfers; the higher the center of gravity above the ground, the more weight transfers; the longer the wheel base, the less weight transfers.

The ammount of pitch does not affect the weight transfer to any significant degree. When the front of the car dives the rear usually elevates, the center of gravity of the car remains relatively the same height.

When a car pitches forward (dives) during deceleration, a weakly sprung car (take an offroad 1/10 scale truck for example) will delay weight transfer to the front until the springs take a full set. A stiffly sprung car will have a more immediate weight transfer to the front. The amount of weight transfer is unaffected by the spring rate.

Last edited by John Stranahan; 02-21-2003 at 09:35 PM.
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Old 02-21-2003, 07:10 PM   #11
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OK here is the description of anti-squat and squat from car and driver magazine

Anti-Squat: this suspension characteristic uses acceleration-induced forces in the rear suspension to reduce squat.

Squat: squat is the dipping of a car's rear end that occurs during hard acceleration. Squat is caused by a load transfer from the front to the rear suspension.


Kick-up or anti-squat acts like having stiffer springs on accelleration, hence limiting weight transfer to the rear tires. It will not eliminate the weight transfer, just limit it.
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Old 02-21-2003, 07:14 PM   #12
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Will only limit squat. Will not limit weight transfer.
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Old 02-21-2003, 07:38 PM   #13
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http://www.geocities.com/radiocontro...geometryf.html

Check this link out, it'll help.
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Old 02-21-2003, 08:04 PM   #14
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this looks like a thread Martin Crisp should be answering

or one should just read the XXX main book on car handling.
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Old 02-21-2003, 09:20 PM   #15
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wilfred - john stranahan is dead on. weight transfer is caused by the couple produced by the force at the ground plane and the center of gravity. as long as the cg is higher than the surface, there will always be weight transfer durring accelleration, whether positive or negative. many people are too concerned with how much weight is transferred instead of how fast weight is transferred.

this is an overly simplistic analogy but....picture two bowling balls (samples) at a given elevation. both are allowed to free fall the same distance before contacting a spring at some reference level. the two springs are vastly different in stiffness rates. what will happen?

at the point that the ball has compressed the spring a maximum amount the ball is stopped for an instant. at this time the weight of the ball, and the force in the spring are equal. this is true for both samples. however, the softer spring will take a larger distance, and consequently, a greater amount of time before reaching this equilibrium force. and conversely, this softer spring will take a longer time to restore the ball back to it's original position (neglecting losses) does the fact that the ball had sunk deeper into the soft spring mean that it transferred more weight? no. it can't so what is the point?

it is this. though weight transfer to the springs are equal for both samples, the time, or RATE that the force is transferred is NOT EQUAL.

again, this was overly simplistic, but it does touch on the idea of the rate of weight transfer. in vehicles, there are more variables to take into consideration, such as roll moments of inertia, pitching moments and the momentum that they are allowed to carry which combine to make many adjustments fall into the grey area concerning their absolute benefits. even with all this theory the best advice is to gather some emperical data through testing on the track. but it is the theory that gives us insight regarding which direction to go.
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Last edited by seaball; 02-21-2003 at 09:53 PM.
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