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Discussion Starter #1
I have read all I can about anti squat and every thread seems to have a different anwer regarding what nuetral squat is. I understand that it is a personal thing, but what is the final answer? is Nuetral Zero, 50 or 100%. This should only be a small calcualtion, in the grand scheme of things, but everyone seems to have thier own interpretation of this illusive number.
 

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Just as confused as you are, and I will be watching this thread for the definitive answer. :confused:
 

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from what I understand, 100% is "neutral". I've setup my rear suspension with a 75-80% antisquat value, which should allow both good flat running and good uphills.

Hopefully, someone smarter than me confirms this tho.....
 

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I to have read everything that I can find, so much my eyes hurt. I think 100% is neutral, but then I found some 4 link plans drawn on cad and it had a 62% anti-squat value and it was said to be a better design than a simmilar one with an AS value of 82%! Go figure!
 

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woody said:
from what I understand, 100% is "neutral". I've setup my rear suspension with a 75-80% antisquat value, which should allow both good flat running and good uphills.

;)
 

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Discussion Starter #6
as far as I can figure, if CG is not calculated accuarately, then your % may vary. I guess what I am looking for is a range.

eg: 52-72% anti-squat is the sweet spot with the higher % allowing less squat. ( or is this wrong too?)

So when you go over 100% what happens?

This is like drinking JD. It kills brain cells that trickle down your spin and collect in your ass, giving you that plumbers crack look:D
 

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Since most are estimating the COG height, anywhere from 75-125 is what I'd shoot for. Mine has 104% with estimated sprung cog height of 36". What does everyone else use for COG height?

CJ
 

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That COG is the killer. Determining it isn't hard. Where is it on a rig that isn't built yet? There will be lots of differnces between my old rig and my new one like spare tire placement, fuel cell etc that can change the COG!
 

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Discussion Starter #9
exactly my point about CG. I am revamping the rear of mine, cutting the rear off including frame, moving the tank behind the seat and the axle back 14". My guess is the hieght of the cam shaft and approx knee location ( forward and aft)

Still......this doesn't answer ............." what does the % of anti squat mean?

If 100 is Nuetral , why would 75 - 125 work? If less than 100% is anti Squat, wouldn't over 100% make it squat?
 

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mudlite said:

Still......this doesn't answer ............." what does the % of anti squat mean?

If 100 is Nuetral , why would 75 - 125 work? If less than 100% is anti Squat, wouldn't over 100% make it squat?

Reword your last statement backwards and you will have it correct:

less than 100%: prone to squat on power

100% neutral

more than 100%: prone to jacking on power (anti-squat).

Static (ride height) values are nice to compare, but the CG accuracy is questionable, and the dynamic change in the IC (to calculate AS%) is as much or more important.

Happy Trails!
 

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(sprung cog height * IC position)/ (wheelbase * IC height)
this is what you all are using, correct?
ok what if you move your weight rearward at the same height that would definately change results but not with this formula.
ya'll remember that if it is neutral on flat ground then it is going to be a much higher percentage when you start climbing.
100% antisquat is when the suspension makes exactly enough force to overcome the weight shift from acceleration to keep it from squating.
 

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Discussion Starter #14
That makes sence when 100% is Neutral, so why would you want less than 100%? Wouldn't that take weight off the rear tires in the process of making it Squat? Or is it adding force onto the tires by bringing the rear down???????


Another brain cell trickled down my ass crack!!!!!


Ed A. Stevens said:



Reword your last statement backwards and you will have it correct:

less than 100%: prone to squat on power

100% neutral

more than 100%: prone to jacking on power (anti-squat).

Static (ride height) values are nice to compare, but the CG accuracy is questionable, and the dynamic change in the IC (to calculate AS%) is as much or more important.

Happy Trails!
 

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mudlite said:
That makes sence when 100% is Neutral, so why would you want less than 100%? Wouldn't that take weight off the rear tires in the process of making it Squat? Or is it adding force onto the tires by bringing the rear down???????

It may look like you are adding weight to the contact patch when the body is squatting but you are actually losing traction. Think of it as the axle going up instead of the body coming down. There are problems associated with a lot of anti-squat such as tires hopping on acceleration and jacking forces.

The amount of antisquat you have just determins how much weight gets transfered through the links and how much gets transfered through the springs. Don't run too much anti-squat(or a lot with a limiting strap?) and you'll be fine.

CJ
 

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Discussion Starter #16
75-125 seems to be a high range? This goes from anti-squat into squat. So if less than 100% looses traction, why wouldn't people go for the +100% range?

Lets put it this way. At what % does this become an issue? When is there too much dive and too much lift?

Is the difference between 62% and 80% splitting hairs?
 

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mudlite said:
75-125 seems to be a high range? This goes from anti-squat into squat. So if less than 100% looses traction, why wouldn't people go for the +100% range?

Lets put it this way. At what % does this become an issue? When is there too much dive and too much lift?
Because there are handling/performance issues when you run a lot of anti-squat. The reason I said 75-125 was because you only have an approximation of your COG. If you knew the exact value you could build the suspension with 100% and be done with it. 75-125 will get you close. Remember, its not that you are losing traction below 100% because you are still driving the tire into the ground. 75% would probably work awesome, will 100% work better? Hard to say....

Some(a lot) people run a lot of anti-squat and put a limit strap between the axle and the body. The limit strap is a great idea but running tons of anti-squat is questionable. Since you are driving the tires down, the body will rise with a lot of antisquat which is bad.

I used to have about 180% in my rear suspension and it caused the tires to hop on hard acceleration. It was really noticable in sand when you were trying to spin the tires or doing burnouts in my culdesac :flipoff2:
 

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I agree with targeting a range, because not only is your CG height an estimate, but on climbs, the effective CG will change, and limitations on your suspension may limit where exactly you put your links.
 

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From my limited understanding of it AS is not only effected in terms of relation of the IC and CG on a vetical plane but also on a horizontal plane. Depending on if the IC is forward or aft of CG will effect percent of rise and your ability to climb hills. This will be dynamic as the suspension loads up when you first start climbing but later level out after you're into the climb and the suspension starts settling.

I'm sure I could be more vague if I truely had a grasp of the whole concept. :flipoff2:
 

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mudlite said:
That makes sence when 100% is Neutral, so why would you want less than 100%? Wouldn't that take weight off the rear tires in the process of making it Squat? Or is it adding force onto the tires by bringing the rear down???????


Another brain cell trickled down my ass crack!!!!!


When you see force on a spring, believe your eyes and expect a force to be present.

Any time a corner spring compresses, the tire and chassis corner experience the same force.

As an example, 600# of additional force to compress the spring when squatting, from weight transfer, is also 600# of force driving the tire into the ground (helping traction). This extra traction can be good.

The problem with too much squat is not the loading of the tire, but the effect when the stored force in the spring eventually unloads, hop/slip. The hop/slip loss of traction is induced by the reduction of force, when the tire formerly loaded by throttle & traction from (what was) best traction with the extra weight, returns to less ideal traction without the weight transfer. The loss of traction occurs faster than a good throttle foot can react (and we as drivers spin the tires and generally make things worse).

When the squat force compressing the springs unloads (because you lift the throttle or the tire slips) the extra traction from the squat compression is quickly removed, making traction difficult to control.

This is where dampening is needed, to reduce the quick unloading of the springs and forces that make traction and throttle control difficult. When you run significantly less AS% than 100%, you tend to need stiffer rebound dampening to prevent the shock of off-throttle induced loss of traction (hop/slip).

The problem with relying on dampening for traction control is that dampeners (shocks) only work when shock travel movement occurs (you have to have shock or wheel travel to have dampening). A secondary problem is that the tire deflection from suspension loading is also a spring, and with a tall sidewall (like a drag slick or an off-road flotation aspect ratio) it's difficult to dampen the tire height deformation and rebound. The race suspension textbooks try to eliminate tire deformation, or ignore it, by running low aspect ratio tires (to go fast on smooth pavement) and they limit suspension movement to minimize radical dynamic changes in suspension geometry that can upset the system and tire contact with the ground. When we drive off-road suspension movement is beneficial to traction but it has to be balanced out with tire contact and driver control, making a the design of a good off-road suspension much more complicated than many pavement racers (IMO).

Make note that driver control is critical, regardless of suspension design quality, and that some of us may never drive like the competition winners.

--

The process of isolating what to tune for an individual design, is one of the aspect of the suspension/springs/and shock discussions on the PBB that I appreciate. As individuals learn the impact of one design parameter (AS%, or roll axis/center height) they begin to learn springs have something to contribute to the resulting ride (that is different for various AS% IC's and ride heights), and then once the vehicle moves there is a need for dampening (which is, again, different for various AS% IC's and ride heights). Then weight changes, as does tire heights and speed, and the process of finding what works best begins again.

This process of almost thinking you/we/I (now) know what makes the best suspension (and achieved "God of Supension" status), just to learn there is more to the process than just idealizing one parameter is true enlightenment. Realizing there is always more to learn (that there is no "Suspension God" status to be had) is something I appreciate. I also like that you guys keep making me relearn long lost concepts (with a much better understanding than what I had in the past), and how the younger members can apply computer technology to the modeling (I am from the "measure with micrometer, mark with chalk, and cut with a axe" era of design analysis and execution).

CJ Lagos, for some reason the PBB PM feature does not work for me (maybe it needs enabled by a webmaster, or I need a red star for it to work)?

Happy Trails!
 
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