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There are a few guys on Priate4x4.com that have been developing a program to analyze 4-link suspension designs and they're requesting some help/feedback. I think this link has been cross-posted before, but I thought some of you guys might have some good/helpful information to contribute.
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Should be noted that the reason they're asking for input is that there is a new version out. They're not just on PoOR, they're also on cK5.com and OFN.
TS
My opinon is worth what you paid me for it.
That's why I posted it, but forgot to mention it. Have you played with it? Any thoughts?
Not the latest version. Downloaded it, but haven't had time to crack it open.
Here's the link: ExcelCAD 3.0
TS
My opinon is worth what you paid me for it.
Didn't we look at this before? As I recall...the squat was highly questionable.
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ok i have been playing with this program for fun and using the stock frame measurements from my truck it is hard to keep the antisquat % under 100, the roll axis in the negitive, and the instant center close to the front of the truck, all at the same time. getting 2 of the 3 is fairly easy. so does anyone have any input as to which of those variables is the most important to try and acheive? what happens when the roll axis in the positive? what happens when the instant center is way out in front of the truck? here are some numbers i got.
Geometry Summary:
Anti-Squat 31.393 %
Roll Axis Slope -0.0171 in/in (Roll Understeer)
Roll Center Height 27.233 in
Roll Axis Angle -0.978 degrees (Roll Understeer)
Instant Center X-Axis 529.765 in
Instant Center Z-Axis 38.412 in
this is mostly just me being curious more than anything.
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As a side note to all this link stuff, Rob Park, "Tin Bender" on Pirate 4x4 now works in my race shop as my lead fab guy and we were discussing how some people try to make comparisons between crawlers and off road trucks today. He and I feel that they have about as much in common as a 1/2 pick up and a Kenworth.
If you are trying to use crawler parameters to build a race truck, you are going to be really misled.
Josh
Designs will be similar, design tools can be the same, design goals are different.
Somewhere in the middle are the street driven trucks.
Percent Anti-Squat makes no sense to me. Define 100% AS, then tell me what 50% means and what 150% means.
TS
My opinon is worth what you paid me for it.
According to what they've said, I believe 100% means you have 100% resistance to squat. Zero lift, Zero Squat. Over 100% means the suspension lifts and under 100% offers some resistance to squat. Basically a system with 75% resists squat more than one with 25%. Hopefully this makes sense.Originally Posted by ntsqd
Like Matt I've been playing with this a bit too, combined with Lower Links 101 I've been able to figure out a bit about geometry of link systems, etc. It's a cool little program to mess around with.
"He is the Michael Jordan, Michael Shumacher of off-road.... Fish is Money! Fish is Money!"
Rock Crawlers and off road race cars are totally different. This program doesnt give you any magical answers of how to build your link suspension, it is just a tool to analyse the characteristics the suspension will have (before you build it) and to compare different configurations. You can take your stand back, tilt your head and squint aproach to link suspension design, and define the caracteriscs of what works for you, so you can apply it to a different chassis configuration.
ntsq: 100% anti means that all the weight transfer is carried by the suspension links and none to the springs, so the suspension will not deflect when accelerating or braking. 0% anti means all the weight transfer is carried by the springs and the suspension will deflect proportion to the wheel rate. More than 100%, suspenion will lift, less than 100%, suspension will squat.
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