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...Also what are some ways to find COG, Roll Center and Roll Axis and other various terms I have seen in the 4-Link discussions?
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Jason,
Have you spent any time looking at ExcelCAD v2.0?
That whole project started when I was asking these same questions about 6 months ago. I didn't understand how all the terms related to each other. Once Triaged starting answering my questions in the forums here (and through massive amounts of PMs!) I started plugging in formulas and generating some very basic spreadsheets....
As we collaborated, Dan started introducing me to more sophisticated ways to calculate things (using more real math, and fewer assumptions) and the chart continued to evolve and grow. Once it had a "graphical" component, my learning curve seemed to REALLY move quickly. I tend to be VERY visually-oriented, so when I could make changes and see the resulting changes in a suspension diagram, the concepts really started to make sense.
If I were you, I'd spend some time with ExcelCAD (it's FREE!) The hardest thing is getting used to using a coordinate (x,y,z) system to take measurements off your existing truck/buggy so that you can plug the data into the sheet in the correct format.
Some quick comments on what you can learn:
1. AntiSquat/AntiDive - Depending on your link design, these values can be all over the place. Making some seemingly minor changes to the design can "reel in" numbers that are way out of line. They are tied to the CG height (and CG is not that easy to figure out) so you still have to make SOME assumptions...
2. Loads - The stuff that Dan did for calculating loads was some of the more fascinating stuff to me. I never had a good understanding how "how much is enough" with regards to tubing thickness, rod end sizing, etc. It was always a "well THAT one looks like it won't break" kind of guess. Now with the safety factor values that are calculated, you will KNOW how well your parts will work.
BTW -> When you start playing around with the position of your end links, you will be amazed at how different the FS values can be. A well designed suspension, can get away with smaller rod ends and be just as safe as lesser designs with massive rod ends. It all comes down to vertical seperation of the links....it's not always easy to do, but if you can make the packaging work in "real life" you can save a small fortune by using the smaller rod ends!
The other thing that really helps (me at least) is mocking this stuff up in real life. (I'm visual, remember?). That experience of building a 3-link front suspension, and then building a 4-link front was priceless. There is nothing like doing something in full-scale.....being able to "cycle" the suspension....realize it has some sort of massive interference problem or geometry problem, then go back to ExcelCAD and try a new setup. Those repeated attempts are another great way to learn in a hurry..... experience is worth a lot.
BTW -> A rear multilink will be a LOT easier than a front suspension design. There's no steering to worry about and the tires won't be trying to turn and rub against your links and do all sorts of wacky stuff... I started at the front because I knew it would be the hardest, but once I get it nailed....designing the rear will be a cakewalk.
I remember talking to Dr. Watson, and he said that his rear suspension came together VERY fast once he had the experience of doing the front. I recall him saying that he designed it, built the first mock-up, cycled the suspension ONCE to confirm that everything was cool.....then he welded it up and went wheeling! /forums/images/graemlins/cool.gif (Your experience may vary.... /forums/images/graemlins/wink.gif)
Anyway, try out the program. Save a copy with your data in it and post it up....we can give you feedback and hints about what looks good, and where the concerns might be.
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