Author Topic: 3 link a arm suspension application. One more time. (Read 8624 times)

Rick S. · « **Reply #30 on:** March 29, 2009, 10:10:15 PM »

Great explanation!
I agree. I like your last sentence. I got jumped on about the 2D comment when I made a similar one on MBN. For some reason most 3D buggy guys don't understand the value of 2D cad. Almost Every 3D designer I work with has an Autocad session running in the background for quick geometry problems.

Engineer · « **Reply #31 on:** March 29, 2009, 11:40:19 PM »

Thanks Rick.

I thought twice about adding the 2D comment. I figured that I would get some flak.

trojan · « **Reply #32 on:** March 30, 2009, 01:07:54 AM »

I'm a little tired of the constant implication, that because I have honest questons (no one here can answer), I "just don't get it".
Don't think for a moment I don't understand what's going on here.
I was after the mathematical expression... coz that's the way I roll - proof not faith

Engineer · « **Reply #33 on:** March 30, 2009, 01:31:14 AM »

Sorry Trojan, wasn't meaning to imply anything.

The math to crunch out and solve for that point would be very complex.

The Cad is doing the math with quite a bit of operator input.

And since you are raising the question, with an unequal length, non-parrallel arrangement, the sweet spot isn't sweet at every point of the travel. The method that I described is "perfect" at the three points of travel that you input, but not necessarily in between. That is why I think that a mathematical expression would be hard to arrive at because your answer has to be limited to certain points of the travel etc.

trojan · « **Reply #34 on:** March 30, 2009, 01:55:57 AM »

Integration, trigonometry & limits

Engineer · « **Reply #35 on:** March 30, 2009, 08:15:10 AM »

Quote from: trojan on March 30, 2009, 01:07:54 AM

I'm a little tired of the constant implication, that because I have honest questons (no one here can answer), I "just don't get it".

I told you honestly that I couldn't (wouldn't spend the time to) do the math.

I layed out an alternative method that many builders have access to.

I never implied that you didn't get it.

I layed out as much info as possible because other people have the same question, and understand much less than you.

I responded to you question because it was the only one that basically asked "how".

Quote from: trojan on March 30, 2009, 01:07:54 AM

Don't think for a moment I don't understand what's going on here.

Either this means that there is a vast link mounting point conspiracy, or that you already knew the cad method?

Quote from: trojan on March 30, 2009, 01:07:54 AM

I was after the mathematical expression... coz that's the way I roll - proof not faith

Ahhhh....... You did say that to begin with.

Quote from: trojan on March 30, 2009, 01:55:57 AM

Integration, trigonometry & limits

Good Luck!!

Camel · « **Reply #36 on:** March 31, 2009, 11:32:23 AM »

Proof of concept, work in progress.....

Rick S. · « **Reply #37 on:** March 31, 2009, 03:34:09 PM »

Doesn't proove anything yet.
Is this why you say work in progress?

Camel · « **Reply #38 on:** March 31, 2009, 05:19:59 PM »

Uh huh. I can get into it again on Sunday. I want to find the optimum locations for the front pivot(s). Solidworks would certainly help.

Rick S. · « **Reply #39 on:** March 31, 2009, 08:41:01 PM »

It should look pretty sweet with the link shown moving in the cone shaped arc.

Doug Heim · « **Reply #40 on:** March 31, 2009, 09:04:56 PM »

And it should prove its function to anyone still in doubt and be a great refrence to those who want to understand how it works. Great work, Cant wait to see it.

Admin · « **Reply #41 on:** April 02, 2009, 12:06:07 PM »

Less toe change, more arc to rear links....

Camel · « **Reply #42 on:** April 14, 2009, 05:22:45 AM »

Here's a video showing how, on a standard barracuda, you can fit a reinforcing strut from the upright forward to another pivot point on the chassis. Like as has been said a few times here, you just need to find the correct point to mount the pivot points.

Camel

fabr · « **Reply #43 on:** April 14, 2009, 08:44:30 AM »

Quote from: Engineer on March 30, 2009, 01:31:14 AM

Sorry Trojan, wasn't meaning to imply anything.

The math to crunch out and solve for that point would be very complex.

The Cad is doing the math with quite a bit of operator input.

And since you are raising the question, with an unequal length, non-parrallel arrangement, the sweet spot isn't sweet at every point of the travel. The method that I described is "perfect" at the three points of travel that you input, but not necessarily in between. That is why I think that a mathematical expression would be hard to arrive at because your answer has to be limited to certain points of the travel etc.

The reason it can't be done mathmatically is due to the FACT that there is a sweet SPOT and not a sweet POINT. The SPOT is a group of POINTS in a very small SPOT that allow it to work with negligible deflection/bind.

trojan · « **Reply #44 on:** April 14, 2009, 01:02:02 PM »

Fab:

Quote from: trojan on March 30, 2009, 01:55:57 AM

Integration, trigonometry & limits

Will actually define the "spot", and it'll read like "For all values of X, such that theta is less than C and greater than B, blah blah bla...." Like Eng said, it's not easy but it is doable