Can I get a visual aid on what "5 link" means?

[Bugpac]

Originally Posted by minibajaman

Once you put it in SW you will understand my point better. The "4 link" version will not be able to move.


That's true, it's not accurate because there will be 0 travel.


I don't have the exact dimensions handy but my personal buggy is very simple. Trailing links are about 24" long, pivots about 5" apart. Toe links are about 16" long, pivots 5" apart. The upper toe link to lower toe link pivot on the frame side is 4.5" to get some camber change. Otherwise there is no funky geometry. Total travel is 13", about 4" droop travel.


It doesn't really matter because there is no possible practical configuration that will work in SW.

I estimated 1" for flex... with a fat guy jumping up and down on it...

[atomicjoe23]

I've run into a slight problem modeling in SW. . .I'm new to the program so I haven't figured everything out yet.

I started out by modeling an XM-8 (1/2"-20 TPI) rod end ball and the shank & housing. . .and once I started trying to assemble the ball and housing I could make them concentric with each other, but that doesn't allow any angularity in the assembly, and it seems that you can't select the center of a space to make them vertically and horizontally aligned to hold the ball inside the housing.

I also don't know how to constrain the ball to a realistic angularity of 12* (w/o high misalignment. . .I haven't modeled that part yet, maybe I should and that will help some. . .I'm not sure, the reason I didn't model any HMA's is that it didn't look like the buggies in the pic's were running any).

Anyway. . .I'm not giving up on doing this (if for no other reason than to figure more stuff out in SW's and to get some experience modeling a suspension system) but it might take quite a bit longer than I thought just because I'm not super experienced in SW's yet and don't fully know how to mate all the parts together properly.

[minibajaman]

You can get solid models of the Aurora rod ends right off their website which is a real time saver if you use a bunch of different size rod ends, or changes types as you design things. It also ensures the models are accurate when you are dealing with tight clearances.

There is really only one way to assemble a rod end in SolidWorks so that it can move properly. I put the rod end body onto my suspension arm or link. Then I put the rod end ball on the frame or upright. You can then mate them together either with the spherical surfaces of the ball and socket, or put an origin point at the center of each and mate those two points. Either of those mates will allow full freedom of the joint. There is no practical way I know of to limit the travel of the ball. You have to just move it around and look at each rod end to make sure they are not binding. You cannot assemble the rod end first and then put it in your main assembly as it will not move. Only components mated in the top level assembly can move, parts mated in sub-assemblies can not move with respect to each other.

[atomicjoe23]

Thanks for the tips minibajaman. . .I like the point of origin. . .sounds better to me.

[bdkw1]

One major item not listed in the pro-con section. Axle plunge.

Trailing arms - plunge
A-arm - no plunge
5 link - no plunge

Well, almost no plunge if designed correctly. Low enough numbers to use non-plunging CV's and let the stars deal with what little there is.

Other downsides not list......

3-link - massive toe changes through suspension cycle.

[atomicjoe23]

Be very careful when dealing with any suspension which allows axle plunge and relying on the CV stars to allow for the plunge. . .you need to make sure that you have covered all your bases and accurately determined your plunge and that you aren't going beyond what the CV can accomodate.

We pulled our CV's out of the housing (past the retaining clips) because of this. . .and we had built splined, plunging drive-axles to accomodate for axle plunge so that we could get all of the travel that our suspension would allow before the CV's reached max. angularity. It turned out that it was easier for the CV's to move than it was for the axles to extend and the retaining rings just weren't up to the task of holding the CV's in under that kind of stress.

[atomicjoe23]

Minibajaman. . .would it be possible for youto post up some more pic's of your buggies rear suspension.

I'd like to see what the area around the rear hub looks like. . .a shot of the rear tire from the middle of the chassis. . .I would like to see your wheel side mounts for your rear suspension links.

Thanks!

[LiveWire]

Originally Posted by bdkw1

3-link - massive toe changes through suspension cycle.

The toe change can be minimized with proper design. The effort of this is why I said I would not suggest for a one off.

If the front pivot of the radius arm is inward of where the lateral links mount, it forms a small pivot arm looking at it from the back. Rotating the radius arm then causes the tire to toe in above and below straight. The camber change during travel causes the rotation. That effect can be made to counter the toe out caused by the arc of the lateral links in relation to the fixed front point of the radius arm.

Plunge can be minimized with a 3-link. The lateral links end up longer than the axle. The forward pivot of the radius arm, the CV joint and the two lateral link ends for both respective ends should all be in the same plane.

I know of two production cars that have the forward pivot directly in front of the later link mounting points and therefore would have massive toe change.

[Bugpac]

Drakart 3 link is not know to have massive toe change like a king or something, the design is there, someone spent time to figure it out...