panhard vs wattlink vs wishbone?

[LILBuzzy]

Originally Posted by 5280/4

Lateral-dynaimcs 3 link uses triangulated lower links with a center upper link and a watts. With triangulated lower links part of the roll center is defined by the intersection point.

i guess that is the type set up i am trying to do. just playing around with some ideas now. thanks for the input.

[exwestracer]

Originally Posted by LILBuzzy

i guess that is the type set up i am trying to do. just playing around with some ideas now. thanks for the input.

The lower links on the Lateral Dynamics setup aren't really "triangulated" either. The angle in the lower links comes from the forward pivots being relocated slightly inboard for tire clearance.

For all intents and purposes, we could consider those "straight" links.

Just posting this to try and help any confusion with the Satchell design.

[LILBuzzy]

Originally Posted by exwestracer

The lower links on the Lateral Dynamics setup aren't really "triangulated" either. The angle in the lower links comes from the forward pivots being relocated slightly inboard for tire clearance.

For all intents and purposes, we could consider those "straight" links.

Just posting this to try and help any confusion with the Satchell design.

Thanks again. I guess triangulated is too far fetched of a description. They are merely angled. I don't mind stealing knowledge though.....so keep on educating me.

[exwestracer]

Originally Posted by LILBuzzy

Thanks again. I guess triangulated is too far fetched of a description. They are merely angled. I don't mind stealing knowledge though.....so keep on educating me.

I just grabbed this picture off the net, but it illustrates the main concern with a true triangulated link suspension.
http://www.akfabshop.com/alaskaoffro...k_Topangle.jpg

In this case, the upper links are the lateral locating device. There is no Panhard bar or Watts, etc. It is the angle between the links that holds the rear axle in place. The wider the angle (red lines), the better the job the links do of controlling side motion. That's why most factory setups are close to 90deg included angle. BUT, this leads to short upper link length, lots of pinion angle change, and a lot of bushing bind in roll. Narrowing up the angle (green lines) frees up the suspension in roll, but does a poor job of keeping the housing firmly in place under side load. In a "lateral-g" car this is far more important than free movement, as travel and roll angles are purposely limited (low ride height and flat cornering). 60deg is the typical minimum included angle for a street vehicle, closer to 90deg would be better.

The intersection of the links does define the roll center in height and location relative to the axle housing. That is one reason I personally am not a big fan of the "reversed" triangulated links (narrow at the front).

Now, back to the lower links... As I mentioned earlier, ideally we would like to keep the lower links as straight (to chassis centerline) and level to the ground as possible. The bigger the tires and engine (torque output), the more important this becomes, regardless of what we are doing with the upper links. The more the lower links are triangulated, the more the "push" from the rear tires/axle is going to try to move the housing around. It may not actually move, but the loads on the link pivots, Panhard bar, etc. go way up; especially when we have a difference in rear tire loading (like accelerating out of a corner?). Combine that with the roll center being low and located way ahead of the axle centerline, and you have the potential for a lot of "monkey motion" from the rear tires during hard use.

Now for my disclaimer...people do all of these "bad" things with suspensions all the time, and enjoy the hell out their cars that way. I believe that designing these problems out from the start gives the driver a better seat of the pants feel and makes the car more consistent, easier to tune, etc. Bottom line is, build it safe, drive it, and have fun...

[LILBuzzy]

that's deep. and i thought explaining photosynthesis and respiration to my freshmen was a job!