Ackermann

[mfain]

For those still thrashing with Ackermann considerations, there is a new, 6-page article by Bob Bolles in the Mar 2010 Circle Track titled "Ackermann Technology, The History, Application, and Truth About..." It offers a good technique for checking Ackermann along with an Ackermann Toe Chart, and it offers techniques on how to change Ackermann. You just have to "filter out" the techniques for the "left turn-only crowd" such as different length left and right steering arms. They don't have the article uploaded on their website yet, but that should happen soon. There is also a pretty good article on GM's new CT525, a 750 carb'ed LS3 that makes 525 hp/471 ft-lbs of torque for less than $10,000. With a different pan, it might make a good Track Day motor??

Pappy

[speedjohnston]

Thanks Pappy, I'll be checking that out.

[JRouche]

Cool!! Thanks for the tip. Ill be looking for the article when it comes online. Im still trying to wrap my head around Ackerman with my front steer. I get it with rear steer, but for some reason I cant visualize it with the front steer. JR

[Bryce]

with front steer the steering arm has to be outside the lower ball joint. Hard to do with a large offset wheel smaller than 17"

but post up a link to that article when it gets on line.

[mfain]

Guys, try this link. It has the chart for checking Ackermann. The bottom line is that if your car is not "balanced" and the outside front tire is doing most of the work in a turn, then Ackermann may help turn entry and will have little adverse affect mid-turn. If, on the other hand, you have a more modern set-up (mostly a function of moment centers and roll stiffness) where both front tires are contributing to the turn, then Ackermann will introduce mid-turn drag that will hurt performance.

Pappy

http://www.circletrack.com/chassiste..._steering.html

[JRouche]

Originally Posted by mfain

Guys, try this link. It has the chart for checking Ackermann. The bottom line is that if your car is not "balanced" and the outside front tire is doing most of the work in a turn, then Ackermann may help turn entry and will have little adverse affect mid-turn. If, on the other hand, you have a more modern set-up (mostly a function of moment centers and roll stiffness) where both front tires are contributing to the turn, then Ackermann will introduce mid-turn drag that will hurt performance.

Pappy

http://www.circletrack.com/chassiste..._steering.html

Thanks Pappy.. I read the entire article. It tends to jump around and talk about the negative parts of ackerman but doesnt really go into the design and measurements needed to get your head around ackerman. More about the effects, hence ackerman effect. But not a great article to determine how to tune the suspension for an "ideal" ackerman effect.

I have read many papers on the effect. But not alot (some) on the design of the suspension and tuning for ackerman. Maybe because its a set figure with the overall package. And you really dont want to sacrifice one critical suspension aspect just to get a proper ackerman effect because the changes are not worth a better ackerman effect just to loose a stronger suspension quality. Or prolly more to the point of some major structural changes in the overall suspension.

The way I see it is ackerman effect is a concern, but its low on the totem poll as far as other geometry concerns are thought of. Mainly the overall packaging of the suspension, front and rear.

Suspension SYSTEMS are a trade off all along the path of creating a balance. Yup, like you said, balance is the key to dialing the proper suspension... Thanks for the article... JR