optimal roll centers

[bkndesign]

Together with a couple of coleagues, (racecar builders), we have a discusion on what is the ideal position and movement of roll centers. the type of car is a rear wheel drive touring car with front engine, solid axle,1300 kg 50/50 distribution, with 2.74 mts wheelbase, 1.65 mts track. we would like to know what others think, since we cann´t decide if it is better to have roll centers above or under the ground, and which should be higher. thank you

 

[GregLocock]

I think mark ortiz has probably discussed this to death.





Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[fade2blue]

I know its bad for you but I would say
, butter.

 

[ATCCO]

gentlemen,

how can i calculate the Suspension roll stiffness at axle roll axis for semi-trailers axles ?!! can anybody help and advise please?? i attached a drawing for SAF type axles..

 

[BrianPetersen]

It would be best to either search the main forum to see if it has been discussed before, or failing that, start your own thread rather than interrupting someone else's. But in any case ... That type of axle has extraordinarily high roll stiffness in comparison to its stiffness in two-wheel bump (in which the whole axle goes up and down relative to the truck frame), because roll or one-wheel bumps can only be accommodated by either twisting the extremely stiff axle, or deflecting the bushings, or deflecting the frame of the truck, or deflecting the trailing arms.

Transport trucks are designed to not have appreciable body roll, because if any appreciable body roll were allowed, it would let the center of gravity shift outward and allow the truck to tip over more easily. It's done by having extraordinarily high roll stiffness, and that's why even trucks with air-ride suspension still have a rough ride ...