Suspesnion Questions - Roll Bar Linkage/Motion Ratio

[LLOGAN]

Miliken RCVD Ch 16.5 cites a 'stabilizer bar linkage ratio'. Pretty sure this refers to the roll bar. Due to the example values of (0.691 & 1.00, unitless) I'm thinking this is roll bar lever displacement / wheel displacement. I've also seen this relation called in degrees of twist / degrees of chassis roll. Can anyone clarify on the Miliken use?

Thanks

[LLOGAN]

Wow that's embarrassing, there's a whole section on defining this term.

Turns out it's deg of bar twist per deg chassis roll. Function of torsion bar stiffness, lever length, lever deflection per wheel center deflection, and track width.

[Claude Rouelle]

Some people describe the ARB motion Ratio as Roll angle / ARB twist angle and some other as wheel movement / ARB lever movement along a tangent to this ARB leverage trajectory.

Personally I prefer the first one because it takes into account inside and outside wheel together, especially if the ratio wheel ARB leverage is not linear. It doesn't matter providing you know exactly what definition you use and you communicate it well within your team.

Just a quick advise: you need to go through these calculations but be aware that the real anti-roll stiffness from you springs and / or ARBs could be very, very different, simply because (but not only) of your compliance. With one of our customers we saw on the K&C machine that the ARB stiffness was 30 % (30%, no kidding) than what they initially calculated in a simple Excel spreadsheet or on their more evolved FEA. Not that their FEA software was that bad; simply there were a few major elements (like the installation stiffness of the ARB brackets / bearings in the chassis) that they did not take into account.