View Full Version : Kinetic Suspension Technology

23-07-07, 11:58 PM
From their web site (http://www.kinetic.au.com/):

Conventional suspension systems exhibit a significant compromise between ride comfort (bounce and single wheel stiffness), vehicle handling (roll stiffness) and wheel loading during articulation (articulation stiffness).These systems do not allow for decoupled roll and bounce damping modes, further hindering the ability to tune a well balanced, safe and capable suspension system for all driving conditions both on and off road.

Kinetics suspension systems are unique in that they can provide reduced articulation stiffness, increased roll stiffness, high levels of comfort and mode decoupled roll and bounce damping all in a passive system. All these parameters are independently tunable. Kinetic systems are not active, they typically require no motors, pumps or computers. Nonetheless can readily be provisioned to provide load levelling and ride height adjustment and can also be adapted to include active or semi active control features to enhance their inherent passive functionality.

Apparently its good enough to get banned from the WRC, according to their news page.

Any idea how it works, and what applications they've got for it? If it works as well as advertised and is available for my car, I'd be interested in their RFS swaybar (http://www.kinetic.au.com/rfs.html) setup and possibly pull out the Teins for their X System (http://www.kinetic.au.com/x.html).

Trolls Royce
24-07-07, 12:11 AM
Looks like it would be a lot more than just a bolt in job though, right? Atleast for the X System.

24-07-07, 12:34 AM
Yeah, it does. :(

The RFS setup, as a swaybar replacement, might be retrofittable.

24-07-07, 05:02 PM
Hmmm, I dunno exactly why but I am slightly skeptical. Obviously their marketing push doesn't go into a whole lot of detail about how such a system would independantly control pitch and roll while leaving wheel articulation unaffected.

My reasoning goes something like this: The wheel articulation involved in body roll is along exactly the same axis as wheel articulation through bumps etc in the road. The main difference being the rate of change of wheel position is much faster in the case of surface corrugations. In order to tell the difference between the two situations, the suspension system would have to incorporate some sort of accelleration or movement sensing and response, making it at least partially active not entirely passive (as is implied and then contradicted by the article)
The operation of the X remains fundamentally passive, however the system incorporates a pump, sensors and controller I believe that this is why it was banned from the WRC as it was seen as an active system by their rulemakers.
As for the RFS roll bar which seems to incorporate some sort of damping piston in the middle of the roll bar as far as i can garnish from the article and i am slightly skeptical of the response of a gas or hydraulic system under rapidly changing conditions...also would it fade under heavy use like dampers on a track?

Having jsut given an Alan style slamming to this product i must say however that it is extremely intruguing and i would love to study it in person.

24-07-07, 05:44 PM
As for the RFS roll bar which seems to incorporate some sort of damping piston in the middle of the roll bar as far as i can garnish from the article and i am slightly skeptical of the response of a gas or hydraulic system under rapidly changing conditions...also would it fade under heavy use like dampers on a track?

The rear strut brace and some lateral rod in the front of the Subaru STI S204 (http://www.subaru-sti.co.jp/s204/technicalnote/damper.html) have dampers in them.

From the reviews I've read of the S204 braces, the damper only gives way at high loads. The purpose is to keep the chassis nice and rigid at low lateral G's for better response, but when you approach the limits the brace allows a bit of chassis flex so the limits are more progressive. It means the car doesn't just suddenly break away (as heavily reinforced cars tend to), and can be more easily balanced on the limit.

But then they are fundamentally street cars, not race cars.

As for how the roll bars work, my suspicion is that its similar to the hydraulic anti-roll system in the original Audi RS4 (which I wrote about here (http://www.350z-tech.com/forums/index.php?s=&showtopic=30623&view=findpost&p=420290), since its also where I found the link on this Kinetic Suspension).

24-07-07, 05:50 PM
Bigger pics of the S204 performance dampers can be found here:

Rear (http://www.rallitek.com/s2repeda.html)

Front (http://www.rallitek.com/s2frchda.html)

24-07-07, 07:12 PM
Hmmm I've thought about this a bit more and i think I've figured it out. But to explain it I will need to give it a bit of backround.
Essentially different systems will have different frequency response curves. The effect of a disturbance on a system will have a varying degree of effect depending on the frequency of the disturbances. (this is a fairly massive simplification as obviously most of the things that happen to suspension are not constant frequency, but if you really want more detail google step response and sinusoidal response).
Now frequency response is determined by a number of factors including the mass of the system, the damping force, suspension geometry and spring rate, suffice to say traditional suspension tends to have poor high frequency response and good low frequency response. This is somewhat frustrating for suspension engineers as cornering forces are a low frequency input, whereas road corrugations are a high frequency input, so in order to keep the ride comfortable, it is necessary to lower the spring rate and damping rates so theat the system has an acceptable level of high frequency response (as a side note, lowering the unsprung mass has the same effect of increasing high frequency response without the detriment of softer springs which explains the increasing use of aluminium for suspension parts in high end cars)
Unfortunately there is a limit to what can be done to change the response curve as most of the parameters that effect it are dictated to a significant extent by other design requirements. What this system seems to be is a method of interconnecting the dampers and by the system of sensors etc varying the damping force from corner to corner in such a way as to force the system to have better high frequency response when its static parameters would seem to dictate otherwise. So it is a passive system in that its response curve does not change as you drive, but it is active in the sense that in order to keep this response curve it requires a degree of control.