question on KDSS
07-30-08, 05:48 AM
#16
Lexus Test Driver
The Kinetic Dynamic Suspension System uses hydraulic control devices to vary the effect of the front and rear stabilizer bars. It will stiffen up when cornering and give it more suspension travel when going straight. It is a early version of the GS460's electronic active suspension. The main differnece is that the KDSS will disconnect the sway for off road use. The active suspension in the GS 460, I think its called APSSS, uses electronice dampeners instead of hydraulic, which makes the system much more responsive and better for on road handling.
07-30-08, 10:42 AM
#17
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My understanding of KDSS is, that it starts to relax at low speed on bad roads (and then it releases stabilizer bar).
07-30-08, 12:22 PM
#18
Lexus Test Driver
Here is Lexus' press release from a few years ago:
The new Kinetic Dynamic Suspension System (KDSS) adds another layer to the GX 470's impressive on-road ride and handling prowess and off-highway capability for 2004. The new system uses electronically controlled hydraulic cylinders to help vary the degree of sway resistance provided by the front and rear stabilizer bars.
The KDSS technology, which has been proven in World Rally Championship (WRC) competitions, provides more sway stiffness when needed for crisp handling response, less sway resistance when cornering, more comfort over bumpy roads, and even disengages the stabilizers for some off-highway driving conditions. With the stabilizers disengaged, the suspension gains more travel and articulation to help handle obstacles. KDSS is the first such suspension system in an SUV to combine all of these dynamic control functions.
The new Kinetic Dynamic Suspension System (KDSS) adds another layer to the GX 470's impressive on-road ride and handling prowess and off-highway capability for 2004. The new system uses electronically controlled hydraulic cylinders to help vary the degree of sway resistance provided by the front and rear stabilizer bars.
The KDSS technology, which has been proven in World Rally Championship (WRC) competitions, provides more sway stiffness when needed for crisp handling response, less sway resistance when cornering, more comfort over bumpy roads, and even disengages the stabilizers for some off-highway driving conditions. With the stabilizers disengaged, the suspension gains more travel and articulation to help handle obstacles. KDSS is the first such suspension system in an SUV to combine all of these dynamic control functions.
07-30-08, 12:57 PM
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07-31-08, 02:25 PM
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07-31-08, 08:02 PM
#22
KDSS takes origin from off-road rally racing. Thus, it is primarily an off-road tool with a side benefit of reducing body roll around corners. Some may not like KDSS because KDSS does increase ride stiffness or make it more "bumpy" over bumps due to the larger anti-roll bars.
Remember, ride comfort is another important reason why car manufacturers do not put on the biggest anti-roll bar as possible. It isn't just off-road capability that limits size of anti-roll bars. Remember, thicker anti-roll bars equal less suspension travel over bumpy surfaces. (Good thing Lexus has KDSS to disconnect/relax them off-road for improve suspension travel...but this relaxation ONLY happens off-road at slow speeds...on-road, you will feel the thicker anti-roll bars all the time whether you're turning a corner or going down poor pavement.)
Thus, between KDSS and non-KDSS, one will notice less body roll around corners on KDSS GX while ride is a bit bumpier.
Complexity at the suspension area is not always desirable. For example, air/hydraulic suspension can fail with age. LX470's shocks/accumulator are known to need "re-tuning" every 60k miles...one or two shocks on my friend's (TEXGX on this forum) KDSS GX failed at less than 50k miles...bad luck? KDSS is a fine technology, but it does have extra hardware hanging down below axle height which can be susceptible to rock damage (if you take it off the beaten path)...in addition, it is operated electronically, which can fail in theory. Of course, the good thing is that electronic reliability is Lexus/Toyota's strong point.
Overall, yes, i would get GX with KDSS simply because i do off-road. However, if one does not off-road (but tows or just crawl around malls), then i think that a regular GX is just perfect. Remember, you should drive at reasonable speed around corners because the GX is still a 4700 lbs tall SUV, not a sports car or even a crossover.
Remember, ride comfort is another important reason why car manufacturers do not put on the biggest anti-roll bar as possible. It isn't just off-road capability that limits size of anti-roll bars. Remember, thicker anti-roll bars equal less suspension travel over bumpy surfaces. (Good thing Lexus has KDSS to disconnect/relax them off-road for improve suspension travel...but this relaxation ONLY happens off-road at slow speeds...on-road, you will feel the thicker anti-roll bars all the time whether you're turning a corner or going down poor pavement.)
Thus, between KDSS and non-KDSS, one will notice less body roll around corners on KDSS GX while ride is a bit bumpier.
Complexity at the suspension area is not always desirable. For example, air/hydraulic suspension can fail with age. LX470's shocks/accumulator are known to need "re-tuning" every 60k miles...one or two shocks on my friend's (TEXGX on this forum) KDSS GX failed at less than 50k miles...bad luck? KDSS is a fine technology, but it does have extra hardware hanging down below axle height which can be susceptible to rock damage (if you take it off the beaten path)...in addition, it is operated electronically, which can fail in theory. Of course, the good thing is that electronic reliability is Lexus/Toyota's strong point.
Overall, yes, i would get GX with KDSS simply because i do off-road. However, if one does not off-road (but tows or just crawl around malls), then i think that a regular GX is just perfect. Remember, you should drive at reasonable speed around corners because the GX is still a 4700 lbs tall SUV, not a sports car or even a crossover.
1) while it's technically correct that a stiffer swaybar can affect ride, this is only the case when the impact the suspension is reacting-to is unequal across a given axle. In many cases, you'll see very little effect from a bigger swaybar on ride. However, it can be pretty noticeable when the impact is uneven. I've tweaked swaybars on lots of my cars, and have felt the differences firsthand.
2) KDSS increases the GX's on-road abilities pretty dramatically. While everyone has an opinion, mine is simply that the non-KDSS GX would drive me nuts. I've grown up driving all sorts of sports/sporty cars, so a car's capability on a windy road is important to me. Yes, the GX is a body-on-frame "truck", but its abilities are very impressive if you drive it well within its limits.
My only aftermarket tweak is 18s from the t4r Limited with cross-terrains. We just got back from a 500 mile trip in our gx across some amazing mountain roads in northern Washington. Roads that I've haunted in most of my past sports cars.
i was blown away with how well the GX did on this trip. Especially on some of the best sports car stretches in the state. We were debating taking my wife's Audi S4, but decided on the GX because of the extra space and comfort. I was worried that the GX would prove to be a "pig" on these roads, but it did amazingly well.
Now, we could have gone a smidge faster in the S4, but we would have been a *lot* less comfortable.
Oh, and we returned an indicated 20.2mpg (probably 18'ish) on this trip. Not bad for really flying across a couple mountain passes, and probably within 2-3mpg of what we would have seen in the S4.
Really, really impressive vehicle!
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