2011 Body Roll / Sway issue

[TeCKis300]

Couple of things that maybe I can help clarify

1) KDSS on the 200-series is completely passive. It does not "disconnect" at low speed. KDSS acts as a stiff sway bar in roll but not warp. Roll meaning same leaning motion on front and rear axles as would be experienced in a turn, but it does not resist warp which is opposite articulating motions on front and rear axles.

2) KDSS does not influence brake dive. Or squat on acceleration.

My interpretation of the OPs "issue" is that it's a characteristic of the stiff sway bars that is this version of KDSS. It's the contrast of a relatively soft suspension that has great bump compliance straight ahead, but feels stiff when reacting to bumps in a turn and transmits into the chassis. It likely feels different to every other truck/SUV that doesn't have the degree of roll stiffness in a turn.

I say this version, as that's what get upgraded in newer versions. KDSS in the 120-series is upgraded with an electronic valve to disengage KDSS under 12MPH. E-KDSS in the 300-series takes it a step further to electronically manage sway resistance front and rear.

The stiffness of KDSS in the 200-series system is also a compromise that can hamper independent-ness of the suspension in fast washboard or fire-roads. There is an accumulator internal to handle some measure of small bump compliance, but it is better managed in the later systems where electronics can better manage when the added roll-resistance is desirable.

I bring this up as it's unknown if the accumulator that serves KDSS can be a wear component that can fail? It looks like it's a spring loaded piston type. As 200-series LCs get into high mileage, more failure modes will be understood. The other possibility is it can leak or lose pressure which would create less sway resistance.

 

[bloc]

I bring this up as it's unknown if the accumulator that serves KDSS can be a wear component that can fail? It looks like it's a spring loaded piston type.

It's actually a stainless steel bellows that inflates or deflates inside a nitrogen-filled chamber. As opposed to the rubber diaphragm in an AHC system.

With the very small movement of that accumulator (under normal operating conditions only temperature-derived oil volume changes) sees I can't imagine it wearing out very quickly.

 

[Valgrind]

Couple of things that maybe I can help clarify

1) KDSS on the 200-series is completely passive. It does not "disconnect" at low speed. KDSS acts as a stiff sway bar in roll but not warp. Roll meaning same leaning motion on front and rear axles as would be experienced in a turn, but it does not resist warp which is opposite articulating motions on front and rear axles.

2) KDSS does not influence brake dive. Or squat on acceleration.

My interpretation of the OPs "issue" is that it's a characteristic of the stiff sway bars that is this version of KDSS. It's the contrast of a relatively soft suspension that has great bump compliance straight ahead, but feels stiff when reacting to bumps in a turn and transmits into the chassis. It likely feels different to every other truck/SUV that doesn't have the degree of roll stiffness in a turn.

I say this version, as that's what get upgraded in newer versions. KDSS in the 120-series is upgraded with an electronic valve to disengage KDSS under 12MPH. E-KDSS in the 300-series takes it a step further to electronically manage sway resistance front and rear.

The stiffness of KDSS in the 200-series system is also a compromise that can hamper independent-ness of the suspension in fast washboard or fire-roads. There is an accumulator internal to handle some measure of small bump compliance, but it is better managed in the later systems where electronics can better manage when the added roll-resistance is desirable.

I bring this up as it's unknown if the accumulator that serves KDSS can be a wear component that can fail? It looks like it's a spring loaded piston type. As 200-series LCs get into high mileage, more failure modes will be understood. The other possibility is it can leak or lose pressure which would create less sway resistance.

How do you test if the KDSS is working correctly? How can you test if it’s leaked or lost pressure?

 

[bloc]

How do you test if the KDSS is working correctly? How can you test if it’s leaked or lost pressure?

A direct pressure measurement probably involves the special service tool owned by some dealers.

It wouldn’t be easy but you could also open the valves then use something like a bathroom scale on a floor jack to measure the downward force at the end of the KDSS arm when it’s disconnected from the lower control arm. Doing the math for the length of the lever arm and the surface area of the piston protruding from the front kdss cylinder, you could work out the internal system pressure.

 

[linuxgod]

How do you test if the KDSS is working correctly? How can you test if it’s leaked or lost pressure?

Try to reattach a sway bar with the KDSS valves closed, then turn the 2 rotations and try again and you'll know real quick if it's pressurized as it's waaaay easier to manipulate them

 

[bloc]

Try to reattach a sway bar with the KDSS valves closed, then turn the 2 rotations and try again and you'll know real quick if it's pressurized as it's waaaay easier to manipulate them

That will lock the pressure into each circuit but won’t tell you if the overflow circuit is up to the specified pressure. That being low could allow foaming in the system and probably allow the over pressure valves to open without much force on the rams (effectively disconnecting the bars when they shouldn’t be.)

To rule out previous leaks by verifying the whole system pressure you’d need to open valves and measure pressure directly or extrapolate it as described above.

 

[m3fan]

I'm at 133K and also wondering about the suspension life. I replaced all of the shocks on my 100 around the same time frame and recall pretty much zero difference, same with my 4R before that. The 200 has always seemed rolly and dive-y, hard to tell what's normal. That said I recently hit a Chicago winter "missing pavement layer" on I94 at speed that unsettled the entire car, moderately scary. Anyway, starting to think about shocks and exploring options.

 

[TeCKis300]

How do you test if the KDSS is working correctly? How can you test if it’s leaked or lost pressure?

This would be hard to objectively test for. As a statically pressurized system, the reality is that it will degrade over time, resulting in less roll control. Until outright failure with total loss of charge pressure and/or hydraulic fluid. Opening and closing the shutter valves might be able to reveal only total loss of function?

That slow degrading might make it hard to assess, but the major symptom of a compromised system is loss of good sway control.

I'd bet with the 200-series aging, there are more compromised and failed KDSS systems than owners are aware of. It's a pure mechanical system with no codes (some later variations of e-kdss have electronics that can reveal error states). From other platforms that have more experience on this, it surely can fail into higher mileage. Leaking down, failed seals, corrosion. It's a robust system, but corrosion seems to be a major source of failure, not unlike AHC.

 

[bloc]

This would be hard to objectively test for. As a statically pressurized system, the reality is that it will degrade over time, resulting in less roll control. Until outright failure with total loss of charge pressure and/or hydraulic fluid. Opening and closing the shutter valves might be able to reveal only total loss of function?

That slow degrading might make it hard to assess, but the major symptom of a compromised system is loss of good sway control.

I'd bet with the 200-series aging, there are more compromised and failed KDSS systems than owners are aware of. It's a pure mechanical system with no codes (some later variations of e-kdss have electronics that can reveal error states). From other platforms that have more experience on this, it surely can fail into higher mileage. Leaking down, failed seals, corrosion. It's a robust system, but corrosion seems to be a major source of failure, not unlike AHC.

One of the failure modes seems to be a sudden pronounced lean when they develop a leak from corrosion.

I agree some hypothetical failures may not have obvious signs but given how little system movement there is during normal street driving (rams stay static during cornering, they only move/wear under articulation) I’d bet most of these are perfectly healthy unless corroded.

Or improperly maintained.. the nice thing there is any decrease in system pressure must be accompanied by a fluid leak which would be pretty easy to monitor for.


This has me thinking about ways to look for failure.. possibly a go-pro mounted to watch what the front and rear ram does during cornering. If they both compress at the same time during a right hand corner, they aren’t doing their job.

 

[linuxgod]

This would be hard to objectively test for. As a statically pressurized system, the reality is that it will degrade over time, resulting in less roll control. Until outright failure with total loss of charge pressure and/or hydraulic fluid. Opening and closing the shutter valves might be able to reveal only total loss of function?

That slow degrading might make it hard to assess, but the major symptom of a compromised system is loss of good sway control.

I'd bet with the 200-series aging, there are more compromised and failed KDSS systems than owners are aware of. It's a pure mechanical system with no codes (some later variations of e-kdss have electronics that can reveal error states). From other platforms that have more experience on this, it surely can fail into higher mileage. Leaking down, failed seals, corrosion. It's a robust system, but corrosion seems to be a major source of failure, not unlike AHC.

Not that KDSS couldn’t wear over time but if I had a lot more sway and body roll I’d look at all the bushing first.

 

[linuxgod]

I'm at 133K and also wondering about the suspension life. I replaced all of the shocks on my 100 around the same time frame and recall pretty much zero difference, same with my 4R before that. The 200 has always seemed rolly and dive-y, hard to tell what's normal. That said I recently hit a Chicago winter "missing pavement layer" on I94 at speed that unsettled the entire car, moderately scary. Anyway, starting to think about shocks and exploring options.

Shocks you can tell are wearing if you pump the brakes in a slow rhythm when coming to a stop and find the truck feeling bouncy. Good shocks will dampen that.

Whenever my truck has felt squirrelly on the highway especially after hitting any sort of bump I’ve ultimately found a suspension component is worn. Upper ball joints and then the steering rack in my case, but lower ball joints or control arm bushings or even sway bar end links might all come into play. Those front sway bar end links on mine looked horrible at 130k, fwiw… the rubber was all sorts of splitting and rotting.

 

[TeCKis300]

Not that KDSS couldn’t wear over time but if I had a lot more sway and body roll I’d look at all the bushing first.

Yeah, all those things can invite more play into the system. Worn bushings would only allow incrementally more roll before their range of motion is exhausted. The sways would come into play with high amplitude roll. Something like a 270-degree on/off ramp to the freeway would be more revealing.

 

[rtong1234]

I'm at 133K and also wondering about the suspension life. I replaced all of the shocks on my 100 around the same time frame and recall pretty much zero difference, same with my 4R before that. The 200 has always seemed rolly and dive-y, hard to tell what's normal. That said I recently hit a Chicago winter "missing pavement layer" on I94 at speed that unsettled the entire car, moderately scary. Anyway, starting to think about shocks and exploring options.

I took it to the Toyota dealer to have them evaluate my shocks and struts to address the "rolly and dive-y" sensation thinking they would take my money for sure. After their testing and inspection, they said it was fine and that I didn't need to replace anything even at 153K. I took it up to the sierras this weekend and she drove beautifully even around the hairpin turns. Oh well, could be just my mind playing tricks on me or too much whining from my passengers.

 

[dubaicruiser]

I am facing this body roll issue since long.
Before i was on Toughdog shocks, and after some long years I upgraded to Dobinson MRR with king springs, new TD panhard road, reduced a bit but its still there. Planning to get drkdss correction bracket now.

I come down the mountain on curves. I have no confidence in taking turns fast.

Same here, also on many interchange curved bridges out here. I feel like ill roll over especially if going over 40-60kmh. Or offroad while side cresting the dunes.

it sounds a little like the KDSS valves might be open to some degree. That condition has a VERY uncomfortable sway-y feeling.

I am doubting this aswell. Sadly no garages I asked here in UAE is willing to even inspect or play with kdss. And Toyota said theyll not touch it either since i have aftermarket suspension.

 

[HighRanch]

Close to a dozen I’d say. I’ve experienced worn out suspensions with tons of dove front to back but this was a new sensation to me. Maybe it’s just the 200 LC.

Sounds like a worn out suspension, I don't think the LC is crazy floaty. But mine is much newer than yours.