Can LX570/LC200 AHC ride be "tuned"?

[TLCLVR]

Does anyone know if the LX570/LC200 AHC ride qualities can be adjusted? It's clear to me that AHC in the US LX570 is tuned to cater to the luxury market--but can that be changed?

- Can I spread the spectrum and make "Comfort" mode softer, while making "Sport" mode firmer?

- Alternatively, can I shift the firmness one direction and make all three modes relatively firmer or softer?

- Can the system be adjusted to adjust high or low-speed damping?

Also, If anyone has driven both a US LX570 and an LC200 fitted with factory AHC, I'd be interested to know if the ride qualities are the same.

I look forward to absorbing your wealth of knowledge!

 

[hickuptruck]

Yes there are AHC globes from Plaedies that have a firmer then OEM ride. Also armored spec globes.

 

[tincan45]

I'm shooting from the hip here, so take this with a grain of salt.

Most likely the 'tuning' is hard coded into the AHC computer. I have not seen any information indicating anyone has even attempted to change it.

You can change out the accumulators with aftermarket globes effectively changing the system pressure across the board. Ebay has several listed that claim better ride characteristics. Mostly it's UK based sellers who seem do a lot more AHC tinkering that we do.

I can only assume the LC with AHC is using the exact same controller as the LX. You could probably look up the part numbers to verify.

I'm always curious why people want to modify systems like these? To me, this is like the 5.7, it works, and it works well. Why mess with a good thing and risk making it unreliable. Sure, AHC lift is probably fine, but if you don't like the ride that much just get an LC and enjoy whatever suspension you want.

 

[TeCKis300]

Does anyone know if the LX570/LC200 AHC ride qualities can be adjusted? It's clear to me that AHC in the US LX570 is tuned to cater to the luxury market--but can that be changed?

- Can I spread the spectrum and make "Comfort" mode softer, while making "Sport" mode firmer?

- Alternatively, can I shift the firmness one direction and make all three modes relatively firmer or softer?

- Can the system be adjusted to adjust high or low-speed damping?

Also, If anyone has driven both a US LX570 and an LC200 fitted with factory AHC, I'd be interested to know if the ride qualities are the same.

I look forward to absorbing your wealth of knowledge!

These are reasonable questions. But perhaps coming from the direction of a traditional suspension system.

You are already aware there are 3 damper settings. Rather then static settings as they relate aftermarket dampers, these should be interpreted as 3 system performance profiles. AHC is a fully active system monitoring many sensors and feedback loops helping it constantly adjust for the load and situation at hand. It's control strategy is dynamic and algorithm based (rather than a single setting) and will access the extents of the physical system possible to achieve the performance profile desired.

Where one can tune the system is perhaps in its spring rates and tires rather than damping. With either different springs (or spacers), different pressure globes perhaps, or different tires. Know that the 200-series AHC system (even more so than the 100-series) is already damn advanced as it implements two system selectable spring rates on the front axle. Yet the spring rate tuning would be more to handle loads. I'd look into tires for actual tuning feel.

The system has a pretty wide bandwidth of adjustment with the 3-position user selectable control to tailor the system to select over its 16-position active damper positions. On tight switchback tarmac, the system has great roll control in every position. High speed damping is adjusted with it in sport which things firm up significantly. On bumpy switchbacks, the high speed damping can be too much (IMO as a previous road racer) causing less compliance and less traction on these types of roads. Normal position is pretty damn good for everything. I often use sport when towing my large camper in the mountains as it further bumps up the damping profile (over its auto adjustment) to better control the large load.

Low speed damping is equally effected by the selector. Comfort is my preferred off-road for max compliance. I have switched to normal running fast washes chasing a Raptor. The system will tailor itself even in comfort, yet does offer an extra measure of control when switch to higher profiles. When dropping off a ledge, selecting sport is useful to increase low speed damping to avoid extra compression coming off the ledge.

The system is hugely capable. We haven't even talked about it's height control functions. More here to give insight into some of its capabilities which far exceed anything else out there.

 

[TLCLVR]

Yes there are AHC globes from Plaedies that have a firmer then OEM ride. Also armored spec globes.

Where would one source armored spec globes?

 

[TLCLVR]

I'm shooting from the hip here, so take this with a grain of salt.

Most likely the 'tuning' is hard coded into the AHC computer. I have not seen any information indicating anyone has even attempted to change it.

You can change out the accumulators with aftermarket globes effectively changing the system pressure across the board. Ebay has several listed that claim better ride characteristics. Mostly it's UK based sellers who seem do a lot more AHC tinkering that we do.

I can only assume the LC with AHC is using the exact same controller as the LX. You could probably look up the part numbers to verify.

I'm always curious why people want to modify systems like these? To me, this is like the 5.7, it works, and it works well. Why mess with a good thing and risk making it unreliable. Sure, AHC lift is probably fine, but if you don't like the ride that much just get an LC and enjoy whatever suspension you want.

Ah, yes... probably the same reason we put big aggressive tires and hang a bunch of stuff all over our 200’s! Always driven with OCD relentlessness to eek every bit of performance from an already incredible machine.

But honestly, Lexus has admirably stayed pretty true to the LC roots, but they still have a customer base to please and sell vehicles too. As you know, the target base for a new LX in the US is more interested in a posh, luxurious ride, and that’s how they’ve tuned it. I’m looking for ways to unlock the LX’s performance potential for a new generation of users interested in tapping into its value advantage over the LC and utilizing it’s full off-road capabilities.

Now if only I could code and hack the control computer...

 

[razzyrazz]

I'm sure it could be tuned if you could get into the, but it is so complex with all the real time adjustments you would need to have extensive knowledge of the system to do it right. I like the overall soft ride, keeps my kids asleep. It's a 3 ton vehicle, that eats bumps, potholes, washboard and rocks. I was on a trail this weekend and the Jeep guys were looking at me like I was crazy because I was going 30 over a rocky trail. Wasnt feeling much in the cabin with AHC comfort mode. Sport mode is good enough to have a little fun on a windy road, but if you're rolling too much you should remind yourself you're in a 6300 lbs+ vehicle.

 

[hickuptruck]

Where would one source armored spec globes?

Offroad-Nestle, Autohaus Nestle GmbH, Dornstetten, Toyota, Neuwagen, Gebrauchtwagen, Offroad-Fahrzeuge, Allrad-Fahrzeuge: Offroad-Nestle

Auf der Website offroad-nestle präsentieren wir unser Unternehmen Autohaus Nestle GmbH in Dornstetten im Schwarzwald. Wir sind Toyota Vertragshändler und ein überregional bekannter Offroad-Ausrüster, bekannt für ausgereiftes Zubehör und Offroad-Umbauten in hoher Qualität.

offroad-nestle.de

 

[bloc]

I'm curious how different globes change the ride. Not that they do, but exactly how this works. Do they change the effective spring rate of the hydraulic portion of the system?

 

[TLCLVR]

These are reasonable questions. But perhaps coming from the direction of a traditional suspension system.

You are already aware there are 3 damper settings. Rather then static settings as they relate aftermarket dampers, these should be interpreted as 3 system performance profiles. AHC is a fully active system monitoring many sensors and feedback loops helping it constantly adjust for the load and situation at hand. It's control strategy is dynamic and algorithm based (rather than a single setting) and will access the extents of the physical system possible to achieve the performance profile desired.

Where one can tune the system is perhaps in its spring rates and tires rather than damping. With either different springs (or spacers), different pressure globes perhaps, or different tires. Know that the 200-series AHC system (even more so than the 100-series) is already damn advanced as it implements two system selectable spring rates on the front axle. Yet the spring rate tuning would be more to handle loads. I'd look into tires for actual tuning feel.

The system has a pretty wide bandwidth of adjustment with the 3-position user selectable control to tailor the system to select over its 16-position active damper positions. On tight switchback tarmac, the system has great roll control in every position. High speed damping is adjusted with it in sport which things firm up significantly. On bumpy switchbacks, the high speed damping can be too much (IMO as a previous road racer) causing less compliance and less traction on these types of roads. Normal position is pretty damn good for everything. I often use sport when towing my large camper in the mountains as it further bumps up the damping profile (over its auto adjustment) to better control the large load.

Low speed damping is equally effected by the selector. Comfort is my preferred off-road for max compliance. I have switched to normal running fast washes chasing a Raptor. The system will tailor itself even in comfort, yet does offer an extra measure of control when switch to higher profiles. When dropping off a ledge, selecting sport is useful to increase low speed damping to avoid extra compression coming off the ledge.

The system is hugely capable. We haven't even talked about it's height control functions. More here to give insight into some of its capabilities which far exceed anything else out there.

@TeCKis300 you are truly a wellspring of knowledge! It's a testament to the capability and complexity of this system that after actively using and studying it for 4 years, I am still learning new things.

I use it much the same as you for highway, towing, and off-road. However, I haven't fully decided which mode I like best at speed on washboards (probably N or C), and I'd never thought of switching to S to stiffen things up going over a ledge. Thanks for that tip! On springs and spacers, I'm currently scouring the other threads on the topic. It's evolving as I get to more current posts. Was a consensus reached on best practices?

As my curiosity was on this was piqued, I spent some time in the manual today and noted that the damping modes for S/N/C change in 4L. I went out and tested it, and C, in particular, felt much stiffer in 4L.

Thanks also for sharing the info pages. Saw some of these on the "AHC Basics" thread, but I've never seen the second and third pages. Are those from the Technical Service Manual? I was struck on the diagram that all the globes are labeled as 'gas' chambers. I thought they are full of suspension fluid?? Also noted the 'Spring Rate Switching Valve'. Anyone know its function?

 

[hkeller]

They are gas on one side and pressurized nitrogen on the other; separated by a membrane. This is the “give” in the system that allows for suspension travel. Hydropneumatic suspension - Wikipedia

 

[UCrazyKid]

Since the vehicle self levels when loaded heavy but does not change the ride quality (damping) I imagine the “spring rate” chamber manages that feature. Just like trading out a traditional spring for a stiffer one in a traditional suspension when a truck is weighted down with accessories.

 

[UCrazyKid]

Since variations of this system have also been used in Range Rovers, Rolls Royce and Citroen vehicles for many years, you can find a lot of info searching for resources and videos for those vehicles as well that roughly translates to the Toyota/Lexus platform.
I liken the “spheres” or “globes” in the suspension platform to how a residential water well’s pressurization tank operates. 1/2 of the tank is filled with a rubber bladder that is pressurized at all times with air. A pump fills the rest of the tank with water that is constantly pushed back against by the rubber bladder. This bladder “spring” then provides the water pressure to the house.

 

[TeCKis300]

To keep this discussion going, we know that AHC is immensely capable, highly performant, proven durable, and on-board maintainable. Way beyond what I can say for aftermarket stuff. Sure, they might do one or two specific things better. Still doesn't come close to the breadth of AHC for varied uses.

So what needs to be improved? That's probably the level of discussion first rather than specific changes like spheres or hacking code.

Because I'm very much interested in tuning the system too.

1) Damping
I'll say this as a connoisseur of damping. The damping is on point. Always on point regardless of load or conditions. Which isn't a surprise as it's an active system constantly adjusting. It's also got huge fluid volumes and remote damping valves which is beyond what we talk about with traditional suspensions having remote reservoir, bypass - "analog" stuff. Upgrading this digital system would require OEM levels of capability to refine the already sophisticated algorithm, increase system response speed, more steps of adjust-ability (it's already 16-way and the system uses all positions, vs a single setting in an static suspension). Or if it would be an active preemptive system with cameras reading terrain ahead of the wheel but that's now crazy talk.

2) Spring (rate)
Spring rate is one area of capability to expand to more non-standard uses. I've seen my stock system handle 30% beyond rated payload - to over 1800lbs with trailer and gear. So it would be the more extreme use that actually needs more. Or perhaps you want enough rate to to jump your car?? I probably wouldn't bother modifying with higher pressure globes. There's an easier way which would be to modify the physical coil springs. Multiple strategies. Either by adding spacers such that the spring rate is increased by pre-load. Or if more is desired, changing the springs themselves with progressively more aggressive springs like one would do with a normally sprung LC. Progressively higher rates could be achieved with things like: LC200 diesel AHC springs from overseas, King 100-series AHC upgrade springs, LC100 non-AHC springs, LC200 non-AHC springs, armored vehicle purple AHC springs (these suckers are built in the range of 8-9k curb weights!$#), etc.

3) Lift (height)
I separated this from #2 as its somewhat a different adjustment in the AHC system. It's sensor based height somewhat regardless of spring rate and load. The hydro-pneumatic part of the system will set the height. 10 minutes with a 10mm wrench to adjust the sensors is all it takes. It is still correlated with spring rate in that we know the physical coils relax with a taller ride height. So lifting without addressing the springs with spacers or higher rate springs will reduce payload capacity. One shouldn't lift the base ride height too far (~2") as that can render "high" position going into the bumpstops, making that mode less useful. Besides, even really lifted static LC's don't see much more as once they put on any load, the suspension sits lower.

4) Suspension travel/articulation
There's opportunity here that's yet largely unexplored in my mind. Tundra suspension swaps keeping the AHC system have been done and that surely will increase stroke at the front. I believe running an LC lift spacer in the front will also extend suspension travel by ~1" and raise spring rate and payload capability lightly. Probably can do the same with the rear shock to increase droop.

Okay, I should break here and jump back to work!

 

[TLCLVR]

To keep this discussion going, we know that AHC is immensely capable, highly performant, proven durable, and on-board maintainable. Way beyond what I can say for aftermarket stuff. Sure, they might do one or two specific things better. Still doesn't come close to the breadth of AHC for varied uses.

So what needs to be improved? That's probably the level of discussion first rather than specific changes like spheres or hacking code.

Because I'm very much interested in tuning the system too.

1) Damping
I'll say this as a connoisseur of damping. The damping is on point. Always on point regardless of load or conditions. Which isn't a surprise as it's an active system constantly adjusting. It's also got huge fluid volumes and remote damping valves which is beyond what we talk about with traditional suspensions having remote reservoir, bypass - "analog" stuff. Upgrading this digital system would require OEM levels of capability to refine the already sophisticated algorithm, increase system response speed, more steps of adjust-ability (it's already 16-way and the system uses all positions, vs a single setting in an static suspension). Or if it would be an active preemptive system with cameras reading terrain ahead of the wheel but that's now crazy talk.

2) Spring (rate)
Spring rate is one area of capability to expand to more non-standard uses. I've seen my stock system handle 30% beyond rated payload - to over 1800lbs with trailer and gear. So it would be the more extreme use that actually needs more. Or perhaps you want enough rate to to jump your car?? I probably wouldn't bother modifying with higher pressure globes. There's an easier way which would be to modify the physical coil springs. Multiple strategies. Either by adding spacers such that the spring rate is increased by pre-load. Or if more is desired, changing the springs themselves with progressively more aggressive springs like one would do with a normally sprung LC. Progressively higher rates could be achieved with things like: LC200 diesel AHC springs from overseas, King 100-series AHC upgrade springs, LC100 non-AHC springs, LC200 non-AHC springs, armored vehicle purple AHC springs (these suckers are built in the range of 8-9k curb weights!$#), etc.

3) Lift (height)
I separated this from #2 as its somewhat a different adjustment in the AHC system. It's sensor based height somewhat regardless of spring rate and load. The hydro-pneumatic part of the system will set the height. 10 minutes with a 10mm wrench to adjust the sensors is all it takes. It is still correlated with spring rate in that we know the physical coils relax with a taller ride height. So lifting without addressing the springs with spacers or higher rate springs will reduce payload capacity. One shouldn't lift the base ride height too far (~2") as that can render "high" position going into the bumpstops, making that mode less useful. Besides, even really lifted static LC's don't see much more as once they put on any load, the suspension sits lower.

4) Suspension travel/articulation
There's opportunity here that's yet largely unexplored in my mind. Tundra suspension swaps keeping the AHC system have been done and that surely will increase stroke at the front. I believe running an LC lift spacer in the front will also extend suspension travel by ~1" and raise spring rate and payload capability lightly. Probably can do the same with the rear shock to increase droop.

Okay, I should break here and jump back to work!

All good points. For my specific tastes, #1 and #2. I'd like to see better damping in comfort, and firmer support through corners in Sport. The difference in feel in my LX between Comfort and Sport is noticeable, but switching between Normal and C/S is almost imperceptible, so I'd like to see a wider distinction between modes. I suppose one could shift the whole system firmer by using stiffer springs, but as has been noted in other threads, there are drawbacks to that because a % of the vehicle's weight needs to be supported by the AHC. I'd love to see a table showing the stock spring rates and required spring rate increases for specific static weight additions.

I must admit though, after reading the comments above I went back through some of the AHC basics forums and realized there is the possibility that some of my irritations with the system stem from a maintenance issue rather than a technical limitation.

I had my AHC flushed 5k miles ago by the local dealer, but just went out and checked it and found that the fluid in the reservoir, though not black, is darker than it should be if it was a full flush. I also checked the invoice and they only used 2 L of fluid. That's barely enough to fill the reservoir in N. Taking it in next week to either have them do it properly or get my money back and do it myself. I'll let you know if there is a noticeable difference in performance.

Regarding #4, why would a LC lift spacer extend travel in front?

 

[bloc]

Regarding #4, why would a LC lift spacer extend travel in front?

The bump stops and lower arm limit up travel, but extended strut length determines down travel. The spacer sits above the strut and moves that whole assembly downward 10mm, allowing about 3/4” more down travel, which effectively extends allowable wheel travel.

 

[TeCKis300]

All good points. For my specific tastes, #1 and #2. I'd like to see better damping in comfort, and firmer support through corners in Sport. The difference in feel in my LX between Comfort and Sport is noticeable, but switching between Normal and C/S is almost imperceptible, so I'd like to see a wider distinction between modes. I suppose one could shift the whole system firmer by using stiffer springs, but as has been noted in other threads, there are drawbacks to that because a % of the vehicle's weight needs to be supported by the AHC. I'd love to see a table showing the stock spring rates and required spring rate increases for specific static weight additions.

When I first got the LX, I wondered why there wasn't as much differentiation between Comfort/Normal/Sport too when turning the dial. My LX470 prior to it showed greater change when switching between them in a straight line.

On the LX570, it's deceiving. The AHC system is much more integrated.

For straight ahead, the ideal damping regardless of C/N/S is not really that different. Why suffer from additional ride harshness just because the dial is in S. Likewise for C, the lowest amount of damping is really defined by spring rate. Less damping is not going to make the ride plusher as the damping job is to quell secondary motions. Springs and tires ultimately dictate primary ride compliance.

Put the vehicle in a dynamic situation, like taking a corner or a bump, and the system shows great differentiation and response. AHC is very integrated and tied into the things like the steering ECU. Give the steering a good turn and it tenses with firmer front axle spring rate and added damping. Likewise for braking and it response with the Anti-dive function. Turn in response is most definitely sharper with the damper set in a higher position.

Personally, I find the bandwidth of adjustment just fine. There are roads when driving in a sporty fashion in tight switchbacks, that Sport is actually too firm, that it unsettles the chassis on irregular pavement. I can hold a faster pace driving in normal, which still find a great balance of response, body control, and compliance. Obviously comfort relaxes things a bit too much but it's a great thing for those long highway slogs.