LX570 AHC height modifications (lift it!) (5 Viewers)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

I agree with this statement. The FSM actually gives you the fixed values for front/rear, but they arent needed if you just offset your own values by the desired difference. That being said, sometimes the HOU simply doesnt like your values and you to pick something different.

I wonder why that is? LOL
 
I guess I've been blocked by a certain user now since there are a ton of gaps in this thread for me and all the posts from one user are gone. Anywhoo...
 
First off, thanks to everyone who has contributed to this thread and all the other threads.

My 16' Lx has the sensor lift and is now pretty heavy with armor, drawers, ext. My AHC works great and I really don't have any complaints about the system in general. However, I have definitely noticed that the ride is really stiff and terrible in High. I now off-road in the regular height setting unless I need the clearance, then I put it in high and then switch back to N when Im past the obstacle.

I know for sure that I load my truck up beyond the payload capacity, and that makes me kind of nervous. I have been thinking about doing some of the proposed options to help unload the AHC by stiffening the springs by replacing them or adding spacers. I called Slee about another project and asked them about it and the opinion the Slee employee gave me was that adding a spacer to the springs would not do much to unload the AHC as the springs are already really soft so that the truck can lower. His advice was either to leave it as is or replace the whole system.

I was one of the folks that had my AHC fail after the dealership did an AHC flush, there is a whole thread about it. Basically the dealership took about a month to sort it out and ended up replacing the AHC pump. Now that my AHC is working, I am nervous to touch it again. I honestly think I will run it as is until it dies or I sell the truck. After that AHC flush debacle, it seems like its best to avoid anymore frustration by not touching it. Thoughts?

I'd encourage you to try spacers. No disrespect to Slee, and they are incredibly knowledgeable on many things, but their experience with AHC probably isn't extensive.

I've probably put more weight on my rear than most (prob except @radman :p ) and have seen 5200lbs on the rear axle. I have 30mm spacers. Also have airbags and can vary the support so have seen the spectrum of behavior there.

Start with the rear. 30mm spacers is an easy 1-1.5hr and straightforward job. As the coil springs are separate and not co-located with the shock, there's no need to mess with the hydraulic lines. It's just as easily reversible without consequence.
 
Appreciate the advice, I think I will try that. While I do not have any complaints or issues with the current set up, I know that I’m overdoing the payload limits. I bet 30-40% of my miles are towing my raft trailer (2-2.5k lbs) and the rest of the time I’m carrying other stuff. I’d like to support the system as much as possible
 
Hi to all.
I have Lexus LX570 2011.
My main problem, I have differences in Hight adjustment between front right and front left around 25mm.
Doesn't matter what I did, this difference never change and same, always 25mm.
I'm trying techstream all parameters, no effect in the difference between left and right, yes front going up and down but affected for both sides together, as well when I change one side left or right, still effect for both.
The same situation with the front sensor at the car, if I change only one side left or right, always affect both sides.

OK, who is smart enough and really know how to adjust the height for one side left or right ONLY, for LEFT FRONT or RIGHT FRONT ONLY.
thanks.
 
Hi to all.
I have Lexus LX570 2011.
My main problem, I have differences in Hight adjustment between front right and front left around 25mm.
Doesn't matter what I did, this difference never change and same, always 25mm.
I'm trying techstream all parameters, no effect in the difference between left and right, yes front going up and down but affected for both sides together, as well when I change one side left or right, still effect for both.
The same situation with the front sensor at the car, if I change only one side left or right, always affect both sides.

OK, who is smart enough and really know how to adjust the height for one side left or right ONLY, for LEFT FRONT or RIGHT FRONT ONLY.
thanks.
There are explanations just before your post of why you can’t adjust left/right level with AHC.
 
I guess I've been blocked by a certain user now since there are a ton of gaps in this thread for me and all the posts from one user are gone. Anywhoo...

Unblocked now. You can read back through, you didn't miss much.

I just didn't want to deal with any disagreements yesterday and have to respond on one of the first nice weather days in a while specially not on a friday, which is my holy day. No offense to anyone or yourself, but what i posted is not just a "theory" to be disagreed with on a whim. Neither did i post it because i enjoy spending half a day writing things out for the good of the community that i just make up as i go. Please if you disagree propose your own theory and solutions for us to be able to enjoy our dialogue because that would actually be constructive. I am happy to have one and I enjoy a good debate and there are people here who cannot lift or level properly.

I want to be friends, i think we probably agree on many a thing. But may i ask why though when someone steps up after 13 years does a ton of work and proposes a comprehensive fix and your first reaction is just to say no? What even is your goal? Why do you feel the need to come out against what I'm saying specially when it works? I spent a year painstakingly trying to figure this out and spoke to one of the product managers responsible for development of AHC. You disagree? Ok solve these peoples problems then. Its a bit disrespectful to be honest with you. Doing all this work for the public, and then not even getting a thank you but then be met with hostility for no good reason at that.
 
Unblocked now. You can read back through, you didn't miss much.

I just didn't want to deal with any disagreements yesterday and have to respond on one of the first nice weather days in a while specially not on a friday, which is my holy day. No offense to anyone or yourself, but what i posted is not just a "theory" to be disagreed with on a whim. Neither did i post it because i enjoy spending half a day writing things out for the good of the community that i just make up as i go. Please if you disagree propose your own theory and solutions for us to be able to enjoy our dialogue because that would actually be constructive. I am happy to have one and I enjoy a good debate and there are people here who cannot lift or level properly.

I want to be friends, i think we probably agree on many a thing. But may i ask why though when someone steps up after 13 years does a ton of work and proposes a comprehensive fix and your first reaction is just to say no? What even is your goal? Why do you feel the need to come out against what I'm saying specially when it works? I spent a year painstakingly trying to figure this out and spoke to one of the product managers responsible for development of AHC. You disagree? Ok solve these peoples problems then. Its a bit disrespectful to be honest with you. Doing all this work for the public, and then not even getting a thank you but then be met with hostility for no good reason at that.
I agree with sentiments of cordial communication and I appreciate that you spent a lot of time writing a post. But it appears to be riddled with misinformation. You consistently suggest that the truck measures pressure at each corner and makes decisions based on this. If so please show a picture of either an actual pressure sensor or documentation from Toyota that there are any pressure sensors in the AHC with the exception of the one at the pump.

I do agree with your assessment of using matching springs as a possible fix for lean. And, applaud you for taking action to test the theory, even if I probably won’t do it myself, but it’s certainly a valid solution.

It’s dangerous to present your opinions as fact, which you have done above, as unsuspecting readers may take it as fact when it my not be fully vetted.
 
25 pages behind, can i have link to post?
Quoted from above.

Ultimately the left to right "levelness" of the truck still relies on the springs and weight of the truck being level, because each axle is hydraulically tied together in the AHC system and the sides of each axle will share fluid during driving, so even if you make static changes, they will go away once you drive and the leveling gates are opened.
 
I agree with sentiments of cordial communication and I appreciate that you spent a lot of time writing a post. But it appears to be riddled with misinformation. You consistently suggest that the truck measures pressure at each corner and makes decisions based on this. If so please show a picture of either an actual pressure sensor or documentation from Toyota that there are any pressure sensors in the AHC with the exception of the one at the pump.

I do agree with your assessment of using matching springs as a possible fix for lean. And, applaud you for taking action to test the theory, even if I probably won’t do it myself, but it’s certainly a valid solution.

It’s dangerous to present your opinions as fact, which you have done above, as unsuspecting readers may take it as fact when it my not be fully vetted.

Do yourself a favor and read it maybe a few more times. You dont even have BASIC knowledge of AHC. You didn't even know shocks could be independently pressurized. You didn't properly understand any of this conceptually and you're doing the internet a service by trying to stop my misinformation? WOW.
You're now one more ignorant retort from being blocked again. What an absolute joke. Please spare me your BS, you even directed someone to my post for help. You dont even have any intellectual integrity to warrant having a conversation buddy.

This is a computer controlled and monitored system, and i dont think you understand that all of this can be programmed without even needing real-time data. I think theres a lot of things you don't understand about IT from the way you are generally "arguing" with me. I think you don't even understand that the sensor values can be summed by a calculation. You also lack basic reading comprehension. Even if youre just upset someone knows something you dont, i take back everything about being friends. The way your coming back for seconds with absolutely nothing of substance is not worth my time.

Also, you don't need to "agree" with spring matching. The guy who helped build the system told me that. You need to take a backseat.
 
Last edited:
Quoted from above.

Ultimately the left to right "levelness" of the truck still relies on the springs and weight of the truck being level, because each axle is hydraulically tied together in the AHC system and the sides of each axle will share fluid during driving, so even if you make static changes, they will go away once you drive and the leveling gates are opened.

No.
 
First off, thanks to everyone who has contributed to this thread and all the other threads.

My 16' Lx has the sensor lift and is now pretty heavy with armor, drawers, ext. My AHC works great and I really don't have any complaints about the system in general. However, I have definitely noticed that the ride is really stiff and terrible in High. I now off-road in the regular height setting unless I need the clearance, then I put it in high and then switch back to N when Im past the obstacle.

I know for sure that I load my truck up beyond the payload capacity, and that makes me kind of nervous. I have been thinking about doing some of the proposed options to help unload the AHC by stiffening the springs by replacing them or adding spacers. I called Slee about another project and asked them about it and the opinion the Slee employee gave me was that adding a spacer to the springs would not do much to unload the AHC as the springs are already really soft so that the truck can lower. His advice was either to leave it as is or replace the whole system.

I was one of the folks that had my AHC fail after the dealership did an AHC flush, there is a whole thread about it. Basically the dealership took about a month to sort it out and ended up replacing the AHC pump. Now that my AHC is working, I am nervous to touch it again. I honestly think I will run it as is until it dies or I sell the truck. After that AHC flush debacle, it seems like its best to avoid anymore frustration by not touching it. Thoughts?

I think spacers would help but I would think about replacing the rear springs and go with OEM spacers on front. Uprated springs designed for AHC definitely help when you are running heavy and I haven’t experienced any negatives after a summer of long highway miles and some pretty tough wheeling. The ride is great and it articulates as expected.
 
Unblocked now. You can read back through, you didn't miss much.

I just didn't want to deal with any disagreements yesterday and have to respond on one of the first nice weather days in a while specially not on a friday, which is my holy day. No offense to anyone or yourself, but what i posted is not just a "theory" to be disagreed with on a whim. Neither did i post it because i enjoy spending half a day writing things out for the good of the community that i just make up as i go. Please if you disagree propose your own theory and solutions for us to be able to enjoy our dialogue because that would actually be constructive. I am happy to have one and I enjoy a good debate and there are people here who cannot lift or level properly.

I want to be friends, i think we probably agree on many a thing. But may i ask why though when someone steps up after 13 years does a ton of work and proposes a comprehensive fix and your first reaction is just to say no? What even is your goal? Why do you feel the need to come out against what I'm saying specially when it works? I spent a year painstakingly trying to figure this out and spoke to one of the product managers responsible for development of AHC. You disagree? Ok solve these peoples problems then. Its a bit disrespectful to be honest with you. Doing all this work for the public, and then not even getting a thank you but then be met with hostility for no good reason at that.

Man, I enjoy your posts and for all I know you may have the mind of Einstein and the artistic sense of Leonardo, but it is hard to take you seriously and I have a pretty high threshold for bs.
 
Man, I enjoy your posts and for all I know you may have the mind of Einstein and the artistic sense of Leonardo, but it is hard to take you seriously and I have a pretty high threshold for bs.

It’s ok, I’m not selling anything.
Nor did anything I say or suggest in any way affect anyones well being or safety. To be accused of that is assenine and I will respond in kind.

Thanks for reading man. I enjoy both writing and reading everyone’s opinion. I even enjoy a good debate. I just don’t tolerate bs when it’s directed at me. Find one instance of provocation directed at an individual on my account which I initiated and I’ll delete it immediately.
 
Quoted from above.

Ultimately the left to right "levelness" of the truck still relies on the springs and weight of the truck being level, because each axle is hydraulically tied together in the AHC system and the sides of each axle will share fluid during driving, so even if you make static changes, they will go away once you drive and the leveling gates are opened.
thanks for the answer, in other words, I must use a spacer on one side to add height? correct?
 
thanks for the answer, in other words, I must use a spacer on one side to add height? correct?
I’m fairly certain there is a pretty heavy feedback loop between “you” and another user, but for sake of correct info on the forum.

Adding a spacer on its own won’t likely fix the issue. At least, it’s not as simple as adding a spacer that is the height you think it’s off to make it level.

If you added a spacer to both sides. the height wouldn’t change at all, because ultimately the height sensors determine the height of the truck. If you spaced both sides, the truck would go to the same height but at lower AHC pressure because the springs would be preloaded to a stiffer setting, changing the balance between the AHC system and the springs.

So, if you add a spacer to one side and change nothing else (specifically HOU or height sensors), when the truck adjusts height, nothing will change, but the truck will require less AHC pressure to lift the spaced side. So, assuming the pressure between the left and right actuators (shocks) is the same now, when the truck opens the gate valve between sides, no heights will change and the truck will stay level, Conversely, if the truck had to apply more pressure to one side or the other to get it to the height sensor requirement, it will add that pressure to whichever and temporarily, the truck will be at whatever the height sensor sets, But when the gate valve opens between the two actuators on the front axle the pressure will equalize and the two sides will shift (up/down) towards equalized pressures which may or may not be level.

To be clear, the gate valve’s primary purpose is to allow the two sides to affect each other for vehicle stabilization in motion, the balancing of pressure is a side affect. In a perfectly tuned system the pressures would be the same before the valve opened and it wouldn’t change height. Edit: This may not be entirely correct. The manual states that the gate valve is to balance pressure between the left and right side. It doesn't specify if that's a primary function nor if there are other reasons it opens/closes. The manual states it's primarily closed, which makes sense, since if it were primarily open, it would negate the work of the center suspension control cylinder.

The truck does all this by using the height sensors. It doesn’t care (or know) what pressure it takes to lift the truck to the height sensor set level. As long as the pump is capable of providing the height it will do whatever you ask regardless of the pressure it takes to do it. This is why you can add 1000lbs to the truck and it will still function as designed. iThe pump will add more pressure to the system to get to the height sensor setting and the truck will go about its business.

To summarize, the only way the truck will sit level is if the same pressure applied to both the actuators results in the truck being level. You have to make any adjustments based on that knowledge. Personally, I don’t think its worth chasing a minor lean because of the difficulty, since it is not easy to measure the pressure at each actuator.
 
Last edited:
4 - bad ride quality
5 - little influence in ride mode damping
___________________________________________

Solution 4,5,6,7,8 - difficulty level 1/5:
If and only if you are unladen know your globes /shocks are good and still experiencing a harsh ride, the easiest way to address that would be to lift your sensors.
This is the best solution to redistribute weight from your springs back to your AHC without modifying your suspension. Only a mild sensor adjustment is needed NOT a max out. Maxing sensors will cause the inverse issue and put your suspension too far out of spec. (this can be negligible depending on your fitment and is not a catch all)
Cause:
There is too little load on the AHC system and too much on the springs. Softening up the AHC dampers doesnt have an effect since the shocks are not being actuated enough to make a difference. The springs are holding the vehicle too far out of the full shock travel range. The inverse solution to this is of course stiffer / longer springs front and rear, as well as shock spacer and trim packers when you are loading up more than the AHC is "supposed" to bear. This is a TUNED system it is vital to remember that for all LX builds. You have to treat it as such to preserve the correct synergy between AHC system/shocks and springs. Otherwise it will always be too soft or too stiff OR you could just be overworking your AHC in the long term. Perform either based on your build and needs.

I did a sensor lift on the front only last night, and was astounded at the improvement in ride quality. I recently replaced globes and flushed AHC fluid and noticed little to no ride change, but the sensor lift seemed to unlock all those improvements - all the little bumpity bumps are no longer communicated through the vehicle; it's a big change for the better. Weird.
 
I did a sensor lift on the front only last night, and was astounded at the improvement in ride quality. I recently replaced globes and flushed AHC fluid and noticed little to no ride change, but the sensor lift seemed to unlock all those improvements - all the little bumpity bumps are no longer communicated through the vehicle; it's a big change for the better. Weird.
Nice, the people who sussed out most of the details of AHC on the 100 series figured out that the balance between the AHC system and the springs is very important in regards to NVH and handling. But between the 100 and 200 series it was much easier to balance on the 100 series platform. On the 100, Techstream approximated pressures for both the front and rear axle, although it didn't measure each individual corner (the 100 system didn't have separate leveling valves for each corner, only one per axle). It's still better than the 200 series which only reports the system pressure while the pump is running and doesn't break out any values between axles. The other aspect of the the 100 series that made balancing the system easier is that it had torsion bars up front so you could preload or unload the front suspension therefore changing the balance between the "springs" and the AHC system with a good bit of precision without changing height.

You can measure the pressure at the corners yourself with the SST LSPV Gauge. Or I'm sure you could rig up something yourself. This would be the ultimate way to balance your height sensors or verify you are running at the correct AHC pressure for good NVH.
 
Nice, the people who sussed out most of the details of AHC on the 100 series figured out that the balance between the AHC system and the springs is very important in regards to NVH and handling. But between the 100 and 200 series it was much easier to balance on the 100 series platform. On the 100, Techstream approximated pressures for both the front and rear axle, although it didn't measure each individual corner (the 100 system didn't have separate leveling valves for each corner, only one per axle). It's still better than the 200 series which only reports the system pressure while the pump is running and doesn't break out any values between axles. The other aspect of the the 100 series that made balancing the system easier is that it had torsion bars up front so you could preload or unload the front suspension therefore changing the balance between the "springs" and the AHC system with a good bit of precision without changing height.

You can measure the pressure at the corners yourself with the SST LSPV Gauge. Or I'm sure you could rig up something yourself. This would be the ultimate way to balance your height sensors or verify you are running at the correct AHC pressure for good NVH.

Having had an LX470 and sussing out the details on the forum there with the same hive mind change from AHC sucks to AHC rocks, it's funny to see how it's similarly playing out on the 200-series. Lots of parallels in the system between the 100 to 200. At the same time, the 200-series AHC is more robust with a much larger sweet spot. My favorite things about AHC on the 200-series is the addition of an additional spring rate on the front axle that better manages brake dive and roll posture. Probably more importantly for modders, handles ~600-700lbs more payload before hitting hydraulic pressure limits in normal position.

The sweet spot is larger as mentioned. It seems to adapt to the span of payload pretty well. As I have effectively variable spring rate in the rear with airbags, been able to try the limits

Too little load on AHC / too much physical spring​

- Damping authority and performance decreases. Intuitively makes sense as the system needs some level of hydraulic pressure to positively engage the remote dampers. I believe the system must be dialing between its selectable damping positions depending on pressure, to maintain level ride quality/performance depending load, or height positions. One caution to using too much spring, is the system may spit out AHC fluid from the reservoir, when going to low position. The system basically continues to evacuate AHC fluid, and if Low is hard or unattainable because of too my physical spring, more of the normally pressured fluid volume in the accumulators will go to the reservoir. And it may never reach low position.

Too much load on AHC / too little physical spring / or too much sensor adjustment for normal ride height​

- The system is constant height until some hydraulic fluid pressure threshold. With a healthy system, this is about 1800lbs-2000lbs if evenly loaded between the axles. Above that, and the system may lean more on the physical springs and sacrifice some height, even if it reports as Normal height. May even report Low mode though this is different from Low ingress mode, and will drive just fine. Both these fallbacks are fine and normal for the system, behaving like a static suspension would. Getting into high position may not be possible. It will try, and if it hits the threshold for hydraulic pressure, may just as soon give up.
 

Users who are viewing this thread

Back
Top Bottom