KDSS lean keeps changing (1 Viewer)

[skmaynard1]

Hey everyone!

I've been looking at this forum for some time, and my wife and I have just purchased our first Land Cruiser. We got a 2013 with 121,000 miles, and we are very happy with it. It is currently bone stock, but will be getting small mods while the wife drives it for a few years. When its time for her to get something new (hopefully a slightly used 2021), it will become our off-roading /camping rig with major modifications.

We purchased the rig sight unseen and had it shipped to us. I immediately noticed that it had a driver side lean, and also knew that there was a KDSS "fix" for this. I did take measurements from hub to fender, and it was 1 inch lower both front and rear. I took it to Toyota for an overall inspection and to have them look at the lean. They suggested that we fully replace all suspension (shocks/springs/strut caps). In all my research I have come to the realization that the issue is likely fatigued springs, and that this would likely correct the issue. I also realize that the KDSS fix is merely utilizing one system to compensate for the failure of another. Still, I did the KDSS fix and everything was great..... for a few days.

About 4 days and 300ish miles after the fix, the car was again leaning towards the driver side. My wife and I talked and decided we should just replace the suspension, and started debating if we lift now or stay stock (thats another conversation).

The next day when my wife got home from work, the car was level again! It is currently sitting level, which should make us happy... but it doesn't. If we don't need to change out the suspension, we plan to just do the front spacers for now as a temporary cool factor upgrade. I don't want to go through all of the effort to install the spacers and get the alignment checked just to have to change it all out again when the car shifts back to unlevel and stays there.

All that said for these questions:

1) What causes the KDSS to shift between leaning and not leaning? Is there something within that system that could be replaced/repaired?
2) If I replace the suspension fully, the KDSS will be able to be fully level again and not holding the "fix" pressure one direction. Do you think this will stop the shifting from lean to no lean?
3) If anyone has experience this, what would/did you do?

Sorry for the long post, just didn't know how to say it all shorter.

 

[lx200inAR]

Don't want to state the obvious, but did you go from a full tank of gas to an empty tank in that 300 miles, then fil up again? A full tank of gas is 150+lbs and the tank is offset to the passenger side.

 

[ElJayBird]

Cruiser lean seems to be tough to eliminate. I replaced springs, shocks and reset KDSS - noticed that the lean returned less than a month later. I'm over it....

 

[TLC2013]

I had been chasing a driver side lean that was up to 1.25” low at the rear driver side. Fronts are generally less then 1/2” difference. It existed both before and after my lift. None of the KDSS tricks worked for me to re-level.

With the rear springs being longer on the passenger side to compensate for fuel weight I just swapped springs so the longer spring is now on the rear driver side and it is now within 1/3” to level depending on the day.

I am done chasing leans. It’s quite a wormhole to dive into.

 

[Markuson]

Make sure you are judging lean on an *absolutely* level surface. Even a slight road tilt like one side by tge curb and other not will give the appearance of a lean.

That said... Its going to always change a little depending on where gou drive, park etc.
I’n OCD about level and it took
years to finally quit obsessing over it. Normal and harmless...just occasionally annoying.

If your driveway isnt level, try alternating whether you pull in forward or reward. Other than ridiculous lean...don’t worry about ill effects from the variability. There really aren’t any.

 

[skmaynard1]

Don't want to state the obvious, but did you go from a full tank of gas to an empty tank in that 300 miles, then fil up again? A full tank of gas is 150+lbs and the tank is offset to the passenger side.

To be honest, I haven’t thought about the fuel level as a factor. I will track the height to fuel ratio for a while to see if that’s the cause of the shift.

If that is the issue, do you guys think that replacing the “weak” springs will at least minimize the effect?

Make sure you are judging lean on an *absolutely* level surface. Even a slight road tilt like one side by tge curb and other not will give the appearance of a lean.

That said... Its going to always change a little depending on where gou drive, park etc.
I’n OCD about level and it took
years to finally quit obsessing over it. Normal and harmless...just occasionally annoying.

If your driveway isnt level, try alternating whether you pull in forward or reward. Other than ridiculous lean...don’t worry about ill effects from the variability. There really aren’t any.

I didn’t put a level on the driveway, but the kids play basketball on it regularly and balls don’t roll without a push. So it’s at least close to level.

 

[Sandroad]

I don't have much to offer, except that the slight lean on mine is just a "is what it is" thing. If you want to chase it down on yours if it comes back, you might consider taking a staged approach, rather than going the full monty on the suspension. I'll hazard a complete guess that if there is a suspension related affect, you may find it worthwhile to just do the rear springs. They are cheap (ballpark $150 at discount dealers) and easy to install. I've had mine out without drama to install airbags and it was a couple hours. Depending on the history of the truck, rear springs may have had the most stress (like towing) during previous ownership.

 

[Lester did that]

I would swear that mine would do the same. The lean would change. So I started measuring it with a tape measure. Then I noticed when I saw it it was parked on un even terrain or a street that was not level. Ie the street was crowned for drainage. It was just knowing about the KDSS lean that made me aware. Sometimes a little knowledge is dangerous. Drove me crazy.

After I had it lifted 2.5" visually it is less noticeable. I just put it out of my head now. I have seen that lean once at a mechanics shop. When its off it is really off. This truck was a low rider on the driver side and jacked on the passenger side. 3" difference between sides. That is a KDSS lean. If your .5" off on any given day it is not an issue. It's an OCD thing.

 

[Taco2Cruiser]

Corrected in post below. I miss understood the original post. Below was left for general understanding of a functioning system.


Completely normal.

I can take a 4Runner, GX460, or LC200 all with KDSS and make them lean to a different side when parked in flat ground. Just stand up on one side’s sliders and bounce. You can shift the level by 1/2-3/4”. I can also do that to any non-KDSS Toyota also, so don’t get wrapped around it being a KDSS thing.

I’m getting a bunch of stuff ready to have these more technical videos in the coming months, but... getting your 200 to sit level on a flat surface is not really the whole picture. You would be missing how the truck rides when bouncing down the road. So don’t get too caught up in static tape measure numbers. How does the truck feel when you drive it? That’s what is the more advanced way of tuning suspension

There’s kinda a lot with this, which is why I’m going do this video I’ve been asked about a few times. But at least in a 200, you can make them sit dead flat, and I feel “cruiser lean” is just something that doesn’t really exist.

 

[Lester did that]

There’s kinda a lot with this, which is why I’m going do this video I’ve been asked about a few times. But at least in a 200, you can make them sit dead flat, and I feel “cruiser lean” is just something that doesn’t really exist.

100%.

But when something is broken with the KDSS it can lean so hard a layman will look at it and see something is wrong. It's not a slight tilt to one side. I saw it one time in a shop and even the owner of the shop said he never saw the system have issues unless it was in a collision. It was a unicorn event. It's such a simple closed system almost nothing can damage it except force like an impact or something hits a line or you mess with the valves. Just leave it alone unless you know what you are doing.

 

[skmaynard1]

Completely normal.

I can take a 4Runner, GX460, or LC200 all with KDSS and make them lean to a different side when parked in flat ground. Just stand up on one side’s sliders and bounce. You can shift the level by 1/2-3/4”. I can also do that to any non-KDSS Toyota also, so don’t get wrapped around it being a KDSS thing.

I’m getting a bunch of stuff ready to have these more technical videos in the coming months, but... getting your 200 to sit level on a flat surface is not really the whole picture. You would be missing how the truck rides when bouncing down the road. So don’t get too caught up in static tape measure numbers. How does the truck feel when you drive it? That’s what is the more advanced way of tuning suspension

There’s kinda a lot with this, which is why I’m going do this video I’ve been asked about a few times. But at least in a 200, you can make them sit dead flat, and I feel “cruiser lean” is just something that doesn’t really exist.

@Taco2Cruiser We are new to owning our LC200 and its our first one as well. We went from a 2017 Highlander Limited, to our 2013 Land Cruiser. I would say the ride is much more "truck like" but also much more comfortable. Given the overall comfort in regards to bumps, and great handling, I do not believe there is anything majorly wrong with the suspension. Which is also why it is somewhat hard for me to believe that it is just "old springs".

If it was just old worn out springs, I would think that the handling would be sloppy. Or at least when I take Right turns and put more weight on the sagging driver side. Also, it seems to me that fatigued springs would exhibit the issue all of the time rather than come and go.

For what its worth, I'm not looking at this from a completely novice point of view. I was an ASE certified mechanic prior to obtaining my engineering degree. So I have a good amount of knowledge both on automotive suspension as well as mechanics of materials. I am a bit limited in the hydraulic department though, so that's more why I'm trying to figure out the KDSS a bit more in depth.

Here is a picture of the truck as it stands today, and yes that driveway is about as level as you can get it.

 

[bloc]

100%.

But when something is broken with the KDSS it can lean so hard a layman will look at it and see something is wrong. It's not a slight tilt to one side. I saw it one time in a shop and even the owner of the shop said he never saw the system have issues unless it was in a collision. It was a unicorn event. It's such a simple closed system almost nothing can damage it except force like an impact or something hits a line or you mess with the valves. Just leave it alone unless you know what you are doing.

Central control valves that have failed due to corrosion can do this too, apparently. Thing is I can’t exactly figure out why, based on my understanding of the system. See the second part of this post.

@Taco2Cruiser We are new to owning our LC200 and its our first one as well. We went from a 2017 Highlander Limited, to our 2013 Land Cruiser. I would say the ride is much more "truck like" but also much more comfortable. Given the overall comfort in regards to bumps, and great handling, I do not believe there is anything majorly wrong with the suspension. Which is also why it is somewhat hard for me to believe that it is just "old springs".

If it was just old worn out springs, I would think that the handling would be sloppy. Or at least when I take Right turns and put more weight on the sagging driver side. Also, it seems to me that fatigued springs would exhibit the issue all of the time rather than come and go.

For what its worth, I'm not looking at this from a completely novice point of view. I was an ASE certified mechanic prior to obtaining my engineering degree. So I have a good amount of knowledge both on automotive suspension as well as mechanics of materials. I am a bit limited in the hydraulic department though, so that's more why I'm trying to figure out the KDSS a bit more in depth.

Here is a picture of the truck as it stands today, and yes that driveway is about as level as you can get it.

View attachment 2622394

Give this thread a look, it’ll help you understand what is going on inside the main KDSS valve/accumulator itself.

Anatomy of a KDSS valve

I think you guys and gals are gonna like this.. HUGE thanks to @jimoldguy who shipped me his rust-damaged KDSS valve after it was replaced for him with a new one. That can't have been cheap. Fortunately for me he kept the old one, and when I PM'd asking if he'd send it for a project I'm working...

forum.ih8mud.com

 

[skmaynard1]

Central control valves that have failed due to corrosion can do this too, apparently. Thing is I can’t exactly figure out why, based on my understanding of the system. See the second part of this post.




Give this thread a look, it’ll help you understand what is going on inside the main KDSS valve/accumulator itself.

Anatomy of a KDSS valve

I think you guys and gals are gonna like this.. HUGE thanks to @jimoldguy who shipped me his rust-damaged KDSS valve after it was replaced for him with a new one. That can't have been cheap. Fortunately for me he kept the old one, and when I PM'd asking if he'd send it for a project I'm working...

forum.ih8mud.com

@bloc
That was a great thread, thank you for sharing and for putting it together. Seeing the inside of the block does help greatly with the understanding. Based on my understanding of the system, I would think that the KDSS could cause a lean if one of those valves was only allowing one way flow. Pressure would build up on one side of the system and the "sticking" valve would not allow it to flow back to a neutral position. It appears that this could not be due to a failed accumulator, as you stated that they are not plumbed independently per system side.

If that is the case, then opening up the balancing valves (while on flat ground) should allow the system to equalize and the truck to go back to level. This could likely be felt by a shift in the suspension right as the valve is opened.

The self correcting and returning of the lean could be the beginning of one of these failed valves in which is sticks and then releases itself with enough force from a hard turn or unlevel driving situation.

Given that balancing the system gets my vehicle back to unlevel, I believe that I do need to replace my springs in order to get a more consistent height. I also fear that I may have a valve going bad and will likely still have the occasional lean situation should not make any KDSS repairs.

 

[Taco2Cruiser]

@Taco2Cruiser We are new to owning our LC200 and its our first one as well. We went from a 2017 Highlander Limited, to our 2013 Land Cruiser. I would say the ride is much more "truck like" but also much more comfortable. Given the overall comfort in regards to bumps, and great handling, I do not believe there is anything majorly wrong with the suspension. Which is also why it is somewhat hard for me to believe that it is just "old springs".

If it was just old worn out springs, I would think that the handling would be sloppy. Or at least when I take Right turns and put more weight on the sagging driver side. Also, it seems to me that fatigued springs would exhibit the issue all of the time rather than come and go.

For what its worth, I'm not looking at this from a completely novice point of view. I was an ASE certified mechanic prior to obtaining my engineering degree. So I have a good amount of knowledge both on automotive suspension as well as mechanics of materials. I am a bit limited in the hydraulic department though, so that's more why I'm trying to figure out the KDSS a bit more in depth.

Here is a picture of the truck as it stands today, and yes that driveway is about as level as you can get it.

View attachment 2622394

Sorry, I reread your original post and missed where you opened the valves up and got everything level. Then it went sideways again.

I would still open the valves up again, and drive around your neighborhood a bit. Really work the fluid around. I know some will say that will damage something, but I don’t see how that is possible when jouncing the system for a minute or two.

Once back in flat ground, bounce on your driver side a few times. Really sink the drive side down. Then leave the truck alone for 20 minutes. That’s what the FSM says. Then tighten it up. If it leans back to the passenger side again, you may have the second reported KDSS failure that this forum has heard of.

I’ve found a few times where I needed to really jounce the suspension to get everything happy again.

Also, don’t know which ASE certs you have or had if they expired, but if you obtained A4 then you should have no troubles finding a collapsed bush. But I would also loosen and re-torque all deflection type bushes on your control arms. Front and rear. Just to make sure it is all set at proper ride height.

I didn’t mean for that last paragraph to sound condescending. It was more to not insult your background and not go into super depth on the subject as you already know what you’re doing there.

 

[bloc]

@bloc
That was a great thread, thank you for sharing and for putting it together. Seeing the inside of the block does help greatly with the understanding. Based on my understanding of the system, I would think that the KDSS could cause a lean if one of those valves was only allowing one way flow. Pressure would build up on one side of the system and the "sticking" valve would not allow it to flow back to a neutral position. It appears that this could not be due to a failed accumulator, as you stated that they are not plumbed independently per system side.

If that is the case, then opening up the balancing valves (while on flat ground) should allow the system to equalize and the truck to go back to level. This could likely be felt by a shift in the suspension right as the valve is opened.

The self correcting and returning of the lean could be the beginning of one of these failed valves in which is sticks and then releases itself with enough force from a hard turn or unlevel driving situation.

Given that balancing the system gets my vehicle back to unlevel, I believe that I do need to replace my springs in order to get a more consistent height. I also fear that I may have a valve going bad and will likely still have the occasional lean situation should not make any KDSS repairs.

Toyota seems to have done a good job protecting the high precision internals of the pop-off and bleed-back valves with filters though. Beyond that I'm not sure what would cause them to fail. System pressure getting low maybe, but then you'd see a leak somewhere.

As mentioned, I'm not quite sure how severe rust causes a lean, but it has done so. So maybe I just don't understand this system well enough.

 

[Taco2Cruiser]

Toyota seems to have done a good job protecting the high precision internals of the pop-off and bleed-back valves with filters though. Beyond that I'm not sure what would cause them to fail. System pressure getting low maybe, but then you'd see a leak somewhere.

As mentioned, I'm not quite sure how severe rust causes a lean, but it has done so. So maybe I just don't understand this system well enough.

It could of been messed up by a shop along the way. A guy called me a few weeks ago about a Toyota dealership tried to install a lift, and didn’t release the set screws. Then at the end of the job, they opened the set screws all the way up and shot fluid on the muffler. They then tightened it up and sent the truck in its way. Customer found smoke coming off the muffler and the drive “felt odd.”

So who knows what “service professional” has done to it along the way. I feel like that needs to be considered more than most issues on these trucks. The amount of things I find under 200 from past work is pretty appalling.

 

[bloc]

It could of been messed up by a shop along the way. A guy called me a few weeks ago about a Toyota dealership tried to install a lift, and didn’t release the set screws. Then at the end of the job, they opened the set screws all the way up and shot fluid on the muffler. They then tightened it up and sent the truck in its way. Customer found smoke coming off the muffler and the drive “felt odd.”

So who knows what “service professional” has done to it along the way. I feel like that needs to be considered more than most issues on these trucks. The amount of things I find under 200 from past work is pretty appalling.

Good point. And really that’s the case with all cars, but we care about these so much..

 

[Taco2Cruiser]

Good point. And really that’s the case with all cars, but we care about these so much..

So true.

All in all, @skmaynard1 I really hope it works out for you. I’d love to hear what you find.

 

[Lester did that]

Central control valves that have failed due to corrosion can do this too, apparently. Thing is I can’t exactly figure out why, based on my understanding of the system. See the second part of this post.




Give this thread a look, it’ll help you understand what is going on inside the main KDSS valve/accumulator itself.

Anatomy of a KDSS valve

I think you guys and gals are gonna like this.. HUGE thanks to @jimoldguy who shipped me his rust-damaged KDSS valve after it was replaced for him with a new one. That can't have been cheap. Fortunately for me he kept the old one, and when I PM'd asking if he'd send it for a project I'm working...

forum.ih8mud.com

That's a great write up. It's always nice to actually see something in real life than a mechanical drawing. Maybe the heavy corrosion just really rotted it out but from the pictures it seemed the exterior was a mess but everything inside looked ok. Unicorn? I mean some times things just happen with no good explanation. Or someone messed with it that did not know the correct path. Who know's?

I am just starting to learn about hydrolic systems at work. They are very durable and very simple closed systems. When something goes wrong it is usually a soft line. A sealed hard line system is almost bullet proof. Almost. Off topic we have a hydrolic press at work and it works almost the same as the KDSS in regards to balancing pressure. I stood by the tech while he was servicing it. 30 year fluid change... He was saying that with the oil that is in there with a sealed system does not need to be changed. He hates opening this press up because its a 50/50 chance that it's going to cause a problem. But owners swear it needs to be serviced. There was a rider on the contract fully spelling this out. But he was really kind with all my questions. I showed him a video of the KDSS and he said yeah its the same system as the press. Side note it is a german made press. kinda cool the entire motor, electric, was submerged in the fluid sealed in the fluid sump. Did not know you can run an electric motor that is completely open in the right type of oil. My mind was blown.

 

[bloc]

That's a great write up. It's always nice to actually see something in real life than a mechanical drawing. Maybe the heavy corrosion just really rotted it out but from the pictures it seemed the exterior was a mess but everything inside looked ok. Unicorn? I mean some times things just happen with no good explanation. Or someone messed with it that did not know the correct path. Who know's?

I am just starting to learn about hydrolic systems at work. They are very durable and very simple closed systems. When something goes wrong it is usually a soft line. A sealed hard line system is almost bullet proof. Almost. Off topic we have a hydrolic press at work and it works almost the same as the KDSS in regards to balancing pressure. I stood by the tech while he was servicing it. 30 year fluid change... He was saying that with the oil that is in there with a sealed system does not need to be changed. He hates opening this press up because its a 50/50 chance that it's going to cause a problem. But owners swear it needs to be serviced. There was a rider on the contract fully spelling this out. But he was really kind with all my questions. I showed him a video of the KDSS and he said yeah its the same system as the press. Side note it is a german made press. kinda cool the entire motor, electric, was submerged in the fluid sealed in the fluid sump. Did not know you can run an electric motor that is completely open in the right type of oil. My mind was blown.

With that one accumulator missing from the valve I cut up I wonder if corrosion caused it to leak or something. Or maybe even a line leaked and due to the corrosion they couldn’t get the lines off the valve so they replaced it too. It does seem the internals were just fine though.

And yeah all kinds of crazy stuff happens that we don’t know about in industrial processes. I used to work with a waterjet.. it pressurized water to 40k psi and forced it through a hole the size of a human hair to cut things on a 2-axis table. Or equipment in well cementing that analyzes how cement hardens, non destructively, by passing ultrasonic waves through it, or stirring it in a cup at 400+ degrees and 40kpsi.

Our KDSS systems share some functions with these things, but also deal with us driving around using them for hundreds of thousands of miles. Toyota is awesome.