2" lean after airbag install on stock 2021 LC - KDSS or Over-Tight Suspension? (1 Viewer)

[Slow Paddler]

I had a local independent shop install my Firestone airbags for me this week, as I don't have access to a lift. He's a Toyota guy, and well respected in the T4R and Tacoma community, but here in northern Ohio, there are very few Land Cruisers.

I sent him a link to the install threads here, strict instruction NOT to unscrew the KDSS valve more than three turns, and links to a couple very thorough Airbag Man videos. He said he was able to install the bags without having to open the KDSS valve at all, by disconnecting the shocks and rear sway bar, letting the suspension hang.

I was in a rush returning home, and while I noticed the rear was higher, I attributed into a need to settle, and that's all the further I looked. Once home, I checked and realized the rear left was 2" higher than the right (measured at the sharp inside corner of the bottom of each reflector by the tailgate.) The pressure in the airbags was 8-9 PSI. In hindsight, I really should have measured all four corners beforehand. But...

I reduced the pressure to 5 PSI as indicated on my gauge (I have a good 0-15 gauge coming) and took it for a short drive to settle the suspension. Not far, and no real suspension loading, but I did some low speed pretty violent turns to induce some roll. Measuring again, I was 1-3/4" higher on the left than right. I'll be taking it to visit family for about 350 mikes, and will measure again when I get home early next week.

Since he didn't open the KDSS, does this just sound like the suspension still needs to settle? Or, maybe something was over-tightened, not allowing it to settle? Or, could the KDSS get out of whack just by him lowering and manipulating it during the airbag install?

Other than that, he did a really clean install, with the valves under the tailgate flap as @TeCKis300 has shown. I also had him put Fluid Film on, and he really coated things well, and got in every nook and cranny. That'll make it fun working under there if something other than suspension settling is needed.

Thanks for any input, and have a wonderful Thanksgiving!

 

[AnyMal]

I had a local independent shop install my Firestone airbags for me this week, as I don't have access to a lift. He's a Toyota guy, and well respected in the T4R and Tacoma community, but here in northern Ohio, there are very few Land Cruisers.

I sent him a link to the install threads here, strict instruction NOT to unscrew the KDSS valve more than three turns, and links to a couple very thorough Airbag Man videos. He said he was able to install the bags without having to open the KDSS valve at all, by disconnecting the shocks and rear sway bar, letting the suspension hang.

I was in a rush returning home, and while I noticed the rear was higher, I attributed into a need to settle, and that's all the further I looked. Once home, I checked and realized the rear left was 2" higher than the right (measured at the sharp inside corner of the bottom of each reflector by the tailgate.) The pressure in the airbags was 8-9 PSI. In hindsight, I really should have measured all four corners beforehand. But...

I reduced the pressure to 5 PSI as indicated on my gauge (I have a good 0-15 gauge coming) and took it for a short drive to settle the suspension. Not far, and no real suspension loading, but I did some low speed pretty violent turns to induce some roll. Measuring again, I was 1-3/4" higher on the left than right. I'll be taking it to visit family for about 350 mikes, and will measure again when I get home early next week.

Since he didn't open the KDSS, does this just should like the suspension still needs to settle? Or, maybe something was over-tightened, not allowing it to settle? Or, could the KDSS get out of what just by him lowering and manipulating it during the airbag install?

Other than that, he did a really clean install, with the valves under the tailgate flap as @TeCKis300 has shown. I also had him put Fluid Film on, and he really coated things well, and got in every nook and cranny. That'll make it fun working under there if something other than suspension settling is needed.

Thanks for any input, and have a wonderful Thanksgiving!

My hunch would be coil improperly seated against its stop flange, or top bucket bumper improperly seated there or something of that nature.

got pics? Might be an easy fix

 

[TeCKis300]

I had a local independent shop install my Firestone airbags for me this week, as I don't have access to a lift. He's a Toyota guy, and well respected in the T4R and Tacoma community, but here in northern Ohio, there are very few Land Cruisers.

I sent him a link to the install threads here, strict instruction NOT to unscrew the KDSS valve more than three turns, and links to a couple very thorough Airbag Man videos. He said he was able to install the bags without having to open the KDSS valve at all, by disconnecting the shocks and rear sway bar, letting the suspension hang.

I was in a rush returning home, and while I noticed the rear was higher, I attributed into a need to settle, and that's all the further I looked. Once home, I checked and realized the rear left was 2" higher than the right (measured at the sharp inside corner of the bottom of each reflector by the tailgate.) The pressure in the airbags was 8-9 PSI. In hindsight, I really should have measured all four corners beforehand. But...

I reduced the pressure to 5 PSI as indicated on my gauge (I have a good 0-15 gauge coming) and took it for a short drive to settle the suspension. Not far, and no real suspension loading, but I did some low speed pretty violent turns to induce some roll. Measuring again, I was 1-3/4" higher on the left than right. I'll be taking it to visit family for about 350 mikes, and will measure again when I get home early next week.

Since he didn't open the KDSS, does this just should like the suspension still needs to settle? Or, maybe something was over-tightened, not allowing it to settle? Or, could the KDSS get out of what just by him lowering and manipulating it during the airbag install?

Other than that, he did a really clean install, with the valves under the tailgate flap as @TeCKis300 has shown. I also had him put Fluid Film on, and he really coated things well, and got in every nook and cranny. That'll make it fun working under there if something other than suspension settling is needed.

Thanks for any input, and have a wonderful Thanksgiving!

I don't have KDSS, but from the way I understand it, it should level itself with some driving to allow the two circuits to balance out. Others have done it this way without opening the balance valves when lifting the suspension.

That said, even if the two bags are at the same PSI at the moment, the higher side will have more volume of air and not allow the balancing to happen as readily. It could help KDSS balance if you put a bit more air (pressure) into the low side, or less air into the high side.

 

[AnyMal]

may have unseated by a pressure test, or could be bound against a coil too.

 

[Slow Paddler]

Thanks, I'll crawl underneath to see if I can see anything with the spring. If not, I'll bump up the pressure on the low side, as they are both currently at the minimum, 5 PSI.

 

[CharlieS]

As Anymal says, make sure the top and bottom of the spring are properly seated. If they aren't, it can make a big difference.

 

[FerrisBueller]

It's definitely worth loosening the KDSS valves too, at least to rule it out. Maybe he said he didn't loosen them, but perhaps started to loosen them before changing his mind. It doesn't take much bolt loosening before the KDSS gives way.

 

[Slow Paddler]

I crawled underneath, and both springs look and feel fully seated. Of course I didn’t check them before, so I can only assume they’re okay based on being centered and both ends engaged with their respective seat.

I pumped the right (low) airbag up to 20 PSI and I’ll drive it tomorrow to visit family across the state. Hopefully that will settle things. If not, I’ll get back with the guy next week.

Thanks for the input!

 

[bloc]

If there is too great of an imbalance KDSS can have trouble equalizing the two circuits.

Toyota specifies balancing the system during or after suspension work for a reason. The job is really easy, totally worth trying out to see if it relaxes the lean. On a 2021 all you need is an 8mm socket, extension, and ratchet. Plus it’s a good opportunity to install some corrosion protection on the valve face.

 

[Slow Paddler]

If there is too great of an imbalance KDSS can have trouble equalizing the two circuits.

Toyota specifies balancing the system during or after suspension work for a reason. The job is really easy, totally worth trying out to see if it relaxes the lean. On a 2021 all you need is an 8mm socket, extension, and ratchet. Plus it’s a good opportunity to install some corrosion protection on the valve face.

Thanks. I drove 150 miles across Ohio today with 5 PSI in the (high) left side and 20 PSI in the (low) right side, as suggested earlier. I haven’t measured because we arrived in the dark, but it doesn’t seem to have changed. Or if it did, it much.

Tomorrow I’ll lower the right side down to 10 PSI. I’ll be retyhome mid week. Once back, I’ll look through the factory service manual for KDSS balancing instructions.

Thanks to everyone for the suggestions!

 

[gaijin]

Is it possible that when your mechanic installed the air bags he inadvertently swapped the Driver's side spring to the passenger side and vice versa? As I understand it, the two rear springs are slightly different lengths - installing them on the wrong sides could easily account for your lean.

HTH

 

[82SC]

This…

 

[bloc]

This…

View attachment 3178062

No.

That bandaid “fix” improperly loads the hydraulic system and sway bars to counteract a lean caused by something else.

Especially inappropriate when in this case the mechanic didn’t even try to follow the recommended procedure for suspension work. OP isn’t even at baseline yet.. that should be one of the first steps.

 

[82SC]

I’m no kdss expert but isn’t the whole kdss system a distribution of the hydraulic fluid to all four corners that then reacts in given loading situations.

The “bandaids” above seem to offer a way to redistribute the fluid to achieve a baseline of level to which the kdss can then respond to.

I think factory tolerance for kdss lean is up to an inch since fuel level, # of passengers, amount of gear in the back can all effect it.

I have the exact suspension setup as the OP which I did DIY and did it the way he had suggested to the shop. And mine is level to the eye ball but about 3/4” off depending on load.

But the two sources for the videos are pretty well respected sources of LC200 info.

And like @bloc mentioned you are supposed to balance the kdss system after any work. Which doesn’t seem to have been done.

 

[bloc]

I’m no kdss expert but isn’t the whole kdss system a distribution of the hydraulic fluid to all four corners that then reacts in given loading situations.

The “bandaids” above seem to offer a way to redistribute the fluid to achieve a baseline of level to which the kdss can then respond to.

I think factory tolerance for kdss lean is up to an inch since fuel level, # of passengers, amount of gear in the back can all effect it.

I have the exact suspension setup as the OP which I did DIY and did it the way he had suggested to the shop. And mine is level to the eye ball but about 3/4” off depending on load.

But the two sources for the videos are pretty well respected sources of LC200 info.

And like @bloc mentioned you are supposed to balance the kdss system after any work. Which doesn’t seem to have been done.

Opening the balance screws on flat ground equalizes the pressure in all three circuits of the KDSS system. If you wonder why there are three, see the thread I’ll link at the end of this post.

Putting one of the tires 4-8” in the air then closing the screws also balances the system.. when that tire is 4-8” in the air. Moving it to flat ground then uses the hydraulic components to apply force to the sway bars and lean the vehicle in the direction it didn’t before.. you are literally preloading the sway bars to correct a vehicle that isn’t level otherwise. On a more traditional system this would be like using different length sway bar end links. If you have to do that to get the vehicle level, something else is wrong.

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

 

[TimCFJ40]

Is it possible that when your mechanic installed the air bags he inadvertently swapped the Driver's side spring to the passenger side and vice versa? As I understand it, the two rear springs are slightly different lengths - installing them on the wrong sides could easily account for your lean.

HTH

This. If he removed both springs during install at the same time fix this first. Then balance the KDSS system while on level ground as described above.

 

[Slow Paddler]

Following up in this post. Back home and finally had a chance to fiddle with the truck. Using the new, more accurate 0-15 pressure gauge, I now have both bags set to 5 PSI +/- 1/4. I opened both KDSS bolts three turns, and drove around the local flat smooth roads.

Returning home, I again checked the measurements, and they were less than 1/4” different. Closed the KDSS valves, and good to go!

Thanks to everyone offering suggestions. Greatly appreciated. With the airbags in and the Redarc brake controller installed, there’s nothing left to do except wait for March to arrive to go pick up the new trailer.

Thank you