Incurable passenger side lean (1 Viewer)

[Humperdink]

Good morning,
I have a 1.25" lean to the passenger side that I cannot get rid of.
I've tried the following:

• Loosening the KDSS screws 3 turns and driving onto 4 inch blocks on drivers F/R then tighten screws, using a jack to compress kdss F/R then tighten screws (I've done this multiple times)
• installing sway bar spacers, 2 in rear, 1 on passenger side front
• installing a 0.5" spacer above the passenger top hat
• throwing my purse at it

after all this the lean is still the same. Since most roads here grade to the passenger side its extremely annoying on the road and handles poor on hard left turns. Any input would be appreciated.

 

[Tommy Argh]

Having the same issue here. Im almost to the point of changing the ride height on the driver side coilover.

 

[Humperdink]

Having the same issue here. Im almost to the point of changing the ride height on the driver side coilover.

I'm running a static lift otherwise id do the same

 

[Hammeredsole]

I'm running a static lift otherwise id do the same

which is why anyone considered a lift should absolutely start with IFP coilovers as an absolute minimum. Buy once, cry once. I have never put a lift in a Toyota (4Runner, 200, or 150) that did not require coil preload adjustments on one side.

 

[Grumpy Uncle]

I had the same problem. I installed the KDSS spacers and the passenger side lean is all but gone. There's still about 1/4" of lean, better than the 1" that was there before.

 

[tingc222]

Make sure you test the lean on a number of very, very flat surfaces. Spin the truck around a few times too, to see if it changes anything. Small floor irregularities can drastically change how much lean there is.

My 2014 GX460 has a lean at 90k miles just like yours (rear passenger side is lower). I have not yet addressed it as it's not really noticeable once the driver sits in it. Sounds like you may have already narrowed the issue down to the springs...Any truck's OEM springs will compress over time especially with higher miles/older age. My family's 2003 4runner with 90k (grocery highway) miles sits at least 1in lower at all 4 corners.

Not all leans come from KDSS. BUT KDSS can in theory exacerbate irregular loss of spring rate (this is my conjecture without actual solid evidence, FYI. I'm not a Toyota suspension engineer); allow me to explain regardless:

1. in a normal truck, loss of rear passenger spring rate will be partially counteracted by the sway bar. Lean is usually minimal as a result. Front is not affected.
2. With KDSS (as a disconnecting sway bar that effectively links opposite F/R wheel articulation), loss of rear passenger spring rate may be exacerbated by the hydraulic "corrective response" from KDSS that permits opposite corner (front driver) to rise. This creates the overall appearance that the passenger side of the vehicle is lower.
   • Resetting chamber pressures (by opening KDSS shutter valves and closing them after placing a block of wood under the high wheel) MAY NOT fix this. If it does, the left KDSS ram must sit shorter to compensate for the softer right spring. So while the vehicle may sit flat, the rear sway bar will appear torqued at baseline.
     • Opening shutter valves equalizes upper and lower KDSS chamber pressure. Equalizing with a wood block under a left wheel will increase baseline volume in the lower chamber (causes the left side to sit lower), while a wood block under a right wheel will increase baseline volume in the upper chamber (causes the right side to sit lower). This should affect the front and rear wheels equally.
   • Using spacers will similarly mask the issue.
3. Why do a lot of leaning GXs lean to the right (there's a survey on the Lexus forums that suggest about 7/8 lean to the right, 1/8 lean to the left)? Some believe that Toyota installed the front springs incorrectly on factory GXs (did not account for the NA market having the driver on the left side), but this wouldn't explain the left sided lean. If you're in warranty, Lexus has a fix for your lean for free, and involves replacing a spring with a different compression rating. I don't know if anyone actually knows if it's a higher or lower spring rate, and there is controversy with regards to which spring to replace.
4. Overall conclusion: spring rates have to be matched well left/right at each axle in order to prevent the lean.

It's hard to determine whether the initial lean condition is from KDSS (causes one side of the vehicle to be ACTUALLY higher than the other) or from spring wear (causes one side of the vehicle to APPEAR higher than the other due to normal KDSS function). Both would cause the KDSS rams to sit longer (or shorter for a left lean) compared to their respective solid sway bar links. But if you ruled out that a shutter valve reset did not fix the issue, then the springs are up for consideration.

One thread supports replacing both rear springs as a fix: KDSS and the LEAN. It's really very simple. - https://forum.ih8mud.com/threads/kdss-and-the-lean-its-really-very-simple.983093/

Personally I'm in the "replace suspension components at 120-150k miles" camp - struts at minimum, bushings, and springs that have lost compression rates. Given the above, KDSS-equipped vehicles are likely especially sensitive to changes in spring rates. So I will be at minimum replacing springs and struts once I'm fed up with my lean. I'll probably consider doing a KDSS bleed and reset at the dealer at some point, too.

 

[r2m]

I wonder if we should have a sticky posted thread on JUST suspension leaning and KDSS???
This is a subject that is far too common.

 

[Acrad]

Possibly a fruitless exercise but kinda wonder if some of the lean issues can be mitigated by turning ON some of the KDSS bypass options and driving into the lean in parking lot at a spirited rate?

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[tingc222]

Possibly a fruitless exercise but kinda wonder if some of the lean issues can be mitigated by turning ON some of the KDSS bypass options and driving into the lean in parking lot at a spirited rate?

Does anyone know how KDSS is natively controlled by the ECU? I used to think it’s a completely passive hydraulic system, but It’s obviously not.

 

[Acrad]

KDSS Overview on 460 post #44

KDSS Info / Problems / Discussion - ClubLexus - Lexus Forum Discussion

GX - 2nd Gen (2010-2023) - KDSS Info / Problems / Discussion - I have a 2010 Lexus GX460 bought in 8/2010. I live in Wisconsin. The vehicle has 49000 miles as of 5/2015. The vehicle has been running great until the winter of 2013/2014 when the KDSS light starts to flash from time to time. I...

www.clublexus.com

 

[tingc222]

That’s great info Acrad thanks. So from what I understand, the system is largely passive, but the valves to the accumulators are ECU controlled, and close under certain conditions such as at higher speeds (to stiffen the system and thus the sway bars).

so vehicle height should have little to do with the KDSS ECU.

I have in fact noticed that vehicle height can change on different days, despite

 

[re_guderian]

Curious how many people with KDSS lean are on OEM front UCA's v aftermarket?

I recently installed aftermarket UCA's, and originally did a crappy job of torqueing the long bolt nut at "ride height" because with oversized tires, there's just no room. I had a lean of at least 1" in the front. Today I went back and retorqued both bolts with the tires off using jack stands and jacking up the lower control arm to "ride height" as determined by hub center up to fender. Re-assembled, drove around a bit, and side-to-side lean gone. Will keep checking over time. My theory is that mismatched torque side-to-side will effectively change the spring rate by adding/subtracting bushing flex from the UCA's into the equation. Crazy theory?

 

[DomGX460]

Curious how many people with KDSS lean are on OEM front UCA's v aftermarket?

I recently installed aftermarket UCA's, and originally did a crappy job of torqueing the long bolt nut at "ride height" because with oversized tires, there's just no room. I had a lean of at least 1" in the front. Today I went back and retorqued both bolts with the tires off using jack stands and jacking up the lower control arm to "ride height" as determined by hub center up to fender. Re-assembled, drove around a bit, and side-to-side lean gone. Will keep checking over time. My theory is that mismatched torque side-to-side will effectively change the spring rate by adding/subtracting bushing flex from the UCA's into the equation. Crazy theory?

I am searching for answers on this topic as I am experiencing some passenger side lean as well. I stumbled upon this thread and was wondering if anyone found a resolution to the issue?
I have a completely stock 2019 GX 460 with 26,000 miles.
I have read there is a TSB from Lexus that essentially changes out the driver side spring to level out the vehicle. I have seen mixed reviews about this with some people seeing good results and others not much. Reading more into the details of the TSB, it says the lean needs to be at least 20mm before Lexus will do anything and anything less than that is "in spec". How can ANY amount of lean be in spec? This seems odd that Lexus would have this issue and not be willing to fix it unless there is excessive lean.

Looking for answers/help/guidance if anyone has found any.

 

[DomGX460]

I wonder if we should have a sticky posted thread on JUST suspension leaning and KDSS???
This is a subject that is far too common.

Was there ever a sticky thread created for this topic?

 

[r2m]

Was there ever a sticky thread created for this topic?

Not as of yet. What you see on the main GX460/150 page is all that's ever been there.