Suspension problem even after replacing almost everything

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V

Vampo

10 Year
Joined
May 10, 2011
Threads
14
Messages
59
Hi,

I been having a stiff suspension problem for a long time. My SUV suddenly gets into a mood where it tightens up its suspension and it feels like the vehicle is driven without any shocks / torsion bars / spring. Everything in the vehicle shakes, starting from the dashboard.

I tried different solutions over the last 2 years (even replaced the accumulators with aftermarket units), and nothing seemed to solve it.

Last week I simply lost it (I mean, I didn't get this SUV to have such a bad ride) and I went and purchased all the parts I can think of for the suspension and replaced them. (almost all parts are Toyota OEM except for the ball joint and rear control arm bushes ). List below.

01) Lower arm ball joint 02 (Febest)
02) Lower arm bush 04
03) Front wheel bearing both side4
04) Engine mount 02
Rear Spring Coils 02
05) Gear box mount 01
06) Front stabilizer bar bush set 02
07) Rear stabilizer bar bush set 02
08) Front axle boot inner 02
09) Front axle boot outer 02



13) Tie rod end set 022
14) Front upper arm ball joint 02 (Febest)
15) Front upper arm bushes 04



18) Rear upper control arm bushes04 (Febest)
19) P/S rack boot 02
20) Steering cross joint 02
21) Front shock absober 02
22) Rear shock absorber 02
23) Suspension accumulators 04
24) Suspension oil







After replacing basically everything I can think of in the suspension, I finally got my SUV out of the workshop today, to be disappointed by the stiff suspension returning. The ride feels much more sturdy (with all the new bushes). But the stiffness still remains. I've almost had it with this vehicle!!!


I do run 20' for my tires. 20' x 285 x 55. I know this effects the ride comfort but I really don't think it can effect this badly.


--------------------------------
2005 Toyota land cruiser (Cygnus) - Same as the 2005 LX470 (Japanese domestic version).
I use the same parts as LX470 - 2005

Tires - 20/285/55
Suspension - Accumulators x 4 (new)
- Shocks x 4 (new)
- All bushes (new)

--------------------------------------


any thoughts / suggestions / help is greatly appreciated.



Thanks!!!
 
AHC system aside (don't have it...don't want it...but someone experienced with AHC will need to chime in)...what is the resting height measurement, from the ground when the truck is sitting on a level surface, straight up vertically to the lower lip of the fender (this line will bisect the center of the front hub). If your resting front end height is too high you will not have enough droop travel...and hence get the very symptom you are complaining about.
 
Sounds like you have an AHC equipped LC. Why would you spend so much money to keep the AHC?

Post a picture of your rig from the side; try to get a representative photo (no weird angles). In addition to the measurements spressomon mentioned, this might help figure out if you have a rake issue.
 
Did you do any diagnostic tests and standard FSM measurements before whipping out the credit card? Are we correct in understanding that the harsh ride is a random issue? or is it constantly bad? Starting from basics: is your overall vehicle height and cross level in spec? any additional weight added? what are your neutral pressures? does it raise/lower normally? any DTCs? height sensor readings at N? number of graduations on the reservoir between H and L? does it respond to the comfort switch settings when driving? fluid changeout history? does it respond to the manual damping 16 step test? Have you checked the resistance of the damping force actuators? Any other mods other than the 20s?

From what you describe, and based on the massive number of parts already changed out, you could be looking at failed damping force actuators. They are the valve bodies that the accumulator globes screw into, they have small motors that step the damping orifices through their 16 steps, in turn controlling the damping through smooth to sport. They have tight tolerances and can gum up and fail, exasperated by old contaminated fluid.
 
spressomon said:
AHC system aside (don't have it...don't want it...but someone experienced with AHC will need to chime in)...what is the resting height measurement, from the ground when the truck is sitting on a level surface, straight up vertically to the lower lip of the fender (this line will bisect the center of the front hub). If your resting front end height is too high you will not have enough droop travel...and hence get the very symptom you are complaining about.
Click to expand...

Hi,

I have taken a photograph of the front wheel and mentioned all the heights. in addition to this picture the rear wheel height from the center of the hub to the fender lower lip is 20.5'. (tire size is the same, 31'). That makes the height from the ground to the fender lower lip 36'.
LC_Cygnus_2005_Front_wheel.webp
 
ElHefe said:
Sounds like you have an AHC equipped LC. Why would you spend so much money to keep the AHC?

Post a picture of your rig from the side; try to get a representative photo (no weird angles). In addition to the measurements spressomon mentioned, this might help figure out if you have a rake issue.
Click to expand...


Here is a picture of the rig from the side.
LC_Cygnus_2005.webp
 
Ok...well 19.5" resting front suspension height eliminates the idea of not enough droop. So I would guess your problem is AHC related but, again, I've got zero experience with AHC.
 
Vampo said:
I been having a stiff suspension problem for a long time. My SUV suddenly gets into a mood where it tightens up its suspension and it feels like the vehicle is driven without any shocks / torsion bars / spring. Everything in the vehicle shakes, starting from the dashboard.
Click to expand...

Does this mood come and go? Or does the suspension feel stiff all the time?

What's your tire pressure?

Did you observe any correlation between the date you installed your 20" tires and the harsh ride?
 
ElHefe said:
Have you replaced your height sensors and inspected all the lines?
Click to expand...
I replaced the front left height sensor as it was getting stuck. The other two seems to be working fine. I will remove them and check the voltage variation during the weekend. Does the height sensor effect the ride comfort ?
 
If the height sensors are malfunctioning, it might cause some irregular variation in fluid transfers to the shocks.
 
dabasscow said:
How much bump stop clearance?
Click to expand...
I haven't really measured that, but if I can remember it had a good clearance. Its not like the vehicle suddenly stops moving up and down (not abrupt), the suspension is stiff during the entire ride.
 
PADDO said:
Did you do any diagnostic tests and standard FSM measurements before whipping out the credit card? Are we correct in understanding that the harsh ride is a random issue? or is it constantly bad? Starting from basics: is your overall vehicle height and cross level in spec? any additional weight added? what are your neutral pressures? does it raise/lower normally? any DTCs? height sensor readings at N? number of graduations on the reservoir between H and L? does it respond to the comfort switch settings when driving? fluid change out history? does it respond to the manual damping 16 step test? Have you checked the resistance of the damping force actuators? Any other mods other than the 20s?

From what you describe, and based on the massive number of parts already changed out, you could be looking at failed damping force actuators. They are the valve bodies that the accumulator globes screw into, they have small motors that step the damping orifices through their 16 steps, in turn controlling the damping through smooth to sport. They have tight tolerances and can gum up and fail, exasperated by old contaminated fluid.
Click to expand...


I had a Techstream cable bought off ebay. I will hook it up and get these readings.

Before I replaced the suspension, the stiffness of the suspension use to vary. Sometimes the first ride in the morning is not so hard (not soft either, even if the comfort switch is set to comfort), but after the rig is driven for a while the problem surfaces. Ofcourse there are days/weeks that the suspension stiffness is continuously felt.

Since yesterday (when I got my rig back), the stiffness is consistently there.
 
Rover4 said:
Does this mood come and go? Or does the suspension feel stiff all the time?

What's your tire pressure?

Did you observe any correlation between the date you installed your 20" tires and the harsh ride?
Click to expand...


Before I changed the suspension there were certain trips that wasn't that harsh. However since yesterday (which is not that long to judge) it has been consistently stiff.

Tire pressure is 34 psi

I have always had the 20' from the time I got the rig. It has always been like this. I'm planning on changing the wheels (from a friends SUV) to 18/275/60 this weekend to check.
 
Hook up your TechStream and get some readings and check for DTCs. Focus on AVS related elements in your system, did it ever respond to comfort switch settings? and attempt the 16 step AHC damping test to see if you can progressively feel the damping increase through the range. It takes 10 minutes to pop out the damping selector switch and clean the sliders in it, maybe it's gunked up after the last coffee spill?, you only have about 9v through it so it's easy to interfere with that signal. Try resetting the AHC computer by pulling the fuse in the driver side kick panel. Pull and clean all the damping force valve connectors, pull and clean the connectors at your AHC module. If there is an AHC/AVS computer comms problem it should throw codes but possible not. Check your damping force actuator common ground is good, it's pin 2 iirc of each damper connector.


Sent from my iPhone using IH8MUD Forum
 
Vampo said:
Before I changed the suspension there were certain trips that wasn't that harsh. However since yesterday (which is not that long to judge) it has been consistently stiff.

Tire pressure is 34 psi

I have always had the 20' from the time I got the rig. It has always been like this. I'm planning on changing the wheels (from a friends SUV) to 18/275/60 this weekend to check.
Click to expand...
Worth a shot. Not too much meat on the 20s.
 
Owning a older 100 series with AHC and dealing with these issues reminds me of the game wack-a-mole. But with AHC it can be a very expensive game. I think it takes a special owner to deal with these issues. I like the KISS approach. " Keep it simple stupid". It's great we have members that are technical and savvy enough to help others work through these complex AHC issues. I also enjoy reading these threads, knowing that if I ever have a complex issue with my beast there are members that can help.
 
I just hooked up the teachstream cable and got some readings by moving the suspension from low to N to high. Pls see if this makes sense as I'm not familiar with these readings.

1). Switch Low -> N (Front - 7.3, Rear 5.5, accumulators 10.4)
1). Switch N -> High (Front - 9.5, Rear 3.2, accumulators 10.3)
1). Switch High -> N (Front - 9.6, Rear 3.3, accumulators 10.3)
1). Switch N -> Low (Front - 9.6, Rear 3.2, accumulators 10.3)
1). Switch Low -> N (Front - 7.4, Rear 5.2, accumulators 10.3)

At the N position I noticed that the front angle sensor FL was 0.0 and FR - 0.4 and Rear - 0.5.

No DTC error for AHC. Only have 2 DTC errors under Immobiliser - B2780, and another under tilt/telescopic - B2602 (key unlock warning switch).

Any help is much appreciated. Thanks.
 
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