LX470 Suspension /steering darty and harsh, ACH or Alignment issues?

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J

JETTIX2

Joined
Jun 4, 2006
Threads
50
Messages
305
Hey guys;

As I wrote this weekend, I love my "new to me" 2005 LX470 that we got last week, with one exception - the Ride/Steering. (See thread here for pics and info https://forum.ih8mud.com/100-series-cruisers/636439-upgraded-fzj80-fzj100-couple-thoughts.html )

Vehicle was just purchased from Lexus of Orlando and had a thorough inspection at time of sale, so there is nothing *visibly* wrong with it. Let me explain, and I will compare it to my 1997 LX450 with stock, original suspension at 175k miles.

On smooth roads, the LX470 rides great. Tracks straight and true under acceleration and braking. (LX450 is same, just way slower, ha ha )

On a 2 lane country road with even just a moderate crown, it pulls to the right, and requires constant adjustment to keep it going in a straight line. (LX450 doesn't pull at all)

On bumpy roads, it wants to pull whatever direction the bumps are........ie, I have to constantly adjust right/left to compensate for the bumps. (LX450 doesn't pull at all, no steering adjustment needed). It reminds me of my sister's Mini Cooper S, which is OBNOXIOUS to drive as it requires constant steering adjustment.

On bumpy roads with left-right pattern of uneven sections, the rear of the truck wants to "porpoise" or "wallow" in the same pattern, at 50mph. (LX450 doesn't wallow at all)

These observations are ALL made with the LX470 in N height setting and Middle shock position. If I go to SPORT shock setting, ride just gets harsher. If I go all the way to COMFORT setting, the wallowing is worse.

LX470 has 108k on it. RF tire has 6/32, the rest have 7/32". Front PSI 28, Rear 32 (approx). I have 9 or 10 graduations variance between LO and HI settings on the suspension in the AHC reservoir, though from the middle position, it doesn't like to raise if you're sitting in Park (the N light is steady and the HI light flashes)........it works better if you drop to LO and then go back to HI (it works perfectly then). Service records show 4 wheel balance and alignment was just done 200 miles ago. Looks like 2 Tie Rod ends done at 92k. Ft Brakes, CV Boot, and Rack and Pinion Assy replaced at 84k.

Any thoughts on where I should start looking? I am 3 hrs from a Lexus dealership, though I have a good Indy shop local here and a Toyota dealer 1 hour away.

I am thinking ft alignment is probably off, causing it to "hunt" and on bumpy or uneven surfaces. What about the porposing/swaying on uneven? Could I have a bad rear shock?

I actually LIKE the AHC ride on smooth roads, I just want it to ride and steer more like my 80 does on rough/uneven stuff, which is most of what we see here in Michigan:)

Thanks for any and all input:)

Ben
 
Last edited:
was the steering rack checked? check AHC fluid.
 
A couple of points you might like to look at:
a. AHC fluid, as mentioned above, run a fresh can through to flush and bleed. AHC likes clean fluid and no air in the system.
b. AHC neutral pressures are possibly a little high due to vehicle age and torsion bars/coils giving in a bit. If you can access techstream check your neutral pressures and adjust TBs if necessary. If you can't get hold of techstream, cranking each TB two full turns could be enough to lower neutral pressures back to spec. Not scientific, but consensus is these vehicles need 2 or 3 TB adjuster turns every five years or so.
c. Tire pressure, for me 31F/34R on P285/60/18s soft roaders provides best ride for unladen daily driving and highway, you might experiment with pressures.
d. With all that front end rack and steering work done you might like to confirm the steering angle sensor (SAS) is zeroed. Additional to vehicle stability feedback it also provides an input to your AHC. Steering wheel angles greater than 35 degrees closes a porting valve that cross connects the front shocks (normally front shocks are hydraulically connected, at wheel angle greater than 35 degrees they are hydraulically isolated ). If the SAS angle is off its will be providing a biased input to AHC and stability ECU's.
e. If you have the printout from the last alignment compare it to the searchable ones posted here.
f. Good luck
 
I just ordered the $35.00 knockoff techstream product, which will let me check N pressure (and do some other things I want, like change the auto locks, etc). I also ordered 2 cans of fresh AHC fluid online, the fluid in the reservoir looks dark, is 2-3 graduations below the LOW level, and has some bubbles after running it from L-H a few times, I'll drain and refresh with new fluid and see how it feels. An inexpensive first step. Then I'll look into B and D below. I don't have the alignment printout, it was done before purchase.

Thanks guys!


PADDO said:
A couple of points you might like to look at:
a. AHC fluid, as mentioned above, run a fresh can through to flush and bleed. AHC likes clean fluid and no air in the system.
b. AHC neutral pressures are possibly a little high due to vehicle age and torsion bars/coils giving in a bit. If you can access techstream check your neutral pressures and adjust TBs if necessary. If you can't get hold of techstream, cranking each TB two full turns could be enough to lower neutral pressures back to spec. Not scientific, but consensus is these vehicles need 2 or 3 TB adjuster turns every five years or so.
c. Tire pressure, for me 31F/34R on P285/60/18s soft roaders provides best ride for unladen daily driving and highway, you might experiment with pressures.
d. With all that front end rack and steering work done you might like to confirm the steering angle sensor (SAS) is zeroed. Additional to vehicle stability feedback it also provides an input to your AHC. Steering wheel angles greater than 35 degrees closes a porting valve that cross connects the front shocks (normally front shocks are hydraulically connected, at wheel angle greater than 35 degrees they are hydraulically isolated ). If the SAS angle is off its will be providing a biased input to AHC and stability ECU's.
e. If you have the printout from the last alignment compare it to the searchable ones posted here.
f. Good luck
Click to expand...
 
Last edited:
SWUtah said:
There is a recall on the 2005lx470 steering if yours has not been done it is free and might make the difference.
Click to expand...

Good call, I forgot to mention the recall has been done already.:)
 
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JETTIX2 said:
On bumpy roads with left-right pattern of uneven sections, the rear of the truck wants to "porpoise" or "wallow" in the same pattern, at 50mph. (LX450 doesn't wallow at all)
Click to expand...

My guess is you've got at least one flat gas sphere (accumulator) - on that corner you're getting the bounce and when the suspension gets unsettled (cornering or bumpy roads) the dynamics are out of whack and the other corner(s) can't overcome as gracefully as it should be able to.

Wish there were an indicator light at each globe or a sensor that could tell you when the globe is bad.
 
agaisin said:
My guess is you've got at least one flat gas sphere (accumulator) - on that corner you're getting the bounce and when the suspension gets unsettled (cornering or bumpy roads) the dynamics are out of whack and the other corner(s) can't overcome as gracefully as it should be able to.

Wish there were an indicator light at each globe or a sensor that could tell you when the globe is bad.
Click to expand...

IS this something I can check easily to see if it's flat?
 
Problem ended up being LF wheel bearing that needed repack and torque, drives like a completely different truck now! :)
 
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