LX470 AHC Stiff Ride Correction (2 Viewers)

[SWUtah]

Hey Guys,
I bought a 1999 LX470 with 165k on the clock. It rides extremely rough on expansion joints but handle speed bumps like velvet. It is all stock and I plan to keep it that way except for some 256/75/16BFG's and roof rack.

After spending countless hours on here I decided to buy techstream for $35 on Amazon and give it a try. It didn't work on my windows 7 but did work on XP. Just needed to go into the program and turn a "0" to a "1". Also turned off the steering wheel autoway mode, since it squeaks like crazy.

When connecting, it defaulted to a 1998 LC, so I had to change that in order to get it to see all the parameters

Then I ran a suspension check. After that I clicked the "data list" button to see the pressures.

AHC Pressure from the FSM-
Spec calls for
Front 6.9+/-0.5 MPa
Rear 5.6-6.7 MPa

Before:
Front 8.1mpa-g
Rear 6.8mpa-g
Accumulator 10.2mpa-g

So, I jacked up the truck and turned the TB bolts 6 complete turns each. Then i drove around the block.
After:
Front 6.7 mpa-g (pressure lowered 1.4) = 0.23mpa-g/1 full turn of TB bolt
rear 7.1 mpa-g (pressure raised 0.3)
Accumulator 10.2 mpa-g

After driving it for a day or two, I would say the ride is about 50% better. I know this is hard to quantify, but it is def better. I can still feel every crack in the road, but it doesn't quite feel like I am going to shake all the bolts loose in the truck.

So, my next step is to add some 30mm coils from an Australian company I just ordered on ebay. I am hoping it will lower the rear pressure about 1.0mpa. If it does not get me below or close to 6.0mpa, I will then order and install new springs with some spacers.
2 Rear Coil Spring Spacers 30mm Toyota Lexus LX470 V8 Polyurethane 4x4 New Pair

You guys have alot more expierience than I, so feel free to sprinkle some knowledge if I am off base here.

Thanks,
Bogie

EDIT: I did flush the AHC fluid with fresh Toyota fluid, that did help a bit. Also I have 10 graduation in my AHC fluid tank when going from low to high and back.

Are the 265/75 tires your running "E" rated

 

[wkbogie]

Right now I still have my 245/16/16 BFG Radial Long Trail T/As on it. They say "standard load" on the side of them? Does that sound right? I was waiting to get the ride figured out before throwing in another variable.

 

[wkbogie]

I also forgot to mention, my "comfort" setting does not feel any different than my "sport". Any ideas? Techstream shows that the switch is communicating with the ecu. Or at least with techstream.

 

[ihadmail]

Well finally got all my parts in for my AHC lift. I will be installing this Friday and will post my results on here (I'll also be starting a build thread). Here's what I'll be installing: King AHC Springs, Japanese Shock Spacers, possibly rear spring spacer if needed, and new sway bar bushings. Goal is to sit at a lifted height (2-2.5"), with stock shock range and stock pressures.

Just a tip, I had to grind some off the end of the front Japan spacer tubes for them to fit into the lower shock mount. Maybe took 1-2 32nds off.

Also be prepared to drill into this lower front mount. If you look at the spacer it's pretty obvious where to drill but you'll need some spray paint to touch up that newly exposed metal. I am thinking it was a hole for a 1/4" bolt.

I also forgot to mention, my "comfort" setting does not feel any different than my "sport". Any ideas? Techstream shows that the switch is communicating with the ecu. Or at least with techstream.

Do you see a change in "front wheel step" and "rear wheel step" when cycling through the different comfort settings? IIRC this number should be low when in comfort, say 2 and cycle up/down 1 to 2 digits as you drive. It should be high (8-10) when in sport and still cycle some as you drive.

 

[aamdesign]

Good Thread. Paddo's easy flush/fill instructions were right on the money. Took me about 15 minutes.

 

[karihizonena]

I'd like to inform another subject.

I have new springs, new shock absorbers, new gas chambers, new torsions. Front suspension pressure is 5.5 mpa, rear suspension pressure is 5.6 mpa. Oil is new genuine toyota. I was not satisfied with this result.

I tried another option.

Damping force control valves have 16 position step motor. These motors adjust oil passages between of shock absorbers and gas chambers. When vehicle speed changes or when damping speed changes than oil passages change.

If you connect a cable from DLC3 TS to chassis ground, than you enter damping force control valve step motor active test mode. If you start engine, increase speed more than 5 km/h without pressing brake pedal, vehicle will always stay in 1st position on step motors until you stop the engine. You can increase speed and drive your land cruiser to test riding comfort. My test was amazing and my car was like a flying carpet.

This is another way to understand where are the main riding comfort point.

Now i am working on to add a electronic drive unit between of AHC ECU and step motors to control step motor levels or i will try to open damping force control valve to modify screw shaped valve spool.