Ok will try. Do I need to have the wheels off the ground to do this? Which height setting should the AHC be in when do it?
Many thanks
As indicated by
@GTV while I was writing, it is easier to wind the torsion bar adjusters with the vehicle on the ground in HI height setting on a level surface engine and AHC OFF, or, with wheels off the ground -- because the torsion bars are carrying less load in those conditions -- if you can do either while camped and much of the load and persons are out of the vehicle.
Hit the adjuster threads and mechanism with generous thread penetrating lubricant several times, wind the adjusters clockwise looking up from below, equally on both left and right sides, say four turns because the loaded vehicle as described really is quite heavy. Four turns is nothing more than a wild guess because the current actual AHC pressures and the actual weight of the loaded vehicle are unknown -- but it seems unlikely to need less than this. The only consequence of overdoing it is too much weight carried by the Front torsion bars, then Front AHC pressure becomes too low, then there is less damping capability and the ride becomes a little 'springy' -- but at least more weight is now being carried by the torsion bars.
Back off the torsion bar adjusters if road test suggests this is necessary, or wind more turns on if felt necessary. Without Techstream or other suitable scanner, the only measuring tool is backside-in-seat. After adjustment, drive around the block to see what the change feels like, allow the suspension to settle into the adjusted position and then check Front 'cross level' -- measure with a tape (or a piece of string or marks on a stick) hub-to-fender at Front LHS and Front RHS -- these need to be equal (to load the torsion bars equally) otherwise the ride and steering will feel different on Left turns versus Right turns.
This effort will transfer weight from the Front AHC system, basically from the 'shock absorbers' (which really are weight-bearing hydraulic struts on an AHC-equipped vehicle), to the Front torsion bars. Damping actually is done at the Damping Force Control Actuators to which the 'globes' are attached, not in the mis-named 'shock absorbers' whose primary function is to regulate the height of the vehicle under the control of the Suspension Electronic Control Unit (ECU) and signals from the Height Control Sensors (two at the Front, one in the Rear).
It also is important to have more travel in the Front suspension than is available at LO height setting -- otherwise there is not much distance to the bump stops and the Lower Control Arms will take a beating in rough conditions. Cracked Lower Control Arms are a known issue in Australia. Later, when suspension work is done on the vehicle, suggest include the prescribed reinforcements in this area.
The Front AHC system and the Rear AHC system are not hydraulically connected but changes at the Front will have some effect at the Rear.
The Rear AHC pressures almost certainly will remain excessive, especially when much of the load will be towards the Rear while travelling. Not much can be done about that on the run -- just be conscious of it and go easy on the vehicle, go slow in any rough conditions encountered.
Suggest check that the level of AHC Fluid in the AHC Tank is adequate. If it is necessary to add fluid, use only genuine Toyota/Lexus AHC Fluid Part Number 08886-01805 -- it might be a struggle to find a Dealer open for business in Adelaide before Tuesday to get this stuff over the counter. The need to add AHC Fluid would indicate that the fluid has gone somewhere -- and there are only two places for it to go -- into failing 'globes' (cannot do much about that short of changing out the 'globes'), or, fluid is leaking out of the system -- so check for leaks around the AHC system under the vehicle, especially around the 'shock absorbers'. Damp-looking 'shock absorbers' due to a minor leak can be lived with -- but monitor closely. A major leak which accumulates on the ground is a much more serious matter -- needs to be fixed before roaming to remote places.
For all of that, enjoy the trip!! The Flinders Ranges and Lake Eyre should be spectacular after the recent rains. If you can set up camp and remove much of the load except passengers from the vehicle, you will be able to explore the environs freely in a relaxed frame of mind. There are lots of great trails in these areas -- some of the tracks in the North Flinders around Arkaroola are spectacular.
Whatever else, don't forget to carry plenty of water and make sure that someone else has details your travel plans and whereabouts over time. Mobile phone reception will be non-existent in much of these areas. Suggest consider hiring a satphone for emergencies and breakdowns.
