I'm a huge fan of the AHC (Active Height Control) system the LX470. The AHC adjusts the vehicle height in accordance with driving conditions. I believe this to be a good balance to fulfill on road and off-road capabilities. On road the suspension adapts to the terrain and the driver can control the dampening from in the car to suit his or her needs. Off-road the Height Hi lets you tackle terrain that requires that little bit of clearance if needed.
On a 21 year old system that has not been serviced it was definitely not functioning as I remembered it from my youth. Definitely not as comfortable, seems like the dampening is lacking. On checking the gradation at the AHC reservoir I was getting about 7 gradation which is on the lower end of the scale for it. Good gradation is in the double digit range. The globes can be the issue here but before I have to shell out for new globes I wanted to see if a fluid flush and torsion bar adjustment would help the system at all.
AHC fluid like any other fluids breaks down over time and well it doesn't work as well as they were intended. Torsion bars like everything else gets weak so that affects the pressures in the system. Same for the rear springs. My plan to refresh the suspensions is the cheapest method first. Which means AHC fluid change and crank up the torsion arms to even out the pressures to get it as close to factory as possible. So did that.. the steps are very well documented so I'm not going to do that here.