From IH8MUD member
@2001LC I have in my notes to ask for 2.8-3 degree of caster.
Yes, I will be asking around for a good shop. Is 200 series same in terms of adjustments on top control arms? If thats a case I may have good luck with a dealer
Suggest use the practical advice from
@2001LC and other IH8MUD Members.
Here are some more details which may help:
Before doing anything concerning AHC adjustments on an AHC vehicle, the first step always is to check and if necessary adjust the front “cross-level” of the vehicle.
The check is done at both Front wheels by measuring with a tape-measure the distance from the centre of the hub to fender lip immediately above, with the vehicle on level ground, and height at “N” setting.
The actual measurement number is not important at this stage. It IS important that the measurements at Right Front and Left Front be equal +/- 10 millimetres – see attachment.
The cross-level adjustment is done only with the torsion bar adjusters, never with the Height Control Sensor adjusters.
The cross-level check and adjustment is done with the engine OFF, for three reasons:
- for safety,
- to avoid any interference or self-levelling by the AHC system during the check and adjustment,
- to comply with stated FSM requirements.
There are two purposes of “cross-levelling”:
- Ensure that each torsion bar is carrying an equal share of the weight of the vehicle – otherwise the vehicle will feel strange on the road and there will be a difference when turning right and left,
- Avoid the vehicle leaning to one side – if the vehicle leans excessively to one side it will be impossible to adjust the Height Control Sensors correctly. Wrongly adjusted Sensors will cause the AHC Electronic Control Unit (ECU) to receive conflicting signals from these Sensors. In turn, conflicting signals will cause other problems, such as the ECU putting the AHC system into ‘fail safe’ mode.
It should be noted that the torsion bar adjusters on an AHC vehicle have only two purposes:
- cross-levelling of the front of the vehicle, and,
- adjusting Front AHC pressures by adjusting torsion bar loads.
Different to a non-AHC vehicle, the torsion bar adjusters are not used to adjust the front height of the vehicle. This would be impossible because any attempt to change heights using the torsion bar adjusters will be corrected as soon as AHC system begins operation. It will then self-adjust the vehicle to the heights determined by the Height Control Sensors. The front height of the vehicle is adjusted only by moving the Height Control Sensor adjusters.
Note: The AHC system is a two-channel system that deals with Front and Rear levels only. It is not a four-channel system. It is not capable of raising or lowering each of the four corners of the vehicle individually. In addition, when the vehicle is stationary such as when testing or adjusting AHC components, Right Front and Left Front are hydraulically connected -- the Front Gate Valve in the Control Valve Assembly is open. This means the AHC Right Front and AHC Left Front are at the same pressure and the vehicle will raise evenly at the Front. It is the same at the Rear.
The following reference leads to a five-page document giving the relevant Factory Service Manual (FSM) specifications for the front end geometry of various LC100 models, including models with AHC. The specifications are slightly different for LC100 models with AHC and for LC100 models without AHC. The front end geometry specifications for LX470 models is the same as the LC100 models with AHC.
In my part of the world, and maybe in USA, it can happen that a workshop looks up the wrong specification of front end geometry in their computer files and applies the wrong settings to a vehicle equipped with AHC. If there is any doubt, suggest print the extract at thefollowing link, take it with you to the workshop and explain the requirements.
https://lc100e.github.io/manual/
At the Index Panel on the left hand side of the opening page, follow the following tabs:
Repair Manual > SUSPENSION AND AXLE > FRONT WHEEL ALIGNMENT (Independent Front Axle> INSPECTION
On the question about whether to do AHC adjustments or wheel alignment and geometry first, the FSM guidance states:
“Before inspecting the wheel alignment, adjust the vehicle height to the specification”.
This is because large departures from the specified vehicle heights, Front or Rear, can affect the front end geometry.
So the sequence is:
- Check and adjust ‘cross-level’, then,
- Check and adjust vehicle 'operating height', then,
- Check and adjust wheel alignment and front end geometry.
At the the first page of the reference at the above link, the FSM gives detailed specifications and measurements for vehicle heights. These are difficult to use and the following approximations are described in IH8MUD threads and elsewhere. These approximations are widely used instead of the FSM details and have been found to be reliable. These are called the ‘operating heights’ or ‘ride heights’, measured with a tape-measure from hub-centre to fender-lip, with the engine ON and AHC operating after the suspension has settled, and with “N” height selected on the centre console. These hub-to-fender distances for a vehicle in stock condition (not lifted or lowered) are:
FRONT: 19.75 inches; REAR: 20.50 inches
Do you need some explanation about the steps to adjust vehicle height, and separately, to adjust the Height Control Sensors to the correct reading at the adjusted vehicle height?
