I cranked torsion bars because it was lower on the driver side. Vehicle did level but a few days later it got lower than where it was before. Wheels were tilted inside too noticeably. Any suggestions? ( haven’t done wheel alignment yet, wanted to make sure torsion bars sit properly)
This reply covers more than is necessary to answer your question but maybe it will also help someone else passing this way ....
As
@PADDO indicates earlier in this thread and elsewhere and as noted in the FSM, ‘cross-levelling’ of the vehicle is best done with
wheels on the ground with engine/AHC “OFF”, front wheels straight ahead, on level ground, as a first step before making any other adjustments. The main purpose of so-called ‘cross-leveling’ is to make sure that both the Left and Right torsion bars are carrying equal loads. If this is not done, the vehicle response will be different in right and left turns and in some cases AHC performance may be affected as well.
'Cross-levelling' also overcomes visual lean of the vehicle -- provided it is done on level floor (not in the street), without even load distributions on or in the vehicle, and without mechanical defects on the suspension or chassis.the
Some find it a little easier to turn the torsion bar adjusters with the wheels off the ground, or with the suspension raised to “HI”. If this is done – OK – but the ONLY measurements that count are those measured with wheels on the ground at "N", looking to get the hub-to-fender measurements equal with wheels on the ground – just get them equal, the actual number is not important at this stage. Most find that torsion bar adjustments can be done on the ground but a good dose beforehand of PB Blaster or other penetrating oil on the adjuster threads does help.
The attached FSM extract mentions tightening and loosening opposite torsion bar adjusters by the same amount when ‘cross-levelling’. This helps to avoid running out of thread on one of the adjusters.
After making the torsion bar adjustments, it is worthwhile to take a short drive around the block to ensure that all suspension parts have settled into the new position. It is not unusual to find that it is necessary to fine-tune the new torsion bar adjustments.
It is worth repeating that in an AHC vehicle, the torsion bar adjusters are NOT used to set the ‘operating heights’ of vehicle, also called 'ride heights' (meaning the heights of the vehicle with engine and AHC “ON” and ‘operating’). These 'operating heights' are set at "N" height using the Height Control Sensor adjusters. IH8MUD Members recommend setting the front operating height hub-to-fender at 19.75 inches (500 millimetres) and the rear operating height hub-to-fender at 20.50 inches (520 millimetres)at "N" as a good approximation to the more fiddly measurements given in the FSM. (Naturally, the actual adjustments are made with the engine/AHC “OFF” for personal safety, then hub-to-fender ‘operating height’ measurements are made with the engine/AHC “ON” after a short drive to ensure that the system has settled).
Note that ‘cross-levelling’ cannot and should not be done with the Height Control Sensor adjusters – because AHC Left and Right sides are connected and at equal pressure with wheels straight ahead or when the vehicle is stationary. Attempts at 'cross-levelling' with Height Control Sensor adjusters is futile, likely to result in the ECU receiving conflicting signals from the sensors and putting the AHC system in 'fail safe' mode in which the AHC system will not operate fully, if at all.
If heights have changed significantly as a result of adjustments, then AHC neutral pressures also will have changed -- so it is worthwhile to check that the AHC pressures are within the specified ranges and then correct the situation if necessary.
Once the ‘operating heights’ are set, they should not change -- unless there is a problem somewhere in the AHC system, for example, faulty Height Control Sensors sending inconsistent signals to the Electronic Control Unit (ECU). Faults in these Sensors are common.
Alternatively, other parts such as the Control Valve Assembly or Return Valve are not operating properly and AHC fluid is returning to the tank – this is possible but not common.
Another alternative is a major external leak somewhere but that will obvious when inspecting under the vehicle.
It can happen that when the vehicle is stopped, that the engine is switched “OFF” before the AHC system has completed its self-levelling function. This can mean that the vehicle appears to be at different heights to those set previously. This is not unusual. In a healthy system, when the vehicle is re-started and moved slightly, the AHC system will respond to signals from the Height Control Sensors and automatically complete self-levelling and the vehicle heights will return to normal. The AHC Pump usually will be heard operating when this situation occurs.
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