AAS damper control rod operation
06-25-11, 12:58 AM
#1
AAS damper control rod operation
Does anyone know how this thing works? I installed new AAS struts, and I'm trying to figure out the range of dampening adjustment.
(I'm not referring to how the AAS computer takes into account the effects of acceleration, braking, low vs. high speed driving, all of which result in a particular setting. This is fully explained here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/aas-708257/#7)
I'm referring to the control rod itself.
I was able to make several full turns in either direction with needle nose pliers without encountering any resistance or hitting a stop. There is a notchy feeling at every 180*, implying the settings are "indexed."
A few CW turns resulted in a soft ride while rotating it CCW noticeably increased firmness.
Until I get the actuator mechanisms working, I was thinking of finding the maximum "firm" setting, backing out a bit, and leaving it at that "medium" setting. But it seems like I can continue turning the control rod in either direction. The rod doesn't seem to extend up or down as it's turned, so it's not a 'threaded' mechanism.
So -
Is there a stop that will be encountered eventually as the rod is turned to full soft or full hard?
If not, does that mean the setting becomes e.g. 'full hard' after a few turns CCW but the rod continues to turn without further alteration to the dampening level?
Or are all three settings (soft, firm, very firm) separated by only 1/2 turn intervals, and I just happened to land on a given setting after cycling through them several times?
And when controlled by a functioning AAS computer & actuators, how far does the control rod turn when the setting is changed from "normal to sport" (all other things being equal)?
(I'm not referring to how the AAS computer takes into account the effects of acceleration, braking, low vs. high speed driving, all of which result in a particular setting. This is fully explained here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/aas-708257/#7)
I'm referring to the control rod itself.
I was able to make several full turns in either direction with needle nose pliers without encountering any resistance or hitting a stop. There is a notchy feeling at every 180*, implying the settings are "indexed."
A few CW turns resulted in a soft ride while rotating it CCW noticeably increased firmness.
Until I get the actuator mechanisms working, I was thinking of finding the maximum "firm" setting, backing out a bit, and leaving it at that "medium" setting. But it seems like I can continue turning the control rod in either direction. The rod doesn't seem to extend up or down as it's turned, so it's not a 'threaded' mechanism.
So -
Is there a stop that will be encountered eventually as the rod is turned to full soft or full hard?
If not, does that mean the setting becomes e.g. 'full hard' after a few turns CCW but the rod continues to turn without further alteration to the dampening level?
Or are all three settings (soft, firm, very firm) separated by only 1/2 turn intervals, and I just happened to land on a given setting after cycling through them several times?
And when controlled by a functioning AAS computer & actuators, how far does the control rod turn when the setting is changed from "normal to sport" (all other things being equal)?
08-25-11, 09:07 PM
#4
Right near Malloy
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Did you mark the shaft position when you got the shocks, before you turned them?
Just a thought:
It still may be threaded... But instead of the rod moving up and down, it may be a nut inside the strut moving up and down...
If that's the case, I would be very wary of turning it too far because if there's no stop, it may fall off the bottom... You can never be too sure of whether clockwise or counterclockwise is loosen because they could be reverse threaded.
What I'd start by doing is having someone activate the "Sport" and "Normal" switches and hit the brakes hard while I watched the motors.
If the shock control screws rotated more than one full turn, then I'd have to say they need to start in a known position. There's no way the motor knows where the shock is set at.
Check the FSM for shock replacement. That's gotta have the procedure to find the start point for the AAS shocks.
Just a thought:
It still may be threaded... But instead of the rod moving up and down, it may be a nut inside the strut moving up and down...
If that's the case, I would be very wary of turning it too far because if there's no stop, it may fall off the bottom... You can never be too sure of whether clockwise or counterclockwise is loosen because they could be reverse threaded.
What I'd start by doing is having someone activate the "Sport" and "Normal" switches and hit the brakes hard while I watched the motors.
If the shock control screws rotated more than one full turn, then I'd have to say they need to start in a known position. There's no way the motor knows where the shock is set at.
Check the FSM for shock replacement. That's gotta have the procedure to find the start point for the AAS shocks.
08-26-11, 03:33 PM
#5
Actually, I've recently stumbled across the answer to this mystery. You can rotate the control rod by hand as many times in either direction as you wish. It won't change anything unless it lands in one of the designated orientations.
The AAS damper control rod rotates a shaft inside the damper piston rod. The shaft has openings that align with orifices in the piston rod -- it's a rotary valve. When the openings are properly aligned, they make two or four additional passages available for fluid to flow between the upper and lower chambers. When the shaft is rotated to block the passages, fluid can only flow through the piston and body valves. Three settings are the result:
"soft": all four passages open
"firm": two passages open
"very firm": all passages closed
Inside the actuator, there are six coils located around its circumference, and a permanent magnet attached to the hollow shaft that attaches to the damper control rod. You can feel the magnet's pull when you insert a screwdriver into the shaft. Depending on the driving conditions (vehicle speed, steering wheel angle, braking, acceleration) and position of the selector switch ("normal" vs. "sport"), current is applied across a pair of opposite-facing coils (i.e., the second coil is 180* away from the first). Since there are three pairs of coils, the magnet can rotate the shaft into three possible positions, separated by 60*.
This is all explained on pages 24 - 28 of the suspension chapter in the s4 FC training manual (see below).
Note that it would not matter if you installed the actuator facing the wrong way (180* away from the "correct" position). When current is applied, the same two opposite-facing coils are energized and rotate the shaft into the same intended position. (And it's normally not possible to install the actuator in any other orientation because the bracket has a "D-shaped" mounting hole that fits on the damper shaft in only one way).
For "manual" operation, you could mark the "soft" and "firm" positions, which are separated by 120*. The "very firm" position is halfway between the two. Or you could activate the brake or accelerator switch with the vehicle at rest, which will rotate the control rod to the "very firm" position.
I'd have to look at a GXL to get a better visualization of those three actuator rod orientations. Another possibility is to take one of my actuators, hook it up to someone's GXL, induce the three different conditions and mark them on the actuator. That would give me a good "template" of the dampening control rod position.
The AAS damper control rod rotates a shaft inside the damper piston rod. The shaft has openings that align with orifices in the piston rod -- it's a rotary valve. When the openings are properly aligned, they make two or four additional passages available for fluid to flow between the upper and lower chambers. When the shaft is rotated to block the passages, fluid can only flow through the piston and body valves. Three settings are the result:
"soft": all four passages open
"firm": two passages open
"very firm": all passages closed
Inside the actuator, there are six coils located around its circumference, and a permanent magnet attached to the hollow shaft that attaches to the damper control rod. You can feel the magnet's pull when you insert a screwdriver into the shaft. Depending on the driving conditions (vehicle speed, steering wheel angle, braking, acceleration) and position of the selector switch ("normal" vs. "sport"), current is applied across a pair of opposite-facing coils (i.e., the second coil is 180* away from the first). Since there are three pairs of coils, the magnet can rotate the shaft into three possible positions, separated by 60*.
This is all explained on pages 24 - 28 of the suspension chapter in the s4 FC training manual (see below).
Note that it would not matter if you installed the actuator facing the wrong way (180* away from the "correct" position). When current is applied, the same two opposite-facing coils are energized and rotate the shaft into the same intended position. (And it's normally not possible to install the actuator in any other orientation because the bracket has a "D-shaped" mounting hole that fits on the damper shaft in only one way).
For "manual" operation, you could mark the "soft" and "firm" positions, which are separated by 120*. The "very firm" position is halfway between the two. Or you could activate the brake or accelerator switch with the vehicle at rest, which will rotate the control rod to the "very firm" position.
I'd have to look at a GXL to get a better visualization of those three actuator rod orientations. Another possibility is to take one of my actuators, hook it up to someone's GXL, induce the three different conditions and mark them on the actuator. That would give me a good "template" of the dampening control rod position.
