Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: SLS operation question

  1. #1
    Join Date
    Dec 2012
    Location
    Perth, WA
    Posts
    2,043
    Total Downloaded
    0

    SLS operation question

    Hey guys,

    I have recently restored the SLS in my Disco as the previous owner had removed the bags and installed coils. So I have never experienced exactly how it is supposed to work.

    The previous owner had removed the fuses and relay but not disabled the SLS in the SLABS so the battery would continue to drain when I bought the vehicle.

    I disable the SLS in the SLABS with nanocom after I got it.

    Now I have the system up and running. The "Off Road Mode" button on the dash works and the rear lifts and then cancels with either pushing the button or exceeding the speed, what ever it is, 30km/h or something.

    I have installed the aftermarket lowering circuit board that emulates the key fob. It works fine and lowers the rear and then cancels with either pushing the switch the oppostie way or exceeding 8km/h or whatever it is.

    One problem I have is the light doesn't come on the dash for either of those modes but it keeping with some of the dodgy stuff that was done to my vehicle before I bought it, the bulb could be just removed.

    My issue is with how often it adjusts. My system is not standard by any means but it is still completely controlled by the SLABS. I have an airtank and compressor that feed a valve that replaces the factory compressor and then a second valve for the exhaust. Both of those valves are controlled by the SLABS and take the place of the factory compressor and exhaust valve. The only issue I could see that my setup could cause with the control of the SLS is the adjustment is pretty quick and I suspect it would be much quicker than the standard system. My air tank is maintained at 110 - 145psi so when the valve opens there is plenty of air to raise the bags. It doesn't cause any issues like the bags going past the target height and then having to lower again or anything but it will complete the "Off Road Mode" lift in under about 10 - 20 seconds and from what I read the standard compressor takes upto 2 minutes.

    Anyway, back to my issue. When I stop, usually at traffic lights, the back raises and the nose dips during braking. When the vehicle comes to a stop, it will hold this position a little. This causes the SLS to release air to lower the back while stopped. Then when I drive off again the SLS will raise again as rear drops from acceleration. This seems to just waste alot of air, depleating my air tank and causing my compressor to run to refill the air. I get about 3 - 4 stops between my compressor running.

    My system is a little noisy as in, when stopped, you can clearly hear the air filling or exhausting so I know when it's working. I don't know with the muffler and all if you guys with the factory system would know if youir system is working like mine is.

    If you guys know when your sytem is working. Can you let me know if it works like mine does?

    I think I could install a normally closed relay in the power feed to the exhaust valve and then connect this to my brake lights to stop the problem. Maybe I have a problem with the SLABS and this is supposed to happen automatically. I just don't know. Everything is working. I just see it as another improvement.

    Happy Days.

  2. #2
    schuy1 Guest
    I suspect the system is working as per standard. With the original system the exhaust does quieten things down a lot to the point it is silent when inside the vechile and motor is running.
    the problem of raising and lowering at braking I suspect is caused by your improved rapid response air delivery! As the nose goes down the sensors detect raising of the rear, exhausts air, then it finds whooy, its now low and raises, but because the system delivers air so fast now it maybe is having to overcompensat!
    I do recall a mates airbag rear doing a slow adjust in stop/go situations like you describe but I dont recall it being fast or doing it a lot.
    Cheers Scott

  3. #3
    Join Date
    Dec 2012
    Location
    Perth, WA
    Posts
    2,043
    Total Downloaded
    0
    Quote Originally Posted by schuy1 View Post
    I suspect the system is working as per standard. With the original system the exhaust does quieten things down a lot to the point it is silent when inside the vechile and motor is running.
    the problem of raising and lowering at braking I suspect is caused by your improved rapid response air delivery! As the nose goes down the sensors detect raising of the rear, exhausts air, then it finds whooy, its now low and raises, but because the system delivers air so fast now it maybe is having to overcompensat!
    I do recall a mates airbag rear doing a slow adjust in stop/go situations like you describe but I dont recall it being fast or doing it a lot.
    Cheers Scott

    Thanks for the reply mate,

    If thats the case, I'm keeen to try my idea of adding the relay to stop adjustments under braking. My next concern will be that as the system wont be able to adjust then it might through an error.

    I supose I'll be testing to see.

    Happy Days.

  4. #4
    Join Date
    Apr 2008
    Location
    Adelaide SA
    Posts
    2,517
    Total Downloaded
    0
    My D2 did exactly what you describe, when pulling up at traffic lights.

    As for extending to off-road mode, 20 seconds or so is about right. I wouldn't think the factory compressor would take kindly to running for 2 mins to pump up the bags. They don't have the duty cycle for it.

  5. #5
    Join Date
    Dec 2012
    Location
    Perth, WA
    Posts
    2,043
    Total Downloaded
    0
    I wonder if it adjusts continuously?

    If I go over a crest in the road and it rises, does the exhuast valve open and then if I go through a dip, does my valve open to raise.

    I just thought those imputs would be dampened (buffered electronically) more in the SLABS. I expected it to take readings over a certain time and then if the average of the readings was high or low then make the adjustment. For example take a reading every second for 500 second and then average of those reading was too high then lower. The 500 readings would be a continuos buffer, for every second read, the reading 501 seconds ago would drop off the average. Without something like this the valves would be constantly clacking away for every bump in the road. If thats the case, it's no wonder the standard compressor has problems and I doubt my valves will last long.

    Happy Days.

  6. #6
    Join Date
    Nov 2008
    Location
    Bruthen, Eastern Vic.
    Posts
    842
    Total Downloaded
    0
    Mine does the same - standard setup.
    Difference with yours is much quicker response and more noise than std.
    So you hear it more.
    The standard compressor is slow to move the bags and the ecu tells the system to lower before it has pumped up too much.
    I suppose you could lower the operating pressure to just enough to get off road mode with a full load. Probably about 100-120 psi

    Terry
    80 109" 2.6 P ex Army GS, saved from the scrappie.
    95 300tdi 130 Single cab tray.
    2010 Guzzi 750

  7. #7
    lewy is offline Wizard Silver Subscriber
    Join Date
    Jan 1970
    Location
    darwin
    Posts
    1,502
    Total Downloaded
    0
    Mine does that.I have a led that tells me when the compressor cuts in.connected under the fuse box to the wire that goes to the compressor.

  8. #8
    Join Date
    Dec 2012
    Location
    Perth, WA
    Posts
    2,043
    Total Downloaded
    0
    Well, I'm going to install a relay connected to the brake lights to stop it letting air out under braking. It just seems like a waste of air to me.

    Happy Days.

  9. #9
    Join Date
    Nov 2008
    Location
    Bruthen, Eastern Vic.
    Posts
    842
    Total Downloaded
    0
    I suppose you could fit flow restrictors into the lines to slow down the response of the airsprings?
    Terry
    80 109" 2.6 P ex Army GS, saved from the scrappie.
    95 300tdi 130 Single cab tray.
    2010 Guzzi 750

  10. #10
    Tombie Guest
    Slight long shot here Joel....

    Are the shocks valved to suit SLS? Your rebound may be a little light on, letting the rear rise up under brakes and engaging the system to lower back down.

    I wouldn't want to disable the system under brakes as part of the benefit is it keeping weight transfer under control.

Page 1 of 2 12 LastLast

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!