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How to modify the A.D.D. for trouble free operation.

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  • How to modify the A.D.D. for trouble free operation.

    There's already a guide here......
    http://www.4x4wire.com/toyota/tech/add/ ......... that shows you how to remove the troublesome vacuum part of the A.D.D., but I've added a few more detailed photos.

    Jack both front wheels off the ground, support truck with axle stands and drain diff oil into a clean container. Or discard thoughtfully if re-newing

    Once you've drained the diff oil from the drain bolt (22mm socket)....


    remove the vacuum operated actuator, four bolts. (12mm socket) white plastic plug and two small rubber hoses...

    Place some rags or bowl on the ground under the diff as more oil will drip out as you remove the actuator. It may need a tap to break the gasket seal.
    This the actuator removed....

    Looking at the diff, you'll see the collar that slides across to lock the passenger side driveshaft to the diff. (collar shown in the unlocked position, (2WD)

    Slide the collar across to the driver's side, you may have to turn one of the front wheels slightly for it to engage the splines.
    This is the locked position.....(4WD)

    Next you'll need to slide the selector fork of the actuator over towards the driver's side...

    Then get a Jubilee clip small enough to fit in the space on the actuator fork's rod, and open it out.........

    Then feed it around the actuator rod, a bit fiddly, and close it back up. No need to be super tight, just pinched closed...


    This will keep the selector fork in the 4wd position.
    Once you've done that, you'll need to either connect to now open vacuum ports with a short length of rubber hose to stop dirt/mud/water ingress...

    Or just squash them closed with some pliers like I do....

    Next you need to scrape off the old instant gasket goop from both mating surfaces of the actuator and diff housing....

    Apply some instant gasket or RTV sealant....


    Now fit actuator assembly back onto diff housing, making sure the collar stays in the 4WD position on the splines as you go.
    Loosly fit the four bolts (12mm socket) and check that the collar is in the 4WD position by turning one of the front wheels. The other side should turn in the other direction.

    Alternatively, select L4 via the transfer lever and grasp the front prop and turn it. Both front wheels should turn.
    If all OK, tighten the four bolts, (two grunts is plenty, you're only preventing diff oil leaks) and plug in the white plastic plug. This will make sure the green 4WD light on the dash still works.

    Now you can discard those two vacuum lines that run from the VSVs on the inner wing down to the front diff...(and the VSVs too if you want to tidy up the engine compartment)


    Now comes the fiddly bit of re-filling the diff oil you drained earlier via the filler bolt just above the electrical connector......


    It took a while, but I used a turkey baster, but you could rig up a hose and pour the oil in from above I suppose, but remember, diff oil bluddie stinks!

    Now move the transfer lever back into H2 position, switch on ignition and press the 4wd button on the transfer lever. Listen as 4WD instantly engages at the press of the button, and disengages when the button is off. The green 4WD light on the dash should still work as normal.
    The same results when L4 is selected via the transfer lever.

    Thats is all, now go out and get smelly!

  • #2
    That's awsome, Danny have you seen this?

    peace
    cal
    Bala Mud, best underseal there is, only £30 per application.


    www.thecellardwellers.co.uk

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    • #3
      I thought Danny had already done this mod?

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      • #4
        I'll copy this in the modification forum as well, so its easier to find.
        4x4toys.co.uk - Keeping you on and off the road...

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        • #5
          OK, ta!

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          • #6
            Nice one vince.This should work on my fourtrak also as its the same setup.
            www.overfab.uk

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            • #7
              Hi, Thanks for the post up on the how-to. Dont want to fill the thread with crap but I have a question since I don't fully understand how the 4wd works.
              Basically, since this does the ADD which is the disconnection of the front prop to the diff (correct?), without free wheel hubs the front prop will always turn correct? At this point, the 4WD is controlled entirely by the transfer box? So when pressing the 4WD button, this now only controlls the positions of the transfer box?

              Hope that makes sense!
              Oh Nana, what's my name?

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              • #8
                No, it permanently joins both front driveshafts to the diff.

                Normally, in 2WD, the passenger side driveshaft is free-wheeling. When the button on the transfer lever is pressed, the electric acutuator on the transfercase engages drive to the front propshaft. At the same time, the vacuum side of the operation slides a collar across to lock the two front driveshafts to the front diff so you get 4WD. (the driver's side driveshaft is always connected to the diff)

                When people have trouble de-selecting 4WD, it's 99.9% of the time due to the vacuum actuator not sliding the collar sufficiently and disconnecting the passenger side driveshaft, due to poor vacuum supply or a faulty/leaking diaphragm/hoses in the actuator on the front diff, which in turn doesn't activate the sensor to tell the electric actuaor on the transfercase to disconnet drive to the front propshaft, so you're stuck in 4WD.

                This modification deletes the vacuum side of things so 4WD is controlled by the actuator on the transfercase only.
                Selecting L4 via the transfer lever works as normal too.

                It's a good idea to fit free-wheling hubs to eliminate any driveline drag when driving on road, but thats only a personal preference.

                Hope I've explained all that OK.

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                • #9
                  It makes it the same as a Hilux pickup. The don't have ADD.
                  4x4toys.co.uk - Keeping you on and off the road...

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                  • #10
                    Originally posted by TonyN View Post
                    It makes it the same as a Hilux pickup. The don't have ADD.
                    Yeah there's two types of T-case on the pick-up isn't there?
                    Electric and manual.

                    Comment


                    • #11
                      I've not ever seen a electric one on a pickup up to 97'ish, maybe the import ones might. Not really worked on anything newer than a MK3/4, so new ones might be.

                      All been H2-H4-N-L4 on the lever.
                      4x4toys.co.uk - Keeping you on and off the road...

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                      • #12
                        Vince , was this the problem with my 4wd not engaging ?
                        Last edited by 3 LIONS; 28 November 2010, 11:38.
                        No king of England is not king of France

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                        • #13
                          Originally posted by 3 LIONS View Post
                          Vince , was this the problem with my 4wd not engaging ?
                          No mate, yours is an electrical problem.
                          I'll be wiring another one up this afternoon, so I'll be able to send you a 'what-goes-where' message.

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                          • #14
                            Thats great Vince, thanks.
                            No king of England is not king of France

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                            • #15
                              Originally posted by Calos View Post
                              That's awsome, Danny have you seen this?

                              peace
                              cal
                              Originally posted by BUSHWHACKER View Post
                              I thought Danny had already done this mod?
                              cal dont know how you can get me and vince mixed up on that thread i might better looking but he is the real mechanic! hehe!

                              but the only thing im worried about vince is now the front diff is 'active' how will the TC act to different rotations of the front and back prop shaft. i only fit the front PS when i go off roading its not on any other time. i know i should get free wheeling hubs but for need to save up for £120 a pair or shouldnt it matter???
                              http://www.hiluxsurf.co.uk/showthread.php?t=55797

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