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Question about ADD

Tech Talk for Cruiser owners.

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Question about ADD

Post by grott »

I am thinking of SASing my 93 sr5 DC. My question is does the 4wd button on the transfer case gear stick engage 4wd by means of the transfer case or by simply engaging the front diff(ADD). If it only engaged/disengaged the front diff this would mean that it is in 4wd all the time if it was SASed. Also can free wheeling hubs be fitted to the ADD as ARB does not have a listing. Any feedback would be greatly appreciated.
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POS
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Post by POS »

ADD is located on the front Diff, their is a Dog clutch set-up. It is on the Right side of the Diff centre.

It basically works by the right hand axle being in two parts, when it is turned off the axle is separated and when you turn it on it slides a splined colar over the second part of the axle and than that will provide drive. The Front diff is continuously turning, whether its in 2wd or 4wd, when the front axle is separated its just like breaking a front axle, No drive to either wheel!

By replacing the IFS with a Solid axle you will not have the ability to do this. The only real advantage of having this type of ADD is that you can switch to High 4 on the fly, you still need to reduce speed when you want to go to low Range.

Yes if you wanted to fit free wheeling hubs you can, it will reduce wear to the CV joints, thats about it! If you do fit Free wheeling hubs to a IFS with ADD then you might as well go with SAS conversion.

The front diffs on the IFS lux/surfs are very weak!
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Post by grott »

what I am trying to find out is, is the transfer case ok to use in a sas or do I need a different type.The gear stick moves front to back Low-Neutral-High wit a button on side for 4wd. ie is the front drive shaft allways driven and the button only disengage/engage front diff. If this was the case it would be in 4wd all the time if it was fitted with a solid front axle
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POS
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Post by POS »

grott wrote:what I am trying to find out is, is the transfer case ok to use in a sas or do I need a different type.The gear stick moves front to back Low-Neutral-High wit a button on side for 4wd. ie is the front drive shaft allways driven and the button only disengage/engage front diff. If this was the case it would be in 4wd all the time if it was fitted with a solid front axle


Yes that is correct!

Meaning that all the front drive line is turning all the time, drive shaft, diff, axles and CV's. (which is something you don't want to happen)

I am pretty certain that you will need to change t/Cases, unless someone knows how to change yours to allow 2wd selection.
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Post by high n mighty »

Well my brother battled with ADD all his life :finger:





note, this is a useless post :D
[quote="fool_injected"]
I pity my brother when she is a teenager[/quote]
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Post by ozrunner »

POS wrote:
grott wrote:what I am trying to find out is, is the transfer case ok to use in a sas or do I need a different type.The gear stick moves front to back Low-Neutral-High wit a button on side for 4wd. ie is the front drive shaft allways driven and the button only disengage/engage front diff. If this was the case it would be in 4wd all the time if it was fitted with a solid front axle


Yes that is correct!

Meaning that all the front drive line is turning all the time, drive shaft, diff, axles and CV's. (which is something you don't want to happen)

I am pretty certain that you will need to change t/Cases, unless someone knows how to change yours to allow 2wd selection.


No that is not correct.

The front driveshaft (tailshaft) does not always turn with an ADD system only when ADD is enaged. The right axle is permanently engaged but it only turns the spider gears not the crown wheel. When the LEFT axle is enaged by ADD then the driveshaft turns. Your transfer is also not permanently engaged.

ADD is operated by an ECU. When pushing the button various signals are received from sensors that then tell the ECU to move to the next step.

The first step is the engagement of the Left axle etc which then causes the front diff to turn the front driveshaft which spins appropriate gearing in the transfer. A sensor sends a signal that the front diff is now engaged to the ECU which then signals the transfer to now fully engage.

You will note you have an electrical motor on the rear of your transfer. This motor connects the transfer to the front driveshaft.

As both tailshafts are now turning at the same speed the transfer can now engage and you get 4wd.

If you fitted a SAS with hubs it makes no difference as your transfer is not permanetly engaged. You could use you existing transfer if you wish by just looping the two wires going to this sensor together so the ECU thinks that it is engaged.

Engage the hubs on your SAS and you can push the button on the fly as per normal as both tailshafts will be turning at the same speed.

All you need to do is fool the ECU by joining this sensors imput and output wires together. They are located on the actuator section of the front diff. If you also have a temp sensor on the rear section join these too as well. Find the color codes at these sensors and then join them further up in the loom.

JD
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Post by grott »

Thanks ozrunner. Thats what I wanted to know.(if the transfer case was compatable or not with a solid axle.)Im still not sure if my hubs are ok to use on the wide track kit.Warn do not have a listing for free wheeling hubs for ADD. I'm not sure if this is because they are not needed or because they are different size or whatnot.
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Post by Surfin Alec »

If your going to do the SAS you use the hubs off the doner diff (free wheelin type) You cant use the IFS free wheelin hubs on the solid diff as they have a different spline - 24 v 26 I think.
I just shorted a couple wires together as Ozrunner said to trick the ECU to allow shift on the fly via the button on the 4x4 stick. Just make sure you hubs are locked other wise I rekon you might hear a few funny noises.

Alec
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Post by 80UTE »

Surfin Alec wrote:If your going to do the SAS you use the hubs off the doner diff (free wheelin type) You cant use the IFS free wheelin hubs on the solid diff as they have a different spline - 24 v 26 I think.
I just shorted a couple wires together as Ozrunner said to trick the ECU to allow shift on the fly via the button on the 4x4 stick. Just make sure you hubs are locked other wise I rekon you might hear a few funny noises.

Alec


This is correct the inner part of the hub the the axle spline fits through is different but all the other parts are the same. I fitted FWH to my brothers 4Runner about 10 year ago and had no problems for the 200,000 KM it dome till he sold it.

Walle
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