Using ADD mod button as electrical 4wd switch at speed

Gearboxs, Transfers, Tailshafts, Diffs, axles and CVs

Using ADD mod button as electrical 4wd switch at speed

Postby eehgil on Sun, 18 Dec 2022 5:15 +0000

I have done the ADD the mod wich is really great ( viewtopic.php?f=13&t=1290 )

In this thread: viewtopic.php?f=12&t=32686 I describe the "problem" that I feel that I need to use a lot of force on the transfer lever to change from 2H to 4H at speed.

Question: Is it somehow damaging to the drivetrain to leave the transfer lever in 4H and use the ADD swith to engage/disengage 4wd in speed?

As it is now with the force needed it "feels" more "damaging" to use the transfer lever.

I live in Norway, and now in wintertime it is nice to be able to change easily beteween 2wd and 4wd as traction is often varying a lot.

If I understand the system correctly it is originally like this going from 2H to 4H:
-transfer lever is moved by the from 2H to 4L
-add is connected
so when using the add-swithch I am only doing the last part? And "mechanically" no difference from original sequence?

When going from 4H to 2H:
-Transfer lever is moved from 4H to 2H
-Add is disconnected
The differnece from original sequence when using the ADD-switch to to change to 2wd is that front driveshaft is enganged to gearbox? Could this in some way be damaging to the ADD?
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Re: Using ADD mod button as electrical 4wd switch at speed

Postby Gipsy on Mon, 19 Dec 2022 4:54 +0000

This could point to the problem.. is the add in the normal setting when changing 2-4wd or do you have the add switch to disconnect? If switching add off before changing 2-4wd this could cause the gears to not mesh correctly. Before the mod, moving the lever from 2-4wd the add switches on at the same time to engage the diff but if you have the mod switched to disconnect the add this will not happen. Only select the add mod after selecting 2-4wd.

Edit: if you are using the ADD mod switch to change from 2-4wd you will almost certainly destroy the ADD solenoid. Also if you keep the transfer case in 4wd and use the ADD switch to change then the transfer case gears are constantly engaged adding to fuel consumption and wear and tear as the gears and input shaft to the front diff are constantly engaged.
Cheers Gipsy :D although I'm sure somebody will challenge that :lol: even Einstein wasn't certain of his theories.
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Re: Using ADD mod button as electrical 4wd switch at speed

Postby hylux on Mon, 19 Dec 2022 3:18 +0000

Toyota says for manual transmission
Going from
2H-4H speed should be lower than 80kmh. In very cold that may need reduced or stopped. Using clutch not required
4H-2H can be done any speed no clutch required. If the 4wd light does not go out drive straight accelerating and decelerating or reverse.

4H-4L Press in clutch, stop or be doing less than 8kmh
4L-4H press in clutch can be at any speed.
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Re: Using ADD mod button as electrical 4wd switch at speed

Postby hylux on Mon, 19 Dec 2022 3:35 +0000

** should have said above is for my australian 3ltr 2011 manual
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Re: Using ADD mod button as electrical 4wd switch at speed

Postby ptrl1600 on Tue, 20 Dec 2022 7:36 +0000

The ADD uses a small electric motor and switch wheel similar to a window wiper motor that drives an actuator arm in order to slide an internally splined hub over the splines of the front diff right hand side output shaft to the splines of the front right hand side axle. There is no syncromesh in the system, but it works because the clearances in the spider gears of the diff that rotate with the left axle do so at similar speed to the right axle provided the car is driving straight which is why sometimes if it doesn't engage, turning the steering can help.

The actual operation of the ADD takes about a second or two to complete, so is not as fast as shifting the small lever into 4H which is why we see the 4WD lamp flash for a second or so during the shift operation. So I would guess that for a short time, the car could be in 4H without the ADD completing it's move. So having said that I can't see that having the ADD switch on or off would make any difference to the shift from 2H into 4H.

When I had the ADD switch mod fitted in my Hilux, I only ever used it to enable low range in rear wheel drive only, so that I could reverse my van on a hard surface without the load on the steering, which worked well. But since fitting the front Lokka, it made the mod obsolete because I now drive at least one front wheel even with the ADD off, so I removed the switch. I understand that you want to use the switch to go from 4H to 2H and back without shifting the lever and I can't see any negatives in doing that provided there is very little load on the system like lifting off the throttle and coasting when using the switch.

My Hilux is a petrol auto, which makes the operation of shifting from 4H to 4L different to a manual because going through neutral in the transfer allows the transmission output shaft to spin up which doesn't allow the shift operation to complete without a lot of crunching in the transfer. The only option then is to turn off the engine and stop the car to complete the shift, but I don't think that I've tried it from 4L back to 4H, so next time I get the opportunity, I might give that a try.
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Re: Using ADD mod button as electrical 4wd switch at speed

Postby eehgil on Tue, 20 Dec 2022 7:12 +0000

Thank you all for replies! :-)
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