How to: Deleting ADD system

I’m not a mechanic but I’m trying to learn so excuse my ignorance please. So after the swap is complete the front drive shaft always is engaged. So when you swap from 2hi to 4hi is the transfer case what controls power being sent to the front?

 

No. The front half shafts or CVs are locked to the wheels and spin from the splines inside the hub. They turn the spider gears inside the differential spinning the front driveshaft that is “unlocked” in your transfer case in 2WD. When you shift into 4HI or 4LO, you lock in the front driveshaft shaft to the transfer case and start pushing power the opposite direction. Engine crank turns, turns torque converter or clutch, then transfer case primary sends power to front and rear driveshaft. Front differential sends set power to the front wheels inversely proportional to their traction through the CV shafts. If one wheel spins, then it receives more power than the one not spinning. Make sense? This is how an open differential works. Locking differential send equal power to both wheels regardless of traction. You probably have the stock open differential.

 

What you said and what he said are the same thing....transfer case drives the front once in 4H.

This is actually not correct. An open differential always sends 50/50 torque to both wheels. The one that spins requires a certain amount of torque to spin...the other wheel is receiving the exact same amount of torque as the spinning wheel, but that is not enough torque to drive the vehicle, so you just sit there and spin the one with the least amount of traction. A locker guarantees the wheels receive equal speeds, but all the torque could potentially go to one wheel, aka the wheel with traction.

 

You said it much better than I. What I wanted to stress that would be different is the ADD system prevents the front drive shaft from turning all the time. If he switches to a manual diff tube it will spin full time.

 

Thanks for the help guys! Recon I might as well get a locking differential when I do this? If so, any recommendations?

 

Opening a new can of worms there. If you're adding in a front diff lock, do you want to regear?

 

Totally separate mod. You don't need to crack open the diff for the FJ tube swap, so not really a justification for doing a locker while you're at it.

 

Well I’m having issues with my front gear coupler where the front actuator connects stuck in the 4WD position. I haven’t drained the front diff yet due to a stripped out drain plug (thank you previous owner). But I’m assuming there is going to be some metal shavings on the plug. I was looking into replacing front diff anyway. Factory gears can clean out my 285/75 no problem. I don’t plan on regearing yet but possibly one day. I still daily this rig so fuel economy is chirping in the back of my mind. Demon on my shoulder is saying to regear while I’m doing all this.

 

the stub shaft gets replaced with the FJ full time tube so if that part of your truck is damaged it will go away with this mod. No need to do anything to the differential itself.

 

So has anyone made a kit to use a cable to move the transfer case in and out of 4wd. Seems like they would sell like hot cakes. Especially as all these Toyotas get old and these actuators take a shit and you can’t find new ones.

 

honestly it’s cleaner to just put a manual case out of an FJ in. You will need to install a shifter mechanism for cable operated one into the cab anyway so might as well put an OEM part in that’s known to be super reliable.

 

Treehouse Offroad tried on his Sequoia, on YouTube, but it didnt work. Like @6 gearT444E said, replace it with a proven Toyota part, and eliminate the actuator that fails

 

Link to the video? My searches were unfruitful; although I now know more than I ever wanted to about suspending treehouses with cables...

 

He mentioned it around 18:20

https://youtu.be/1-pLyGRmtnc?si=IPvS3h3T-9sO9oDj

 

Ahh, ok that explains it, was looking for a video specific to that effort. Thanks!