ID Hubs: Manual, Auto, Locked/ADD

Edit: Never mind. After more research I realized that the ADD and hubs are different systems (although they are commonly reference together and related). Full explanation below.



I'm looking for a clean 2nd gen 4Runner. I prefer the Aisin manual locking hubs. I realize it's easy to swap Auto hubs for Manual hubs. And it's much more difficult to swap ADD hubs to manual.

http://www.4x4wire.com/toyota/tech/autohub/

My question is, how do you ID whether a 2nd gen has Auto or ADD hubs? Did the ADD system only come on automatic transmission vehicles?

PFA


Thanks!

 

I thought they(ADD/auto-locking)were the same thing tbh.
When I swapped front axles in my 88 to get factory 4.88s, the G144 option, I cut off the entire ADD system. A bunch of guys on a different forum said I’d need a special socket to remove the ADD... ha! Nothing the trusty Sawzall couldn’t handle! You’ll need to use a Timken bearing seal to keep the gear oil where it belongs. I tapped it into place using the sliding collar from the ADD system...I used the axle out of a ‘93. I believe ADD was only an option on automatics.

 

ADD are exactly that, "auto" as it stands for automatic disconnecting differential.

When looking up parts a parts store, manual hub setups are normally called "free wheel"

The front differential will be the same, but the diff tube attached to it will be different. One will have an actuator to engage/disengage whereas manual hubs are engaged manually by turning the lever.

Turning the lever only engages the wheel hub and axle though as you'll still be in 4x2 until you shift your t-case to 4x4.

 

Ok guys, I did a little more research and figured everything out. I also realized that I posted this in the 1st gen section, even though I'm speaking about a 2nd gen. No matter, the info is relevant either way. I'm going to try to explain everything the best I can, if not solely for my own benefit.

Pre-1995 4WD Toyota Pickups and 4Runners came with three different types of 4x4 hubs - Manual, Auto, and Locked (sometimes referred to as "ADD"). The nomenclature gets a little confusing because the terms overlap and they are related. I will try to clear that up below.


Manual Hubs - These are the conventional hubs we all know and love. They are super-simple and reliable, but require you to exit the vehicle and physically manipulate the hub dials to lock or unlock the hubs. There is a spline-count difference between solid axle Manual Hubs, and IFS Manual Hubs. So if you want to swap to Manual Hubs, make sure you get the correct spline-count.





Auto Hubs - Some 1984 to 1989 4Runners and 1984 to 1988 Pickups also came with Auto Hubs. The Auto Hub has a clutch inside the hub that will lock when it receives forward movement of the axle. The Auto Hubs are less reliable than the Manual Hubs, and will sometimes unlock when the vehicle is in reverse. It is fairly common to swap Auto Hubs to Manual Hubs: http://www.4x4wire.com/toyota/tech/autohub/



Locked Hubs - This is where the nomenclature gets a little confusing. Locked Hubs are neither manual nor automatic. They use a drive flange which effectively means the hubs are locked all the time. These Toyotas engage and disengage the front 4WD system only via the differential and transfer case. But the hubs themselves are locked all the time. This process is "automatic" in the sense that you do not have to get out and lock/unlock the hubs. But it should not be confused with the "Auto Hubs" referenced above. They are two different types of hubs.





But, what the heck is ADD?


Automatic Differential Disconnect (ADD) - Toyota introduced the Automatic Differential Disconnect (ADD) 4-wheel drive system on the Pickup in 1989, and on the 4Runner with the 1990 redesign. This system is composed of a vacuum-activated shift fork in the front differential driver's side axle tube: when the transfer case lever is moved to the 4Hi position, vacuum is applied to the fork which in turn moves a sleeve to lock the inner stub axle shaft from the carrier to another shaft in the tube. This axle assembly powers the driver's side wheel, while the passenger side is a single shaft from the carrier to the inner CV joint. While in 2WD, the driver's side axle is disconnected within the tube. All ADD-equipped Toyotas came with Locked Hubs. ADD is a different but related component to the Locked Hubs referenced above.



ADD Lockout/Delete & Manual Hubs - It is possible to lock out or delete the ADD system and swap the Locked Hubs to Manual Hubs on certain year model Pickups/4Runners.

ADD Lockout: http://www.4x4wire.com/toyota/tech/add/


ADD Delete: It is also possible to swap to a pre-1990 driver's side axle tube and delete ADD altogether.


I hope this helps!