Bumpin' Yota

Ok, I thought I had the ADD system from toyota on my 2nd gen yota. But today going up some hills near the beach (lots of sand) in 4wd Low, I noticed that my tires still spin independant of one another. Is this normal and will lockers make the front 2 tires lock as a unit?

Another question, on the stock 4wd yota's, the front 2 axles and cv's rotate with the tires. Will lockers (if unlocked) allow the axles and cv's to not rotate, there by reducing wear when you are on road?

Thanks guys,
steve

Los Gatos?

yes, lockers make the front 2 tires lock as one unit. ADD simply referes to the hubs (or lack of hubs I guess, since it uses flanges or whatever) ...ADD just means they lock automatically when you shift into 4wd, manual are where you gotta get out and lock them in. ADD doesn't do anything to the differential.

I don't believe lockers do anything in terms of stopping the axle and cv rotation, when a locker is unlocked it operates exactly the same as an open diff (correct me if I'm wrong here)...you can do a manual hub swap if you want to lower wear on ure shafts/cvs.

upndair

Actually, the ADD is for Automatic Differential Disconnect and doesn't have anything to do with the hubs. In the 2nd gen 4Runner, the there's no real hubs to speak of. There is a vacuum activate system that lets the differential run free when 4wd is not engaged. I believe that this is to reduce the wear and tear, not to mention the drag of having the front drive train engaged.

A open differential allows the tires to spin at different speeds to assist in turning. The locker forces both wheels to turn at the same speed and forces the power to both wheels rather than just the wheel that's turning the fastest.

Bumpin' Yota

Ok cool, I noticed though that when i was in 4WD LO that all the tires still spun independant of one another....is that normal?

I had thought when my toy was dropped into the lowest 4wd gear that it would lock everything together.....

Salue

Correct me if I'm wrong, but I think you have ADD confused with being locked(with lockers). ADD is just what Gibby states and it just means that if you have it, your hubs or lack thereof are always in the 'lock' position(meaning you never have to go out to the wheel and turn a knob to set it to 'lock', instead you just shift into 4Hi or 4Lo and you're in 4WD). If you replaced the ADD flanges with manual hubs, then your outer axle shafts and cv joints/boots will not turn when they are in the 'free' position. So, when you are in 4 Lo, the tires will spin independently since you do not have a locker in the differential. Hope that makes sense.

Salue

Flygtenstein

ADD is a vaccuum operated system that slides collar to connect the short side axle with the differential. It has absolutely nothing to do with the hubs. Putting on manual hubs has no influence on the ADD system at all. Gibby said all of this.

When I lock my RD90, both my front tires spin at the same speed if one is in the air while the other is on pavement.

Open diffs allow differentiation side to side resulting in the tire with the least traction getting the power.

upndair

You are mostly correct. Even if you put the manual hubs on, you would still have an ADD system. If you look to the driver's side of the diff, you'll see a box with a couple vaccum hoses coming out. This is the ADD system that disengages the front diff when it's not being used. The ONLY real problem with this is that there is a weak spot in the long axle shaft where the ADD fork is. These axles frequently break at this weak point, especially if you add an LSD or locker. When I was running IFS, I found the parts from an older truck that didn't have the ADD and put that on instead. That's when I found that my long axle was broken and I was only getting anything out of the front wheels because I had a limited slip diff to give some power to the intact driveline.

Bumpin' Yota

Ok, I got that the ADD = automatic differential disconnect and has nothing to do with the hubs. Im a complete newbie to the drivelines and suspensions and stuff...sorry guys. :cry:

So basically I have an open differential up front even when in 4LO?

CTB

Yes, you have an open differential up front no matter what you are in - 4Hi, 4Lo, etc.

BajaTaco

1. your axles and CV boots will spin when the truck is rolling, regardless of whether or not the truck is in 4wd, or if you have a front locker or not.

2. Without adding a locker, your front diff is OPEN whether in 2wd or 4wd. This means the wheel with no traction will get all of the power whenever you lift a tire, or get into loose or slippery stuff.

3. Adding a full time locker will mean that whenever you engage 4wd, the front differential will become locked, giving equal traction to both front wheels, whether you like it or not.

4. Adding a selectable locker will mean that whenever you engage 4wd, the front differential can either be open, or locked depending on your preference.

ATC

I have to ask a question now.

I also have the ADD on my '95 4Runner. If I added manual hubs would I have to get out & lock them if I wanted to switch into either of my 4wd settings just to drive around?

upndair

No. you could use your 4wd setting, but your front wheels would be useless until you lock in the hubs :o)

BTW, you shouldn't just drive around in 4wd, you should ONLY engage 4wd when you are in loose traction situations. Your front and rear wheels will turn at slightly different speeds which is OK on wet, or slippery surfaces but is really tough on the drive train on dry pavement.

ATC

No I don't just drive around in 4wd all the time. Let me be more specific. When I am in 4wd it is in snow, mud, creeks, or other driving conditions where 2wd won't cut it.

Now back to my original question. Do you mean that the ADD would be useless if I installed manual hubs?

What I want to know is if I am driving down the road for example & I hit a traffic jam & want to turn around in the median. Right now I can just shift into 4wd w/ the ADD & go. If I have the manual hubs can I still do this or do I have to get out & engage them as well?

upndair

I think you're missing the point. The ADD has nothing to do with your hubs. It has to do with letting your front differential run free when NOT in 4wd, reducing wear and tear on the drive train.

The disadvantage of the manual hub is that yes, you would have to get out and engage your hubs for your 4wd to work. But again, this has absolutely nothing to do with your Automatic Differential Disconnect (ADD).

Let's look at it this way. If you have a "full time hub" like the 2nd gen 4runner the front drive train is constantly in motion even in 2wd. This not only increases wear and tear it also increases resistance, thus decreasing fuel efficiency, etc. When you're NOT in 4wd, the ADD system lets the axle spin, since they are always engaged, but it disconnects them "in a sense" from the differential. When you engage 4wd there is a vacuum activated system that connects the axles to the differential, thus the power from the transfer case can get to the wheels.

This is sort of a version of an automatic locking HUB, but not a locking differential.

Stump1883

Okay I have been meaning to ask this for awhile now. What in the world is the ADD system? Sorry if that is a stuid question, I'm 2WD and I'm pretty sure that the ADD system pertans to 4WD systems. Thanks.

EDIT: Sorry about that questions above, good ol' AOL, just now loaded all the responses to this post, so now I can read them all and get a pretty good idea of it all. ADD is nothing more than just the Autmatic Locking Hud System right?? Is there anything else I'm missing here orould anyone like to "ADD"(very punny, not really I'm jst an idiot) something to my understanding. Thanks again.

BajaTaco

Here is a link...

http://www.off-road.com/toyota/tech/add/

4x4CPOSEADOG

Or try this link......

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

Noel