I've read the 4runner history pages but couldn't figure this one out. When did Toyota add ADD and when did they stop offering the non-ADD 4runner?

 

I think 1989 or 1990.

 

88 I believe.

 

the add started in the second gens 90-95, and continued in the 3rd gens 96-02, and is still in use in the fourth gens 03-0?, some of the second gens did still come with manual hubs, Ive never seen a 3rd gen with hubs (from the factory)

 

Do you know if they stopped offering the non-ADD 4runners when the ADD system was introduced on the 2nd gens, or did they co-exist for a while?

 

Yes, both ADD and non-ADD with manual hubs were available up until 95.
I *believe* you will not find any non-ADD automatic transmission combos, but I could be wrong about that.

 

Thanks for the info. Now I need to tell the f'ing transmission place that replaced my transfer case that they put the wrong one in (one for a non-add 4runner). The non-add transfer case seems to be missing a synchro that lets you shift into 4wd as you go. I guess this makes sense since the if you don't have ADD you would have to stop to lock your hubs anyway.

 

hmmm, that's weird. even on my 1989 without ADD, (but with auto hubs) the chain driven Tcase could be shifted on the fly up to about 30 MPH. I thought all the chain t-cases could do this?

Earliest ADD I've seen is 1990.

 

Far as I know, all conventional tcases could do this, period. The front driveshaft has to be turning (i.e. hubs engaged) so the front and rear driveshafts are spinning at the same speeds, - then just shift it into 4wd. Any difference in speeds (like from the tire radius being different fr to rr because inflated load radius are different) will make it harder, and the difference will become greater the faster you go - this is why you can usually only go so fast before it won't go into 4wd.

 

I don't know if I am right or wrong about this, but here's my theory after studying the FSM and the posts here and some other 4runner history pages.

- There is a difference between the ADD and the non-ADD transfer case, at least according to the FSM. The most noticeable difference is a synchro sitting right by where the front drive is being engaged, which is present on the ADD transfer case and missing on the non-ADD transfer case.
- This syncro is needed for the ADD system since the front differential is not turning when you try to engage 4wd. I think the ADD engages after the transfer case shift is complete.
- For a non-ADD 4runner, the front diff will be turning after you have locked out the manual hubs. Therefore, the synchro is not needed, at least at lower speeds.
- If you put the non-ADD transfer case in a ADD 4runner, you get my problem, where I can't engage 4wd unless I'm at a complete stop. If I try when I am drving, I just get a lot of scraping/grinding noises.

Does this make sense?

 

yes, that could be your problem

 

V6 or 4cyl?
I'm basing this on the assumption of a 22re 4Runner.
If you got the one for a non-ADD setup you got the better end of the deal! It would have to be a gear drive version which is much stronger and more durable.
Manual hubs on 4cyl 2nd gen 4Runners were only available from 1990-1993 and, I believe, were only available when put in combination with the W56 transmission and gear drive case.
Once again, that info is for 4cyls ONLY! V6s are whole different story somebody else can tell
Also, if this is a V6, I don't think they could put the wrong one in without adding an adapter plate. The only thing that would fit would be a chain drive case. Then it would have to clarified whether or not chain drive cases that are set for ADD are any different than ones with a v6 5sp with hubs.
Just a newbies opine.
Edited to try and and help prove I really don't know what I'm talking about.

 

It's a V6. And from the FSM it seems like the transfer case for the ADD version is slightly different than the Manual Hub version (see my previous post regarding the synchro). I looked at it this afternoon and I am pretty confident it is the chion drive case from the descriptions here (5 bolt cover).

 

Heres a question for you who have messed with the ADD, and is somewhat on topic...Can you put a locker in the front, specifically an air locker, while retaining the ADD...i've heard some swear you can't, and some swear you can, and i'd like to know what's what...

I'm pretty sure the syncro deal is right....you have to have that syncro to get everything spinning with the ADD hubs....if you have drive flanges then you don't have this, but i'm pretty sure they never used those on the 4runners/pickups...

 

I haven't really touched the ADD, and I have no experience in installing lockers, so I can't answer that question for you. Just to be clear, ADD has nothing to do with your hubs, it works on the front axle. I have the flanges, but with the ADD disconnected in 2wd, the axle from the front diff into the transfer case is not moving, and that's what the synchro is supposed to help with.

 

this might be a stupid question... but what does "ADD" stand for?

 

Automatic Disconnecting Differential

 

thanks

 

Attention Deficit Disorder

 

can you put a locker in a ADD diff?

Well sure. Why not? But all the ADD will give you is the ability to choose between 3 and 4 wheel drive.

If it is an automatic locking locker like a lockright or an EZ locker (both exist for the 7.5) The driveshaft will always spin with or without the ADD locked in. So ADD lets you pick 3 or 4 wheel drive. You will want/need manually locking hubs here to prevent senseless front driveshaft rotation.

With an ARB (The only selectable locker I know for 7.5 ADD diffs) It would function as open diff (no driveshaft spin) until you locked it, then the driveshaft spins with or without engaging the ADD unit. Again, ADD only lets you pick 3 or 4 wheel drive. Might as well ditch the complexity and switch to manual hubs and remove the ADD.


ADD stands for Automatic Differential Disconnect.