ADD front diff into manual hub Tacoma

[rs23]

Would an ADD diff ('99 4runner) swap into my manual hub '96 Tacoma? I would of course be keeping my manual hubs. I know they make an ADD and non-ADD version, but I'm wondering what is required to do the swap - if its just removing the solenoids/actuator/electronics. For those that do the ADD to Aisin manual hub conversion, I don't recall any diff swapping required. Any help is greatly appreciated.

[ShowStop]

Originally Posted by rs23

Would an ADD diff ('99 4runner) swap into my manual hub '96 Tacoma? I would of course be keeping my manual hubs. I know they make an ADD and non-ADD version, but I'm wondering what is required to do the swap - if its just removing the solenoids/actuator/electronics. For those that do the ADD to Aisin manual hub conversion, I don't recall any diff swapping required. Any help is greatly appreciated.

On the Tacoma models, the diff itself is the same between the manual hubs and ADD. All thats done to make one or the other is to bolt on the necessary extension tube for the manual hubs or the actuator for the ADD. If the diff is the same between the Tacoma and the 4runner, then yes you can use that diff for your truck. Just swap the necessary parts to maintain your manual hub configuration.

[SloPoke]

Mind if I ask why YOU'd be goin' to an ADD diff???

[GoHack]

Your going to find that the A.D.D. setup doen't shift into 4Hi as smooth as the non-A.D.D..

Reason, the A.D.D. actuator (vacuum or electric) has to first engage in order to get the differential to turn, turning the driveshaft, thus allowing the transfer case gears to mesh.

I deactivated the A.D.D. on my '92 4Runner by replumbing the vacuum lines, allowing the actuator be be closed (both in 2wd and 4wd) vs. the normally open. I did this, as well as put manual hubs on. Not only did it shift into and out of 4Hi a lot easier, but I also gain in gas mileage because nothing is turning in the front anymore w/the manual hubs unlocked. I gained around 3 mpg.

I wish my Tacoma was as easy to convert as my 4Runner was.

[yota18]

i just did exzactly what your talking about this past weekend, i reconnected all the vacume lines and the electrical stuff, if you could help me out as to how i rework the wiring that would be greatly appreciated....as to the initial question, as long as the 4runner diff is the same as the tacome diff everything will work just fine
Chris

[SloPoke]

Yota18: am I to understand you put an add diff in you truck that came with manual hubs? So, now you'll have add and manual hubs. That right? What's your reason for goin with an add diff, if you don't mind me asking????

I'm contemplating the same thing....swapping in an add diff in lieu of my non add diff. I'm just wonderin' why others are doin' it.

[hawaiianbro]

So what exactly do you need to change from stock auto-locking hubs to the manual aisin hubs? Cvs? Spindles? or jus the hubs themselves?

[SloPoke]

Originally Posted by hawaiianbro

So what exactly do you need to change from stock auto-locking hubs to the manual aisin hubs? Cvs? Spindles? or jus the hubs themselves?

Outer most part of the CV's are different (same tripod joint though) so you'll need them and manual hubs. Weather or not you disconnect the ADD system is up to you. Correction from post below: Spindles are different.

[TacoCrazy]

Originally Posted by SloPoke

CV's are different so you'll need them and manual hubs. Weather or not you disconnect the ADD system is up to you. As far as I know, spindles are the same.

The inner joints are the same, it's just the outer's that are different..
But it's just easier to change the entire cv as you said..

[yota18]

well the reason i did this was i regeared the rear with 4:88's well insstead of taking out the front diff and regearing it, i luckily found a member ho did a swap and sold me his front diff with 4:88's installed for about $200 cheaper than the gears and instal would have costed me, also decided while truck was apart i found a good deal on man. hubs so i swaped them in also i had the entire assemble due to the fact that member did a SAS so he did not need the additional parts, hope this is clear enough, and hope i can figure out how to re-configure my diff......

[Dick Foster]

I had that setup before the SAS so know. The driver side axle spins the carrier all the time and the transfer case has synchros. The axle only turns with a manual hub truck and the transfer is in 2WD if the hubs are locked. The inside of the diff is the same only the passenger side axle tube varies. The ADD mechanism makes for a very handy lazy man's disconnect if he installs an automatic (Lockrite) type locker at the same time. If I had a front diff out, I'd at least put one of those in if not the ARB in there. Putting a switch on the ADD is the same as getting out and unlocking a hub if and when the front axle gets bound up on a hard surface.

[Dick Foster]

Spindles and outer axle ends are different between ADD and Manual hub trucks. However the inner axle ends that attach to the diff are the same.

[TacoCrazy]

Originally Posted by Dick Foster

Spindles and outer axle ends are different between ADD and Manual hub trucks. However the inner axle ends that attach to the diff are the same.

Isn't the bare spindle the same, just the hub different??

[Dick Foster]

No, it's not and you really don't want to change the thing either because it's a major PITA. Ask me how I know. The best thing to do is to get complete knuckles from a manual hub truck and swap those. However by the time it's all said and done, it's best and probably cheaper to just keep the ADD setup, put a swicth on the actuator and put an ARB locker in there. The lockrite was the only option when I did mine so that is why I did the manual hub conversion in the first place. If I were doing it today, I'd go the ARB route. Another thing is that the ADD outer axle stub is stronger than the manual hub style unit. The manual hub axle is a little smaller and has a weak point where the outer C clip goes. I twisted the end right off of one of them.

[SloPoke]

Dick, That's the same reason I want to add the ADD tube to my non ADD diff., to get a cheap mans disconneect for running a lockrite. I don't want to have to get out and unlock all the time so I was goina try this. Now I just gotta figure out how to pipe in the vac. lines on my non ADD truck.

[odonekanobe]

That is a great idea! I have a '93 4runner but it would essentially be the same, right? I already swapped to the manual hubs, but I have the ADD diff in there still. Couldn't you essentially just weld the front and just disconnect for the tight turns? (I know this is cheap, but if we all had the money for an arb we wouldn't even need this!) Then you would have just one wheel turning, instead of both.

[Dick Foster]

No don't weld the diff, especailly a front diff. All you have to do is put a switch on the actuator control.

[odonekanobe]

I was just saying as a cheap locker. I know the turning radius is shorter with a locked front end, which is one reason for a selectable. But my theory is that if you hook up a switch, it doesnt matter if the front two sides of the diff are locked together, because one of the tires will not be hooked to it. Right?

So essentially you could have a spool or welded front, and just throw a switch and have three wheel drive and your original turning radius back. (Im not suggesting people go out and weld their front, just that it could work in theory.)

[mr.trd]

If anyone needs, I have ADD spindles just sitting in the garage from when I did my ADD to manual conversion....but my best suggestion is to just keep the ADD and go with a switchable locker or a put a switch on the ADD actuator.


Hey Dick, did you have a switch on your truck when you had the lockright and manual hubs? And when you went to manual hubs did you keep the ADD passenger side tube or did you have a new passenger side tube also? I have the lockright and manual hubs but still have all ADD stuff, could I just put a switch in that to gain my three wheel drive???

[SloPoke]

Mr TRD: Yes

My ? is.... how do I hook up the vac lines for an ADD actuator and diff tube on a truck that came originally with manual hubs? I'll need a switch but what's the piping/tubing routing? That's what I'd like to know. I'd love to not have to get out and unlock a hub to turn and I'm a poor guy so I can't afford an ARB.

[mr.trd]

Originally Posted by SloPoke

Mr TRD: Yes

My ? is.... how do I hook up the vac lines for an ADD actuator and diff tube on a truck that came originally with manual hubs? I'll need a switch but what's the piping/tubing routing? That's what I'd like to know. I'd love to not have to get out and unlock a hub to turn and I'm a poor guy so I can't afford an ARB.

Yes what??

I can take some pictures if I can get into that area to take the pics, but basically there are just two vacuum lines that run down to the little actuator on the ADD passenger side diff tube. On a manual hub truck I have no idea where you would get these vacuum lines from I think that they are just coming off of a vacuum line from the engine, in fact I know that mine are cause when I first put the s/c on I didn't have the vacuum lines right and I had no 4 wheel drive. Will you have the ADD passenger side diff tube too or are you going to try and make your own? If so I would wait to find a diff tube with the actuator on it already. And now that I think of it, I have or at least did have a complete extra front diff with everything for ADD. It just has a broken ring and pinion in it and the case was ground down from broken parts rubbing on it, so I am not sure if the case is good, but the tubes are...

If I didn't even come close to anwering your question, sorry, let me know and I will try again.

[SloPoke]

Originally Posted by mr.trd

Yes what??

To this question....

Originally Posted by mr.trd

I have the lockright and manual hubs but still have all ADD stuff, could I just put a switch in that to gain my three wheel drive???

Sorry bout the lack of clarification.

Originally Posted by mr.trd

I can take some pictures if I can get into that area to take the pics, but basically there are just two vacuum lines that run down to the little actuator on the ADD passenger side diff tube. On a manual hub truck I have no idea where you would get these vacuum lines from I think that they are just coming off of a vacuum line from the engine, in fact I know that mine are cause when I first put the s/c on I didn't have the vacuum lines right and I had no 4 wheel drive. Will you have the ADD passenger side diff tube too or are you going to try and make your own? If so I would wait to find a diff tube with the actuator on it already. And now that I think of it, I have or at least did have a complete extra front diff with everything for ADD. It just has a broken ring and pinion in it and the case was ground down from broken parts rubbing on it, so I am not sure if the case is good, but the tubes are...

If I didn't even come close to anwering your question, sorry, let me know and I will try again.

I have an ADD diff I removed after a buddy sas'd. It's a vac. actuated one and yes, it has 2 tubes on it. One to each side of the diaphram. If you could get me a pic of the vac. line your is tapped in to/off of that would be a great help. That would tell me where to hook everything up and leave me with just gettiing a switch or knob for the dash to get this working.

Thanks.

[odonekanobe]

I know on the 93 add diff, you hook the passenger side vacuum line to engine vacuum, and then cap the drivers side. That will lock it. I dont know if its the same on the newer ones though.

[Dick Foster]

Having the front welded is always a bad idea with an IFS truck, even for a trail only rig or solid axle truck for that matter. There is really no such thing as cheap in the end. You're only putting off some kind of expense until later. Typically you wind up in the situation of chasing pennys with dollars by breaking stuff and winding up stuck out on a trail somewhere. Doing this wheeling thing has some costs associated with it, the sooner you come to grips with that reality the better off you'll be. Cost wise, you'll be much better off in the end to just wheel what ya got for now and save your money for a little while longer and do it right the first time. Look at it this way, with that approach you'll have that much more to look forward too and you get to enjoy the hobby for that much longer. Just slapping shit together is not gonna make you a happy camper in the end and you'll wind up getting all pissed off and loose your hobby. Don't rush it, take you time and savor every moment.

[SloPoke]

Originally Posted by Dick Foster

There is really no such thing as cheap in the end. You're only putting off some kind of expense until later. Typically you wind up in the situation of chasing pennys with dollars by breaking stuff and winding up stuck out on a trail somewhere. Doing this wheeling thing has some costs associated with it, the sooner you come to grips with that reality the better off you'll be. Cost wise, you'll be much better off in the end to just wheel what ya got for now and save your money for a little while longer and do it right the first time. Look at it this way, with that approach you'll have that much more to look forward too and you get to enjoy the hobby for that much longer. Just slapping shit together is not gonna make you a happy camper in the end and you'll wind up getting all pissed off and loose your hobby. Don't rush it, take you time and savor every moment.

One of the best if not THE best post I've ever read. GREAT ADVICE!!!!

[Dick Foster]

Thanks. I just hate seeing folks waste time and money only to frustrate themselves.

[odonekanobe]

First of all, I just mentioned welding the diff as hypothetical. I would never weld a 7.5" diff. I dont think you were reading my post carefully. I was just using that as an example of the axle being "locked". I just wanted to see if I understood the theory of what you were talking about with the switch installed.

Now as for welding the rear diff, I DO recommend that. If you have the money for an arb, than by all means get that. But if Money is tight, and its between that and a crawler box, get the crawler. I have a welded rear on my '83 and absolutely love it. Sure it's not the best for driving everyday on the street, but that's not what I do with my rig. Not everyone drives their junk on the street everyday, and that's usually a good thing for everyone else on the road.

I don't see what welding my rear is going to cost me in the future.....rings, pinions? They are stock so I was going to change that out if I put a selectable in there anyways. My front is still open though, because I know that there is a big difference between welding the two. If that's all you were talking about, I apologize and will step down off my high horse.

[Dick Foster]

"First of all, I just mentioned welding the diff as hypothetical. I would never weld a 7.5" diff. I dont think you were reading my post carefully"

You very clearly made distint reference to welding the front axle in no less than two seperate messages. Want me to post up some quotes from them?

BTW Welding any diff, front or rear, is just plain shadetree hack type stuff. IMHO

[odonekanobe]

Well, like you said, that is your opinion. There are many who would agree with what I said. Go to the pirate board and ask there, Im sure you will get many who respond in favor on a welded rear.....people who are definately not shade-tree, and definately not afraid to put money into their rigs.

All I did was post an opinion, you should respect that. How many welded rears have you seen fail? I have seen many lockers fail on the trail, especially the selectables. (Due to snagged air lines, etc.) In my opinion, which is just that, when I get to the top of a trail with either more gear on my truck, or money in my wallet, Im happier