Twin Stick Transfer case

Ok. This is one of those post that gets to me every time. First of all there is more to a twin stick mod than just cutting of a price of metal. That piece of metal is put in there by Toyota as a safety feature and when you cut it off it can cause an extremely dangerous situation. I put that safety feature back in during my modifications.

Also. The Tacoma case CANNOT be modified in the same manner as the fj case because they are NOT the same internally. They have one shift rail to control 2wd/4wd and hi/lo.

I'll have more on this issue when I get to my computer.

 

hell, doin the mods yourself aint all that hard either

 

I think you will find that the devil is in the details. Even assuming you get it done, will it be cheaper than buying something proven? I've done all kinds of conversions and swaps over the years. One thing I've learned is that I rarely come out ahead by going it alone. If you get it though, post it up, and be sure to log your investment

 

Couple newb questions:

One stick engages the transfer case into 4wd; the other switches between high and low?

So now the 'weak' point is the ADD servo. Are you planning on permanently engage the ADD to eliminate that servo failure possibility?

 

what is this ATRAC j00 speak of?

 

Hey Wyatt,
I'm doing fine, and I do appreciate the effort you have put into making this swap a true upgrade. So many times these types of things fix one problem only to create another. Living as I do, I cannot afford problems. Both the workmanship and the engineering behind the conversion have been flawless. You know I tow a lot, and often that trailer is in places it has no business being. I never know where I'll be next. The Tcase makes such situations much easier to handle. I also don't have to worry about getting bound up in something where the servo refuses to engage. I'm just very happy with the whole deal. Hope everything there is well with you and your family!

 

There is no reasonable way to get around that servo yet, but I'm hoping some day we will get a manual hub conversion. I will say though that the ADD servo is MUCH less problematic than the one actuating the Tcase. I have never had a situation yet where it has been balky. Even if it does fail, I still have a 2lo option with an ARB. Eliminating the ECU is also a big plus. It will not allow the truck to move while engaging low range, but sometimes a little movement helps line things up. My worry was always going off the road and getting in a position where nothing would engage. Now I can goose things around a little and get it to pop in, just like the good ole days

Edit: one other point is that the ADD can be actuated in advance so that you can shift in and out of 4wd as needed. It does not have to be actuated with each engagement as in the stock case.

Edit: yes, one stick is hi/lo, the other is 2/4. You also gain a neutral position.

 

Some one needs to get on that

 

Good work! Time for a mass mailing.

 

Yep. If they made one, I'd probably go with an FJ tcase in a heartbeat.

 

i know what it is. i just dont have it

 

That's on the six speed. With the automatic there is not the room for the single stick. If you use a crawler in front of the. Ase you can use either the twins or the single sticks. I've used both.

 

The more I read this post the more I realize you've never had either of these cases apart and you don't know what your talking about. Please don't post up information that you don't know anything about. That's how people end up with screwed up vehicles at best or worst get hurt.

I'm going to post up in this thread the difference between the two case's and why you cannot modify the Tacoma case in such a manner.
I'm going to address each statement in this post so that it clear to others what is fact and what is fiction

Man I hate it when people don't know what they are talking about.

I want people to have all the correct information. I have addressed these issues before but will do it again for those that haven't seen them.

 

OK.... Lets get into the 05+ tacoma t case and the FJ Cruiser t case.

First, the FJ Case.

As you look down into the case from the shifter spot, you'll notice that there are two separate shift rails in there. Both have a slot for the shifter to go into but one has an extra nub if you will at the very end. This is the hi/N/lo shift rail. The other one is the 2wd/4wd shift rail.


Now lets look into the same shifter hole in the 05+ Tacoma t case. Notice that there is nothing there except the planetary gear set. No shift rails or slots for a shifter to go into.


So lets look at one of the first statements that is not really correct.

Quote "The "twin stick" type of modification could be done on the Tacoma case like this: The same "cut" made to allow the two shift rails to operate independently of each other would leave only the 2/4 shift on the existing servo. The back of the case would need to be drilled to expose the end of the H/L shift rail, which could be drilled and tapped to allow the connection of a pull/push cable (or a rod extension).

There is only one true shift rail in the 05 + Tacoma t case. That is the long rail shown in this picture. You can see that it protrudes from the rear of the case and is activated by the actuator at the rear of the case. The other rail is a stationary rail that is an indent positioning rail. It tells the servo to "stop here" for 4wd and to "Stop here " for 4lo. It cannot move back and forth no matter what you try to do to it. It's design is to simply keep the shift fork in position.


Now lets look at another statement that will get folks into a world of hurt.

Quote "As far as the "internal modifications" go, it is a matter of grinding off a piece between the 2/4 and the L/H shift rails, to allow them to operate independently of each other. In some cases, it is also necessary to replace the input shaft with the one that came from the target truck."

Lets look at what really needs to be done to get these two shift rails to function independently of each other.

Here is the FJ T Case split in half. You are looking at the two shift rails and forks. The shift rail closes to you is the hi/N/lo shift rail


A closer look and now you can see the hi/N/lo shift rail on the left and it has a protutsion at the end of the shift rail slot. That is what will be ground down but this alone will not allow you to shift them independently of each other. We'll get to that later.


We then take the hi/N/lo shift rail off and grind that appendage off.





But thats not the only thing that is done.
At the rear of the case there is a "pill" that needs to be taken out to separate the two shift rails so that they will function by themselves.


Now... Toyota put those two items, the pill and the extension of the hi/N/lo shift fork for a very good reason. With those two items now missing, the t case can shift by itself from hi to neutral or from lo to neutral leaving your vehicle to roll freely. Imagine that happening as your wheeling up that long steep slope and you hit a small bump and your t case pops out of gear. I've seen this happen and it's not a pretty sight. Now when this happens, you cannot just throw the hi/lo shifter into one of the gears. You must come to a complete stop, put the transmission into neutral, and then shift the t case back into hi or lo gear from neutral. Why is this you may ask??? Because there are no synchro's in the hi/N/lo gear set. That is why you must come to a complete stop to shift the stock Tacoma case as well. Marlin and I came up with a fix for this in the form of a spring that keeps the hi/N/lo shifter in it's position.

Now lets move over to the Tacoma case.
You cannot "split" the hi/lo 2wd/4wd shift rails on the Tacoma case because they do not exist. there is only one shift rail that controls both of them and it simply moves back and forth. Now I only know of one person who has done a manual shift for this case but in my opinion it's not a good option for a number of reasons.
One. To do this you would have to remove the actuator and on the end of it that goes into the T case there is an oring that keeps oil from coming out of the rear of the case. Oil flows from the case into the geared portion of the actuator to lubricate it. That would take some machining to come up with something to take care of that situation.

Then there is the shifting mechanism that you would need to fabricate. Keep in mind that some of the issues with this case is that that very shift rail jams and is the cause of some of the actuator failures. I've tried to manually move a jammed Tacoma shift rail and it took a hammer and a pair of pliers to do it.

I think this is a poor design and is prone to failure when used by wheelers.

I also feel that the FJ Cruiser conversion is the best fix for this issue whether I do it or someone else does. Thats why I posted on both this site and mine on how to do it.

There are reasons why Manufactures build their products a certain way and as you modify that product, it would do you and others well to fully understand why they did so before you change what they spent millions of dollars on designing. Remember, "If your going to build a rig, build it as if your loved ones lives depend on it"

 

Thanks. I try.

 

Shemp is quiet

 

Devil in the details Thanks for the refresher Wyatt!

Wyatt is very willing to share what he knows. A lot more willing than I would be, considering the investment to learn these things . When I went down for the install he showed me the Tcase internals and the issues involved, pitfalls that he ran into, etc. We worked shoulder to shoulder on the install, and at the end he handed me a complete copy of his wiring notes with sources for things like the ADD switch. He wanted me to understand what was done, and to have everything I might need down the road. It's things like this that make Wyatt a cut above to do business with. The only dissappointment was not getting a ride in the awesumDC . It was down for suspension mods

 

Wyatt also contributed 3 different articles that were published in Tacoma Magazine. They cover even more or the process. Click the link below to find the previous issues with the Transfer case articles.

http://www.tacomamag.com/tacoma-articles/all-tacoma-magazine-issues

 

If you'd like anything other articles let me know. Would love to get some more done for you.