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I want to replace the TCase shift controls (bypassing the computer)

reaper

Well-Known Member
Messages
459
Location
Denver, Colorado
Has anyone done this? Any reason not to?

I'd like to bypass the computer, so whenever you press the damn buttons, the tcase shifts. I don't want the shifter to ask the computer "if it's okay to shift or not". I just want the f'er to shift!

For example, right now I've got an ABS fault and it won't shift in our out of 4 high/4 low. Dammit if I want to shift I want to shift!!!!! I don't want to be stuck having to drive 4low on the highway and I don't want to be stuck without 4 low when I really need it.

So has anyone else done this? I can't be the first guy to want to do this.
 

4speedfunk

Well-Known Member
Messages
4,197
Location
Tardville
I'm not sure the computer has to give permission to shift modes. I suspect your issue is the shift fork itself, in which case a manual selector would not do much to help you. I know you can pull the encoder off, and turn the stud with a pair of pliers to put it in whatever mode you wish. But there again...it doesn't help if the real problem is the shift fork.

You could probably fab a lever & cable to replace the encoder unit but, I question the purpose of this. If the t-case isn't shifting properly...it almost has to be the encoder or the shift fork. Its a pretty simple rig and very reliable of those two things are good.
 

atvspeed4

Well-Known Member
Messages
1,170
Location
massachusetts
We are in the process of a manual transfercase figured out. Doing a np241 to prove concept but then plan on a Dana 300 with 4:1 kit. It's waaay more involved tricking electronics on an automatic H3 than we expected but finally getting there. It is impossible to press the button and force it to shift. The encoder motor is a worm drive gear motor with an encoder that tells the computer what position the motor is in at start, what direction it needs to turn to reach next position when you press button, after it starts to rotate tell computer when next position is reached etc. If you take actual encoder off the motor and try to turn to reach a position without motor attached it goes into fault.
 
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06 H3

a.k.a. "The Jackal"
Messages
9,347
Location
Meridian, ID
I saw an NP241 install on a colorado. All they did was extend the VSS wire and made a manual stick for it to shift. I would use cables since they are easier to route into a cab.

Then leave the encoder motor attached, when you want to be in 4lo and want the computer to work correctly put it in neutral and push 4low and the encoder motor shifts to that thinking its in 4 low but in all reality you already did it manually.

I usually fix, modify or change things on my H3 after I have problems with it. I havent had problems with my 4:1 or shifting so I havent touched it but if I ever do thats the route I will take. I want to keep the 4:1 though. Nice thing is that many t cases have VSS provisions for them since the most common swap for big HP buggies is GM drivetrains, which use the VSS which is in our T case and all other GM transmissions/ tcases
 

4speedfunk

Well-Known Member
Messages
4,197
Location
Tardville
Some one already makes the lever thingy. You bolt it on and manually turn it to get whatever mode you want. There is no cable however....it's sort of a trail emergency device.
 
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06 H3

a.k.a. "The Jackal"
Messages
9,347
Location
Meridian, ID
Yea, I don't wanna be getting under the truck to manually change the t case mode Everytime I wanna shift...especially if I was in mud.

Emergencies it would be perfect though
 

alrock

El Diablo
Staff member
Messages
10,421
Location
Scottsdale
How about having anti-lock brakes when you need it? Might wanna fix the problem before you worry about the symptoms :whaa:

(I know you're asking a long-term question but the ABS does serve a legitimate purpose)
 

atvspeed4

Well-Known Member
Messages
1,170
Location
massachusetts
I want to be able to shift the lever (cable actuated) on the np241 or Dana 300 and have it recognized in the right mode in the computer. I'm not half assing this and leaving encoder motor and pressing the button each time it shifts. Honestly the hardest part is finding where to put the shifter lever as there is no room in the console. This is where we are hung up lol the electronics part is figured out
 

reaper

Well-Known Member
Messages
459
Location
Denver, Colorado
Thanks for the replies guys. The issue is the ABS-- and yes I'm getting them fixed (todayish), and when the ABS light is on OR any of the speed sensors is off, the tcase won't shift. You should know that about your H3, it will save you lots of misery and grief. :)

@4speed: yes, the computer absolutely needs to give you permission to shift. The ABS or speed sensors will block it. Trust me, I've spent a LOT of time in and around my tcase, and have a complete disassembled tcase in the garage for when I'm bored. :)

But why not just bypass the electronics to the tcase, and make it ALWAYS shift? If I did that and used my own switches (disconnecting the dash buttons that get stuck with dust anyways) would that screw up anything with the computer-- does it need to know that it's in 4low or does it not care? Was considering taking the h3 to an auto electric shop and get my own tcase shift buttons made.
 

4speedfunk

Well-Known Member
Messages
4,197
Location
Tardville
@4speed: yes, the computer absolutely needs to give you permission to shift. The ABS or speed sensors will block it. Trust me, I've spent a LOT of time in and around my tcase, and have a complete disassembled tcase in the garage for when I'm bored

Of course. I was assuming everything else was fully functioning, and you simply wanted to change modes. Pliers!
 

06 H3

a.k.a. "The Jackal"
Messages
9,347
Location
Meridian, ID
I want to be able to shift the lever (cable actuated) on the np241 or Dana 300 and have it recognized in the right mode in the computer. I'm not half assing this and leaving encoder motor and pressing the button each time it shifts. Honestly the hardest part is finding where to put the shifter lever as there is no room in the console. This is where we are hung up lol the electronics part is figured out

On the side of the console by the passenger?
 

alrock

El Diablo
Staff member
Messages
10,421
Location
Scottsdale
4 low turns off stability control so that's something you'd need to address with manual shifting unless you want ABS suddenly applying brakes to one or more wheels when you're out having fun.
 

reaper

Well-Known Member
Messages
459
Location
Denver, Colorado
How about having anti-lock brakes when you need it? Might wanna fix the problem before you worry about the symptoms

Well Al, it turns out I gotta replace the CV joint (Yay, I have a spare!!!), which broke the speed sensor ($120 part). It was a trail repair, so I don't feel too bad about it. So it's a weekend project. But I still want to replace the tcase controls unless that's a horribly bad idea-- I don't ever want to not be able to shift that bastard when I want to! I suppose I should just find one of those manual shifters , but pulling the encoder motor and bolting that on is really only a last-resort fix.
 

atvspeed4

Well-Known Member
Messages
1,170
Location
massachusetts
On the side of the console by the passenger?
Unfortunately that won't work as I cannot slide the passenger seat forwards with the shifter there. I like to be able to slide seat forward so rear seats can be folded down and sleep platform can go all the way forward
 

4speedfunk

Well-Known Member
Messages
4,197
Location
Tardville
Has anybody thought of simply using a Colorado/Canyon t-case?

Its a passenger-drop, just like the BW3393/4 except it has a 2WD mode. I realize it isn't much of an "upgrade" but, I wonder if this case could be swapped and if the buttons on the H3 dash would work with the CC t-case encoder. I have no problem with an electric shifter. It would be nice to push the H3's 4HI-Street button, and have it switch to a traditional 2HI mode instead. Us solid axle guys can then unlock the front hubs and BAM...the 2WD H3 we always wanted! (although without 4:1 low).
 

06 H3

a.k.a. "The Jackal"
Messages
9,347
Location
Meridian, ID
Unfortunately that won't work as I cannot slide the passenger seat forwards with the shifter there. I like to be able to slide seat forward so rear seats can be folded down and sleep platform can go all the way forward

On the side of the driver seat but in between the door and seat?
 

atvspeed4

Well-Known Member
Messages
1,170
Location
massachusetts
Our H3 is an automatic and the shifter tower under the console is huge. We are thinking of fabricating a much thinner tower which should give us enough room next to it for a custom cable shifter.
 

Ryan212

Well-Known Member
Messages
144
Location
Orlando
Atlast 2 that u have what ratio 2:1 or? And what did u do with encoder? I just zip tied it next to case on H2.

not sure ratio, but it feels far more agressive than 2:1, I need to call advanced to get the specs.

I have none of the stock powertrain left. , so the encoder, 4by 4 switches are all long gone.

Ryan
 

fatkatsupra

Member
Messages
12
Location
South Maryland
Such good timing! I have been pondering doing the same thing but for different reasons. I sold my h3t and got a ram 3500 ctd but want to install the 4494 in place of the trucks 4474. I poured over the tech manual and the encoder motor is a key part in the transfer case operation. It communicates position of the shift fork to the transfer case control module which then based on all the other inputs like abs and speed decide when it is safe to do things.

But the good thing is, the encoder motor is basically a 12vdc motor and should be able to be manually controlled. I was researching an audrino setup whereby you could control the motor rotation with a small rotary switch.

I dont have a TC to test on though so I am theorizing. My big hurdle would not be transfer case control but the spline adaptor for the transmission, the custom adaptor btwn the transmission and TC and then rerouting the oil pickup since the TC will sit opposite of the hummer setup...
 

Mb30sdl

Hamster that pokes Bears
Messages
1,586
Location
Irvine,ca
not sure ratio, but it feels far more agressive than 2:1, I need to call advanced to get the specs.

I have none of the stock powertrain left. , so the encoder, 4by 4 switches are all long gone.

Ryan


Then u may have 3:1 that is what you have but wishe I can redue it with 4speed 3:1,6:1. But u running same set it muinus d-max and I got pro-rock 80 rear.
Are u running 3link front 4 rear with coilovers?
 

Ryan212

Well-Known Member
Messages
144
Location
Orlando
It is a 4 link setup with a 5th as a Panhard type setup on the front with coilovers. Rear is leaf springs with a springover with 2 extra links added.

Hope this helps
 
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