np136 to np236

Re: np136 to np236

Postby racrx7 » August 11th 2015, 11:41pm

Thank you Leeann!!! :banana:
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Re: np136 to np236

Postby Captn.Crunch [OP] » November 29th 2015, 6:54pm

What started out as a crazy thought in my head two or three years ago has come to see the light of day it appears. For those of you who have put up with my ramblings all this time I thank you. What looked like a long shot is turning out to be anything but. Congratulations to racrx7. You showed up with a van, a willingness to sift though all of the posts here and ask all the right questions. You did what I've been shooting for for awhile now and good job. Not gonna lie, I wish I had gotten mine to work first but hell we all get to benefit from racrx7's hard work and the addition of the np246 parts is just over the top stuff. A shout out to meggabuddys over on the zr2 site. He is hip deep in modding these clutched transfer cases and is doing four wheel smokeshows in his 600hp turbo'd zr2 blazer.
Hurry up with the wiring tutorial will ya. If I can't be first, seconds the next best thing! Once again good job
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Re: np136 to np236

Postby Corsemoto » November 29th 2015, 9:33pm

Thanks to both of you guys for the 236/246 info. :thumbup:
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Re: np136 to np236

Postby racrx7 » November 29th 2015, 10:01pm

Thanks to both of you guys for the 236/246 info. :thumbup:


Anytime :dance:
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Re: np136 to np236

Postby robinasu » November 11th 2017, 1:20am

How did this wind up? Are the results in a new thread?
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Re: np136 to np236

Postby AstroWill » November 11th 2017, 1:35am

robinasu wrote:How did this wind up? Are the results in a new thread?


See the links at the end of this page.
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Re: np136 to np236

Postby robinasu » November 11th 2017, 4:03am

Much appreciated, Sir.

In summary for future searchers:

(Please correct if I am off)

So, looks like to me the 236 allows AWD mode (4WD auto), traditional 4WD/hi/low, and 2WD. Since our stick hubs don’t disconnect, 2WD mode isn’t useful. The conversion requires some electrical work, but not bad with all awesome documentation by others.

The 233 conversion is more straight forward. This TC is offers 4WD/hi/low and 2WD.

Questions remaining for me:

What are the long terms reliability impacts of the 236 if driven in 4hi all the time? Is the TC motor running all the time?

What are the long term impacts of running the 233 in 4hi? I read one driver had TC problems. Was this an isolated case?
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Re: np136 to np236

Postby racrx7 » November 11th 2017, 3:39pm

I'm not sure I understand, "2WD isn't useful"? I drive mine all the time in 2WD on the highway.
As for the encoder motor staying on in 4WD, it's not. Once the clutches are applied by the encoder motor, a brake in the encoder motor itself is applied and power removed from the encoder motor.
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Re: np136 to np236

Postby robinasu » November 11th 2017, 4:46pm

Got it, thx.

When in 2WD, I understand the CV’s and front drive shaft still spin. Why not just keep it in 4hi all the time?
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Re: np136 to np236

Postby M_a_t_t » November 11th 2017, 7:06pm

The front axles and driveshaft still spin because the front wheels are spinning.

I haven't owned an AWD or 4wd so I don't know about why not to run in 4hi besides maybe wear and tear.
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Re: np136 to np236

Postby Rinny » November 11th 2017, 7:23pm

Crunch thanks for pioneering this mod. Racrx7 thanks for all the hard work and hours you put in. I am close to getting the installed 236 to work properly and could have not done it without the finished tutorial retrieved from photobucket by sowgeek on our sister site. I hope I did not leave anyone out and if I did please quote me and add them. It does seem that someone else might have helped out on the front axel disconnect circuit with the wire that has to go to the PCM, I do believe that is my shifting problem into 4L. I might have an issue with the transfer case itself but that remains to be seen.
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Re: np136 to np236

Postby racrx7 » November 11th 2017, 7:47pm

"When in 2WD, I understand the CV’s and front drive shaft still spin. Why not just keep it in 4hi all the time?"

Because it will burn the clutch pack up inside the transfer case. Yes, all four wheels theoretically are turning at the same speed. The truth is that there may be enough difference in tire sizes, either in manufacturing or due to varying air pressures, or even when turning, to cause a slight differential in rotations speeds between the front and rear tires. This would cause the clutches in the transfer case to slip, eventually burning them up. On dirt or mud, the traction, or lack of rather, provides the slip.
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Re: np136 to np236

Postby Corsemoto » November 11th 2017, 9:20pm

And... you have to turn and stuff... :)
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Re: np136 to np236

Postby robinasu » November 11th 2017, 9:30pm

racrx7 wrote:"When in 2WD, I understand the CV’s and front drive shaft still spin. Why not just keep it in 4hi all the time?"

Because it will burn the clutch pack up inside the transfer case. Yes, all four wheels theoretically are turning at the same speed. The truth is that there may be enough difference in tire sizes, either in manufacturing or due to varying air pressures, or even when turning, to cause a slight differential in rotations speeds between the front and rear tires. This would cause the clutches in the transfer case to slip, eventually burning them up. On dirt or mud, the traction, or lack of rather, provides the slip.


Roger that. Thx.
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Re: np136 to np236

Postby Captn.Crunch [OP] » November 20th 2017, 7:23pm

Just to reiterate on how this all works I’d like to make a few observations. The 4x4 vehicles we grabbed these transfer cases from had a front axle disconnect. When in 2hi the passenger side axle was disconnected. When any other button was pressed an actuator slid a coller to create a one piece axle. The np236 has a clutckpack with a preload of approx 5lbs. This keeps the front shaft spinning to allow “shift on the fly”.
If you put the 236 in your van nothing will change. In 2hi the encoder motor is shut down. The 5 lbs of clutch preload is still present and your front driveshaft will spin. If you choose 4 auto the encoder motor will be actively waiting to be told of wheel slip and will apply pressure to the clutch pack till all wheels are spinning at the same rate. It will then remove pressure from the clutch pack. If wheel slip is stilll present it will continue to cycle until traction has increased and wheel slip has been eliminated.
If you choose 4hi the encoder motor will crank in full pressure on the clutch pack and a second circuit will lock the motor in that position. This brake circuit is the only difference between the awd encoder motor and the 4x4 encoder motor. Torque will be supplied in a 50/50 split until another selection is chosen.
You can select 2hi safely. The only way to damage the clutches would be to have marked differences in front to rear tire speeds for extended periods of time. Such as long smoky burnouts after a V-8 swap!
I have taken it a step further by installing a Torsen style limited slip in my front end. I still run in awd and have no I’ll effects
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Re: np136 to np236

Postby Rinny » November 20th 2017, 11:09pm

Al, great info Captain. I will soon be running the missing link wire from the computer to my TCCM and see if that fixes the issues I am having. I am getting some encoder motor sound when switching between 2HI, 4Hi, and AWD but no engaging of the front diff as far a s I can see. Need to get ir on stands and confirm. No worries though I am very close to getting it ironed out. might be in for a new clutch pac, we will see.
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Re: np136 to np236

Postby TurnNburn » November 20th 2017, 11:12pm

That only tells that ECU that its in 4lo, and to ignore the fact that the input and outputs of the transmission/t-case don't match. if left unplugged, it will not shift out of 1st in 4lo.
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Re: np136 to np236

Postby Rinny » November 20th 2017, 11:18pm

TurnNburn wrote:That only tells that ECU that its in 4lo, and to ignore the fact that the input and outputs of the transmission/t-case don't match. if left unplugged, it will not shift out of 1st in 4lo.

I had that problem when I first drove it till I found the encoder motor was toast and also had a broken wire and one that pulled out of the TCCM connector. All that got straightened out and now it will not go into 4L. No worries though I just need to wind up some other stuff on and that will be the next gremlin.
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Re: np136 to np236

Postby TurnNburn » November 20th 2017, 11:20pm

Oh, it physically isn't engaging 4lo?
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Re: np136 to np236

Postby Rinny » November 20th 2017, 11:26pm

UMHMMMM
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