Chevy Trailblazer SS Forum banner

1 - 11 of 11 Posts

·
Registered
'06 AWD
Joined
·
100 Posts
Discussion Starter #1
This info is only for TBSS rigs that have (or will) replaced the AWD Torsen transfer case with the 4x4 RPO NP8 NVG226 transfer case for RWD use only. This info addresses the complaint of the 4x transfer case slipping out of 2Hi into neutral while driving around with no transfer case actuator/shifter motor bolted on. GM confusingly calls this electric motor shifter an "Encoder Motor" that some folks with NP8 transfer cases leave off.

The problem is clocking the female actuator to the male transfer case shifter shaft to hold the TC in 2Hi. As many have noticed, the actuator has an internal locking mechanism that prohibits you from clocking it at all. It requires a 9 pin connector, another damn computer called the Transfer Case Control Module (TCCM), a special dashboard switch, and more electrically controlled front axles widgets that engage and disengage the front axle/wheels.

I haven't heard of any successful transplants of all that stuff into a TBSS yet.

I gutted a perfectly good encoder motor and discovered the guts are stupidly complicated considering a simple cable, lever, and bracket could easily have accomplished the same thing. No wonder the damn things break on the 4x guys all the time. The actuator is never going to turn from the TC side, it can only turn from the electric motor side due to four internal planetary gear sets that apparently slow down a million rpm electric motor down to a few mm of travel either way. GM wins the Darwin Award for that encoder design.

The solution (for RWD only) is gloriously simple.

You need any encoder moter, working OR NOT. (You threw it away? Back to the junkyard.)

Remove the electric motor cover by removing the two torx head screws.

See my album for the picture.

That big blue electric motor rotor can be spun by hand, either on the bench or installed on the transfer case. Spin it a million times each way and watch the female actuator move painfully slowly back and forth. Clock it so it matches the TC shaft position, bolt it on TC with 4 bolts.

Then check the front output shaft. If it doesn't spin with transmission in park, the TC is in 4x something, maybe hi, maybe low, but it's not in 2wd or neutral yet.

Spin the blue wheel ClockWise (from the driver side framerail view) by hand until the transfer case clutch pack is completely DISengaged.

See if the rear axle is locked to the tranny. If so, you're permanently in 2Hi.

If both front and rear spin with tranny in park, your transfer case is in neutral. So spin the blue wheel CW a whole bunch more until the rear is locked to tranny, and front output shaft spins freely.

Test drive, do RWD burnout, reinstall cover, high 5 and drink beer.

It will never fall out of 2Hi again.

Cheers.
 

·
Registered
08 TrailblazerSS AWD
Joined
·
342 Posts
Good info
 

·
Registered
TrailblazerSS 3SS
Joined
·
893 Posts
I went and grabbed a transfer case today there were several there and compared them all and they were all the same thing. On the round tag it says GM226HD not one of the vehicles had the option tags to find the RPO code. But I did get the motor and everything with it.
 

·
Registered
TrailblazerSS 3SS
Joined
·
893 Posts
DOne with swap, black raising hell marks all over the road now.....
 

·
Registered
TrailblazerSS
Joined
·
804 Posts
Reviving this thread. I have one of these transfer cases laying around at my shop. Thinking about doing the swap. Is just the TC, encoder motor and gaskets needed? And how is it holding up.
 

·
Registered
TrailblazerSS 3SS
Joined
·
893 Posts
Mine outlasted the trans again......did a night at the track with 7 runs, all with 100 shot and got in the deep 7's with it and the transfer case did fine. Next day 2nd gear does not like the hill in front of my house at all.....so right now in the process of going 4l80 built so there not an issue any longer after that.... It was not a bad job to do, just had to doulbe nut a few studs to put in the case before putting it back in....
 

·
Registered
TrailblazerSS
Joined
·
804 Posts
Still haven't gotten around to this. But I was looking to use this transfer case to go back and forth from 4wd hi to 2wd hi. Any reason this is strictly for 2wd? Is it the positioning of the lever that's the problem? Could a manual transfer case used?
 

·
Registered
08 TrailblazerSS AWD
Joined
·
342 Posts
I believe this way is just the quickest, easiest, and cheapest, way to convert from awd to rwd. There are some ppl here on the site that has done the selectable 2wd to awd swap. It is a lot more involved. I'll see if I can find that thread and repost it.
 

·
Registered
08 TrailblazerSS AWD
Joined
·
342 Posts

·
Registered
TrailblazerSS
Joined
·
804 Posts
AWD -> RWD NP8 4x4 transfer case shifter cure

Thank you. I was thinking of manually switching from 2wd to 4x4hi under the truck. Maybe making a locking lever once the correct positioning is found.
 
1 - 11 of 11 Posts
Top