4wd disconnect actuator motor...loose normal?

redbandit98

Original poster
Member
Aug 8, 2012
28
hello all. It seems like Im having to go through this 4wd system component by component. First off I bought the truck and the front axle disconnect was worn out..the 4wd worked, but the bearings in it were shot and the cv axle had tons of play in it. I replaced the unit with an aftermarket one. Everything seemed to work (or so I thought). It shifted into 4wd ok but I never actually verified the front wheels were pulling. Anyways fast forward a few months, and my TCCM goes out. No lights on switch etc. I replaced it with one from a later model and the lights came back to life, as well as the transfer case motor works again. I can run it in all modes and the tcase switches fine but my front wheels are not pulling. I also didnt hear anything from the front of the truck as if the disconnect was trying to engage. Here is my question. When I replaced the disconnect, I noticed the torque spec for the motor was very little..inch pounds if I recall. Anyways If I would have left it like that, the motor would have been very loose. In other words with the screws tightened to spec, I could grab the motor and it would wiggle around. I tightened it up to where it was firm against the disconnect. I got to thinking about it and am wondering if the looseness was normal? Maybe it was designed that way to help the actuator rod center up in the disconnect or something? My initial thought was the disconnect motor mounting holes just needed a tap ran through them or something but its got me thinking its bound up now. I plan on looking at it later in the week, just was gonna throw a line out and see if anyone could offer some assistance. I plan on pulling the motor off and checking it off the disconnect. I failed to do that when I replaced the disconnect because it was working fine before.
 

redbandit98

Original poster
Member
Aug 8, 2012
28
nevermind..i took the actuator off..its working fine. I actually think the clutch packs in the tcase are shot...:frown: Can anyone verify what years or if all years tcases will interchange? There are several here locally in the junkyard, some with pretty low miles.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
All years of transfer cases can interchange. They beefed up an internal bearing mount in 2005 or so to remove a failure point. Some folks who overused the A4WD mode tended to be more at risk for breaking it, due to the energy involved in a quick clutch engagement.

Just make sure you get the NP226 with the low range, not a NP126 from the vehicles that only had AWD.

Has yours been kept up with the 50K fluid changes?

The front axle actuator can extend its actuator pin when it's removed from the vehicle and still not work if the internal fork or shaft collar has a problem. You can push in on the fork through the hole left by the actuator and see if the front wheel will bind up if you leave the system in 4HI and try to spin the tire if you raise just that one off the ground.
 

redbandit98

Original poster
Member
Aug 8, 2012
28
the roadie said:
All years of transfer cases can interchange. They beefed up an internal bearing mount in 2005 or so to remove a failure point. Some folks who overused the A4WD mode tended to be more at risk for breaking it, due to the energy involved in a quick clutch engagement.

Just make sure you get the NP226 with the low range, not a NP126 from the vehicles that only had AWD.

Has yours been kept up with the 50K fluid changes?

The front axle actuator can extend its actuator pin when it's removed from the vehicle and still not work if the internal fork or shaft collar has a problem. You can push in on the fork through the hole left by the actuator and see if the front wheel will bind up if you leave the system in 4HI and try to spin the tire if you raise just that one off the ground.

I have no idea,..i bought it used with 130k miles on it. I changed the fluid and it was pretty nasty. I did take them motor off and manually extend the plunger. Everything seemed to work ok. I guess I really need to take it somewhere so I can get all four wheels off the ground in gear.
 

redbandit98

Original poster
Member
Aug 8, 2012
28
just a quick question. Is there any chance the actuator motor could be weak and causing the disconnect not to fully engage, yet not give a service 4wd light? Not knowing how the motor works, and being that its fairly cheap, I would assume its just a limit switch type pin in the motor. I ask becuase I am afraid my disconnect was not working out of the box, or it broke while I was testing it. The front wheels would not turn, and then all of a sudden it seemed like it binded up then a loud bang. Im assuming it it was the shift fork or gear tooth breaking. I switched into 4wd, I heard both motors but I had nothing at the front wheels. I could jack up the passanger side and spin it freely with the key on and in 4wd. I drove around a while like this and then all of a sudden it acted like it wanted to work then bang. I had amazon send me another disconnect and am gonna put it on tonight. I installed the new motor mounts and struts last night so Ill get to the disconnect later. I just wonder about the motor. I hear it work, I can take it off and watch it work, I get no problems with it saying its engaged, but yet I have a hard time believing a brand new actuator was bad. I dont know, it is probably china made so who knows. I was just contemplating buying a new actuator or not. Its a 100 dollar bill for a new one. I hate to buy one when mine is perfectly fine. I should have just got the AWD disconnect and ran it locked. I may rebuild my old one and make it an AWD just for kicks if I ever get this one sorted out. :crazy:
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The actuator can indeed get weak, but the limit switch ensures that it fully extends its button when actuated.

Here's my theory or operation master post on the OS, for more reading.

Repairing Front Axle Actuator, and theory of operation - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

But that was for a fault where the actuator worked fine outside the vehicle, but didn't have the strength to push in the shift fork when installed in the vehicle. In that case, the limit switch was NOT satisfied about the amount of motion, and the 4WD mode switch indicator lamp flashed.

Your problem is 99% mechanical and localized to the shift fork, collar, or splined parts. Your actuator is fine if the mode switch lamps aren't flashing after a mode change.
 

redbandit98

Original poster
Member
Aug 8, 2012
28
well, turns out the disconnect was bad from the factory I guess. I installed the new one last night, as well as finished up the motor mounts and struts. Everything seems to be working ok thankfully. I did not want to have to tear into it any further.
 

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