NP208 Help

[83JCode]

I'm putting my NP208 (out of an '83 GMC) back together after a rebuild and have come across an odd issue. When I torque the tail housing down onto the case, the t-case locks up when in 4L. It spins freely and correctly in 2H, 4H, and Neutral, but locks up in 4L. If I take the tail housing off or just loosen it, then the t-case will spin when in 4L. Any ideas what might be causing this?

Thanks.

[dvdswan]

so it doesn't turn in 4L?  my 1st though is are all the bolts the correct size for the tailhousing?  did you get all the snap rings in the correct grooves?  can you shift it out of 4L when the bolts are tight?

[83JCode]

Yeah, they're the correct tail housing bolts and are all the same length.  I looked on the inside of the case and they don't interfere with anything either.  It doesn't turn at all in 4L when the tail housing is bolted down to the case.  If I loosen the tail housing or if the tail housing is off, then it will spin freely in 4L.  Yeah, I can shift in all of the ranges when the bolts are tight and everything seems fine in 2H, 4H, and Neutral.  I was hoping not to avoid splitting the case again, but I might have to. 

[bake74]

I'm putting my NP208 (out of an '83 GMC) back together after a rebuild and have come across an odd issue. When I torque the tail housing down onto the case, the t-case locks up when in 4L. It spins freely and correctly in 2H, 4H, and Neutral, but locks up in 4L. If I take the tail housing off or just loosen it, then the t-case will spin when in 4L. Any ideas what might be causing this?

Thanks.

     Just a thought, I would say something is wrong with the 4L gear set up.

[83JCode]

Thanks for the info.  I'll split it open again and take a look around.

[dvdswan]

I was just thinking maybe the shaft is moving and binding on the tail housing when shifting into 4L

[83JCode]

Yeah, it's binding with the tail housing bolted down, but I didn't think the whole assembly would shift or move that much when shifting into 4L. Looks like I'll split it apart again this weekend.

[83JCode]

Well, I've taken this thing apart and put it back together 2 or 3 times and still haven't found anything; still having the binding issue.  I've noticed that the planetary gearset sounds like it rubs on the lockring when it's in 4L.  Is that normal?

Thanks.

[Mario]

The only thing I can think of is if the speedometer housing is installed in the tail housing during installation, then the plastic worm gear teeth might not mesh and cause it to bind.  What about the tabs of the plastic pump housing?  Better luck, and post your finding please.