Np205 Help!

[Collers9640]

Ok I rebuilt my tc, I'm certain I put everything back in correctly.
Now it spins freely when turned by hand, however it doesn't even come close to spinning like it was when I removed it.
Is this normal? Does everything have to settle before things loosen up inside. I know didn't over torque the idler shaft but I simply don't understand. I've had it apart and back together 3 times trying to figure it out no BS I really have.
Any NP205 guros out there who can help?

[dazedandconfused]

Bill should chime in soon. He has been through them before

[Philip]

What did you set the end play on the idler gear at??

What all did you replace?

[matthewh]

Idler endplay is the biggie, if its too tight, then it takes more effort to spin. Also, if you replaced the output seals, and/or speedi-sleeves the yokes, that adds a ton of friction and drag to everything.

[thrashingcows]

You have to preload the bearings on the idler to set the end play. I had to make a fancy rig under the bench to load the bearing up with a small bottle jack. Took me a couple hours at least to finally get that end play set.

[Collers9640]

I couldn't torque the idler down more then 90 ftlbs or else it would bind.
I replace the idler bearings but I bought a kit and it didn't have timkin bearings in it and yes I replaced the output seals. But by them adding friction are you saying initial friction that will go away soon?

I did not preload the idler bearings to set the end play either... I lost on how to do that is there a video somewhere?

[bgilbert]

The torque spec for the idler and both yokes is 138ftlbs. I ratchet strap the the case to the bench to hold it in place while torquing to 138ftlbs.

Most of the time, even after replacing the idler gear bearings and races, you can get the required end play by reusing the shims that came out of it before rebuild. If the idler gear is too tight, you need to ADD a shim or build up your shim pack to loosen up the gear. With fewer shims or a shorter shim pack, it allows the two tapered bearings to squeeze tighter on the races/idler gear when torqued down. You end up with a hard to move idler gear. The greater the shim pack measurement is, the looser the gear will be. When tightened down, the distance between the two tapered bearings will be greater, allowing the gear to 'float' so to speak between the races. I ran into this recently when building a case for my crew. I couldn't wrap my head around it. My experience with the Getrag, the more shims you add, the tighter the preload would be. I started out with one .040" shim, after a year of sitting in pieces, I lost the .005+- shim, so the preload was tight when I finally got around to putting it together. All I had was additional .040" shims. Two .040" shims made the gear incredibly loose, like flop back and forth, let alone new the allowable .002" end play. I would have thought .080" of shims would make it super tight?? Then after some gear grinding in my head I figured it out. A call to Zbag to order a shim kit. Believe I went with a .040 and .005+- to put me in the happy zone of .001 end play. At this point, it's tight enough to break in the bearings and give them a long life, but not too loose or too tight. Less than .001" and it will be too tight.

Here's an easy way to set end play out of the case before assembly. Assemble the idler gear, shaft, two tapered bearings, spacer and shim(s). Place them in a hydraulic press. Find a socket big enough to fit over the threaded end of the shaft and sit on top of the bearing. Think I used a 3/4 drive 1 1/2" socket. Apply some pressure down on the top bearing with the press and socket to hold it in position and emulate 138ftlbs. Set up a dial indicator with a magnetic base. Set the pointer to zero on top of the gear. Lift up on the bottom of the gear with a large screw driver. Too tight and you'll not see the dial indicator needle move. More than .002" and it's too loose. I like to get it as said before at .001". Luckily, most of the time reusing the original shims will put you right there. Assuming everything was in good working order.

It is normal after rebuilding a transfer case to think you've got it set up too tight. A good rebuild should not spin freely like the price is right wheel. It should take some effort to spin the shafts or idler gear if that's where you are at.

The end play can be checked with the idler gear in the case as well. Just assemble the gear, shaft, bearings, spacer and shims in the case, tighten to 138ftlbs, while turning the shaft if possible. Then set up your dial indicator on top of the gear, lift up on the bottom with a larger screwdriver. The downside to this method is if you need to adjust play, you have to take everything back out of the case, then repeat. Clear as mud?