NP 229 behavior questions

[Lumpskie]

Hey guys,

As I prepare to get my Jeep ready for some basic trail duty, I've started to play with the transfer case a little bit. Shifting from 2wd to 4wd and back goes smooth and easy. On the other hand, shifting to low range and back up seems to give my t-case a little trouble. It seems to work ok if I put the rig in Neutral and let it roll a little bit while moving the lever. But, from a dead stop, it's a toss up whether the lever will move or not. Also, occasionally, I will get a gear grind sound when trying to get in or out of low range.

Is there a shifter fork in there or something that meshes the low range gear set with the output? Is this issue related to the fact that this Jeep may have never been in low range before I bought it? Any insight on this issue would be a big help for me. The second concern is that I hear a whine coming from the t-case while in low. If I hold the trans in 1st gear, the whine is rather faint but if I keep it in drive and get up to 20 mph or so, it the sound is very apparent. What are your thoughts on this?

Thanks, in advance, for your continued instruction with my newb questions.

[carnuck]

How's the fluid level/condition? First thing I do is switch NP cases to synthetic oil.

[Lumpskie]

I'll check the fluid tomorrow... what oil do you use?

[carnuck]

Whichever is handy if no Amsoil is nearby,

[FSJ Guy]

All in all, it sounds pretty normal to me.

You will have to pull on the range lever (High-Low) A LOT harder than you would think. It's not like the gear shift on your steering column.

Generally, to shift in and out of low range, I like to shift into neutral and roll to stop by applying the brake. While KEEPING my foot on the brake, I'll THEN shift into Park. KEEP THAT FOOT ON THE BRAKE!! : D

NOW pull (or push) the range lever and shift the transfer case. Shift back into gear (drive, first, or whatever) and release the brake. Everything should go smoothly and you should not hear any gear grinding.

If you shift the range lever while in gear, you can get grinding noises if you don't shift fast enough. That's why I like to do the above technique. You can only shift on the fly from 2WD to 4WD. (mode change) You can't shift your range while moving. Well, you probably COULD, (remember, you can do most anything once! LOL!) but your t-case won't like you very much.

[Lumpskie]

^This is good for me to know. On my other trucks, the shifter mechanism is a lot different and I've created my own processes to make everything work as good as possible. I'm eager to try this process out and see if it helps! So... what about coasting to a stop and keeping your foot on the brake makes the difference, do you think?

[Cheap Hobby]

I am thinking (based on research in several vehicles) you make sure everything in the drive train has stopped moving and dose not have a load from stopping in mid rotation. Keeping your foot on the brake keeps the vehicle from rolling, or moving as you shift. Don't forget you are putting the drive train in neutral as you change from high to low and it is full don't want to roll down the hill brake. You should follow the exact same procedure for moving back to high range. You may even have to stop roll the stop again to get out of low.

As for 20mph in low that's about right give or take a few mph. That is why most organized runs require a working low range so you can stay off the brakes as much as possible.

[FSJ Guy]

Cheap Hobby nailed it. You want the drivetrain to have all the tension taken out of it. If you leave it in gear or even in Neutral, the transmission output is applying torque to the t-case input (Trying to move the truck. Yes, even in neutral the gears will spin a little bit) and when you shift into neutral, now it can spin freely. If you are really quick, you can keep shifting and catch the gears just right and prevent grinding. But I'm usually not that quick and I don't like grinding gears.

Putting it into Park with your foot on the brake makes sure that all driveline tension is relieved. If you let it roll against the parking pawl (in Park), now you've just added tension to the driveline.

[carnuck]

If the trans has a lot of miles or even been heated up a lot, the clutches can stay partially engaged and drag things around, putting pressure on the drivetrain. Almost like being in gear, yet not in drive. The 727 in my '84 J10 did that just before it died. I had to shut the truck off just to shift to low or high with my NP208.

[Lumpskie]

This is my first auto vehicle, so thanks for the explanation. I'm used to neutral being total disengagement. Hopefully, I'll get some time to play with the case today and see if the process makes it work better. Do you guys think that the case never being put into low range could, over the years, make it a little harder to shift? (I'm secretly hoping that working the system a little might smooth things out) And, to be sure, is this the oil that you guys run in your t-cases?

http://www.teamgrandwagoneer.com/amsoil ... 1974-1991/

Thanks again for all the help,

[FSJ Guy]

You would think that in Neutral, the output shaft wouldn't spin. But it does. Weird, I know.

The linkage might loosen up a bit after use, but you really do have to yank on the range lever to shift it. It seems almost like you're going to break something! LOL!

I'd just put regular Dexron ATF in there. I don't see a need for fancy (and $$$) synthetic stuff. Original spec was Dexron III or something like that. Most all Dexron made now is backwards compatible.

It's just a bunch of gears inside. Nothing super fancy like they have now. I have a 2008 VW VR6 motor and that thing has variable valve timing and all sorts of close tolerances, so I use synthetic in that, but the NP229 is far less sophisticated.

[wag4x6]

I have to stop in neutral, shift to reverse , to drive , then back to neutral. If that doesn't work then I turn the engine off and that will allow me to shift between low and high range every time.

[Stuka]

How's the fluid level/condition? First thing I do is switch NP cases to synthetic oil.

By oil you mean ATF right? Early to mid 80's ones did come with motor oil until New Process found out they ate bearings. So they were all switched to ATF, and there was a TSB for already sold ones to switch them to ATF.


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[carnuck]

That's correct. Synthetic ATF

[Lumpskie]

Just a quick update... I got a chance to take the waggy up some mild trails this weekend. I used the procedure you guys suggested and it shifted hi/low/hi absolutely perfectly! (I think getting the t-case warm helped a little too) Thanks for the help, guys.

[FSJ Guy]

Great news! Thanks for the update!

[Lumpskie]

Bumping my old thread here...

Just to be sure, do both the t-case and transmission just take regular dextron ATF? I'm planning to drain and refill both sometime here in the near future...

[RockRollin]

Dexron ll was OE, Dexron lll didn't come out till 92-93ish. Dexron is backwards compatible, and the D lll holds up better IMO.