NP231 not working in 2wd

cjs_tj

cjs_tj

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Joined
Oct 3, 2021
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8
Location
Long Island, NY
Hi all. I've read around the forums and most people have it the other way around — in my case, the 4wd hi and lo both work great, but 2wd hi isn't working at all.

I bought the jeep, 2wd worked on the test drive with the clutch feeling like it was about 95% of the way out (or maybe I am imagining this).
Trailered it about 100 miles with the front tires on a dolly and the rear on the road. When trying to move it off the dolly, 2wd wouldn't work. 4 lo/hi work, neutral works, and I was able to get it off just fine in 4 lo, with about 70% of the clutch depressed.

In neutral transmission and 2wd, the front drive shaft spins. Same in 1st gear, except it moves freely.
In neutral transmission and 4lo/hi, front and rear drive shafts spin. Same in 1st except it tries moving the wheels.
In neutral/neutral, front drive shaft spins.

In 2wd, release clutch, I hear a low tapping noise. The noise isn't there in neutral tc + 1st trans.

I have the stock linkage. The previous owner added a metal plate to accommodate the 5" lift. I've heard about the novak / savvy cable shifter mods, but I don't know if it will fix my issue. I can feel, see, and hear the transfer case linkage going into 4 hi, lo, neutral, and 2wd. I don't really have a problem with the linkage on this jeep and don't want to throw $200 at something without being sure it's the issue

Any ideas where to look around?
Thanks!

2000 Jeep Wrangler SE 4-cylinder 5-speed manual, ~4" lift + 1" body lift, NP231 Transfer Case, AS72 Transmission

20211005_111408.jpg
 
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When you towed it with the rear wheels on the ground, what position was the transfer case and transmission in?
 
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The transfer case is supposed to be in neutral, but the transmission needs to be in gear.

Per the manual:
https://wranglertjforum.com/threads/how-to-properly-tow-your-jeep-wrangler-tj.2479/post-29844
  1. Depress the brake pedal
  2. Depress the clutch pedal
  3. Shift the transfer case into N (Neutral)
  4. Start engine
  5. Place manual transmission into gear (second or third gear are the most popular. Don’t make the mistake of putting it into Neutral as this will prevent the transmission from being lubricated and it will burn up while being towed.) For automatics, place the transmission into park (P).
  6. Release brake pedal to ensure no movement
  7. Shut engine off and place the ignition key into the unlocked OFF position (this allows the steering wheel to turn while being towed).
  8. Apply parking brake
  9. Attach Jeep to tow vehicle
  10. Release parking brake
 
Irun said:
The transfer case is supposed to be in neutral, but the transmission needs to be in gear.

Per the manual:
https://wranglertjforum.com/threads/how-to-properly-tow-your-jeep-wrangler-tj.2479/post-29844
  1. Depress the brake pedal
  2. Depress the clutch pedal
  3. Shift the transfer case into N (Neutral)
  4. Start engine
  5. Place manual transmission into gear (second or third gear are the most popular. Don’t make the mistake of putting it into Neutral as this will prevent the transmission from being lubricated and it will burn up while being towed.) For automatics, place the transmission into park (P).
  6. Release brake pedal to ensure no movement
  7. Shut engine off and place the ignition key into the unlocked OFF position (this allows the steering wheel to turn while being towed).
  8. Apply parking brake
  9. Attach Jeep to tow vehicle
  10. Release parking brake
Click to expand...

Ouch... Thanks for the tip. Forgive my newness, but if the transmission got burnt out, wouldn't that mean 1st gear in 4wd shouldn't work either?
 
So you test drove it fine in 2wd, put it in N to tow it on the dolly, and now 2wd doesn’t work? Are you 100% sure it’s engaged in 2wd all the way? If it was a trans or clutch issue, you wouldn’t have 4hi or 4lo

Sounds like with the lift, the linkage is potentially binding and not fully engaging in 2wd, leaving you between selections. I’d check the linkage from underneath while some cycles it, and make sure the handle isn’t hitting anything (the trim/center console). I had this issue when I did a Tummy Tuck (I also had a different handle).

As a side note, the savvy cable shifter is worth EVERY penny. Shifts like butter!

C2F735FC-1C21-44D8-9DDA-F8354694FC5B.jpeg
 
cjs_tj said:
Ouch... Thanks for the tip. Forgive my newness, but if the transmission got burnt out, wouldn't that mean 1st gear in 4wd shouldn't work either?
Click to expand...
You can always unhook the linkage then shift it by hand underneath the jeep and see what works. Probably a linkage issue.
 
cjs_tj said:
Ouch... Thanks for the tip. Forgive my newness, but if the transmission got burnt out, wouldn't that mean 1st gear in 4wd shouldn't work either?
Click to expand...
Your comment about verifying the driveshaft wasn't spinning would negate any damage. Unless a driveshaft spins, I'm not sure how any damage could occur. Like @CAJACK said, I'd start by verifying the linkage.
 
Linkage is separated, but I absolutely cannot move the piece on the transfer case. I tried using a pipe for leverage, and still not budging.. Any ideas?
 
Jeep_guy3 said:
So you test drove it fine in 2wd, put it in N to tow it on the dolly, and now 2wd doesn’t work? Are you 100% sure it’s engaged in 2wd all the way? If it was a trans or clutch issue, you wouldn’t have 4hi or 4lo

Sounds like with the lift, the linkage is potentially binding and not fully engaging in 2wd, leaving you between selections. I’d check the linkage from underneath while some cycles it, and make sure the handle isn’t hitting anything (the trim/center console). I had this issue when I did a Tummy Tuck (I also had a different handle).

As a side note, the savvy cable shifter is worth EVERY penny. Shifts like butter!

View attachment 281978
Click to expand...

It really doesn't work that way based on the way the mode and range forks engage the sector plate inside the case. The rear output shaft doesn't disengage from the input shaft until you get to the range fork, which is on the opposite side of the 4hi position.

I'm not really following the OPs descriptions of driveshafts "spinning". Are you saying they spin when the engine spins them, or that you can grab them (with the tires off the ground) and spin them by hand (which would indicate they are not mechanically engaged inside the transfer case? They are both always engaged and driven by the axles when the vehicle is in motion.
 
freedom_in_4low said:
It really doesn't work that way based on the way the mode and range forks engage the sector plate inside the case. The rear output shaft doesn't disengage from the input shaft until you get to the range fork, which is on the opposite side of the 4hi position.

I'm not really following the OPs descriptions of driveshafts "spinning". Are you saying they spin when the engine spins them, or that you can grab them (with the tires off the ground) and spin them by hand (which would indicate they are not mechanically engaged inside the transfer case? They are both always engaged and driven by the axles when the vehicle is in motion.
Click to expand...
They spin with the jeep in neutral with the tires on the ground
 
Ok, the transfer case is fine. It's the rear axle....

That tapping noise I hear is the rear driveshaft spinning, but the tires going nowhere

Gonna pull apart the rear differential this weekend and see what's going on.
 
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when I bought a TJ with a junk rear axle I took it as the perfect opportunity for a Dana 44 upgrade. The axle swap cost less than half what new gears would have. I put in stock with 3.73 gears that matched my front axle, have been upgrading it ever since (now has 4.88 and an E-locker) and is now under my LJ, the third Jeep it's been in.
 
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