Please help me - what's causing my drive shaft to make this noise shifting out of 4lo

[JMFK]

For what it’s worth years ago I put a Dana 300 transfer case into my CJ7 that I bought refurbished by a company called Novak. When they assembled it a brass bushing wasn’t properly installed which caused a lot of slop for which ever gear it was supposed to be on. I don’t recall exactly what shift pattern cause my sound but it was similar to the “ping” you heard. I’m guessing the gear was loose enough that when I shifted it didn’t slip into place nicely it more hammered into place. Your video kinda shows the same thing. The drive shaft has a quick rotation then rebounds with a ping. My issue was deeper than just the ping though because the bushing was just loose on the inside of the tcase and the grinding it caused was way worse than the ping. Hopefully the dealership will just replace the tcase for you and the problem goes away. Good luck.


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[tylerbrinks]

For what it’s worth years ago I put a Dana 300 transfer case into my CJ7 that I bought refurbished by a company called Novak. When they assembled it a brass bushing wasn’t properly installed which caused a lot of slop for which ever gear it was supposed to be on. I don’t recall exactly what shift pattern cause my sound but it was similar to the “ping” you heard. I’m guessing the gear was loose enough that when I shifted it didn’t slip into place nicely it more hammered into place. Your video kinda shows the same thing. The drive shaft has a quick rotation then rebounds with a ping. My issue was deeper than just the ping though because the bushing was just loose on the inside of the tcase and the grinding it caused was way worse than the ping. Hopefully the dealership will just replace the tcase for you and the problem goes away. Good luck.


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That makes sense. I don't know the internals of the nv241s very well - I was thinking maybe the shift fork or something that moves with enough velocity or stores up ample torque. I guess I'll leave it up to the dealer at this point because I'm not about to tear open a part under warranty

 

[wayoflife]

Hi Eddie! I've never tried shifting in our out of 4hi/lo with the engine off. I'm happy to give it a try and see, but it sounds entirely mechanical so I'd assume so. I'll give it a try when I run out for lunch in an hour.

Typically, you really need to be moving about 2-3 MPH when shifting in or out 4LO. Does it still make that sound when you do? When doing this with your engine off, you may find it necessary to push your Jeep a bit forward or back just a bit to get it to shift. You don't need your Jeep to be rolling, just enough movement to free things up.

 

[VeruGE*144]

Sounds like you are replicating the same ping with the shaft disconnected form the tcase. Just not as intense. I would suggest you inspect the shaft more closely as suggested by WJCO before jumping into conclusions. Most of the tcases are a bitch to shift sometimes, including mine.

 

[tylerbrinks]

Sounds like you are replicating the same ping with the shaft disconnected form the tcase. Just not as intense. I would suggest you inspect the shaft more closely as suggested by WJCO before jumping into conclusions. Most of the tcases are a bitch to shift sometimes, including mine.

When the shaft is disconnected I can get it to make noise, sure, but it's a hollow piece of metal. It's basically ringing a bell, so I'm not sure that confirms anything. I'm still hunting what would cause the impact or vibration. Rear drive shafts are so long, any noise or vibration is going to tend to be exaggerated there more than elsewhere from what I've heard. I'm tending to agree that the way the t-case is jerking one direction and then the other isn't a good sign. Hopefully when it's on the lift next week I can have the shaft looked at while the dealer confirms the t-case is or is not in good order. I had the local fabricator inspect the shaft this morning even though it was on the vehicle. They seemed to think it was in good shape as best they could tell without unbolting it... :hmm:

 

[tylerbrinks]

Typically, you really need to be moving about 2-3 MPH when shifting in or out 4LO. Does it still make that sound when you do? When doing this with your engine off, you may find it necessary to push your Jeep a bit forward or back just a bit to get it to shift. You don't need your Jeep to be rolling, just enough movement to free things up.

You might be on to something, so here's the facts and new discoveries.

1. I was not able to reproduce the sound when shifting (eithe direction) with the car turned off. Now, part of that may be due to the fact that a few times I simply couldn't get it into 4hi from 4lo - it just got stuck in neutral. Nonetheless, car off did not cause the issue.

2. With the car turned on it happens almost every attempt. Not every time - on rare occasion it's smooth as butter, maybe 1 out of 8 tries. The rest of the time it causes the issue.

3. At one point I got stuck in neutral trying to get to 4hi. Years ago I come across that old Teraflex where Dennis shows a few 'tips' for encouraging a difficult shifter. So, since I was stuck in N, I was going to toggle the tranny into R and D a couple times to get the gears spinning. Mind you, the tranny and t-case were both in neutral at this point. To my surprise, when I dropped into drive the Jeep rolled forward. T-Case was in the neutral position physically and all dash lights off, but somehow the 4lo was still engaged. That one has me scratching my head but it sure feels like something just isn't quite right down there.

4. I never have trouble getting into our out of 4lo. I never have trouble from 2hi to 4hi (obviously synced). The only trouble and the only cause of the noise is from 4lo (or neutral) to 4hi.

As a postscript, even in 2hi I get the noise to happen when I shift from P to R if I've parked on an incline and get the parking pawl to engage when the car rolls and adds a bit of torque.

Again, in case you suspect anything in particular, so far it's only happened with the car running.

 

[tylerbrinks]

Typically, you really need to be moving about 2-3 MPH when shifting in or out 4LO. Does it still make that sound when you do? When doing this with your engine off, you may find it necessary to push your Jeep a bit forward or back just a bit to get it to shift. You don't need your Jeep to be rolling, just enough movement to free things up.

Did some light wheeling over the weekend, and the T-Case kept popping out of 4hi back to 2wd on the first part of the trial. She needs some attention for sure. Took the Jeep to the dealer this morning. They're saying I may have to purchase Mopar drive shafts and have them replace my CV shafts in order for them to confirm if it's the t-case or transmission under warranty. That seems sketchy to me, but I suppose it could be part of the cost of ownership :doh:... Worse yet, they only have one transmission tech, and he's newer. Good thing I'm traveling for the next couple weeks because they need the car at least that long.

 

[tylerbrinks]

Did some light wheeling over the weekend, and the T-Case kept popping out of 4hi back to 2wd on the first part of the trial. She needs some attention for sure. Took the Jeep to the dealer this morning. They're saying I may have to purchase Mopar drive shafts and have them replace my CV shafts in order for them to confirm if it's the t-case or transmission under warranty. That seems sketchy to me, but I suppose it could be part of the cost of ownership :doh:... Worse yet, they only have one transmission tech, and he's newer. Good thing I'm traveling for the next couple weeks because they need the car at least that long.

My real concern is, if they want to put factory shafts back on, how much more the rear pinion's crush sleeve can take. I doubt it has a factory swap and another CV install without needing a new sleeve. I'm sure they're happy to charge for labor and parts for that too...:naw:

 

[tylerbrinks]

Well - at least at the moment the 'official' answer is one I didn't expect. On top of replacing the u-joints I took my JK to two different dealerships, one of which has a 20 year transmission veteran. It's under warranty, so a free opinion can't hurt.

The prevailing opinion is that the noise is totally normal for a CV shaft and, and simply a result of the torque built up in the drive line. There's still no explanation as to why. Loose non-threaded yoke at the t-case, contact with the centering yoke and the ears, who knows. Good news is the transmission and t-case have been verified in good order. So, unless anyone else has creative ideas, I sound like Sugar Ray going in for a knockout round every time I go wheeling.

 

[WJCO]

Well - at least at the moment the 'official' answer is one I didn't expect. On top of replacing the u-joints I took my JK to two different dealerships, one of which has a 20 year transmission veteran. It's under warranty, so a free opinion can't hurt.

The prevailing opinion is that the noise is totally normal for a CV shaft and, and simply a result of the torque built up in the drive line. There's still no explanation as to why. Loose non-threaded yoke at the t-case, contact with the centering yoke and the ears, who knows. Good news is the transmission and t-case have been verified in good order. So, unless anyone else has creative ideas, I sound like Sugar Ray going in for a knockout round every time I go wheeling.

It's easy for a dealer to give out the phrase "normal" like Halloween candy. I don't recall ever hearing a noise like that on any JK or any other vehicle for that matter.

There is a tool out there called "chassis ears." It has a receiver that goes next to the driver. Then there are several microphone transmitters that are installed on various parts of the vehicle and they have numbers on them. The receiver can select each number individually. So when the noise occurs, the receiver will pick it up on channel 4 for example. Wherever you installed transmitter 4, that's the area that the noise is coming from.

 

[nbunga]

Well - at least at the moment the 'official' answer is one I didn't expect. On top of replacing the u-joints I took my JK to two different dealerships, one of which has a 20 year transmission veteran. It's under warranty, so a free opinion can't hurt.

The prevailing opinion is that the noise is totally normal for a CV shaft and, and simply a result of the torque built up in the drive line. There's still no explanation as to why. Loose non-threaded yoke at the t-case, contact with the centering yoke and the ears, who knows. Good news is the transmission and t-case have been verified in good order. So, unless anyone else has creative ideas, I sound like Sugar Ray going in for a knockout round every time I go wheeling.

Did they address the issue of the transfer case popping out of gear?

 

[VeruGE*144]

My tcase likes to be a pain to engage into 4lo sometimes as well. Usually I do it while standing still and not even rolling, put the trans on neutral, use the tcase lever to shift into 4lo, then I keep a little pressure on the lever at 4lo position and use my other hand to pop the trans back into drive. Works like a charm.
As far as the noise you are having, it is strange for sure. Maybe look for some take-of factory shafts at a good price, put them on and have the dealer look at it.

 

[Arrcherr]

My tcase likes to be a pain to engage into 4lo sometimes as well. Usually I do it while standing still and not even rolling, put the trans on neutral, use the tcase lever to shift into 4lo, then I keep a little pressure on the lever at 4lo position and use my other hand to pop the trans back into drive. Works like a charm.
As far as the noise you are having, it is strange for sure. Maybe look for some take-of factory shafts at a good price, put them on and have the dealer look at it.

My tcase can be a PITA to get into 4lo as well. I started doing this after Matt suggested it and it works like a charm

 

[tylerbrinks]

My tcase likes to be a pain to engage into 4lo sometimes as well. Usually I do it while standing still and not even rolling, put the trans on neutral, use the tcase lever to shift into 4lo, then I keep a little pressure on the lever at 4lo position and use my other hand to pop the trans back into drive. Works like a charm.
As far as the noise you are having, it is strange for sure. Maybe look for some take-of factory shafts at a good price, put them on and have the dealer look at it.

My only issue with replacing the CVs with factory shafts is that with the after market shaft installation I've already applied proper torque to the rear pinion's crush sleeve to get it back to about 10 inch pounds to turn the rear axle shafts. Going back to Mopar shafts and then a 4th time if I reinstall my CVs is likely going to end up crushing it beyond a usable limit and I'll end up burning up the bearing.

Their recommendation was to put the car in neutral, engage the parking brake, and then park to keep torque off the drive line. Short of WJCO's method of audibly inspecting the internals, I'm not sure what options are viable at this point. Good news is the transmission and t-case keep their warranty even with the after market shafts. Worst case scenario is something breaks and I get a new setup :rolleyes2:

 

[tylerbrinks]

It's easy for a dealer to give out the phrase "normal" like Halloween candy. I don't recall ever hearing a noise like that on any JK or any other vehicle for that matter.

There is a tool out there called "chassis ears." It has a receiver that goes next to the driver. Then there are several microphone transmitters that are installed on various parts of the vehicle and they have numbers on them. The receiver can select each number individually. So when the noise occurs, the receiver will pick it up on channel 4 for example. Wherever you installed transmitter 4, that's the area that the noise is coming from.

That's a great idea. I'm going to see if anyone in one of the local Jeep clubs has one I can borrow. At least then I could eliminate the transmission or t-case as the source of the issue. I might even try it with the drive shaft off and see if/how that changes any noises picked up. I took the drive shaft off entirely yesterday and gave the centering yoke a once over (visually it looked off) and installed a new u-joint up front but nothing changed. I think I may remove it again and leave it with the local fabricator while I travel next week. The part of the whole puzzle is why the drive shaft is making noise in the first place. There has to be impact or metal to metal somewhere. The shaft also has a warranty, so I might as well exercise it and eliminate that as a possibility.

 

[WJCO]

That's a great idea. I'm going to see if anyone in one of the local Jeep clubs has one I can borrow. At least then I could eliminate the transmission or t-case as the source of the issue. I might even try it with the drive shaft off and see if/how that changes any noises picked up. I took the drive shaft off entirely yesterday and gave the centering yoke a once over (visually it looked off) and installed a new u-joint up front but nothing changed. I think I may remove it again and leave it with the local fabricator while I travel next week. The part of the whole puzzle is why the drive shaft is making noise in the first place. There has to be impact or metal to metal somewhere. The shaft also has a warranty, so I might as well exercise it and eliminate that as a possibility.

I just realized your in Colorado. I have the tool. I'm just north of Denver. Send me a PM if you're close. I can't let you borrow it, but I'd be happy to help out and set it up with you if I can.

 

[tylerbrinks]

For those following along, I took the drive shaft off entirely and had the fabricator inspect it. They added a bit of weight to rebalance it, but otherwise confirmed it's in good shape. I'll reinstall the drive shaft and keep working on the troubleshooting process. For now here's what is known:

1. Two different dealerships indicate the transmission and t-case are operating normally (take that for what it's worth).
2. All the u-joints are in good shape. They're all the Spicer Life variety so no grease is needed. No play in them at all, and only 3000 miles on them.
3. The transfer case yoke doesn't seem to have loosened at all (red thread lock). It's still torqued to about 160 ft/lbs.
4. The pinion yoke appears to be torqued properly and still takes about 10 inch/lbs to rotate the axle shafts (preload). Preload was 5 inch/lbs before the after market shafts went on, and the new yoke was torqued until it took 10 inch/lbs which is in line with adding 5 inch/lbs to get the crush sleeve back to spec. That happened at 160 ft/lbs which just happens to be what everyone recommends as a default torque.

The reason I mention the rear pinion yoke is that it's the source of my next theory. My thought is there could be too much backlash or pinion depth in the rear pinion & ring gear after installing an after market yoke. I'm thinking too much backlash/depth might cause metal to metal contact when the drive shaft (and thereby pinion) rapidly changes direction. We know that's when the noise occurs, and since the pinion is directly connected to the drive shaft (at least via the yoke) it seems like it's worth considering. The problem with that theory is the sound is easier to reproduce closer to the t-case, not the rear diff. The sound/impact would have to travel through the slip and up the stub shaft. It's no smoking gun, but at least something to try to measure. Trouble is I have no idea if i can test backlash without getting into the diff, nor do I have the tools to do so. Even if I did, I'm guessing I'd need a master install kit to do it correctly, and at that point I might as well regear

 

[WJCO]

Trouble is I have no idea if i can test backlash without getting into the diff, nor do I have the tools to do so. Even if I did, I'm guessing I'd need a master install kit to do it correctly, and at that point I might as well regear

You can check backlash with a dial indicator if you pull the cover off.

As far as pinion depth, even if the crush sleeve moved a little during yoke replacement, as long as it's tight now with no play, the depth should be the same as it is set with a shim. The crush sleeve is there to properly preload the bearings.

Regardless, I've seen some fucked up out of spec diffs and still haven't heard that noise you're hearing. Anything's possible but usually if something is out of spec in the diff, you'll have way crazier noises than that.

 

[tylerbrinks]

Quick update for those following along or having a similar issue.

I'm traveling this week which means my JK is sitting in the garage not being worked on. In the meantime, I got the drive shaft back from the fabricator. He added a bit of weight, but otherwise gave it a clean bill of health. It would seem the shaft announces the issue, but isn't the likely source of the problem.

Since I've been sitting in a hotel room with little to do, I've changed the search terms I'm using. Specifically, if I broaden the search to all vehicles instead of just Jeeps, I actually get results. It turns out other 4x4 vehicles like FJs, Tacomas, trucks, and even a few AWD vehicles have a similar issue. The 2 common causes seem to be u-joints (which I'm assuming are good) and parking pawls. Since the issue happens most often on an incline going from park to reverse, that puts the parking pawl or parking gear at the top of my list. Unfortunately I can't do anything about the possibility for at least another week, but at least I have a direction to continue research while I'm stuck in a hotel room. For those interested, here's a few (seemingly) related ideas:

If you've never seen how a parking pawl/gear work for an automatic
Similar issue from a Mustang
The only relevant Wrangler post I've found
Exploring the backlash idea further

 

[WJCO]

Quick update for those following along or having a similar issue. The 2 common causes seem to be u-joints (which I'm assuming are good) and parking pawls. Since the issue happens most often on an incline going from park to reverse, that puts the parking pawl or parking gear at the top of my list.

I could definitely see a parking pawl making a noise like that.