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

I reinstalled the drive shaft in between trips and only had time to drive around the block, so we'll have see how things shape up once I have a chance to give it a proper test run. The drive shaft was in great shape after it's checkup with the fabricator ("was" being the key word). He added just a bit of weight to the slip side. Hopefully I'll be able to continue to narrow down the noise source next week.

I made the bonehead mistake of trying to reinstall the shaft without lifting the rear end or connecting both ends of the shaft. I put the Jeep in neutral having only 2 of the 4 t-case yoke bolts secured to rotate the DS. There was enough fluid movement in the transmission that it spun the drive line with the shaft at full droop (CV side by the t-case) and thrashed the slip end on my garage floor. Despite my lapse in attention, the drive shaft reinstalled okay, and the joints still seemed okay. But now from time to time there's an audible "clunk" when starting from a dead stop (or accelerating?). So it ought to be fun to troubleshoot multiple issues at once. I may just swap out all the u-joints as a precaution and inspect the H-yoke and centering yoke/pin to make sure I didn't damage anything in the process. Like I said, the shaft was in good shape. It's pretty stout, so it's probably fine, but I certainly didn't help my process of making things better.

As a side note, if anyone knows the right thread size for double cardan yoke bolts, I probably need to pick up 4 new bolts. I've taken the DS off and on so many times the edges are starting to round out. That'd be a bad day when I couldn't remove the bolts... Seems like I recall 5/16 x 24 is correct. I really just need to take one to the hardware store, but maybe y'all can save me the pain of removing it yet again.
 
More drive shaft investigation

-== Another update for anyone reading along or dealing with something similar ==-

The noise has been consistent with more than just shifting out of 4lo. It's basically any time there is torque in the drive line that changes direction. Specifically, almost any time going from Park to Reverse (sometimes even Drive to Reverse) causes it. The more torque (e.g. the pawl engaging and then releasing), the more noise (torque) there is.

I'm back to suspecting the drive shaft is the culprit. Why? Two reasons. First, I disassembled and rebuilt the whole shaft from yoke to yoke and that made no difference whatsoever. More on that later. Second, and more importantly, I just happened to be pop into my local 4x4 shop. They're like a candy store, only with really, really expensive candy. I was shopping for a new fire extinguisher mount and I figured I'd ask they guys there if they've ever heard of something similar. The shop's tech lead overheard and asked if he could take a look. Next thing you know, my JK is on the lift and a 4 techs all looking at the funny sounding drive shaft :clap2:

They concluded the transmission and t-case are fine. They think the issue is the drive shaft is made with tubing that is too thin-walled. I don't doubt that at all because I got both shafts for "free." They were fabricated by a local drive shaft fabricator (a reputable one) in trade for services. Being that we traded services instead of paying cash, and that he turned them around in 48 hours, it wouldn't surprise me if the body was made with materials he had around his shop. The workmanship is fine, but compared to a couple same-sized shafts on some of the other rigs at the 4x4 shop, the body is just a little less stout in their thickness. The tech are guessing that the body just thin enough to resonate with any rapid change in direction. Maybe it's the bolts making contact with t-case yoke, maybe it's a small tolerance between a u-joint and the housing, maybe it's the centering stud against the centering yoke. Who knows... but it seems to make sense.

They had a decent, short-term fix too. They zip tied foam tape around the middle of the shaft and it's mostly silent as a result. So far no wobbles either, at least up to 55 mph.

Like I said, before my field trip to the 4x4 shop, I decided to rebuild the whole drive shaft to check a few items off my list.

  1. It wasn't u-joints. I replaced all 3 and nothing changed.
  2. The stud, H-yoke and centering yoke, are all in good shape https://imgur.com/a/r0ehhje
  3. The pinion yoke is nice and tight - no up/down or left/right movement
  4. The pinion preload is about 17 inch/lbs seems fine https://streamable.com/g7bvd
  5. The t-case lash is normal (from a poor man's view) https://streamable.com/i82xc
  6. The diff/pinion lash is normal (a poor man's view) https://streamable.com/n9e0p

In other words, I think my problem can be narrowed to having a lemon of a drive shaft. But if a $0.15 piece of foam and a zip tie quiet things down... then maybe I just call it a Jeep thing and drive happy :naw:
 
Wow, good tho hear you got it figured out. Depending on tire size you run, the shaft being so thin might shear off and wrap within itself under heavy load/torque.
I am not saying it’ll happen but, I’ll be cautious on the trail for sure. Kind of like this stock one
IMG_7078.JPG
 
tylerbrinks said:
-== Another update for anyone reading along or dealing with something similar ==-

The noise has been consistent with more than just shifting out of 4lo. It's basically any time there is torque in the drive line that changes direction. Specifically, almost any time going from Park to Reverse (sometimes even Drive to Reverse) causes it. The more torque (e.g. the pawl engaging and then releasing), the more noise (torque) there is.

I'm back to suspecting the drive shaft is the culprit. Why? Two reasons. First, I disassembled and rebuilt the whole shaft from yoke to yoke and that made no difference whatsoever. More on that later. Second, and more importantly, I just happened to be pop into my local 4x4 shop. They're like a candy store, only with really, really expensive candy. I was shopping for a new fire extinguisher mount and I figured I'd ask they guys there if they've ever heard of something similar. The shop's tech lead overheard and asked if he could take a look. Next thing you know, my JK is on the lift and a 4 techs all looking at the funny sounding drive shaft :clap2:

They concluded the transmission and t-case are fine. They think the issue is the drive shaft is made with tubing that is too thin-walled. I don't doubt that at all because I got both shafts for "free." They were fabricated by a local drive shaft fabricator (a reputable one) in trade for services. Being that we traded services instead of paying cash, and that he turned them around in 48 hours, it wouldn't surprise me if the body was made with materials he had around his shop. The workmanship is fine, but compared to a couple same-sized shafts on some of the other rigs at the 4x4 shop, the body is just a little less stout in their thickness. The tech are guessing that the body just thin enough to resonate with any rapid change in direction. Maybe it's the bolts making contact with t-case yoke, maybe it's a small tolerance between a u-joint and the housing, maybe it's the centering stud against the centering yoke. Who knows... but it seems to make sense.

They had a decent, short-term fix too. They zip tied foam tape around the middle of the shaft and it's mostly silent as a result. So far no wobbles either, at least up to 55 mph.

Like I said, before my field trip to the 4x4 shop, I decided to rebuild the whole drive shaft to check a few items off my list.

  1. It wasn't u-joints. I replaced all 3 and nothing changed.
  2. The stud, H-yoke and centering yoke, are all in good shape https://imgur.com/a/r0ehhje
  3. The pinion yoke is nice and tight - no up/down or left/right movement
  4. The pinion preload is about 17 inch/lbs seems fine https://streamable.com/g7bvd
  5. The t-case lash is normal (from a poor man's view) https://streamable.com/i82xc
  6. The diff/pinion lash is normal (a poor man's view) https://streamable.com/n9e0p

In other words, I think my problem can be narrowed to having a lemon of a drive shaft. But if a $0.15 piece of foam and a zip tie quiet things down... then maybe I just call it a Jeep thing and drive happy :naw:
Click to expand...

While reading before I got to the foam I was going to suggest wrapping it really tight with some kind of tape to see if that changed anything


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VeruGE*144 said:
Wow, good tho hear you got it figured out. Depending on tire size you run, the shaft being so thin might shear off and wrap within itself under heavy load/torque.
I am not saying it’ll happen but, I’ll be cautious on the trail for sure. Kind of like this stock one
View attachment 306616
Click to expand...

35s at the moment. I'll replace the DS if I ever move up to 37s anyway, but I've got a couple more upgrades before I can make that jump (regear + big bore). Let's hope what I have isn't as malleable as the stock shafts.
 
tylerbrinks said:
-== Another update for anyone reading along or dealing with something similar ==-

The noise has been consistent with more than just shifting out of 4lo. It's basically any time there is torque in the drive line that changes direction. Specifically, almost any time going from Park to Reverse (sometimes even Drive to Reverse) causes it. The more torque (e.g. the pawl engaging and then releasing), the more noise (torque) there is.

I'm back to suspecting the drive shaft is the culprit. Why? Two reasons. First, I disassembled and rebuilt the whole shaft from yoke to yoke and that made no difference whatsoever. More on that later. Second, and more importantly, I just happened to be pop into my local 4x4 shop. They're like a candy store, only with really, really expensive candy. I was shopping for a new fire extinguisher mount and I figured I'd ask they guys there if they've ever heard of something similar. The shop's tech lead overheard and asked if he could take a look. Next thing you know, my JK is on the lift and a 4 techs all looking at the funny sounding drive shaft :clap2:

They concluded the transmission and t-case are fine. They think the issue is the drive shaft is made with tubing that is too thin-walled. I don't doubt that at all because I got both shafts for "free." They were fabricated by a local drive shaft fabricator (a reputable one) in trade for services. Being that we traded services instead of paying cash, and that he turned them around in 48 hours, it wouldn't surprise me if the body was made with materials he had around his shop. The workmanship is fine, but compared to a couple same-sized shafts on some of the other rigs at the 4x4 shop, the body is just a little less stout in their thickness. The tech are guessing that the body just thin enough to resonate with any rapid change in direction. Maybe it's the bolts making contact with t-case yoke, maybe it's a small tolerance between a u-joint and the housing, maybe it's the centering stud against the centering yoke. Who knows... but it seems to make sense.

They had a decent, short-term fix too. They zip tied foam tape around the middle of the shaft and it's mostly silent as a result. So far no wobbles either, at least up to 55 mph.

Like I said, before my field trip to the 4x4 shop, I decided to rebuild the whole drive shaft to check a few items off my list.

  1. It wasn't u-joints. I replaced all 3 and nothing changed.
  2. The stud, H-yoke and centering yoke, are all in good shape https://imgur.com/a/r0ehhje
  3. The pinion yoke is nice and tight - no up/down or left/right movement
  4. The pinion preload is about 17 inch/lbs seems fine https://streamable.com/g7bvd
  5. The t-case lash is normal (from a poor man's view) https://streamable.com/i82xc
  6. The diff/pinion lash is normal (a poor man's view) https://streamable.com/n9e0p

In other words, I think my problem can be narrowed to having a lemon of a drive shaft. But if a $0.15 piece of foam and a zip tie quiet things down... then maybe I just call it a Jeep thing and drive happy :naw:
Click to expand...

That's awesome you got it fixed, or at least isolated.
 
WJCO said:
That's awesome you got it fixed, or at least isolated.
Click to expand...

I think so. I only drove from their shop back to my place due to rain (top & doors off...). I need to take it for a few test drives, but I think I'm on the right track. I might just head over to Front Range Driveline and see if they have some kind of permanent version of the fix like an isolator I could weld on. Or a new drive shaft altogether :thumb:
 
Good news is that after many days of driving, my drive shaft is silent! I'm declaring victory over that battle, but I haven't won the war. My temporary fix is working fine, but I still want a professional opinion as to whether there could be an underlying problem or possibility of destroying it with too much torque as VeruGE*144 pointed out. I took my Jeep to one of the best drive line fabricators in town yesterday. It didn't even take him 15 seconds before he said the drive shaft is too short. Next week he's going to cut it open and lengthen it to the correct length after I re-measure from the correct u-joint centers.

I did re-center my rear wheels in the wells and set my pinion angle when I installed the shaft originally, so the axle did move back 3/4 inch. But the guy who built the shaft knew exactly how far back I was going to move the axle and accounted for that, or so I was told. Oddly, even without moving the axle it was still a bit too short, so somehow the original measurements didn't do me any favors.

As for the ringing, this new fabricator is going to insert cardboard as a dampener while he has the tube cut open . I knew I'd heard about that before while researching my issue. Apparently that's a thing... (Google it for several examples)

On the home stretch for sure.
 
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tylerbrinks said:
Good news is that after many days of driving, my drive shaft is silent! I'm declaring victory over that battle, but I haven't won the war. My temporary fix is working fine, but I still want a professional opinion as to whether there could be an underlying problem or possibility of destroying it with too much torque as VeruGE*144 pointed out. I took my Jeep to one of the best drive line fabricators in town yesterday. It didn't even take him 15 seconds before he said the drive shaft is too short. Next week he's going to cut it open and lengthen it to the correct length after I re-measure from the correct u-joint centers.

I did re-center my rear wheels in the wells and set my pinion angle when I installed the shaft originally, so the axle did move back 3/4 inch. But the guy who built the shaft knew exactly how far back I was going to move the axle and accounted for that, or so I was told. Oddly, even without moving the axle it was still a bit too short, so somehow the original measurements didn't do me any favors.

As for the ringing, this new fabricator is going to insert cardboard as a dampener while he has the tube cut open . I knew I'd heard about that before while researching my issue. Apparently that's a thing...

On the home stretch for sure.
Click to expand...
If you think it's the drive shaft itself see if you can find someone with the same times and swap theirs in. I have a 1310 rear trail spare that I'd let you try out if you lived close.

Sent from my 2PYB2 using WAYALIFE mobile app
 
Last edited by a moderator:
tylerbrinks said:
Good news is that after many days of driving, my drive shaft is silent! I'm declaring victory over that battle, but I haven't won the war. My temporary fix is working fine, but I still want a professional opinion as to whether there could be an underlying problem or possibility of destroying it with too much torque as VeruGE*144 pointed out. I took my Jeep to one of the best drive line fabricators in town yesterday. It didn't even take him 15 seconds before he said the drive shaft is too short. Next week he's going to cut it open and lengthen it to the correct length after I re-measure from the correct u-joint centers.

I did re-center my rear wheels in the wells and set my pinion angle when I installed the shaft originally, so the axle did move back 3/4 inch. But the guy who built the shaft knew exactly how far back I was going to move the axle and accounted for that, or so I was told. Oddly, even without moving the axle it was still a bit too short, so somehow the original measurements didn't do me any favors.

As for the ringing, this new fabricator is going to insert cardboard as a dampener while he has the tube cut open . I knew I'd heard about that before while researching my issue. Apparently that's a thing... ***link removed***

On the home stretch for sure.
Click to expand...

Glad everything is getting sorted. Please, as forum rules state, do not direct members to competing forums.

https://wayalife.com/faq.php?faq=wayaliferules

Sent from my iPhone using WAYALIFE mobile app
 
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tylerbrinks said:
They had a decent, short-term fix too. They zip tied foam tape around the middle of the shaft and it's mostly silent as a result. So far no wobbles either, at least up to 55 mph.
Click to expand...

Well that is interesting for sure. :hmm:

Glad you found it though! :beer: IF its a 1310, I wouldnt really worry about the thickness of the tube, its loaded in shear
anyway, unless you pin it up against a rock or something. if its a 1350, I would have your driveline guys just retube it, it should only cost $100 or so, and will hopefully be right this time around. :twocents:
 
jesse3638 said:
If you think it's the drive shaft itself see if you can find someone with the same times and swap theirs in. I have a 1310 rear trail spare that I'd let you try out if you lived close.

Sent from my 2PYB2 using WAYALIFE mobile app
Click to expand...

Unfortunately that's unlikely in my case. My drive shaft was custom built with 1310s at the t-case and 1350 at the pinion. It'll be hard to fine anyone with that setup.
 
DWiggles said:
Well that is interesting for sure. :hmm:

Glad you found it though! :beer: IF its a 1310, I wouldnt really worry about the thickness of the tube, its loaded in shear
anyway, unless you pin it up against a rock or something. if its a 1350, I would have your driveline guys just retube it, it should only cost $100 or so, and will hopefully be right this time around. :twocents:
Click to expand...

It's a hybrid. 1310s at the H-yoke and a 1350 at the pinion flange.
 
jesse3638 said:
Why did you have it built this way?

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Click to expand...

BaddestCross said:
That's a first. Why?

--
Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407
Click to expand...


A few reasons, really. I'm slowly building my rig to (properly) support 37s. I still have the option to go entirely 1350s, but for now I want to keep the short circuit at the drive shaft. It costs a whole lot less to replace a u-joint than anything along the rest of the train. I run chromoly shafts front and rear, and they're super stout. They're certainly not the weak link. Eventually I'll regear which can introduce another weak link at the pinion/ring gear. Having a pair of 1310s is an easy insurance policy.

So why not just go all 1310s? Good question. If/when I do decide to make the jump to all 1350s, with my setup I can do so without touching the pinion yoke. Crush sleeves can only be re-crushed so many times, and I'm already set for a 1350 at the differential. I'll never have to count exposed threads, reset bearing preload, or worry about reusing a deformed pinion nut (they come pre-crushed and aren't great to reuse). I can simply have my drive shaft re-welded with new ears and a 1350 h-yoke for under $100. It's super simple to swap out the flange at the t-case. So I chalk it up to planning ahead for what I need today but want tomorrow.

Lastly, when I moved to CV shafts, I asked a few local drive line fabricators and they all suggested that setup given how I use the rig today and also where it'll be in a year or two. Sure, I could go buy a mass produced after market shaft, but I prefer to talk to professionals, have it measured properly, and built exactly to my specs. Now, I realize that didn't happen in this case; my shaft is just a bit too short with the rear axle being recentered. But I can get it fixed 2 miles from my office, same day service. That's so much better than mailing a drive shaft out of state or dealing with warranty phone calls for weeks on end with a Jeep is out of commission.

I know that I could have bought a reputable shaft online, but even guys that sell a ton of JK shafts like James Adams and Tom Woods will tell you it's best to measure properly and have one built for what you need. Honestly, you learn a lot about your Jeep talking to these guys. Shoot, I talked to James Adams twice in the process. He's a remarkably helpful guy and he's happy to take your call. But I really like to shake hands with the guy doing the work, and supporting local business is something I prefer to do.

All in all, I like the setup. It works for my needs today and it's flexible. And, as of next week, permanently fixed.
 
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End Result

Finally got my drive shaft back and reinstalled. They lengthened it by 1.25 inches and it and inserted a tightly would roll of cardboard as a dampener. The good news is it's 100% silent now with the dampener. Plus it's totally rebalanced (the entire tube is new).

The alarming part was how short it was to begin with. No splines were exposed at ride height, but it was right on the edge. 1.25 inches is a lot when you're talking about how far your rear drive line can droop.

That fact lead to the root cause of the problem. I got a fun lesson in harmonics from the drive line guys. Think of a drive shaft tube like a bell or a tuning fork. Vibrations travel up and down and can create a tone depending on length, density, moment of area, and a whole bunch of factors (Google it if you're a math nut - it's interesting). Because my shaft was too short, it was the perfect length to resonate at a frequency that produced an audible tone even from small transverse vibrations like shifting into reverse or out of 4Lo. It may have done so even if it was slightly longer, but not to the same degree. In essence, even a small vibration was enough to create a longitudinal wave and the shaft was just the right frequency/length/density/thickness/etc. to resonate the wave like bell. Totally safe, totally annoying, and super easy to fix.

As a side note, the temporary fix was a great stop gap. If you find yourself in need of something similar, here's the $0.89 of materials it took. Sticky foam rubber and a large zip tie. :thumb:

IMG_2127.jpg
 
tylerbrinks said:
Finally got my drive shaft back and reinstalled. They lengthened it by 1.25 inches and it and inserted a tightly would roll of cardboard as a dampener. The good news is it's 100% silent now with the dampener. Plus it's totally rebalanced (the entire tube is new).

The alarming part was how short it was to begin with. No splines were exposed at ride height, but it was right on the edge. 1.25 inches is a lot when you're talking about how far your rear drive line can droop.

That fact lead to the root cause of the problem. I got a fun lesson in harmonics from the drive line guys. Think of a drive shaft tube like a bell or a tuning fork. Vibrations travel up and down and can create a tone depending on length, density, moment of area, and a whole bunch of factors (Google it if you're a math nut - it's interesting). Because my shaft was too short, it was the perfect length to resonate at a frequency that produced an audible tone even from small transverse vibrations like shifting into reverse or out of 4Lo. It may have done so even if it was slightly longer, but not to the same degree. In essence, even a small vibration was enough to create a longitudinal wave and the shaft was just the right frequency/length/density/thickness/etc. to resonate the wave like bell. Totally safe, totally annoying, and super easy to fix.

As a side note, the temporary fix was a great stop gap. If you find yourself in need of something similar, here's the $0.89 of materials it took. Sticky foam rubber and a large zip tie. :thumb:
Click to expand...

Glad to hear it's fixed.
 
tylerbrinks said:
Finally got my drive shaft back and reinstalled. They lengthened it by 1.25 inches and it and inserted a tightly would roll of cardboard as a dampener. The good news is it's 100% silent now with the dampener. Plus it's totally rebalanced (the entire tube is new).

The alarming part was how short it was to begin with. No splines were exposed at ride height, but it was right on the edge. 1.25 inches is a lot when you're talking about how far your rear drive line can droop.

That fact lead to the root cause of the problem. I got a fun lesson in harmonics from the drive line guys. Think of a drive shaft tube like a bell or a tuning fork. Vibrations travel up and down and can create a tone depending on length, density, moment of area, and a whole bunch of factors (Google it if you're a math nut - it's interesting). Because my shaft was too short, it was the perfect length to resonate at a frequency that produced an audible tone even from small transverse vibrations like shifting into reverse or out of 4Lo. It may have done so even if it was slightly longer, but not to the same degree. In essence, even a small vibration was enough to create a longitudinal wave and the shaft was just the right frequency/length/density/thickness/etc. to resonate the wave like bell. Totally safe, totally annoying, and super easy to fix.

As a side note, the temporary fix was a great stop gap. If you find yourself in need of something similar, here's the $0.89 of materials it took. Sticky foam rubber and a large zip tie. :thumb:

View attachment 307862
Click to expand...

Glad its fixed. That would have driven me nuts. Side note, it was explained to me that as the axle droops it actually shortens and when it compresses it lengthens. Is this what the driveline shop explained?
 
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