Driveline Vibrations

J

jrod1290

New member
Hi everyone, I am going to try and keep this as short and simple as possible with hopes someone on here can point me in the right direction.

I have 2016 JKU 75th anni, 35 inch toyos, (34.25 actual) 3.5 rubicon express lift with adjustable control arms. I recently bought a pair of custom made Tom Woods driveshafts and it drove great. I commute 30 miles to work so there were times i got up to 80mph on the hwy with zero issues or vibrations. 2 months later i went from stock 3.21 gears to 4.56 (flashcal calibrated to match the gears and tires). This is where the issues started. I was getting vibrations after 60 mph that got worse the faster i went. The vibes were oscillating, more of a hum sound that can be felt in the floor board. So I removed the front driveshaft and took it for a spin, i had much less vibrations but i can still feel some between 70-80mph, went away after 80mph. I took the shafts to get rebalanced and now my ride is a whole lot smoother, but I am still getting slight vibes between 73mph and 80mph that go away after 80mph. I took the rear driveshaft off and drove it on 4 high and the vibes are completely gone. So I new it's the rear shaft that has the vibes, so I took it to my 4wheel drive shop and they told me my rear shaft had a bit of up/down play in the slip yoke spline, so i took to my driveshaft shop and they are telling me that the tiny bit of play it has is perfectly normal. They are going to swap out the u-joints to see if that's the issue, but i'm getting really tired of chasing my tail with this.

Anybody have a similar issue? Should i look into my pinion angles? I used an angle finder and this is what i got:
 

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In other words, your drive shafts weren't balanced right out of the box. The reason you didn't feel the vibrations before is because of the tall factory gears you were running. The 4.56 gears cause your shafts to spin a LOT faster and that's why you started to feel them. Everything you've done up to this point has been spot on to find and address vibrations. Movement in your rear axle is normal due to torque and while what you've got is very close, I would try to get the 2 angles to be the same. Typically, that helps for most situations.
 
wayoflife said:
In other words, your drive shafts weren't balanced right out of the box. The reason you didn't feel the vibrations before is because of the tall factory gears you were running. The 4.56 gears cause your shafts to spin a LOT faster and that's why you started to feel them. Everything you've done up to this point has been spot on to find and address vibrations. Movement in your rear axle is normal due to torque and while what you've got is very close, I would try to get the 2 angles to be the same. Typically, that helps for most situations.
Click to expand...
Yeah the 4.56s definitely exposed my driveshafts. I never really got it passed 80 mph with factory gears, so now when I go 80mph it's like i'm going 100mph LOL. Thanks so much for the feedback, I'll definitely adjust the pinion to match the DS. Would you suggest i adjust the upper or lower CAs?
 
WJCO said:
Hopefully the ujoints being replaced helps out. Tom Woods was notorious for using cheap Chinese ujoints in the past. Not sure if they still do or not.
Click to expand...
This is exactly what my driveshaft shop said, looks like Tom Woods still uses the Chinese u-joints. I'm going with Spicer and adjusting the pinion a tad. Hopefully I get my driveshaft back today. Hoping for the best here.
 
jrod1290 said:
Yeah the 4.56s definitely exposed my driveshafts. I never really got it passed 80 mph with factory gears, so now when I go 80mph it's like i'm going 100mph LOL. Thanks so much for the feedback, I'll definitely adjust the pinion to match the DS. Would you suggest i adjust the upper or lower CAs?
Click to expand...
Your lowers are meant to set your axle position. The uppers are made to set pinion angle.
 
I would check on a possible bad transfer case yoke. Put the rear diff on jack stands so the tires are off the ground, have a helper apply the brakes, start the engine and put the transmission in drive. While watching the drive shaft close to the yoke, ask your helper to release the brakes. As the driveshaft starts to spin, watch the shaft for any up and down movement. If you see any amount of up and down movement, that's the cause of your vibration. Check the pinion side of the driveshaft as well! Hopefully this info helps. Keep us posted....
 
JeepFan said:
I would check on a possible bad transfer case yoke. Put the rear diff on jack stands so the tires are off the ground, have a helper apply the brakes, start the engine and put the transmission in drive. While watching the drive shaft close to the yoke, ask your helper to release the brakes. As the driveshaft starts to spin, watch the shaft for any up and down movement. If you see any amount of up and down movement, that's the cause of your vibration. Check the pinion side of the driveshaft as well! Hopefully this info helps. Keep us posted....
Click to expand...
Thank you, I’ll definitely try this after i get my driveshaft back. I didn’t even consider this or had heard anyone mentioned this. I did check the torque on the yoke and pinion flange with my torque wrench, but never thought of trying this. I should get my driveshaft back tomorrow, gonna adjust the pinion and take it for a test drive. If i get vibes, I’m trying this next.
 
Got my driveshaft back. All 3 u-joints were replaced with spicers. They even replaced the slip yoke. Perfectly balanced, i was there with the tech watching him balance it. They wanted to show me that it was perfect, they sped it up to 3,600 rpms and it had zero vibes. I was getting vibes at around 3,300 rpms (driveshaft rpms).
Well long story short, the guy told me that if it still had vibes to bring it in so he can put it on a lift and check the transfer case yoke. And you guessed it, still vibrating. It vibrates the same exact way it has before. I haven’t adjusted the pinion angle, but i feel like .5 degrees wouldn’t make a world of difference, but still going to try it before i take it back to the shop. Idk what to do anymore. Could a bad gear install cause vibes? I didn’t get vibes when i was driving without the rear shaft, but then again the differential was not under load. I’m so frustrated guys!
 
When your gears were changed if the pinion wasn't properly torqued, or if the right wahers weren't used, or the crush washer was over torqued on the first try it could cause premature pinion bearing failure. Also your thrust angles look really high to me, did you zero out on the input yoke of the differential? The pinion angle is the difference of the drive shaft in relation to the input yoke of the diff. In other words if your diff input yoke is 3 degrees and your drive shaft is 5 you have a 2 degree pinion angle. With taller lifts it may not be possible to get a 0 degree pinion angle but you should generally try and get it as low as possible. There's a trade off though where things can start crashing into other things if your diffs end up with too much angle on them while chasing pinion angle with tall lifts (along with some other possible problems). Sometimes its a find a happy medium game. If you run at too high of a pinion angle for too long you can also damage the pinion bearing and the vibe wont go away just by correcing the angle. You may be chasing more than one problem at the same time. I would have them open the diff, and verify proper install of rhe gear set and make sure the gears are meshing correctly by checking the pattern between pinion and ring gears. Sorry, not a smoking gun, but driveline vibes can be caused by a number of things like death wobble can. You gotta go through everything and might have to fix more than one thing.
 
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JimLee said:
When your gears were changed if the pinion wasn't properly torqued, or if the right wahers weren't used, or the crush washer was over torqued on the first try it could cause premature pinion bearing failure. Also your thrust angles look really high to me, did you zero out on the input yoke of the differential? The thrust angle is the difference of the drive shaft in relation to the input yoke of the diff. In other words if your diff input yoke is 3 degrees and your drive shaft is 5 you have a 2 degree thrust angle. With taller lifts it may not be possible to get a 0 degree thrust angle but you should generally try and get it as low as possible. There's a trade off though where things can start crashing into other things if your diffs end up with too much angle on them while chasing thrust angle with tall lifts (along with some other possible problems). Sometimes its a find a happy medium game. If you run at too high of a thrust angle for too long you can also damage the pinion bearing and the vibe wont go away just by correcing the angle. You may be chasing more than one problem at the same time. I would have them open the diff, and verify proper install of rhe gear set and make sure the gears are meshing correctly by checking the pattern between pinion and ring gears. Sorry, not a smoking gun, but driveline vibes can be caused by a number of things like death wobble can. You gotta go through everything and might have to fix more than one thing.
Click to expand...
Now that you mention all this, I did leave out an important detail. After i got my gears installed, i went through the break in process, did the initial heat/cool cycles like i was supposed to. Then after the first 200 miles of driving it easy, i got it up to hwy speeds which is when i initially discovered the vibes. I drove it easy after that, changed the oil at 500 miles and got it up to hwy speeds again and vibes were still there. I took it back the installer and he noticed there was up/down in/out play in the rear pinion flange. He retorqued and said they hadn’t properly crushed the sleeve. I still had vibes after that and started chasing it through the driveshaft since the vibes were gone once i removed the rear one. I guess I’ll have the installer check the rear diff once i play with the angles a bit.
 
TrailHunter said:
I checked my angles last night.. (stock rear drive shaft) they are right there with yours… 81.7 & 7.8 give or take.
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Unfortunately driveline angle in relation to flat ground really means nothing. You gotta get the angle difference between the diff and the driveline to get the pinion angle. On bro dozers with massive lifts it is possible to have like a 15 degree driveline angle or more and still get a 0 degree pinion angle if the axle is adjusted with the pinion high enough. Of course then you end up crazy high angles at the TC, that's where double cardan joints come in. The OP isn't running a huge lift obviously, I just think its a good example to help visualize the difference between driveline angle and pinion angle.
 
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jrod1290 said:
Now that you mention all this, I did leave out an important detail. After i got my gears installed, i went through the break in process, did the initial heat/cool cycles like i was supposed to. Then after the first 200 miles of driving it easy, i got it up to hwy speeds which is when i initially discovered the vibes. I drove it easy after that, changed the oil at 500 miles and got it up to hwy speeds again and vibes were still there. I took it back the installer and he noticed there was up/down in/out play in the rear pinion flange. He retorqued and said they hadn’t properly crushed the sleeve. I still had vibes after that and started chasing it through the driveshaft since the vibes were gone once i removed the rear one. I guess I’ll have the installer check the rear diff once i play with the angles a bit.
Click to expand...
Your angles may not be bad, Im just not sure if you were measuring driveline angle referenced to ground or referenced to the pinion. Those numbers for driveline angle aren't bad, those numbers for thrust angle are massive. Its all about keeping the output of the TC, the driveshaft, and the input of the dif (pinion) in as straight a line as possible, the more pinion angle you have the harder your u joints have to flex and the more stress is put on your pinion bearings.
 
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JimLee said:
Unfortunately driveline angle in relation to flat ground really means nothing. You gotta get the angle difference between the diff and the driveline to get the thrust angle. On bro dozers with massive lifts it is possible to have like a 15 degree driveline angle or more and still get a 0 degree thrust angle if the axle is adjusted with the pinion high enough. Of course then you end up crazy high angles at the TC, that's where double cardan joints come in. The OP isn't running a huge lift obviously, I just think its a good example to help visualize the difference between driveline angle and thrust angle.
Click to expand...
I was just showing I am also within 1 degree under 90.
 
jrod1290 said:
Hi everyone, I am going to try and keep this as short and simple as possible with hopes someone on here can point me in the right direction.

I have 2016 JKU 75th anni, 35 inch toyos, (34.25 actual) 3.5 rubicon express lift with adjustable control arms. I recently bought a pair of custom made Tom Woods driveshafts and it drove great. I commute 30 miles to work so there were times i got up to 80mph on the hwy with zero issues or vibrations. 2 months later i went from stock 3.21 gears to 4.56 (flashcal calibrated to match the gears and tires). This is where the issues started. I was getting vibrations after 60 mph that got worse the faster i went. The vibes were oscillating, more of a hum sound that can be felt in the floor board. So I removed the front driveshaft and took it for a spin, i had much less vibrations but i can still feel some between 70-80mph, went away after 80mph. I took the shafts to get rebalanced and now my ride is a whole lot smoother, but I am still getting slight vibes between 73mph and 80mph that go away after 80mph. I took the rear driveshaft off and drove it on 4 high and the vibes are completely gone. So I new it's the rear shaft that has the vibes, so I took it to my 4wheel drive shop and they told me my rear shaft had a bit of up/down play in the slip yoke spline, so i took to my driveshaft shop and they are telling me that the tiny bit of play it has is perfectly normal. They are going to swap out the u-joints to see if that's the issue, but i'm getting really tired of chasing my tail with this.

Anybody have a similar issue? Should i look into my pinion angles? I used an angle finder and this is what i got:
Click to expand...

here’s the thread I was referencing. I never did find a cause and chalked it up to a resonance issue. I installed a vibration dampener on the transfer case which helped. The rest of the vibration slowly went away I assume as the gears broke in and frequency changed.

Rear Driveshaft vibes

Hey guys, As I mentioned in my build thread, I just had my 4.10's swapped with 5.13's on my JKU and now have what seems to be a driveshaft vibe. I thought it was coming from the front since it's an aftermarket CV shaft (with less than ideal pinion angle) so I pulled it and still have a vibe...
www.wayalife.com www.wayalife.com
 
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JimLee said:
Your angles may not be bad, Im just not sure if you were measuring driveline angle referenced to ground or referenced to the pinion. Those numbers for driveline angle aren't bad, those numbers for thrust angle are massive. Its all about keeping the output of the TC, the driveshaft, and the input of the dif (pinion) in as straight a line as possible, the more thrust angle you have the harder your u joints have to flex and the more stress is put on your pinion bearings.
Click to expand...
What do you define as Thrust angle? I thought that was the rear axle being perpendicular to the centerline of the vehicle.
 
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