Ozon8r
Member
I need some help solving a driveline vibration introduced with a gear install. I had a shop re-gear my Dana 44 axles to 5.13s from 4.10s and now I have a wicked driveline vibration starting at 50mph and peaks at 65mph. It is so bad that it is difficult to carry on a conversation because of the buzzing noise within the cabin and the mirrors are useless because the whole vehicle is vibrating at such a high frequency objects in the mirrors are out of focus.
Troubleshooting has isolated the issue to my rear driveshaft or the rear differential. The tires are neither the issue nor the front driveline.
I picked up a dial indicator and the rear shaft in front of the yoke has a 0-400th of an inch variance when rotated 360 degrees. Rotating the shaft in the yoke yield the same results, but on opposite sides of the shaft. Is this normal? Does it indicate that the yoke or pinion are not running true or that they are bent? While this may have been a pre-existing condition, it certain only became apparent after installing the new gears.
I also measured the front of the rear ds next to the t-case yoke and the variation was 1/100th of an in and did not change when flipping 180 degrees in the yoke.
I am not sure I’m doing the measurement right. I posted a video of how I took the measurements here:
Some background…
I picked up the jk a week ago Friday from the shop after re-gearing to 5.13s and immediate noticed a driveline vibration starting at 50mph and peaking at 65mph. The last time I experienced a similar issue was when I bent a rear shaft on Holy Cross trail. I didn't quite understand what was going on with the Jeep not having an issue with the 1310 aftermarket shaft since install 9 months prior. The Jeep was running fine just a little slower with 37s on 4.10 gears, but certainly no driveline vibration. Since the day I picked it up from the shop, above 50mph, the entire jeep buzzes and my mirrors vibrate so bad I can’t focus on any objects appearing in the mirrors. Additionally, the tailgate sounds like its going to vibrate off the hinges creating a significant buzzing sound within the cabin. So, I immediately assumed it was the gears and called the shop to see if this was normal and part of the break in process. Of course they said no and to bring it back in the following Wednesday. Going back to my suspicion that my ds was bent or out of balance, I spent the weekend troubleshooting. First I dropped the front ds and no change, vibration remained. Next, I dropped the rear and the vibration went away and in my mind eliminated any issue with the tires or the front end. I also checked engine and tranny mounts, dropped into neutral during the vibration, and revved the engine in neutral at a stop to see if there was any relationship to rpm. Nothing of interest.
Monday I took the ds in for balancing at the shop that built the shaft for me. It was in balance. The jeep was vibration free while the rear shaft was off running in 4high on just the front ds.
I dropped the Jeep off with the shop on Wednesday so they could investigate. They called on Thursday and informed me that by rotating the tires, they moved the issue to the front and suggested I have the tires balanced. However, the frequency was too high to ever be a tire issue and I know what tires out of balance do and how a vehicle feels. And when I picked up the Jeep, the vibration was still there in the seat of the Jeep and not in the steering, same as before. Again, dropping the rear shaft and the vibration stopped. But just for grins, I had a friend loan me stock tires that were well balanced. An interesting ride for sure with 5.13s, but even revving out the engine running 60mph, the vibration was still there with the rear ds reinstalled. I am absolutely certain the tires are not related.
I've spent 40+ hours researching this issue and talked with a guy who had a similar experience after upgrading to 4.88s. Turns out he had a bad inner pinion bearing in the master install kit. Of course the shop blamed the tires as well until they finally gave in and opened up the diff.
Appreciate any help I can get.
Thanks
Troubleshooting has isolated the issue to my rear driveshaft or the rear differential. The tires are neither the issue nor the front driveline.
I picked up a dial indicator and the rear shaft in front of the yoke has a 0-400th of an inch variance when rotated 360 degrees. Rotating the shaft in the yoke yield the same results, but on opposite sides of the shaft. Is this normal? Does it indicate that the yoke or pinion are not running true or that they are bent? While this may have been a pre-existing condition, it certain only became apparent after installing the new gears.
I also measured the front of the rear ds next to the t-case yoke and the variation was 1/100th of an in and did not change when flipping 180 degrees in the yoke.
I am not sure I’m doing the measurement right. I posted a video of how I took the measurements here:
Some background…
I picked up the jk a week ago Friday from the shop after re-gearing to 5.13s and immediate noticed a driveline vibration starting at 50mph and peaking at 65mph. The last time I experienced a similar issue was when I bent a rear shaft on Holy Cross trail. I didn't quite understand what was going on with the Jeep not having an issue with the 1310 aftermarket shaft since install 9 months prior. The Jeep was running fine just a little slower with 37s on 4.10 gears, but certainly no driveline vibration. Since the day I picked it up from the shop, above 50mph, the entire jeep buzzes and my mirrors vibrate so bad I can’t focus on any objects appearing in the mirrors. Additionally, the tailgate sounds like its going to vibrate off the hinges creating a significant buzzing sound within the cabin. So, I immediately assumed it was the gears and called the shop to see if this was normal and part of the break in process. Of course they said no and to bring it back in the following Wednesday. Going back to my suspicion that my ds was bent or out of balance, I spent the weekend troubleshooting. First I dropped the front ds and no change, vibration remained. Next, I dropped the rear and the vibration went away and in my mind eliminated any issue with the tires or the front end. I also checked engine and tranny mounts, dropped into neutral during the vibration, and revved the engine in neutral at a stop to see if there was any relationship to rpm. Nothing of interest.
Monday I took the ds in for balancing at the shop that built the shaft for me. It was in balance. The jeep was vibration free while the rear shaft was off running in 4high on just the front ds.
I dropped the Jeep off with the shop on Wednesday so they could investigate. They called on Thursday and informed me that by rotating the tires, they moved the issue to the front and suggested I have the tires balanced. However, the frequency was too high to ever be a tire issue and I know what tires out of balance do and how a vehicle feels. And when I picked up the Jeep, the vibration was still there in the seat of the Jeep and not in the steering, same as before. Again, dropping the rear shaft and the vibration stopped. But just for grins, I had a friend loan me stock tires that were well balanced. An interesting ride for sure with 5.13s, but even revving out the engine running 60mph, the vibration was still there with the rear ds reinstalled. I am absolutely certain the tires are not related.
I've spent 40+ hours researching this issue and talked with a guy who had a similar experience after upgrading to 4.88s. Turns out he had a bad inner pinion bearing in the master install kit. Of course the shop blamed the tires as well until they finally gave in and opened up the diff.
Appreciate any help I can get.
Thanks
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