DRIVELINE VIBRATION

[azwjowner]

It looks like I have two things to check. The pattern and replace the carrier. sucks

Since you’re buying a new carrier, it’s at least a good time to consider a Truetrac (awesome mechanical limited slip) instead of paying for another open differential carrier.

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[RDoverland]

Since you’re buying a new carrier, it’s at least a good time to consider a Truetrac (awesome mechanical limited slip) instead of paying for another open differential carrier.

I think that’s what I have. Not sure. I’ll look into it thanks

 

[RDoverland]

Since you’re buying a new carrier, it’s at least a good time to consider a Truetrac (awesome mechanical limited slip) instead of paying for another open differential carrier.

I think that’s what I have. Not sure. I’ll look into it thanks

Never mind. I don’t think I have this one.

 

[roaniecowpony]

Hello, I’ve got a bit of a head-scratcher. I’m experiencing driveline vibrations above 67 MPH. A few months ago, I had my JL re-geared. After completing the break-in period, I resumed normal and highway driving and noticed the vibrations.

To rule out the driveshaft, I installed a brand-new Adams double cardan driveshaft (this is the second one), had the tires balanced, and corrected the driveshaft angles. I even experimented with different angles, but the vibration occurs at the exact same speed every time.

During the re-gear, my differential carrier was scuffed but reinstalled. Could that be causing the vibration? Do differential carriers need to be perfectly balanced? I attached some photos for reference.
ANY IDEAS?

Do you have a lift on your jeep? Does it have a working FAD? If so, can you check the front driveshaft for freedom to rotate when In 2Hi ?

 

[RDoverland]

Do you have a lift on your jeep? Does it have a working FAD? If so, can you check the front driveshaft for freedom to rotate when In 2Hi ?

Front driveshaft is not engaged when in 2WD. Spins freely. FAD is working fine. When I drive under more load and close to 70mph I feel more vibes and when I release the throttle I feel it more as well. Once I slow down to below 70 the vibes go away.

 

[roaniecowpony]

Front driveshaft is not engaged when in 2WD. Spins freely. FAD is working fine. When I drive under more load and close to 70mph I feel more vibes and when I release the throttle I feel it more as well. Once I slow down to below 70 the vibes go away.

I've bent 2 rear driveshafts over the past couple years, both were factory shafts. But, I see you have a new Adams in there.

When I checked my driveshafts, I jacked the rear, chocked the front and put it in gear in 2 wd. The runout of the driveshaft was easy to spot. Both times they vibrated similar to your situation.

 

[RDoverland]

I've bent 2 rear driveshafts over the past couple years, both were factory shafts. But, I see you have a new Adams in there.

When I checked my driveshafts, I jacked the rear, chocked the front and put it in gear in 2 wd. The runout of the driveshaft was easy to spot. Both times they vibrated similar to your situation.

I just replaced my Adams driveshaft (new) with a brand new driveshaft. I doubt two new driveshafts would have the same problem idk. Possible but idk.

 

[roaniecowpony]

I just replaced my Adams driveshaft (new) with a brand new driveshaft. I doubt two new driveshafts would have the same problem idk. Possible but idk.

When a problem isn't obvious, you just have to keep looking. It's a machine. The problem is there. Check the runout of the driveshaft where it comes out of the transfer case, check the wheels for runout.

 

[RDoverland]

When a problem isn't obvious, you just have to keep looking. It's a machine. The problem is there. Check the runout of the driveshaft where it comes out of the transfer case, check the wheels for runout.

Will do

 

[chevymitchell]

Front driveshaft is not engaged when in 2WD. Spins freely. FAD is working fine. When I drive under more load and close to 70mph I feel more vibes and when I release the throttle I feel it more as well. Once I slow down to below 70 the vibes go away.

Between 65-70 is where most harmonics show up. Looking at the pattern you provided, the setup is likely the issue, especially since you say you feel it more on decel. The coast side is what’s used on decel and the coast side pattern isn’t right.

Got a few things to get done right. You’ll be happy you had it all done right in the end.

 

[RDoverland]

Between 65-70 is where most harmonics show up. Looking at the pattern you provided, the setup is likely the issue, especially since you say you feel it more on decel. The coast side is what’s used on decel and the coast side pattern isn’t right.

Got a few things to get done right. You’ll be happy you had it all done right in the end.

Thanks. Looks like I’ll be taking a trip back to the shop. Hopefully I don’t get the runaround.

 

[Nokones]

Just to be on the safe side especially if you lifted the vehicle, may sure that the pinion and driveshaft angles are not more than 2 degrees difference between the two components.

Usually, if you have a vibration at 60-70 MPH it is the driveshaft balance. It it was a vibration 35-45/50 MPH it is the pinion angle.

If you are driving at 65-70 and experience the vibration, what does it feel like when you let up a tad as you relieve/take the load off the driveline?

 

[RDoverland]

Just to be on the safe side especially if you lifted the vehicle, may sure that the pinion and driveshaft angles are not more than 2 degrees difference between the two components.

Usually, if you have a vibration at 60-70 MPH it is the driveshaft balance. It it was a vibration 35-45/50 MPH it is the pinion angle.

If you are driving at 65-70 and experience the vibration, what does it feel like when you let up a tad as you relieve/take the load off the driveline?

I have a brand new driveshaft from Adams (this is a second one because I thought the first one was defective) I made sure the pinion angle was at 0. I then readjusted to no more than 2*. No difference. Vibrations start at about 67-70, it doesn’t matter when I coast, under load or let off the gas pedal. I feel it when I let off the gas pedal too. Going up hill. When I put the Jeep in Neutral driving at that speed I also have vibration. I thought it was the driveshaft but this is the second one that was replaced. Idk

 

[RDoverland]

Quick update on the vibration issue:
The old carrier has been removed and replaced with a Detroit Truetrac, along with new pinion and carrier bearings. The violent vibrations above 65 mph are gone — the difference is night and day. The new carrier is much smoother overall. I still feel a very slight vibration above 75 mph (barely noticeable, especially with wind noise), the pinion angle is within specs but I will readjust it to 0* as per Adams driveshaft. Overall, a huge improvement. Thank you everyone for your help!

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