Slow speed vibration

[TJ4X4HORTON]

Hi Folks, At a dead end...
I remove a 4" lift on my Tj, replaced it with a RC 2" lift. replaced the drop pitman arm with a stock one.SLOW SPEED VIBRATION...
I have taken out the front drive shaft, just to confirm it wasn't a u-joint problem.. it wasn't. iI have dropped the crossmember from stock location to 1/2" drop, 3/4" drop, 1" drop and 1 1/2 " drop ,, same vibration... the rear shaft feels tight ,,,no SLOP IN IT....
Put an angle finder on the differential it read 11 degrees, the drive shaft reads the same 11 degrees,,,,
SAME VIBRATION.. It is in the drivetrain , somewhere...

Thanks

 

[AndyG]

Hi Folks, At a dead end...
I remove a 4" lift on my Tj, replaced it with a RC 2" lift. replaced the drop pitman arm with a stock one.SLOW SPEED VIBRATION...
I have taken out the front drive shaft, just to confirm it wasn't a u-joint problem.. it wasn't. iI have dropped the crossmember from stock location to 1/2" drop, 3/4" drop, 1" drop and 1 1/2 " drop ,, same vibration... the rear shaft feels tight ,,,no SLOP IN IT....
Put an angle finder on the differential it read 11 degrees, the drive shaft reads the same 11 degrees,,,,
SAME VIBRATION.. It is in the drivetrain , somewhere...

Thanks

Remove the rear shaft and drive it in 4 high.

The shaft can have a slight Bend... It takes a dial indicator to catch this.

The shaft can need balanced to a higher speed.

It can be assembled out of phase.

There can be other things..I'd start with this.

also what speed is it present and are there certain speeds that it is not present.

 

[eastbloc]

Driveshaft and yoke will only go one way to assure balance.
If you have not marked them before removing, you will have to do a trial and error to get it back to the way it was.

There are only 4 ways it can be put back together, and one of them is correct way.
Your way is 1 and wrong.
Axle yoke was not rotated so that leaves only two other variables - ds and t-yoke.
If you didn't rotate transfer case yoke, that leaves drive shaft as the last variable.

 

[Vtx531]

What speed?

 

[TimboSlice]

Is it an auto or manual? I get a vibe if I shift at a lower RPM than normal (slower speeds) and it goes away as I accelerate. I have seen this in everything I have driven with a manual trans.

Do you have adjustable control arms? If so, did you retain them and re-adjust to accommodate your lower suspension?

Its great to hear you ditched the drop pitman arm, but i dont think that is your vibration.

Are you sure you are measuring at the correct points with the angle finder?

 

[MtnRanger160]

How low of speed? I'm dealing with this as well but found my issues was the rear driveshaft centering ball was trashed. What @AndyG recommended by taking the rear DS off and moving to 4H is what I did to settle that thought. There was no spring and needle bearings were gone. New parts on the way and should fix it. Have you rechecked front end alignment and adjusted your track bar after dropping it back to 2"?

 

[AMS417]

Was the vibe present with the 4"? Have you checked wheels for runout, and tires for balance. I have bent wheel that gives a little low speed hop. Balances out a little at speed though. Replacing wheels soon.

 

[AndyG]

How low of speed? I'm dealing with this as well but found my issues was the rear driveshaft centering ball was trashed. What @AndyG recommended by taking the rear DS off and moving to 4H is what I did to settle that thought. There was no spring and needle bearings were gone. New parts on the way and should fix it. Have you rechecked front end alignment and adjusted your track bar after dropping it back to 2"?

Good post.

CV drive shafts are wonderful but if they ever lock up they can cause catastrophic damage.

 

[Goatman]

Changing the lift height will require a re-toe in adjustment. If your toe is too far off it can act squirrelly, it could cause a 'vibe' as each wheel tries to track straight, or even feel like you are floating all over the place. Be certain to have the steering wheel centered perfectly too.

 

[Vtx531]

Was the vibe present with the 4"? Have you checked wheels for runout, and tires for balance. I have bent wheel that gives a little low speed hop. Balances out a little at speed though. Replacing wheels soon.

What wheel? Any pics of the bend?

 

[AMS417]

What wheel? Any pics of the bend?

The wheels in your Jeep. You might have a bent wheel or out of balance tire.

 

[TJ4X4HORTON]

Hi Folks, At a dead end...
I remove a 4" lift on my Tj, replaced it with a RC 2" lift. replaced the drop pitman arm with a stock one.SLOW SPEED VIBRATION...
I have taken out the front drive shaft, just to confirm it wasn't a u-joint problem.. it wasn't. iI have dropped the crossmember from stock location to 1/2" drop, 3/4" drop, 1" drop and 1 1/2 " drop ,, same vibration... the rear shaft feels tight ,,,no SLOP IN IT....
Put an angle finder on the differential it read 11 degrees, the drive shaft reads the same 11 degrees,,,,
SAME VIBRATION.. It is in the drivetrain , somewhere...

Thanks

I will remove the rear drive shaft thus week and i,ll keep you posted... Thanks