Another Driveline Vibration (research showed this should work)

Ericshere03

Ericshere03

TJ Enthusiast
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So, I read most of the threads about driveline angles... I SHOULD be vibe free. I have had 3 other jeeps with similar lifts I put together without vibes.

So...

I have an 05 TJ with the NSG 6 speed
OME HD lift
Extended LCAs (Synergy)
Adjustable UCAs (Synergy)
1” MML/BL

Rear Axle pointed up 9 degrees
Transfer case pointed down 9 degrees
Stock Driveshaft is 18 degrees

Everything tells me that this should be just fine, but getting that nice high frequency buzz around 60mph.

ODDLY, only while accelerating and coasting, deceleration seems to be good.

Rear bushings are super tight DDB (polyurethane), so I didn’t feel the need to adjust for axle movement when engine torque is applied ...

The only thing I suspect is that the working angle of 9 degrees is excessive, the TEXTBOOK answer is 3 degrees, but is 9 degrees working angle TOO MUCH ???

Thanks!
 
That nice high frequency buzz... ahhh. Yes, we're all so used to that, but there is some relief on the horizon.

Someone on here has figured it out 100% (well, the shop who fixed it for them I mean), and should be posting their findings in the coming days. I don't want to say who or get ahead of myself, but his was the worst I've ever experienced, and it has 100% been solved via "active vehicle balancing".

Stay tuned, he'll be posting about it within the next few days I'm told.

This is one of those issues that has been impossible for most people to solve until recently (and if some have solved it, they sure as hell haven't been telling us about it as far as I know).
 
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“Active” ... is it like those “active” tire balances that are basically metal beads in a hoop that will actively counter balance any imbalance?

Let me know how it works. I was thinking of either rebuilding the shaft or biting the bullet and doing an SYE
 
Ericshere03 said:
“Active” ... is it like those “active” tire balances that are basically metal beads in a hoop that will actively counter balance any imbalance?

Let me know how it works. I was thinking of either rebuilding the shaft or biting the bullet and doing an SYE
Click to expand...
Those are called Centramatic.
 
S.McArthur said:
I hope it's soon, I'm ready to rip these 5.13's out of my axle or burn this jeep to the ground.
Click to expand...
Oh no! You have Vibs too?

To @Ericshere03 You have how much lift going on with a factory DS? You said OME, but I've heard of OME being anywhere from 2 to 2.75" Have you checked the U-joints themselves? Have you tried isolating to front or rear DS?
 
S.McArthur said:
I hope it's soon, I'm ready to rip these 5.13's out of my axle or burn this jeep to the ground.
Click to expand...

Don't do it, trust me.

It can be solved, but the only person who can solve it effectively will be a drivetrain shop that specializes in active vehicle balancing. Balancing the vehicle as a whole as oppose to trying to balance an individual component.
 
Chris said:
Don't do it, trust me.

It can be solved, but the only person who can solve it effectively will be a drivetrain shop that specializes in active vehicle balancing. Balancing the vehicle as a whole as oppose to trying to balance an individual component.
Click to expand...
I'm researching vibrations and how to determine the cause by the Hz produced. I am going to work on an excel file to do the calculations, I also need a vibration measurement tool. The odd thing, it seemed to have gotten more intense the longer I drive it.
I can't even find "active vehicle balancing" through google. I'll wait until the mystery person post their results.
 
Mike_H said:
Oh no! You have Vibs too?

To @Ericshere03 You have how much lift going on with a factory DS? You said OME, but I've heard of OME being anywhere from 2 to 2.75" Have you checked the U-joints themselves? Have you tried isolating to front or rear DS?
Click to expand...

Ujoints look new from the previous owner, they also look cheap, like the kinked radiator hoses I already replaced. SO! I plan on replacing with the Spicer SPL grade joints (non greasable) and see what happens.

It’s totally the rear, Pro Comp rear springs it was fine, swapped to OME and immediately got vibes, adjusted the rear pinion to be parallel with TC and still have vibes above 65 during mild acceleration.
 
Ericshere03 said:
The only thing I suspect is that the working angle of 9 degrees is excessive, the TEXTBOOK answer is 3 degrees, but is 9 degrees working angle TOO MUCH ???
Click to expand...

Forget all of this. Your Jeep is going to be different than the next guys Jeep with exactly the same lift.

Ericshere03 said:
adjusted the rear pinion to be parallel with TC
Click to expand...

Do you have an SYE (or is it a Rubicon)?
 
Forget coventional wisdom and keep adjusting the pinion angle until you find a happy place. Don't be afraid to lower the t-case too.
 
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3.5" Metalcloak lift w/ adj upper and lower arms
SYE
Adams rear drive shaft
35" KO2's
32RH trans
stock height Brown Dog motor mounts

1) no vibration

added G2 Dana 44 rear axle w/4.88 gear and 4.88 gear in the front Dana 30

2) vibration started at about 55 - 60

I tried:
1" T case drop (removed when no improvement)
adjust rear opinion angle (many times)
re-balance rear drive shaft (twice)
run without rear shaft
run without front shaft
road force balance tires

3) All these had some effect on vibes but nothing solved it.

I installed 1" MML (Brown Dog)

Smooth as glass to 75 mph. That's as fast as I've run with 4.88
 
Chris said:
That nice high frequency buzz... ahhh. Yes, we're all so used to that, but there is some relief on the horizon.

Someone on here has figured it out 100% (well, the shop who fixed it for them I mean), and should be posting their findings in the coming days. I don't want to say who or get ahead of myself, but his was the worst I've ever experienced, and it has 100% been solved via "active vehicle balancing".

Stay tuned, he'll be posting about it within the next few days I'm told.

This is one of those issues that has been impossible for most people to solve until recently (and if some have solved it, they sure as hell haven't been telling us about it as far as I know).
Click to expand...
Chris said:
That nice high frequency buzz... ahhh. Yes, we're all so used to that, but there is some relief on the horizon.

Someone on here has figured it out 100% (well, the shop who fixed it for them I mean), and should be posting their findings in the coming days. I don't want to say who or get ahead of myself, but his was the worst I've ever experienced, and it has 100% been solved via "active vehicle balancing".

Stay tuned, he'll be posting about it within the next few days I'm told.

This is one of those issues that has been impossible for most people to solve until recently (and if some have solved it, they sure as hell haven't been telling us about it as far as I know).
Click to expand...
Chris, did the solution get posted? How do I find it?
Thanks, Bob
 
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