New Vibration...Diag Help?

ADA OZ

ADA OZ

New member
I have a 'low frequency' vibration about 50mph that I can't seem to get rid of. Jeep is smooth and comfy without front drive shaft. Install front shaft, which is aftermarket and the vibration comes back.

Pulled the shaft for rebalancing. Jeep runs butter smooth. Local shop made some repairs and rebalanced the shaft. Re-installed now the vibration is back. Any thoughts?

Front axle is a D30 w/ 4.88s and a TruTrac.


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How much caster are you running? If it's anything more than 4°, that'll be your problem.
 
Other than the caster as Eddie mentioned, the only thing I can think of to check is to check for play at tcase output or front pinion output.
 
Drive line angle? Single U-joint or Double Cardan? They need to be aligned differently, pinion to transfer case.
 
Back from the dead.

Sorry but still chasing this. Have been MIA.

Caster is set currently at 3.5*. Aligned and all is well.

As an update this 'vibration' only occurs when no power is being provide to the front axle and it occurs above 50-55mph. So, 60mph in 4 high is smooth until power is removed and deceleration begins.

Sitting here with Jeep apart. Any help would be appreciated. Backlash is set at 9 thousandths.


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Dont know much about jk drivetrain, but I dont think they have a ujoint at the front diff correct? I had a bent pinion yoke that allowed the ujoint to slide around in the ears. That was my tj, and I know my rubicon does not have ujoint front.
Secondarily, the angle as was already mentioned is key. I see you have 3.5" lift, are you still running stock front driveshaft? You said double cardan, so does the pinion yoke angle directly up to it?
Sorry for the ginormous pic, and also if that is not accurate to the jk driveline.
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wayoflife said:
How much caster are you running? If it's anything more than 4°, that'll be your problem.
Click to expand...

Don't mean to thread hijack, but this only the case on stock axles correct?
A PR44 should be able to run 6-7 degree without vibes I'd assume?
 
JKDream said:
Don't mean to thread hijack, but this only the case on stock axles correct?
A PR44 should be able to run 6-7 degree without vibes I'd assume?
Click to expand...

Yes IF the housing was built with the extra caster. They offer it either way.
 
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