So, I’m trying to kick a vibration problem - not a violent death wobble but one that can be felt in the cab when driving at certain speeds. Symptoms seem to line up with this being a drivetrain issue: Only vibrates when accelerating, most noticeable around 40mph… U joints appear to be okay, so now I’m looking at my rear pinion angles.
If I’m understanding correctly, conventional wisdom for a single cardan (non CV) driveshaft setup like mine is that the transfer case and differential should be setup as parallel to -1 degree downward tilt on the differential, to optimize for successful cancellation of the U joints’ inherent elliptical rotational velocity patterns. Additionally, I’m hearing that you want the angle between driveshaft and transfer case as well as the angle between driveshaft and differential to stay under 10 degrees. If the lift of the vehicle increases either of those angles beyond 10 degrees, it seems that the recommendation is to swap the driveshaft with a CV or double cardan type driveshaft and adjust the diff angle to sit parallel to -1 degrees in line with the driveshaft rather than parallel to the transfer case.
Well, here are the current angles on my TJ with a 3” lift:
Between trans. case and diff: 2.2 degrees
Between trans. case and driveshaft: 9.5 degrees
Between diff and driveshaft: 7.1 degrees
So, my differential angle is a little lower than ideal (2.2 instead of 0 to -1 degrees). My driveshaft angles relative to the diff and transfer case are below the recommended 10 degree limit, but I wonder if those angles are close enough to the limit that I should consider upgrading to a CV type driveshaft.
What do you guys think? Do these numbers seem bad enough to be causing a noticeable vibration problem? I currently have non-adjustable control arms, so I thought I’d scan for feedback before spending the money on them, just to change the diff angle by 1.5 degrees.
Thanks in advance for any insight!
If I’m understanding correctly, conventional wisdom for a single cardan (non CV) driveshaft setup like mine is that the transfer case and differential should be setup as parallel to -1 degree downward tilt on the differential, to optimize for successful cancellation of the U joints’ inherent elliptical rotational velocity patterns. Additionally, I’m hearing that you want the angle between driveshaft and transfer case as well as the angle between driveshaft and differential to stay under 10 degrees. If the lift of the vehicle increases either of those angles beyond 10 degrees, it seems that the recommendation is to swap the driveshaft with a CV or double cardan type driveshaft and adjust the diff angle to sit parallel to -1 degrees in line with the driveshaft rather than parallel to the transfer case.
Well, here are the current angles on my TJ with a 3” lift:
Between trans. case and diff: 2.2 degrees
Between trans. case and driveshaft: 9.5 degrees
Between diff and driveshaft: 7.1 degrees
So, my differential angle is a little lower than ideal (2.2 instead of 0 to -1 degrees). My driveshaft angles relative to the diff and transfer case are below the recommended 10 degree limit, but I wonder if those angles are close enough to the limit that I should consider upgrading to a CV type driveshaft.
What do you guys think? Do these numbers seem bad enough to be causing a noticeable vibration problem? I currently have non-adjustable control arms, so I thought I’d scan for feedback before spending the money on them, just to change the diff angle by 1.5 degrees.
Thanks in advance for any insight!
