desertrunner
Active Member
so after my axle swap and re gear i have been trying to think of things that might be causing a small vibration i have been feeling, just looking for confirmation on what i think is going on.
background i have a PR44 Unlimited with 4.88 and all stock front control arms. pinion angle is 2.5* caster 7.5* and the drive shaft is at 4.5* (2* difference from pinion angle).
I am getting a very high frequency deep bass vibration starting at about 45MPH that is consistent through 70, that has a resonance about once/2 sec. nothing violent but enough to tickle the feet a little on the floor and to buz an empty can in my cup holder.
I pulled the front shaft and took it for a drive. the vibe at 45 MPH went away but starting at 60 consistent to 70 im still getting a very similar vibe as described above just enough to buz a can in my cup holder.
first thought is the 2* difference in pinion and driveshaft angle. If i get adjustable uppers i can get them the same leaving me with 4.5* pinion and 5.5* caster but that still wouldnt change the vibe i have with the front shaft out.
second thought was maybe im just feeling vibrations from the tread on the coopers on the pavement so i dropped the pressure 5PSI lower and that didnt change a thing.
my next thought is to pull the rear shaft next and check that too but i suspect im going to end up with the same vibe at 45MHP that i had before.
so before i go spending money on front uppers, could that 2* difference in the drive shaft and pinion cause that vibe im feeling? Or am i worrying about something that isnt that big of a deal and its just a product of driving a jeep with MTs and 4.88s?
Last thing i want to do is grenade my Rubi T-Case due to a vibration i failed to address. :icon_crazy:
background i have a PR44 Unlimited with 4.88 and all stock front control arms. pinion angle is 2.5* caster 7.5* and the drive shaft is at 4.5* (2* difference from pinion angle).
I am getting a very high frequency deep bass vibration starting at about 45MPH that is consistent through 70, that has a resonance about once/2 sec. nothing violent but enough to tickle the feet a little on the floor and to buz an empty can in my cup holder.
I pulled the front shaft and took it for a drive. the vibe at 45 MPH went away but starting at 60 consistent to 70 im still getting a very similar vibe as described above just enough to buz a can in my cup holder.
first thought is the 2* difference in pinion and driveshaft angle. If i get adjustable uppers i can get them the same leaving me with 4.5* pinion and 5.5* caster but that still wouldnt change the vibe i have with the front shaft out.
second thought was maybe im just feeling vibrations from the tread on the coopers on the pavement so i dropped the pressure 5PSI lower and that didnt change a thing.
my next thought is to pull the rear shaft next and check that too but i suspect im going to end up with the same vibe at 45MHP that i had before.
so before i go spending money on front uppers, could that 2* difference in the drive shaft and pinion cause that vibe im feeling? Or am i worrying about something that isnt that big of a deal and its just a product of driving a jeep with MTs and 4.88s?
Last thing i want to do is grenade my Rubi T-Case due to a vibration i failed to address. :icon_crazy: