chief_shotts
Member
- Joined
- Nov 29, 2021
- Posts
- 40
- Reaction score
- 36
- Location
- beaverton, OR
- First Name
- edgar
- Truck Year
- 1986
- Truck Model
- k30
- Engine Size
- 383
The truck in question is a 1982 k30 crew cab with 6In of lift.
I've recently been experiencing some vibrations at about 3k + Rpms. The vibrations come on with a pulsation to them. The pulsating vibes directly correspond to an increase in rpm and subsequently decrease as rpm slows. No recognizable vibration at anything below 3K rpm.
The engine is fresh.. maybe 500-1500 miles. The transmission, transfer case, and rear diff are all relatively low miles (more than 500 less than 10,000). I just got done rebuilding the front dana 60, king pins, and hubs a week ago. I was convinced the vibes were coming from something in the front axle as it was in rough condition.... no change.
A few days ago when inspecting the rear axle i noticed something odd. See for your self...
As you can see the u bolts, saddle and spring are a bit cockeyed... or the axle housing is cockeyed on the springs.
My current theory is that the u bolts were unevenly torqued from the beginning therefore holding the axle housing at an angle or the ubolts were loose and the axle housing and bocks shifted under hard driving conditions ( lots of axle wrap). Regardless of how it happened the axle housing/lift blocks are not resting evenly on the leaf springs causing my pinion angle to be off by a few degrees. And as engine speed increases, the torque increase, the axle wrap increases, and my already incorrect pinion angle increases more and that is what is causing the pulsating vibrations.
Id like to know if my logic is logic-ing. Does my theory sound about right? Obviously ill be replacing the u bolts regardless because what's going on in those pics definitely isn't right.
I've recently been experiencing some vibrations at about 3k + Rpms. The vibrations come on with a pulsation to them. The pulsating vibes directly correspond to an increase in rpm and subsequently decrease as rpm slows. No recognizable vibration at anything below 3K rpm.
The engine is fresh.. maybe 500-1500 miles. The transmission, transfer case, and rear diff are all relatively low miles (more than 500 less than 10,000). I just got done rebuilding the front dana 60, king pins, and hubs a week ago. I was convinced the vibes were coming from something in the front axle as it was in rough condition.... no change.
A few days ago when inspecting the rear axle i noticed something odd. See for your self...
You must be registered for see images attach
You must be registered for see images attach
As you can see the u bolts, saddle and spring are a bit cockeyed... or the axle housing is cockeyed on the springs.
My current theory is that the u bolts were unevenly torqued from the beginning therefore holding the axle housing at an angle or the ubolts were loose and the axle housing and bocks shifted under hard driving conditions ( lots of axle wrap). Regardless of how it happened the axle housing/lift blocks are not resting evenly on the leaf springs causing my pinion angle to be off by a few degrees. And as engine speed increases, the torque increase, the axle wrap increases, and my already incorrect pinion angle increases more and that is what is causing the pulsating vibrations.
Id like to know if my logic is logic-ing. Does my theory sound about right? Obviously ill be replacing the u bolts regardless because what's going on in those pics definitely isn't right.
