2009 Chevrolet Suburban vibration

chevrolet
suburban

#1

I have a 4x4 Z71 2009 Chevy Suburban with 178,000mi. It has a vibration that is very slightly felt at 55-60, and by 78 the car is shaking like a high school kid on prom night, and then 90-95 it dissipates (what ever causes the vibration is going too fast at that point). The vibration is not RPM dependent, but speed dependent. While car idles, the motor hesitates occasionally. New MOOG suspension and front hubs (everything new, dropped all parts and installed new at one time to avoid doing the same work over and over), U-joints on the main shaft, all fluids changed / inspected, new carrier bearings on the rear axle, new motor mounts and transmission mount, P0304 cylinder “misfire in cylinder 4” code, oil consumption issue (Moroso air/oil filter installed in PCV system to prevent oil into the intake manifold), new wheels (2018 stock), new tires (BFG). Here’s the fun part, the vehicle is a work vehicle, and carries 3-450 lbs of medical equipment in the cargo area. When unloaded it seems the vibration is less. Besides purchasing a new rear axle, t-case and front differential, what can I do?


#2

Well , I don’t know what the cause is but I do know that driving 90 to 95 in a vehicle that vibrates and shakes is not wise.


#3

Given how much work was done and what work was done, I’d start with balancing the wheels. I’d check the u-joints while it was up to see if one is loose. Check the pinion shaft on the axle for looseness and smooth rotation as well. The pinion bearings might be failing.

I’d also look for tell-tale marks where a driveshaft weight WAS but isn’t now. Could have been knocked off when servicing. It could be an un-balanced driveshaft causing this based on more vibration with a load than without.


#4

I would suggest figuring out if the vibration is in the front or the rear (Hint: Steering wheel = front, seat back = rear)

Then rotate the tires front to rear. Did the vibration move? If so, then it is tires/ wheels/ etc.

If not, it is something else. I’m going to guess it is U joints.


#5

When the U-joints were replaced, Was the slip joint properly clocked?

I realize the vibration was there before the U-Joint replacement, but if they have been replaced before, the slip joint may have been improperly clocked then and re-assembled incorrectly the 2nd time also.


#6

do you need the 4 wheel drive? You could remove the driveshaft for the front diff and see if that helps (i don’t seem to see where you addressed anything on this driveshaft.)
Many moons ago, I was told removing the front driveshaft would help fuel mileage. It didn’t seem to do much, though.