Posted by ezobens on November 19, 04 at 06:44:16:
I have a 1985 K1500 GMC Suburban with 88K miles. This truck is in great shape for it's vintage but I've had this nagging issue since I bought it about a year ago.
At speeds above 35MPH or so (it varies with intensity at any given speed), I get this low frequency rumble or vibration that is driving me crazy. I don't feel anything in the steering wheel but I watch the center console trying to rip itself from the floor due to this vibration.
I am running Goodyear 'Tracker' 31x10.5x15's all the way around (Wal-Mart private label) that have less than 10K on them (they came with the truck). The alignment is right on (ball joints, springs, tie rods are all tight and to spec), I have the tires all balanced and the front/rear axle bearings are all new and to spec. I even replaced ALL the u-joints on the front/rear driveshafts and the front axle to no avail.
Since I am running out of ideas, the only thing I have noticed is that the rear axle (and the front axle, to a lesser degree) doesn't appear to be centered from one side to the other. Measuring from the front mounting bolt of the leaf spring to the centerline of the axle, I am off about 1/2" from side to side. The same is true when I measure the distance from the tire itself to the edge of the wheel well. To me, this doesn't seem right and the factory shop manual doesn't make any comment as to how to align the axles on the springs or if it even needs to be checked.
Driving the truck, it doesn't seem to be dog-tracking, but without following it I can't be sure. Shouldn't the front/rear axles sit perfectly perpendicular to the frame/centerline of the truck? Would this being off by 1/2" introduce the vibration that I am experiencing?
By the way, the rear springs are new and were recently replaced by the former owner (why do the 4x4 solid axle Suburbans always sit higher in the front than the rear, even with new rear springs?).
Any suggestions and advice would be greatly appreciated. Thanks!