99 Suburban Highway Rumble

[Buick]

My suspicion tends toward the wheels. could one be out of true a bit? Since it only happens at a certain speed it sounds like some kind of harmonic. Before I dug into it I would try to borrow a full set of tires/wheels and switch them out and see if anything changes. I know you said no difference between old tires and new but the wheels have always been the same if I read it right.

That’s correct, same wheels. If I can find a place that will road force balance, I may give it a shot.

 

[Buick]

My Trailblazer had a terrible highway vibration, worst at ~73 mph. Seemingly gone below 68 mph, gone above 80.

Rear U-joint was chewed-up; coupled to a rear driveshaft that wasn't perfectly true. The driveshaft shop claimed they got "most" of the bend out of the shaft; and they installed new front and rear U-joints on that rear driveshaft. Perfectly smooth afterwards--in fact, once the vibration was MISSING, I realized that I'd had minor vibration from 25 mph on up.

Lasted about two years and then came back--same vibration, same speeds.

Looked at the rear U-joint. Perfect.

Went to the Treasure Yard, got a whole different rear driveshaft. Put a rear U-joint in that one (cause it was totaled) and installed that shaft on my Trailblazer.

AGAIN, found that I'd had minor vibration starting at 25 mph that was now GONE. That's about two years ago--so far, so good.

Unfortunately, he replaced the drive shaft with a brand new fabricated & balanced unit with new spicer ujoints and it did not solve the problem. I don’t believe it is a driveshaft problem.

 

[Erik the Awful]

- New Rear Driveshaft & U-Joints (single piece driveshaft)

For once I tried to read the original post carefully. He gives us plenty of information, and the only thing I could spot was the rear wheel bearings and diff bearings.

 

[Coveman]

Its not an exhaust drone is it? I removed the rear carpet to clean up a mess and it was crazy loud on the freeway.

 

[Buick]

Its not an exhaust drone is it? I removed the rear carpet to clean up a mess and it was crazy loud on the freeway.

Nope, throwing it in neutral and coasting on the highway with engine off does not change the sound.

 

[MechMike]

I’m dying to know what happened here. Let’s see if I can resurrect this! I have seemingly the same issue (99c1500 suburban). I have replaced the rear wheel bearings and hasn’t really changed anything. Now I haven’t don’t anything else to remedy this but really don’t have the time or $ to just throw parts at it. (Also always ends in a screaming match with my wife…she has no respect for the ol’ girl).

PLEASE UPDATE IF YOU CAN!

 

[Schurkey]

One-piece rear driveshaft? Costs nothing to pull four bolts, drop the driveshaft OUT, and pull the caps on the rear U-joint.

One wonders if the original poster was so careful to mention "one piece driveshaft" because it was converted from a two-piece shaft, and the new, too-long shaft is getting close to critical speed.

 

[Macs Garage]

I had u joints sieze once. Had a vibration and little hum. Drove me and the tire guy nuts. Never considered the u joints because they weren't very old. Finally the u joint broke and then there was a lot of noise and a beat and bent drive shaft. Replaced the drive shaft. Now every time I change oil I drop the drive shaft out and make sure the u joints are getting grease. Moral of the story is just because something was replaced, doesn't always mean it was installed correctly, or just a bad replacement part. No one has mentioned from hubs?

 

[GoToGuy]

Said front hubs done during major service. Crap hubs?

 

[MechMike]

One-piece rear driveshaft? Costs nothing to pull four bolts, drop the driveshaft OUT, and pull the caps on the rear U-joint.

One wonders if the original poster was so careful to mention "one piece driveshaft" because it was converted from a two-piece shaft, and the new, too-long shaft is getting close to critical speed.

Yes one piece aluminum driveshaft. 155k they were def replaced at some point. I have no problem putting u joints in because I know I have a slight pinion seal leak so that’s getting fixed in the near future.