first post and new to the forum, So heres the deal i have a 99 suburban with 105k on it. withing the past 4 months it has developed a very odd vibration that shows up around 50-55 mph and does not go away until the speed is reduced below 50 again. and when i say vibration it is in every inch of the floor and making a god awful moan. So at first i thought it was the u joints because they were factory so i replaced them front and rear, did not fix it. then i went to wheel bearings on both sides, no play but replaced them anyways, did not fix. did the brakes, did not fix. So after that i opened the rear differential and removed the carrier pin and noticed that the bolt that holds it in place was wore terribly and the hole in the carrier pin was all wallered out and my sider gears were wore as well, so i found a smokin deal on a 10 bolt with new yukon axles, i installed it figuring that was the culprit and to my suprise the vibration was there.After that I didnt know what else to do so i put the truck on jack stand and ran it up to 55-60 mph ( i know its not safe) and without the load on the truck the vibration was 100 times worse, i layed on my side and was watching my drive shaft going crazy so I figured that was the issue, go get a new drive shaft re install it and its still vibrating. Im at a loss at this point and trying not to turn this thing into a raging bon fire lol, Im guessing its coming from the transmission now (torque converter) any input would be very appreciated!!

 

Welcome to the forum.

Did the new drive shaft come with new U-joints?

 

no it didnt, but i put new ones in. I've pretty much eliminated all the drive line aft of the transmission.

 

When you are at 55+ and put the transmission in neutral, does the vibration stop?

 

Bad tire? Balance issue? Bent wheel or shaft? Check your rear wheel runout with a dial indicator.


I had two bad tires on my suburban that were causing horrible shaking at highway speed. I doubt it's the torque converter as your RPMs would be relatively low at 55 MPH. You'd have higher RPMs during acceleration at lower speeds and would notice the vibration at certain RPMs.

 

I know it's an old thread. I experienced similar issue. the vibration was caused by the engine misfiring due to bad crankshaft sensor. Look into that and good luck.