Cause(s) of what seems to be driveline vibration...

[ATBScott]

Hi all, I'm a newb to these forums. Recently purchased an '04 GX 470 with 208K miles. Overall in nice shape, a bit of paint fade but I think it will polish out. I have noticed a low-to-mid frequency vibration. The sensation is that the entire vehicle seems to have a gentle pulse or thrum as I am driving. Becomes very apparent at around 20 mph, and it increases in frequency with speed. No change as the tranny shifts, etc... Pretty much goes away by about 55-60. I had a vehicle in the past that had a U-joint go out on me and it was a similar feeling (though the old one was worse) and it clunked as I started out. The GX does not have a clunk when starting or letting up on the accelerator. I crawled under the rig and gave each drive shaft a push. I couldn't feel any play, but I am wondering if it could be resistance in an older U-joint bearing? I Know it is at a frequency that is about 3-4 times the speed of the tires. I can't see any weights missing on the driveshaft in the rear. Need to jack it up to get a better look at the front.

Picked up a grease gun this evening to inject new lube into the Joints. I figured I'll start with the rear-most first, then drive it. Then the front of the rear shaft, etc... until the noise disappears, just to ID the bad UJ. I'll lube all of them. If this cures the vibration I'll replace both the joints in the offending shaft, and get to the other one a bit later. Is there anything else I should consider as being the cause of this vibration? Excited about the "new" rig, but a bit bummed I am working on it already.

Thanks for any input!
ATBScott

 

[toyotaboy80]

Is there a carrier bearing in that truck?
Pull the shafts and feel the joints. They should be tight play wise and smooth rotationally. Grease wont necessarily rule out a fk'd u-joint. Slip joints should have little to zero radial or rotational play.