Cause(s) of driveline vibration (1 Viewer)

[ATBScott]

I also posted this in the general tech forum - hadn't had a response from that, and since this is in my GX I was hoping someone here may be more likely to have an idea if I am barking up the right tree....

... 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

 

[Brake Weight]

I don't see a need to change shaft section. Just swap out the U joint and enjoy it. I had one go out on my Tacoma years ago and the parts house couldn't get a greaseable in a sufficient amount of time for me to go to work so I put in a non-greaseable and it's still rolling along. Probably has 90,000 miles on it since. Just a thought.

Take it for a quick spin and once you get to where it vibrates the worse, put it in Neutral and let it coast. If it stops the vibrating it is surely a U joint. Do you remember if the shaft sections have the little counterweight tabs welded onto them? May have possibly had one pulled off crawling by previous owner. If there aren't any look for paint discoloration where there may have been one.

 

[TahoeLX450]

Like above it's probably a U joint...But, that said, did the truck sit for a long period of time? Flat spots on the tires or treads separating from the carcass of the tire can also cause a slow speed vibration that decreases with speed as opposed to a wheel/tire out of balance which is more pronounced at speed.