Another Vibration thread, but with a twist!

2005 v6 manual trd OR, 76k on the clock.

at random points in time, at random speeds from 60-80 plus, i get a very bad rear end vibration. it does not get better if you go faster. it gets worse. if you slow down, it also stays there and does not go away until you get back below 55 ish. and it is VIOLENT. like scares me violent. and it has slowly gotten worse... i can feel it in my feet/ass whole cab shakes.

Sometimes though, it will cruise 75-80 and feel like a Cadillac!? so naturally i just ignored it. until now, as its happening more often....this has been going on for 6 months ish.

i put brand new tires on it falken AT4W's, changed all diff fluid (rear diff was terrible tbh, but i filled, ran for 100 miles, then emptied filled again to flush it) nothing really changed. rotated tires after 5k, vibration was still in rear, so im assuming its not balance.

Initially, i thought it was the blown suspension( it was blown, og 20 year old struts lol), so i redid all of it.....2" lift all around, new leafs(icon), new struts(5100s), new bumps (archive/wheelers), new front coils(ome), Uca's(jba), Ecgs bushing, and of course an alignment. this changed nothing in terms of vibration. and the truck acted exactly as before.

so, at this point with it being a 20 year old truck with original drive line, i got u joints, and a carrier bearing...... well today i took the drive shaft off, took the u joints out, and and the u joints were.....PERFECT. clean grease, all needles there, intact. to me it seemed i touched them for no reason, but maybe im missing something.......

My hope is. it was just the carrier bearing.... if its not that..........could it be my rear diff?
The rear wheel bearings sound fine and feel fine. could those still be going bad?

all driveshaft weights are there too.

Any insight where to check next would be helpful

 

you bought square tires, Road force match them

 

A Subaru I recently fixed had a bad front wheel bearing. It made no noise and I couldn't feel any play.
Using a gauge I measured axial play at 0.008" (spec is 0.002" max).
I tried everything else, so I replaced the bearing/hub. Problem solved.

I'm thinking that Toyota also probably has a method/spec for measuring the bearing play.
If it's out of spec, replace.