I have a 1990 4runner 3.0 Auto transmission, once in a while I would get vibration from an unknown place while driving in short intervals not related to any specific speed. Recently it will start every time I drive it, stopping a few seconds before I stop. I feel it slightly, sounds like the rear end of the vehicle has something rubbing. I've found nothing indicating contact, damage, or wear. None of the rims feel even remotely warm like I have a bearing conducting heat. Braking has no effect on it, nor will it happen while idling. Ant advice would be great

 

First jack it up with the bottle jack and check the driveline.

Youtube for "checking u-joints"

 

u joints were a bit floppy on the rear driveline and needing grease for sure, but there wasn't any play in them. I also found the steering idler has a bunch of play, two bolts on the front sway bar were backing out, and the lugs on my front driver wheel weren't quite tight enough. There is some play on the rear diff too. I could rotate the pinion flange about 3/16 too 1/4". pinion nut was tight with no signs of backing off. I'm going to swap out the idler because I have a good one from a sas job last year and Ill probably swap out the u joints too just to be sure.

 

Remove rear driveline and test in front wheel drive. Vibration gone? Ujoints or slipjoint or balancing.

 

Yes, above checks with all wheels off the ground.
Control rpm remotely with this:


Listen with organic stethoscope

 

I swapped out the idler arm Sunday night, but didn't have time to replace the u joints. a good bit of the vibration has stopped with that alone. I no longer feel it in the steering wheel. I greased the damper (not sure what it is called really) for my 4wd linkage where it drops down behind the transfer case before wrapping around to the drivers side also. that still makes a small bit of noise, but quieted down significantly also. I'm sure its the u joints causing it now. I greased them up and took it for a little roll up the street and they were silent, on my way home from work the next day it started making noise again. It sounds like a u joint issue now though, like some of the other sounds and feelings were making it difficult to weed it out.