So it's been awhile since I have been on here but I just noticed this problem with my 1990 4runner. When I am coasting in gear at between 30-40 miles per hour I get this vibration that is enough to shake the rear window and my toolkit in the back. I also notice it when I am not coasting around the same speed getting on the freeway. Does anybody have any ideas? At first I thought I threw a weight from my tires but found none missing. My tires are BFG's all terrains which where rotated about a month ago and this problem just started a few days ago.

 

if it does it costing and maybe under acel then it could be your ujoints i say check them out buddy

 

hows the steering damper? that could cause a front end shake

 

I had a similar problem but it occured right between 60-65mph - when I got up to speed the Runner would shake pretty bad and then as I increased speed past about 65 it would level off - turned out to be a bent rim - changed the rim and now it seems to be ok - also needed an alignment though so either could have been the cause - hope this helps

 

Drop your rear driveshaft by removing the 4 bolts at each end (make match marks on the flanges so they line back up perfectly) and drive around in 4 wheel drive. If the vibration goes away, it's most likely a U-joint. If it stays, it's probably a rim or wheel bearings.

 

I'm sorta with JohnP here on this one, but I'm gonna maybe go a little beyond bent rim, but maybe out-of-round tire.
machine balancing can sometimes compensate for (on the machine at least) a bent rim or out-of-round tire.
But put it back on the truck and the rim is still bend or the tire is still not round, so things bounce and you get a vibration.

also, how old are your shock absobers?

 

Thanks for the input. After crawling around and getting dirty I found that my rear u-joint was loose slightly and a consult with a friend of mine who is a mechanic for a yota dealership here confirmed it. So we swapped runners and he is fixing it for me at the dealership with all the right tools.