ok guys... i was wondering if anyone knew what could be the cause of the problem. while i am slowing down (25 mph and below) or taking off (20 mph and below) i notice this rotation viberation (dont know any other way to put it) its really bad when i am slowing down. it makes the whole truck shake and it also makes like a deep waa waa waa noise ( hehe..sorry for the bad sounds with words) the tires (Michelin XCX/APT) are loud but im not sure if that would cause them to be. the steering wheel also shakes. could it just need the tires balanced and rotated? bad cv joints? any ideas guys? thanks a lot. sorry for using "slowing down" a lot but this is when i really notice it.


i have a 1990 4runner 4x4...just incase you didnt notice below...

 

My guesses would be wheel bearing(s) or driveshaft.

 

I had a wheel bearing go on one of my back wheels and it made a sound similar to the one you are describing. However, it did not cause my rig to shake - I'm not sure if a front bearing would cause shaking, but I doubt it. Also, when my bearing went, it only whined above 30mph, the opposite of your symptom. If it wasn't for the fact that it only happens at low speeds, I'd guess that it was a ceased front caliper.

 

i just had my front wheel bearings repacked, and brakes done..so im guessing its not them. what would be wrong with the drive shaft? i just lubed it a month or so ago. it does not matter if i am braking or not..it still does it.

 

A worn or unbalanced drive shaft could cause the acceleration shaking. I had the exact same symptoms (accelerating only) on my 79 Supra, and it was the driveshaft balance.

It would lightly shake from 0-30 under hard acceleration.

I dont know about the deceleration part of the problem...

 

A worn out U-Joint on the driveshaft will also cause the symptoms you described. Never heard one make a noise though.

 

hmm...i guess its not making a noise...the waa waa waa is the vibration or shaking manor(know what i mean?) any ideas on what to do?

 

Crawl under your truck and grab the driveline with both hands and see if you can feel any excessive slack in it when you try and turn it from side to side. Make sure you have it in gear. It should feel pretty solid if you get any slop try and locate it and go from there.

 

ok..i did this tonight after work..and its solid. i looked at the u-joints and they didnt look bad..but im know things arent always as they appear. what do i do now?

 

 

When is the last time you rotated the tires? Sometimes the tires from not being rotated/balanced/air pressure maintained frequently wear uneven. You might be noticing the noise more frequently when "slowing down" because the weight transfer from back to front causes the tires to become pre-loaded and any imperfections (flat spots, cupping) can cause the noise you are describing. I have a similar noise problem on my explorer with Goodyears. Started to rotate the tires every other oil change and the noise has almost disapeared. Just a thought.