Hello everyone, i'm new to both Toyota's and this forum and hope your knowledge can help me out. i have a 90 4runner (auto), the vibration comes during highway speeds of 55+ and gets more intense as the speed increases. the tricky problem is it seams to happen only when there is no force being applied to the drive shaft. in other words when accelerating no vibration, and when engine is braking also no vibration. the vibration happens in a "sweet" spot between the two. also under cruise control and going down hill it seems to find this sweet spot and the vibration is constant. i have checked the u-joint they are nice and tight, i can rotate the drive shaft about a 1/4 in in rotation by hand but no side to side or up an down movement. please help me diagnose the issue.

 

The driveshaft will always have play in it. check the U joints again would be my suggestions

 

I had a u-joint that felt right with the driveshaft installed, but was fubar when on the workbench...... replaced and vibration went away......

something in your tire(s) maybe?

Perhaps a bearing spun into oblivion in your 3rd member..... or t-case..... or worse, its all in your head! (the one attached to your neck, of course).......

 

These guys are right, but I wanted to clarify. Are you checking the u-joints when there is a load on them? as in sitting in park? try chalking the wheels, and leaving the transmission in neutral instead of park. I had a similar problem, as my u-joints would feel fine when the truck was parked in gear. I happened to be greasing them one day, under the truck with it in neutral, and noticed sloppiness in the pinion u-joint. If I hadn't done that, I'd still be chasing my tail tryin to find my vibration.

 

Well I replaced all of my ujoints and I still get the noise in mine... so let me know if you figure out what it is. Both my differential and t-case main nuts are tight so the flange isn't loose... who knows.

 

Ditto to all of this! Check those u joints! I just corrected this problem last week and once the shaft was off my joints were clearly fubar.

 

when i checked my u joint the truck was in park i will check them in neutral and also remove the drive shaft. if it is the u joint then i'm hoping i'll notice it right away. i'll keep you guys posted, thank you all

 

sorry for the delay in response. i change both u joint and the vibration is a lot less now but still there my next guess would be the transmission mount. ant thoughts???

 

Balance the driveshaft.

:wabbit2:

 

If you pull the driveshaft to have it balanced, go ahead and throw it in 4wd and drive around see if the vibration persists with the rear DS out. While the DS is out tighten your flange nuts on rear differential and/or transfer case. I forget the size (1 3/16" socket worked, IIRC) and torque to 90ish lb. The nut is staked, and you'll have to unstake it somehow.

 

30mm

I'm assuming you put dshaft back together in phase.

:wabbit2:

 

confirm your dshaft is installed correctly. there's a diagram in the FSM which illustrates the orientation of the grease zerks when you look at it from one end.

if any segments of the d-shaft were reassembled incorrectly, those zerks will show it.

this is what wabbit meant by "out of phase". one end could be 180* the wrong way. first thread in my search results had this link:
http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

 

sounds like a pinion bearing to me, any slop

 

The all have some rotation slop. He stated no up and down movement.

 

mine had alot of vibration , even after changing ujoints. I great the slip yoke real real good and almost all of it has disappeared. just a slight amout when coasting in neutral or just a slight amout of throttle.

 

makes sense a little grease can take up some of the slop if its good stuff i use chemsearch maxilube #2, H2. it is awesome and about 23 bucks a tube. itt sounds like alot but i service equipment for a living and alot of bearings werent survivng the water penetrarion between greasing with cheap grease and this stuff i can cut the schedule in half and bearing last for years now and im not changing them every season, a little off topic but when dealing with u joints the best grease is the best. the downside is you have to buy a whole case. if your new joints are in phase and no slop anywhere maybe a simple balance will solve it

 

i never even thought about the phasing. in fact i never new it to be an issue but after reading the article you guys gave me earlier, i will check that out. also i will check the torque on the pinion nut. and grease the slip yolk

a lot of info guy thanks a lot i'll work on the old girl tomorrow and let you guys know

 

I usually find no-load vibration is often due to something being loose. Just fixed a mild vibe in mine due to a slightly loose pinion flange nut. But could be either flange, the u-joints or the slip yoke, grease it well and see what happens. I like to pull it apart and brush grease on the splines vs. just relying on grease from the fitting getting to it.

Reason why is at no load, loose parts can vibrate, under load, they tighten up and the vibration usually stops.