Tranny??? Help??

[vermonttacoma]

I have a 98 tacoma 4x4 2.7. After getting it real muddy it usually vibrates some on the highway. The vibration goes away after hosing off the undercarridge.

A couple of weeks ago it began vibrating REALLY bad, but only at 40mph and above and only while accellerating. I've pressure washed everything underneath multiple times. Going down hills at speeds above 40 mph, it does not vibrate.

I have not taken it off road anytime in the last month or two. The only thing that I can think of that could have hurt it was that my friend barrowed it. He got it stuck in a field (wet grass) and got towed out because he didn't realize it had manual hubs. I was not there, however I doubt he could have managed to blow the transmission.

So it seams to be directly relating to acceleration. I'd assume this means theres somthing wrong with the transmission, rear diff, drive shaft...SOMETHING that transmits torque from the engine to the wheels.

I beat it pretty hard when 4x4ing, but with only 112k miles and a new clutch I wouldn't think the drivetrain is anywhere near the end of its life. The only mods on it are 31"mudders (225-75;s were stock).

I'm pretty good in maintaining it, although I havn't changed the 'grease' in the diffs since 80k.

Do any of you guys have any ideas what might be wrong? The vibration is VERY noticable, and only during accelleration (or even when given very slight throttle when in gear) over 40mph.
I'd appriciate any help alot.

Thanks, Ben

[DeadlyPeace]

Try checking the driveline for play. I'd say that you more then likely have a bad u-joint.

[danstoy]

pull the rear shaft and ck for a tight u-j, poss may be a cv joint (the part that has 2 u-js) or loose as far as that goes..

[89toyrobb]

yeah u-joints,but at the beginning of the post before you stated under accel only I would of said mud in the rims which cause an out of balance condition. Even a small amount of mud will cause really bad vibrations. The first time it happened to me I thought my truck was gonna fall apart! Remember My cousin Vinny!

[89toyrobb]

to be more clear.. the mud in the rims would vibrate all the time not just accel.

[vermonttacoma]

Thanks for your help guys. I checked things out yesterday. I can turn u-joint a few degrees in each direction. It doesn't wiggle back and forth at all but it will rotate to some extent. I dont know if that qualifies as 'play'.

Another thing i noticed was a high pitched squeaking or rubbing sound that gets faster and louder the faster i accelerate, even at speeds under 40. I think it is probably due to the same problem.

I'm probably going to take it into a shop sometime this week. I'm at college and all my tools are 200miles away. From the way it vibrates at highway speed I dont think i should risk the drive.

Thanks again
Ben