Thump from under seat on hard acceleration

Replaced u joints at 80k. With greasable ones that I keep pulled full every oil change.

It's a pretty significant slamming sound/thump that radiates through my seat when I accelerate hard on the freeway. There is no thump coming off a stop or slowing down.

I'm thinking transmission mount? Thoughts? 06 prerunner.

 

Are you sure there isn't something under the seat that rolls around on hard acceleration?

 

Most definitely not. It's coming from the drivetrain.

 

How is the center bearing?

 

That sounds like dry or bad u-joints to me, my '04 does the same thing when I shift gears under heavy load...I can feel it "THUD" underneath me where the driveshaft is. It gets better when I grease it up. Weird that your's is doing it with brand new ones, I wonder if it's coming from the transmission and not the driveshaft? Transmission serviced regularly?

 

If your certain it isn't the u-joints I'd check the carrier bearing. Also 05 and some 06 Tacoma's had weak motor mounts, maybe one is cracked or damaged causing the thud, would also be worth a look.

 

I'm at 104k now so my ujoints aren't exactly new. And when they went bad last time I shook so bad on the freeway the rearview mirror wasn't usable. So different symptoms

 

Yea I started reading about the motor mount issues today. Gonna crawl under it this afternoon for an inspection..

And as for the center bearing.. It's original... I did the Ome drop bracket a few years ago to help relieve the 10-15mph shake.. It helped tremendously.. I may temporarily remove it and see if it gets better/worse.

 

Since you're a prerunner, there's no slip yoke. I know when I lifted mine the driveshaft was too short and kept pulling out the center of the carrier bearing. I ordered a drive shaft spacer to alleviate that and my bearings have been lasting longer. 104k is a long time on that stock bearing for a 2wd.

 

My 05 did this on hard accelerations after my frame replacement
I flipped my carrier bearing and it stopped
the bearing is not perfectly center so flipping it lowers the d shaft a little
on hard accelerations the shaft hits the trans tunnel
2 min fix take out 2 bolt rotate bearing put back bolts

didn't realize you had prerunner so i could be wrong
Don't know if you have carrier bearing

 

Sounds like a motor mount. Common in tahoes and suburbans, mostly any gm v8 from 2007 to present. It's funny to watch a v8 jump 6 inches up in the engine bay.