Shaking when accelerating, u joint or trans?

Whenever I get to 2000 RPMs it shakes pretty bad up under the seat, not the steering wheel or dash, and at around 70 mph if you touch the gas at all it shakes and vibrates loudly and when you let off it's completely silent, I thought I had a bad u-joint front end because I can see the bearing dust sprayed all up under the undercarriage and took it to the shop and the guys didn't think it was bad and thought it was the transmission and I keep seeing on here that people got a transmission flush and it fixed the shaking problem, what do you guys think? Also I keep reading that it's bad to flush instead of just refill, I have 264,000 MI and tow a lawn mower and trailor daily for my business,, any thoughts?

 

My second gen had a similar issue last year. Dealership told me it was my “off road tires” which I knew it was not the case. They didn’t even put it on a lift or test drive it …

Took it to another dealer and after a test drive and physical inspection, they found 2 very badly rusted ujoints with the other 2 not far behind. Got them replaced and that took care of the shudder/vibes. (09 OR w/150k at the time)
I was always told to not monkey with high mileage sealed transmissions especially if they haven’t been serviced regularly .

With milage as high as yours, if its not driveline related then a transmission shop would be my next visit. But you may have a hard time having a shop to just do a flush, as any damage is already done and the old fluid is whats keeping it working.

Aside from a flush, Toyota dealers dont work on Tacoma transmissions. They just replace them.

 

Wipe the dipstick and smell, is it black? smell burnt? Maybe its low. Never hurt to check. Last time you did a drain and fill? I wouldnt flush it unless you know when was the last time you did it, I would only do as a last resort.

 

Dipstick

 

My guess is a bad universal joint .
Did the shop remove the driveshaft to inspect your universal joints ? You cant tell if they are seized when the driveshaft is on the truck . Its only 10 bolts to check

Will you be doing any diagnostics yourself or taking the truck to a shop to have any worked performed ?
Considering your transmission is a sealed 5 speed automatic , does the vibration continue when you use 4th gear instead of 5th ?

There is a vibration thread here that will help you narrow things down ?
Go down the list and eliminate possibilites
https://www.tacomaworld.com/threads/vibration-diagnostics-for-all-tacomas-write-up.520607/

 

Hello! 2008 Tacoma sport 264k miles shuddering and vibrating under seat whenever i hit 2k rpm or hard acceleration but only does this towards the end of a gear or higher rpm,, not at all at low rpm or from a start,,, i was sure it was my front ujoint as i saw the bearing dust stripe on my undercarriage but the shop said no they think its transmission. Ive read alot that a flush fixed this problem and u joints. Do you think i should change it out and this might work and if so do i HAVE to change filter? or does his sound like ujoint? One day i did hear i tiny squeak from ubder the truck when i accelerated further making me think its a u joint. BUT i got the truck at 100k miles and is now 264k and ive NEVER changed the fluid yet (i know dont hate me),, any suggestions? Great channel btw, open to anyone who wants to help thanks!

 

It's not the tranny if it doesn't do it at low speed/ rpms.

U joint or wheel bearing is my guess.

 

When was last engine tune up ? spark plugs , throttle body cleaning ?


How to properly service a transmission .
https://www.tacomaworld.com/threads...e-2nd-gen-transmission-pan-and-filter.726329/

 

Its spark plugs were changed a couple years ago (regular mileage per year 15kish), nothing else done ever except oil changes,,, i am getting a a hit on the scanner but its just the 0456 (small leak in the evap system) which i think is just my gas cap or something simple but also ive had problems in he past with he mass airflow sensor causing it to start and then immediately shut off and it does that a couole times and i let it sit for 10 minutes and then it starts, inly does that anout once evey 6 months and i e since gotten air flow sensor cleaner and just clean it from time to time until i get a new sensor,,,, from a dead start its fine and if i eeeeease up to a shift i can keep it from doing the shudder but if i hard accelerat or im going up a hill and downshifts for some oomph it does the shudder and i have to let off,, also when its shudderinf theres a noticeable loss of power and it kind of tops out until i let off a but and it kind of pucks up power but during the shudder it will only accelerate so much,,,no ahudder in the dash or steering wheel just the frame and under he seats and floorboard maybe

 

Stall test the truck . If you took it to me , this is one of the first tests I will be performing
Allow your truck to warm up . Truck engine must be warm
You already know you feel vibes at 2000 rpm when the truck is under load at hiway speeds .
Lets do this in your driveway without driving the truck .

Hold your brakes hard and place the transmission into forward .
Slowly hit the gas and bring the rpms up to where you normally feel the vibration ...close to 2000 rpm rite ?
Does the truck shake at 2000 rpm ? you are going to feel the complete truck shake at 2000 rpm but your truck is not moving .Its not going to be the exact shake you feel when moving
Under normal operation as you slowly accelerate the engine will be linear and smooth . RPMs will slowly move up to 2000 rpms and you wont feel anything other than your brakes holding the truck from moving
This is going to eliminate a lot of possibilties
Allow the transmission to cool in park for 5 minutes when you are done .
Report back

 

Awesome will do, thanks!

 

Oh one more thing,,, when i check my driveshaft everybting seems solid wih no play,,, can a bad u joint not have any clank or play and still be bad? Or i suppose it could be solid and just need grease?

 

Golly , thought you were gonna try a stall test in the driveway ?

You gotta take the driveshaft off to determine if the universal joints are pooched . You cant tell if they are seized when the driveshaft is bolted up .The stall test is going to help eliminate the driveshaft universal joints . You can throw as much grease to a seized universal joint and it will still be seized . There are tiny bearings inside each individual universal joint and there are 4 cups of bearings on each joint . There is no way you can tell if they are faulty without removing the driveshaft ..Once again , its only 10 bolts . You need 2 - 14 mill wrenches and a 14 mill socket to drop the drivehsaft to verify your universal joints are working properly . The universal joints should move by hand all the way left and all the way to the right .
Universal joints with grease zerks need to be greased at every oil change just like a lawn mower blade should be sharpened and balanced after every 20 lawns
Go give a stall test a try and report back . Dont be afraid to try a stall test . You are not going to cook your trans by doing this .Allow the transmission to cool in park when your done
Hold brakes hard with the engine warm , put the truck in forward and slowly accelerate to 2000 rpm .
Does the the truck shake and sputter when the engine rpm hits 2000 rpm ?


Picture your lawnmower with a nasty bent blade after accidently hitting a rock . The whole lawn mower is going to shake very very bad . The stall test is like removing the bent lawn mower blade and running the engine on the lawn mower

 

Oh sorry! yeah i deff will, it was about 1030 pm here so i just decided to wait until the morning,, the family was winding down etc,, i really appreciate ya ill let you know asap tomorrow morning but no rush on the realonse i appreciate it