21 Tacoma still vibrates after TSB.

I have a 21 Tacoma 4door long bed 4x4 automatic. From mile 0 to now 11,000 the truck will shake when slowing down to a stop, downshifting makes it work. It will still vibrate while slowing down even if I am not using the brakes but it most noticeable when I do use the brakes. I can also pull up on the e brake it will vibrate. Here where it gets confusing. It does NOT do it all the time. Sometime it will be smooth as butter and others it feels like the truck is going to shake apart. So I took it to the dealer and the agreed with me. The replaces the rear drums, surfaced the front rotors and replaces the rear leaf spring under a TSB. T-SB-0071-19. All the work changed nothing. At first I thought warped drums, but it doesn’t do it all the time. Then I thought maybe the pinion angle is off when braking because of the leaf springs. Now I have no idea. Anyone have any insight on the issue? The truck is going back to the dealer in about a week. Here is the link to the TSB. I would say the TSB describes the problem well


https://static.nhtsa.gov/odi/tsbs/2020/MC-10187246-9999.pdf

 

keep bringing it back with the same complain. Document what has been done, dates and by whom. Win the Lemon arbitration and you'll end up with a brand new 2022. Gluck.

 

Ok I'm confused. That TSB covers through MY 2019. You said you had a 2021. How does it apply to your truck?

 

What do you mean by, "downshifting makes it work"?

 

I think he meant "worse". Come on, don't you speak typo? LOL

 

Don’t use your brakes

 

I’ve learned to speak not only typo but also autocorrect in these modern times haha

 

No, I doughnut.

 

Oops. “Worse”

 

yes it applies to my truck. 2016-2021

 

Downshifting is the computer or you in S-mode

 

That would be cool. Time will tell on this one. Thanks

 

When the computer makes it downshift.

 

Just had my 2021 access cab tacoma fixed for the 25 mph area vibration.
They replaced the leaf springs, added a steering wheel damper and checked the drive shaft angle. Now it drives so much better with almost no detectable vibration... I noticed this issue at about 400 miles on the truck.
I had a 2010 v6 4.0 tacoma for 10 years so I was so disappointed to deal with this from a brand new truck also the service tech told me this issue has been active in tacomas since 2015

 

In particular speed range?
I'm guessing around 35mph?

 

Mine was at 25 mph mainly but could also feel it anywhere between 20 - 30

 

I said the same thing ...but they did fix it with no cost to me except my time

 

it’s most noticeable below 35 mph but it will do it at any speed. I can just drive down the highway and gently pull up on the E break and it will do it most of the time. It feels exactly like warped brakes.

 

I can't understand how leaf springs would cause this but I assuming that toyota is making changes to them to fix this issue.
I will check my paperwork an see if they did a direct replacement or if it was a new part #.

 

I think what is happening is the “driveline” angles change when the rear brakes are applied or you give it gas. The axle is twisting up when you give it gas and down when you break. The leaf springs that were in it we’re not strong enough to counteract those effects. The leaf springs that they put in it seem way stronger. I think this is also called axle wrap. when the driveline angles become too much it can cause vibrations.