Bad Vibration at 5MPH

I have fought with Toyota and opened a case, but they still maintain this behavior is normal (It isn't).

http://www.tacomaworld.com/forum/2nd-gen-tacomas/132447-vibration-24-29-mph.html

http://www.tacomaworld.com/forum/2nd-gen-tacomas/136672-fixed-more-vibes-free.html

I plan on realigning the carrier bearing and potentially dropping it 1/4"-1/2" (Seems a bit much for just the Rear Leaf TSB) but I did have a question.

I do experience the take off shudder (Probably most likely ~5MPH) and the vibrations ~25, but at 5MPH the whole truck is practically bouncing up and down (Just coasting at 5MPH). ONLY at 5MPH (+/- 1MPH). The frequency is lower than the other vibrations - could this still be the carrier bearing and drive angle?

Additionally, as a general question, why would the vibrations only appear at certain speeds? Simple harmonics blending into the rest of the car or something?

Thanks,
-SP

 

i have some similar problems after adding my lift but i went and lowered my CB and i still feel the vibes at low speed and then again at 60 on the HWY but i really dont know what it could be. I have looked into everything.

 

I just started experiencing this issue about a week ago. Took it to a mechanic who told me the tires were faulty. So I went to pep boys where I got my tires (cooper discoverer at3 with 8,000 miles on them). They proceed to tell me my suspension is shot and my tires are cupped causing the vibrations. $1,200 Of brand new suspension all around and new tires later and I’m still having the problem. There giving me some Falken wildpeak A/t3W’s because he said it could be the tire brand causing it. I then “had some words” (To put it nicely) with him before agreeing to take the wildpeaks. To be fair my OEM bilsteins were in rough shape but I Wish I would have known this is an issue.

 

I also have falken wildpeak A/T3W'S it vibrate early in the morning when the tires are cold, after a few miles the vibration goes away, and it drives great.

 

So... are those tires made from the same material as the Space Shuttle O-rings?