2006 4x4 double cab, 120K miles, just put on front 5100's set at 2.5". Did all the work myself by the book. No diff drop was installed.
Had it aligned and I have WICKED vibes between 25 and 40 mph (I didn't even try driving faster than that for fear of blowing something up). I did the test that has been discussed a number of times to diagnose a potential front diff problem -- switched to 4H and, indeed, the instant I switched the vibes disappeared, and the instant I switched back to 2H the vibes re-appeared. I have read a number of posts here that suggest that this is indicative of a blown front diff bearing.
But I called 3 different Toyota stealerships, 4 different 4wheelparts stores, and 1 Les Schwab store that does its own 5100 installs and none of the 10+ different people that I talked to at all these places had ever heard of such a thing. ALL the people I talked to said that they had never received one complaint about vibes developing after lifting a Taco 2.5" -- they've only heard of vibes with 3" or greater lifts. These places have collectively lifted hundres of Tacomas and this was a mystery to everyone.
But there are threads upon threads here about vibes with as little as .85" of lift, so what gives???
As of now, I am planning on disassembling everything and resetting to 0" lift so I have time to reassess the situation. Any thoughts?