Front end vibration through floor

I recently bought an 02 Tacoma 4x4, V6, Auto and did a huge service when I bought it because nothing was really done by the previous owner. I had the front and rear diff fluids changed and also added the Bilstein 5100's up front set at the middle ring. After I got it back, there is a vibration / growl between 40-50mph.

Ive searched and found some threads on it, but no real answers. The vibrations go away when 4wd is engaged. Some say wheel bearings, others say some bearing in the front diff, but has anyone narrowed it down to a specific item?

 

Several things occur to me after reading this. In no particular order, I would check:

front diff fluid level, especially if someone else did the service

wheel balance, especially on the front wheels

Alignment. You did have it aligned after adding the lift, right?

Inspect the inner and outer cv axle boots. Verify none of the fins on the boots are touching their neighbor.

In general, vibs at 40-50 are wheel vibs, vibs transmitted/felt in the steering are front wheels, vibs felt in your seat are from the rear. You did not mention what you did to lift the rear.

Finally, I had a high speed vib post lift, similar to what you describe. It only showed up at 50-55 mph. Faster and slower it would disappear. I found that some of the inner cv boot fins were just barely touching, enough where a small groove in the rubber had begun to appear.

 

i would say the first thing and easiest thing you could do is, jack up the front end and spin the tires and listen for a worn bearing.

My 01 right front bearing just went out, had a growl and vibration in the floor board.

 

the biggest give away is that the vibration goes away in 4WD.. if it's wheel bearing, that would not be the case.

It's most likely the front diff bearing. Google up on it.. it's not just the Tacoma, there will be many examples of other trucks with this "rumble strip" vibration in 2WD.

 

How involved is replacing the front diff bearing?