Vibration in the drivetrain...

2004 4x4 Tacoma:
I have researched and read and researched for the typical things that cause a vibration in the drivetrain. And I'm still baffled.
1. I replaced the needle bearing in the front diff that was really worn. Got the new one from East Coast Gear.
2. New CV shafts.
3. New drive shaft carrier bearing that appeared to be well worn. All the u-joints appeared to be in good shape. Greased them.
4. New tires.
!! Still has a vibration from 'something spinning'. I can feel it when slowing to turn into/onto a road from full speed, and just as I get to about 10 mph, it quits.
Could it be possible that it is the double knuckle U-joint right behind the carrier bearing? Anyone else ever encounter this?

 

It's entirely possible that the double cardan on the drive shaft. However, when you mention turning, I would lean towards wheel bearings.

I'd pull the rear shaft out, put it in 4x4 and go for small drive around surface streets to see if that eliminates the vibration. If it does, there is a chance it's something in the rear end. Could be something in the drive shaft or even 3rd member / differential.

Even if pulling the drive shaft eliminates the vibe, it could still be something in the front end- as putting in 4x4 might keep a constant load on the front end parts- with that load applied, you might not get the same results without it.

Again, turning = front wheel bearings.

 

thanks for your input. You may be totally right, but when I mentioned turning, I only meant it as the 'slowing down' factor. It does 'it' even if I'm not turning a corner as such. I'm gonna lift up the rear axle and put in Drive and observe. We'll see. The one thing about a wheel bearing, in my experience is that it will get worse fairly rapidly the more you use it. I have put over 4000 miles on it since i bought it and it is 'about the same consistency' vibration. Just wondered if anyone else out there has had the same baffling perplexities.

 

Without going to all the details (unless you really want them)- My front wheel bearings took a LONG (years) time to fail. I've also had friends who ignored their bearings for years, so I have a different experience to you.

My front bearings didn't show the normal signs of failure- squeak every once in awhile that I could never chase down. Only ever felt a slight vibration when turning at high speed under load (think driving up a mtn pass, but not down it). I did EVERYTHING before finally doing the front bearings. Would have been a lot cheaper to start there.

The other consideration, and what ultimately ended up being the source of my other prolonged driveline vibration was my rear drum brakes- specifically the drums themselves were out of round (after being turned at a local shop). With the axle off the ground, I could hear the shoes drag at different points of the rotation. New drums and the problem went away.

Prior to that, I had been down a major rabbit hole. New wheels and tires, new drive shaft, carrier bearings... It's a process of elimination- start at the cheapest parts, and work up to the wheel bearings

 

well thanks! I totally understand. I'm gonna start at the double knuckle on the drive shaft. and then one step at a time...