Weird Vibrations Help!

Hello. I have some odd driveline vibrations going on, and need some help diagnosing it. It's a 1995 Tacoma single cab V6.

Here are the symptoms:
-transfer case stick pretty much always vibrates, with varying harshness.
-5th gear creates a pretty nasty rattle in the stick below 50 and above 63mph. Doesn't happen in 4th. Slightly in 3rd, but barely noticeable.
-the truck vibrates pretty badly between about 50-63mph. Gets worse when it is in neutral.


What I've done (to no avail)
-had driveshaft balanced and put in new u-joint
-had same drive shaft lengthened and rebalanced.

Any ideas of what is going on? I'd really hate to blow something up on my commute.

 

Also, I've ordered some marlin crawler heavy duty shifter seats for both the tranny and transfer case. We shall see if that helps.

 

How are your tires? Could possibly stem from a wheel or tire.

 

Why would it only vibrate in 5th gear and not 4th gear?

 

Could very well be the road speed .

Might be the road itself .

Lifted with Big Tires ??

 

Have you checked the motor and transmission mounts?

 

center/carrier bearing?

 

Single cabs don't have the bearing. It's a 1 piece.

 

I'll take my truck to discount and have them rebalance and rotate them. Worth a try.

 

Vibrations suck. I had vibes around 70mph and got rid of that by balancing and rotating the tires.

 

Tire rotation did not help. On to axle shims.

 

Bummer. Were the wheels balanced also?

 

Did you check the driveline angle?

https://www.tacomaworld.com/threads/drive-shaft-vibrations-solved-step-by-step.244535/

Are you ADD or manual hubs?

https://www.tacomaworld.com/threads/front-driveshaft-vibration-is-in-the-front-diff.500458/

 

I'm actually going to Toytec after work to pick up some 3 degree axle shims.
I have manual hubs.

 

Wheels were balanced.

 

Also, thanks for the first article. It will be super helpful.

 

How do you know you need 3 degree shims? If you have a one piece driveshaft, the u joint angles will cancel when the rear pinion flange is parallel with the transfer case output flange. If you only lifted your truck a couple inches, I don't see how that relative difference could have changed by 3 degrees.

 

I also agree with this. I can go up 3" and not have that happen. Could by something else. How are your brakes? Something dragging? How is your rear end? Is it quiet or a little noisy?

 

As bad as it sounds, it was suggested by some friends. Kindof a shot in the dark.

 

Honestly, with the tire noise and exhaust leak, I'm not entirely sure I would notice any rear end noise.

What in the brakes would cause a vibration while cruising?