Drive Shaft Vibration (one piece shaft)

First, I would like to say HELLO and introduce myself as I am new to this forum. My name is Bruce Hornberger and have a 1998 Tacoma that was converted to 4WD from a Prerunner. I am in the process of doing some upgrades to the truck to better allow reliable exploring in the desert southwest. During this process, I have found myself with a bit of a problem.

The problem I am trying to solve is a drive shaft vibration problem that comes on at about 60 MPH. The truck has a Tom Woods one piece drive shaft that worked great until I lifted the truck a bit over 2 inches. (it had about an inch+ of droop in the rear and now it is now an inch over factory ride height). As I’m sure many know, Tom Woods no longer will make drive shafts for Tacoma’s because they have had too many issues with vibrations that they can’t solve. Since I already had a Tom Wood drive shaft, they volunteered to help solve my problem. They were wonderful to work with and I can say nothing but great things about there effort to solve my problems but for some reason, the vibration is still there. As the truck sits currently, all the drive line angles are within limits and should be vibration free. I am really at a loss on what to do now and was wondering if anyone else had this issue and how did you solve it. Thank you in advance for your help!

 

What are the angles set at?

 

One thing I didnt mention in the origional question, is that this shaft is a 2 U-Joint shaft (not a double cardan shaft)
I have 5.1 degrees at the transfer case and 5.8 at the differential end. From what the guys at Tom Woods were telling me, the angle issues would result in low speed vibrations where as high speed vibrations (what I seem to have) is a result of a balanceing issue. is that correct??

 

Are you sure it's the driveshaft?

 

THe frequency of the vibration seems to be about right for a drive shaft issue but not 100% sure. I had all the wheels balanced and the vibration persisted. Dont know what eise it could be.

 

Alignment, tire balance/inflation, some combination of mildly worn suspension components that passed a visual inspection..? Carrier bearing

 

its a one peice drive shaft, so no carrier bearing in the system. as part of the lift, I upgraded with a 1 inch lift new spring set from alcan springs with all new bushings and shackles. the front end received all new OEM bushings, ball joints, etc along with SPC UCAs. An allignment was performed after the upgrades.