Driveline vibration

Looking for some help, explanation. I had a 1.5" add a leaf and truck was good no vibrations. We'll know the truck has a new frame and new 4 leaf pack, sucks truck sits a bit lower than an inch from the front looks like crap. Going to add a 2" add a leaf to the rear, and looking at the axle shims trying to figure out 2.5 or 3 degree shims. Been researching and digging on here and Google. Found some contradictions. Read some people saying the rear pinion should be at the same angle as the second shaft coming down to the pinion or slightly lower under normal load. Then I found some stuff online from drive shaft shops and some institute that built a drive line to show what different angles do to the pinion. If I can find it again I'll add to the post. But the shops and video seem to show the pinion matching or as close to the same angle as the transmission shaft. The second shaft is 4 degrees down and the pinion is about two degrees down forming a slight v. I am thinking 3 degree should be good. Also from what I found on many web sites is don't even bother the carrier bearing. Any thoughts or guidance.

 

Ok guess no thoughts or opinions. So I'll go with getting the pinion equal to what the video I found shows and make it about the same as the transmission. Thanks anyway

 

For those who may have wondered the same thing I am. I called three drive shaft companies. The pinion should be as close to the same angle as the transmission. Input on the shaft and output of the shaft cancel any abnormalities.

 

driveline vibrations have been beat to death.

Unfortunatly the way the tacoma 2 piece is designed, with its floppy dick center carrier bearing (which causes the majority of the vibrations if there is any angle at the center joint) simply can not be setup properly. By putting the pinion and trans joint at opposing similar angles, and the center joint close to zero yes you are getting close... BUT the front and rear joints are 90* out of phase. Idealy if you were to run this setup you spin the center slip joint (on the 4x4) or center yoke by 90* to put the front and rear joints in phase. Unfortunately you can not do that because the slip joint and yoke are indexed (from pictures and research that i have seen)

The most ideal would be to run the transfer case / transmission joint at close to zero, then the center and rear joint at opposing similar angles. This tucks the driveline up out of the way higher and has all proper phasing and angles. Problem with this, is the fact that then there is now a side load at the center carrier due to the larger angle. Typically this would not be a problem, BUT with the carrier bearing rubber being SOOO soft this allows the driveshaft to oscillate very bad, and this is how you get the really bad take off vibes / vibes at 15-20mph.

The reason the center CB is so soft is due to the way the prerunner driveline is setup. There is NO slip joint on the prerunner between the center and rear most joint. The driveshaft can not expand and collapse for suspension movement. Instead the driveshaft moves forward and back by flexing the center CB and moves in and out of the transmission itself. This same CB is used on the 4x4 models


If i get a wild hair up my ass one of these days i am going to fill the center carrier bearing rubber support with some permatex ultra black or some sort of dense RTV to stiffen it up and see what happens.

 

I know it's been beat to death, I have been trying to learn as much as I can. And just seamed to be contradicting. This why I asked. And from what I know mechanically it sounds like the vides may never go away unless one is to go to a one piece shaft. Thanks for the explanation, appreciate the reply.