RatLabGuy

'93 Ext cab w/ the 2-piece loooong driveshaft.
How much can the driveline be perturbed from level before vibes etc become a problem?

I'm debating a combo of 1" body lift, longer shackles (~1.5") and a 2" t-case lift (via BudBuilt skid).
That would raise the output pinion, and unless I also add motor mount lift blocks (prefer not to) would also raise the output angle.
The front half of the shaft is a U-joint on the T-case end, but how much angle can the CSB take beyond straight?
The back end of the CSB is a CV joint, so I figure that won't be a problem.

waskillywabbit

iTrader: (-1)

Body lift doesn't matter.
Results are going to vary but DC should absorb angle increase.

:wabbit2:

91mtngoat

I have thought about that one also. I would like to do the flat belly mod as well. Do most people change to a one piece shaft or raise the bearing carrier to match the tc output?

RatLabGuy

The BL I only mentioned b/c it helps make room for the 2" tranny lift.
On that note, I'm assuming there's an inch extra space above the trans for that...

on the DC shaft, its the input side of the CSB that I wonder about, esp in combo w/ increasing the U-joint angle.

RatLabGuy

btw you can't really raise the CSB, unless your cut off/remove that crossmember it is mounted on.

91mtngoat

I read a site where they raised the bearing cross member. It said for a double cardin joint, the front portion of the ds needs to be on the same plane as the tc. The diff pinion should be pointed at the bearing. Before I went four link, I ran a 6" shackle. It vibrated bad enough to ruin the pinion seal. I then bought a 2* spring shim and it was fine.

benmlee

Went thru the whole vibration thing years ago. Here is my webpage:

http://benmlee.com/4Runner/driveline/U-JOINT.htm

If is a daily driver, keep it under 2 degrees. 1 if possible. However, there are tricks you can do. If say the u-joint at transmission is off by 4 degrees, you can compensate by rotating the rear axel so that the rear u-joint is off by 3 degrees on purpose. The net result is you will be off by 4-3=1 degree at the wheels. Whether the angles are up or down makes no difference. Only the magnitude they are off by make a difference. Is pretty easy to angle the rear axel. Get some shims from Roger Brown. Just realize that with this method, the wheels will have no phase error, which is good, but the driveshaft itself will have phase error. That is not so bad since driveshaft is relatively light compared to the entire car. If angles are not too large, some driveshaft phase difference will not hurt.

Or you can just ignore phase error and live with drivetrain wear and tear. I don't like to do that because is no fun fixing the drivetrain every several years. Kept my truck for over 10 years now.